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2 LIBRARY
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This is to certify that the
thesis entitled

Biogeochemical Impacts of Reservoirs on the Kalamazoo
River System

presented by

Nicole J. Reid

has been accepted towards fulﬁllment
of the requirements for the

MS. degree in Zoologg

 

 

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BIOGEOCHEMICAL IMPACTS OF RESERVOIRS ON THE KALAMAZOO RIVER
SYSTEM

By

Nicole J. Reid

A THESIS

Submitted to
Michigan State University
in partial fulﬁllment of the requirements
for the degree of

MASTER OF SCIENCE
Department of Zoology

2005

ABSTRACT

BIOGEOCHEMICAL IMPACTS OF MAJOR RESERVOIRS ON THE
KALAMAZOO RIVER

By

Nicole J. Reid
The Kalamazoo River (Michigan, USA) has six run-of-the-river dams. The two
hydropower reservoirs’ residence times vary from 2 up to 11 days during the year. The
four decommissioned impoundments residence times vary from a quarter of day to 1.5
days during the year. Inﬂows and outﬂows for the two hydropower reservoirs were
sampled weekly in order to quantify the roles of reservoirs as sinks or transformers for
nutrients. Three longitudinal river surveys from Morrow Lake inﬂow to Lake Allegan
outﬂow were conducted at varying discharges. Special emphasis was placed on above
and below Plainwell, Otsego, Allegan City and Trowbridge decommissioned
impoundments. Despite their spatial proximity, a Total Maximum Daily Load for
phosphorus (P) was deemed necessary for Lake Allegan to control summer algal
blooms, whereas Morrow Lake lacks nuisance summer algal blooms. Lake Allegan
outﬂow waters exhibited potential silica and nitrogen limitation in the late summer
while Morrow Lake did not, which may explain the undesirable algal blooms in Lake
Allegan. The longer residence time allows phytoplankton to build up to undesirable
levels within Lake Allegan, but not in Morrow Lake. High algal abundance was
observed in the Lake Allegan inﬂow, which may have resulted from Morrow Lake’s
algae transported downstream, or new algal biomass build-up as the river passed

through semi-impounded reaches; the results reported here support the latter hypothesis.

ACKNOWLEDGEMENTS

I thank my advisor Steve Hamilton for his patience, understanding and guidance. My
committee members of Pat Soranno, Elena Litchman and Dave Long were very
supportive in providing feedback. David Weed, Hamilton lab manager, was
instrumental in teaching me my laboratory methods and QA/QC procedures. David,

thanks for letting me be second shadow. Your patience will not be forgotten.

Academic support was essential in sharing ideas and understanding nutrient ratios with
Spencer Hall, entering the world of algae with Elena Litchman and Tara Darcy-Hall,
many Systat lessons and academic answers provided by Sarah Emery, and lab meetings

shared with my labmate, Amy Burgin.

Research information provided by many sources: William Schoelin from Consumer
Energy, Jeanine Kilnge from STS Hydropower, Dean Baas, from MSU Land and
Water, Scott Markham and Patricia Fenn from the Kalamazoo River Watershed
Council, Sylvia Heaton from the MDEQ, Cynthia Rachol from the USGS and Bryon

Lane from the MDEQ Dam Safety.

Entertainment provided by the KBS community relieved all worries: Game nights, the
beer garden at Bell’s, few movie nights, summer Barb-B-Ques, the many-many

potlucks, and good chats with Heather Sahli , Lindsey Walters and Sara Parr.

iii

Lillian and Non'is Reid another voyage has ended, thanks for the many years of support
and love.

I can do all things through Christ which strengthen me (Phlip 4:13).

iv

TABLE OF CONTENTS

LIST OF TABLES ................................................................................................. vi
LIST OF FIGURES ............................................................................................... vii
CHAPTER 1
Abstract .................................................................................................................... 1
Introduction ............................................................................................................. 3
Literature Review: Effects of impoundments on river hydrology,
biogeochemistry and ecology ...................................................................... 4
Study Site ..................................................................................................... 9
Total Maximum Daily Load (TMDL) for Lake Allegan ........................... 11
Objective and Hypothesis ...................................................................................... 13
Methods ................................................................................................................. 14
Results ................................................................................................................... 17
Climate and River Hydrology ................................................................... 17
Statistical predictors of algal growth in the reservoirs .............................. 17
Lake Allegan ............................................................................................. 19
Morrow Lake ............................................................................................. 26
Discussion .............................................................................................................. 32
Comparisons between reservoirs ............................................................... 33
The role of Silicon ..................................................................................... 37
Ratios of NzTP and Si:N as indicators of potential nutrients .................... 38
Implications for the TMDL ....................................................................... 38
Comparison of P forms above and below each reservoir .......................... 38
Literature Cited ...................................................................................................... 41
CHAPTER 2
Abstract ............................................................................................................... .117
Introduction ......................................................................................................... 1 18
Study Site ................................................................................................. 120
Total Maximum Daily Load (TMDL) for Lake Allegan ......................... 122
Objective and Hypothesis ........................................................................ 123
Methods ............................................................................................................... 124
Results ................................................................................................................. 126
Kalamazoo River longitudinal survey conducted at low discharge ........ 126
Kalamazoo River longitudinal survey conducted at medium discharge .127
Kalamazoo River longitudinal survey conducted at high discharge ....... 128
Morrow Lake Longitudinal Survey ........................................................ .129
Discussion ............................................................................................................ 131
Algal growth in the river ......................................................................... 132
Implications for the TMDL ..................................................................... 135
Literature Cited .................................................................................................... 136

LIST OF TABLES

CHAPTER 1

Table 1. Morphometric features of Morrow Lake and Lake Allegan ................... 44
Table 2. Regression coefﬁcients and p-value for residence time (RT) and/or
outﬂow total phosphorus (TP) as predictors of outﬂow chlorophyll a for the
spring and summer 2003 sampling period (15 weeks) .......................................... 45
Table 3. Regression coefﬁcients and p-value for residence time (RT) and/or
outﬂow total phosphorus (TP) as predictors of outﬂow chlorophyll a for the
spring and summer 2004 sampling period (7 weeks) ............................................ 45

Table 4. . Regression coefﬁcients and p-value for residence time (RT) and/or
outﬂow total phosphorus (TP) as predictors of outﬂow chlorophyll a for the

spring and summer 2003 and 2004 sampling period (22 weeks) .......................... 46
CHAPTER 2

Table l. Morphometric data: Hydropower reservoirs H and Decommissioned
impoundments D .................................................................................................. 135
Table 2. Longitudinal river sampling location on the Kalamazoo River ............ 136

vi

LIST OF FIGURES
CHAPTER 1
Figure 1. Kalamazoo River and Watershed ........................................................... 47

Figure 2. Mean daily discharge below Morrow Lake (Comstock gauge) and above
Lake Allegan (Trowbridge gauge). Data from the US. Geological Survey ......... 48

Figure 3. Hydraulic residence time for Morrow Lake and Lake Allegan. Sampling
periods are marked along the abscissa ................................................................... 49

Figure 4. Mean air temperature 2003 and 2004. Data from Kellogg Biological
Station’s Long Term Ecological Research site ..................................................... 50

Figure 5. Lake Allegan residence time (days) preceding each sampling date in,
A) 2003 and B) 2004 ............................................................................................. 51

Figure 6. Lake Allegan inﬂow and outﬂow chlorophyll 0 concentrations,
A) 2003 and B) 2004 ............................................................................................ 52

Figure 7. Lake Allegan inﬂow and outﬂow total soluble phosphorus
concentrations, A) 2003 and B) 2004. ................................................................... 53

Figure 8. Lake Allegan inﬂow and outﬂow total phosphorus concentrations,
A) 2003 and B) 2004. ........................................................................................... 54

Figure 9. Lake Allegan inﬂow and outﬂow soluble reactive phosphorus
concentrations, A) 2003 and B) 2004. ................................................................... 55

Figure 10. Lake Allegan inﬂow and outﬂow soluble organic phosphorus
concentrations, A) 2003 and B) 2004 .................................................................... 56

Figure 11. Lake Allegan inﬂow and outﬂow ammonium concentrations,
A) 2003 and B) 2004. ............................................................................................ 57

Figure 12. Lake Allegan inﬂow and outﬂow nitrate concentrations,
A) 2003 and B) 2004. .......................................................................................... 58.

Figure 13. Lake Allegan inﬂow and outﬂow silica concentrations,
A) 2003 and B) 2004. ............................................................................................ 59

Figure 14. Lake Allegan inﬂow and outﬂow dissolved inorganic nitrogen (DIN)

to total phosphorus (TP) ratio. Dashed lines show the thresholds of potential nitrogen
limitation (DIN:TP less than 10) and phosphorus limitation (DIN:TP greater than 20),
A) 2003 and B) 2004. ............................................................................................ 6O

vii

Figure 15. Lake Allegan inﬂow and outﬂow silica (Si) to dissolved inorganic nitrogen
(DIN) ratio. Dashed line shows the threshold of potential silica limitation (less than 1),
A) 2003 and B) 2004. ............................................................................................ 61

Figure 16. Lake Allegan inﬂow and outﬂow dissolved inorganic nitrogen (DIN)
and Silica (Si) ratio versus inorganic nitrogen (DIN) to total phosphorus (TP) ratio.
Nitrogen limitation is represented by the solid-line square, phosphorus limitation
represented by dashed line, and silica limitation represented by dotted-dash line,

A) 2003 and B) 2004. ............................................................................................ 62
Figure 17. Lake Allegan inﬂow and outﬂow temperatures,

A) 2003 and B) 2004. ............................................................................................ 63
Figure 18. Lake Allegan inﬂow and outﬂow total suspended solids concentrations,
A) 2003 and B) 2004 ............................................................................................. 64
Figure 19. Lake Allegan inﬂow and outﬂow oxygen concentrations,

A) 2003 and B) 2004 ............................................................................................. 65
Figure 20. Lake Allegan inﬂow and outﬂow percent oxygen saturation,

A) 2003 and B) 2004 ............................................................................................. 66
Figure 21. Lake Allegan diel cycle on 8-9 August 2003 ....................................... 67
Figure 22. Lake Allegan inﬂow and outﬂow pH, A) 2003 and B) 2004 .............. 68

Figure 23. Lake Allegan inﬂow and outﬂow calcium concentrations for 2003.... 69
Figure 24. Lake Allegan inﬂow and outﬂow alkalinity concentrations for 2003 .70
Figure 25. Lake Allegan inﬂow and outﬂow calcite saturation index for 2003.... 71

Figure 26. Lake Allegan inﬂow and outﬂow magnesium concentrations
for 2003 ................................................................................................................ 72

Figure 27. Lake Allegan inﬂow and outﬂow sodium concentrations for 2003.... 73
Figure 28. Lake Allegan inﬂow and outﬂow potassium concentrations for 2003 74
Figure 29. Lake Allegan inﬂow and outﬂow chloride concentrations for 2003 75
Figure 30. Lake Allegan inﬂow and outﬂow sulfate concentrations for 2003.... 76
Figure 31. Lake Allegan vertical proﬁle concentrations of total phosphorus (solid line)

and chlorophyll a (dashed line). The inﬂow total phosphorus concentration
for the day 44.8 ug/L and the inﬂow chlorophyll a concentration was 2.8 pg /L .77

viii

Figure 32. Lake Allegan vertical proﬁle concentrations of total soluble

phosphorus (TSP) (solid line) and soluble reactive phosphorus (SRP) (dashed line).
The inﬂow total soluble phosphorus concentration for the day was 32 ug/L

and the inﬂow soluble reactive phosphorus concentration was 18.2 ug/L ................ 78

Figure 33. Lake Allegan vertical proﬁle concentrations for ammonium (solid line)
and nitrate (dashed line). The inﬂow ammonium concentration on the sampling day
was 16 pg N/L and the inﬂow nitrate concentration was 1320 pg N/L .................... 79

Figure 34. Lake Allegan vertical proﬁle of temperature (solid line) and oxygen
(dashed line). The inﬂow temperature for the day was 19.5 C and
the inﬂow oxygen concentration was 9 mg/L ........................................................... 80

Figure 35. Lake Allegan vertical proﬁle of conductance (solid line) and pH
(dashed line). The inﬂow conductance for the day was 689 uS/cm and
the inﬂow pH was 8.4 ................................................................................................ 81

Figure 36. Morrow Lake residence time (days) preceding each sampling date in,
A) 2003 and B) 2004 ................................................................................................. 82

Figure 37. Morrow Lake inﬂow and outﬂow chlorophyll a concentrations,
A) 2003 and B) 2004 ................................................................................................. 83

Figure 38. Morrow Lake inﬂow and outﬂow total soluble phosphorus concentrations,
A) 2003 and B) 2004 ................................................................................................. 84

Figure 39. Morrow Lake and inﬂow and outﬂow total phosphorus concentrations,
A) 2003 and B) 2004 ................................................................................................. 85

Figure 40. Morrow Lake inﬂow and outﬂow soluble reactive phosphorus
concentrations, A) 2003 and B) 2004 ........................................................................ 86

Figure 41. Morrow Lake inﬂow and outﬂow soluble organic phosphorus
concentrations, A) 2003 and B) 2004 ........................................................................ 87

Figure 42. Morrow Lake inﬂow and outﬂow ammonium concentrations,
A) 2003 and B) 2004 ................................................................................................. 88

Figure 43. Morrow Lake inﬂow and outﬂow nitrate concentrations,
A) 2003 and B) 2004 ................................................................................................. 89

Figure 44. Morrow Lake inﬂow and outﬂow silica concentrations,
A) 2003 and B) 2004 ................................................................................................. 90

ix

Figure 45. Morrow Lake inﬂow and outﬂow dissolved inorganic nitrogen (DIN) to
total phosphorus (TP) ratio. Dashed lines show the thresholds of potential nitrogen
limitation (DIN :TP less than 10) and phosphorus limitation (DIN:TP greater than 20),
A) 2003 and B) 2004 ............................................................................................. 91

Figure 46. Morrow Lake inﬂow and outﬂow silica (Si) to dissolved inorganic nitrogen
(DIN) ratio. Dashed line shows the threshold of potential silica limitation
(less than 1), A) 2003 and B) 2004 ........................................................................ 92

Figure 47. Morrow Lake inﬂow and outﬂow dissolved inorganic nitrogen (DIN)
and Silica (Si) ratio versus inorganic nitrogen (DIN) to total phosphorus (TP) ratio.
Nitrogen limitation is represented by the solid-line square, phosphorus limitation
represented by dashed line, and silica limitation represented by dotted-dash line, A)
2003 and B) 2004 .................................................................................................. 93

Figure 48. Morrow Lake inﬂow and outﬂow temperatures,
A) 2003 and B) 2004 ............................................................................................. 94

Figure 49. Morrow Lake inﬂow and outﬂow total suspended solids,
A) 2003 and B) 2004 ............................................................................................ 95

Figure 50. Morrow Lake inﬂow and outﬂow oxygen concentrations,
A) 2003 and B) 2004 ............................................................................................. 96

Figure 51. Morrow Lake inﬂow and outﬂow percent oxygen saturation
concentrations, A) 2003 and B) 2004 .................................................................... 97

Figure 52. Morrow Lake oxygen and temperature diel cycle on
25-26 August 2003 ................................................................................................ 98

Figure 53. Morrow Lake inﬂow and outﬂow pH concentrations,
A) 2003 and B) 2004 ............................................................................................. 99

Figure 54. Morrow Lake inﬂow and outﬂow calcium concentrations
for 2003 ............................................................................................................... 100

Figure 55. Morrow Lake inﬂow and outﬂow alkalinity concentrations
for 2003 ............................................................................................................... 101

Figure 56. Morrow Lake inﬂow and outﬂow calcite saturation index
for 2003 ............................................................................................................... 102

Figure 57. Morrow Lake inﬂow and outﬂow magnesium concentrations
for 2003 .............................................................................................................. . 103

Figure 58. Morrow Lake inﬂow and outﬂow sodium concentrations
for 2003 ............................................................................................................... 104

Figure 59. Morrow Lake inﬂow and outﬂow potassium concentrations
for 2003 ............................................................................................................... 105

Figure 60. Morrow Lake inﬂow and outﬂow chloride concentrations
for 2003 ..................................................................................................................... 106

Figure 61. Morrow Lake inﬂow and outﬂow sulfate concentrations
for 2003 ..................................................................................................................... 107

Figure 62. Lake Allegan vertical proﬁle concentrations of total phosphorus (solid line)
and chlorophyll a (dashed line). The inﬂow total phosphorus concentration for the
day 44.5 pg/L and the inﬂow chlorophyll a concentration was 2.7 pg /L ................. 108

Figure 63. Lake Allegan vertical proﬁle concentrations of total soluble phosphorus
(TSP) (solid line) and soluble reactive phosphorus (SRP) (dashed line). The inﬂow
total soluble phosphorus concentration for the day was 31 pg/L and the inﬂow soluble
reactive phosphorus concentration was 11.8 pg/L .................................................... 109

Figure 64. Lake Allegan vertical proﬁle concentrations for ammonium (solid line)
and nitrate (dashed line). The inﬂow ammonium concentration on the sampling day
was 37.2 pg N/L and the inﬂow nitrate concentration was 777 pg N/L .................. 110

Figure 65. Lake Allegan vertical proﬁle of temperature (solid line) and oxygen
- (dashed line). The inﬂow temperature for the day was 23.1 C and the inﬂow
oxygen concentration was 7.8 mg/L .......................................................................... 111

Figure 66. Lake Allegan vertical proﬁle of conductance (solid line) and pH
(dashed line). The inﬂow conductance for the day was 597 pS/cm and the

inﬂow pH was 7.9 ...................................................................................................... 112
Figure 67. Morrow Lake and Lake Allegan mean phosphorus concentrations,

A) 2003 and B) 2003 ................................................................................................. 113
CHAPTER 2

Figure l. Kalamazoo River and Watershed ............................................................... 137

Figure 2. Mean daily discharge below Morrow Lake (Comstock gauge) and above
Lake Allegan (Trowbridge gauge). The individual symbols represent survey sample
days. Data from the US. Geological Survey ............................................................. 138

xi

Figure 3. Longitudinal river survey of temperature and oxygen at low discharge

(18 August 2003). The solid line boxes represent the active hydropower reservoirs
(Morrow Lake and Lake Allegan) and dashed line boxes represent the
decommissioned impoundments (Plainwelldam, Otsego darn, Trowbridge dam

and Allegan City dam) .............................................................................................. 139

Figure 4. Longitudinal river survey of conductance and pH at low discharge

(18 August 2003). The solid line boxes represent the active hydropower reservoirs
(Morrow Lake and Lake Allegan) and dashed line boxes represent the
decommissioned impoundments (Plainwelldam, Otsego dam, Trowbridge dam

and Allegan City dam) ............................................................................................... 140

Figure 5. Longitudinal river survey of total phosphorus and chlorophyll a at low
discharge (1 8 August 2003). The solid line boxes represent the active hydropower
reservoirs (Morrow Lake and Lake Allegan) and dashed line boxes represent the
decommissioned impoundments (Plainwelldam, Otsego dam, Trowbridge dam and
Allegan City dam). The letters represent point sources discharges to the Kalamazoo
River (A) Kalamazoo Waste Water Treatment Plant and (B) Menasha Paper
Company .................................................................................................................... 141

Figure 6. Longitudinal river survey of temperature and oxygen at low discharge

(3 September 2004). The solid line boxes represent the active hydropower reservoirs
(Morrow Lake and Lake Allegan) and dashed line boxes represent the
decommissioned impoundments (Plainwelldam, Otsego darn, Trowbridge dam

and Allegan City dam) ............................................................................................... 142

Figure 7. Longitudinal river survey of condutance and pH at low discharge

(3 September 2004). The solid line boxes represent the active hydropower reservoirs
(Morrow Lake and Lake Allegan) and dashed line boxes represent the
decommissioned impoundments (Plainwelldam, Otsego dam, Trowbridge dam and
Allegan City dam) ..................................................................................................... 143

Figure 8. Longitudinal river survey of total phosphorus and chlorophyll a at low
discharge (3 September 2004). The solid line boxes represent the active hydropower
reservoirs (Morrow Lake and Lake Allegan) and dashed line boxes represent the
decommissioned impoundments (Plainwelldam, Otsego dam, Trowbridge dam and
Allegan City dam). The letters represent point sources discharges to the Kalamazoo
River (A) Kalamazoo Waste Water Treatment Plant and (B) Menasha Paper
Company .................................................................................................................... 144

Figure 9. Longitudinal river survey of temperature and oxygen at low discharge

(2 July 2004). The solid line boxes represent the active hydropower reservoirs
(Morrow Lake and Lake Allegan) and dashed line boxes represent the
decommissioned impoundments (Plainwelldam, Otsego dam, Trowbridge dam

and Allegan City dam) ............................................................................................... 145

xii

Figure 10. Longitudinal river survey of conductance and pH at low discharge

(2 July 2004). The solid line boxes represent the active hydropower reservoirs
(Morrow Lake and Lake Allegan) and dashed line boxes represent the
decommissioned impoundments (Plainwelldam, Otsego dam, Trowbridge dam

and Allegan City dam) ............................................................................................... 146

Figure 11. Longitudinal river survey of total phosphorus and chlorophyll a at low
discharge (2 July 2004). The solid line boxes represent the active hydropower
reservoirs (Morrow Lake and Lake Allegan) and dashed line boxes represent the
decommissioned impoundments (Plainwelldam, Otsego dam, Trowbridge dam

and Allegan City dam). The letters represent point sources discharges to the
Kalamazoo River (A) Kalamazoo Waste Water Treatment Plant and (B) Menasha
Paper

Company .................................................................................................................... 147

Figure 12. Longitudinal river survey of total phosphorus and chlorophyll (1 within
Morrow Lake and downstream in the river (27 August 2004). The solid line box
represents Morrow Lake ............................................................................................ 148

Figure 13. Longitudinal river survey of total phosphorus, total soluble phosphorus

and soluble reactive phosphorus within Morrow Lake and downstream in the river
(27 August 2004). The solid line box represents Morrow Lake ................................ 149

xiii

Chapter 1. Analysis of changes in river water passing through two major reservoirs
(Lake Allegan and Morrow Lake)

Abstract

The Kalamazoo River (Michigan, USA) has six run-of-river dams (four small
decommissioned ones and two larger ones producing hydropower). The hydropower
reservoirs’ residence times vary from 2 up to 11 days during the year. Lake Allegan has
a longer maximum residence time of 11 days, compare to 7 days in Morrow Lake.
Inﬂows and outﬂows for the two hydropower reservoirs were sampled weekly in order
to quantify the roles of reservoirs as sinks or transformers for nutrients. Lake Allegan is
hypereutrophic impoundment, located downstream of Morrow Lake, a eutrophic
impoundment. No major tributary inputs exist between the reservoirs. Despite their
spatial proximity, a Total Maximum Daily Load for phosphorus (P) was deemed
necessary for Lake Allegan to control summer algal blooms, whereas Morrow Lake
lacks nuisance summer algal blooms and has a more desirable ﬁsh community. During
the summer, Lake Allegan inﬂow total phosphorus average 83 pg/L, while in Morrow
Lake it averaged 54 pg/L. In both reservoirs there was a decline in soluble reactive
phosphorus from, and an increase in particulate phosphorus from inﬂow to outﬂow.
Nitrate decreased in both reservoirs during longer residence times, but to a higher
degree in Morrow Lake as opposed to Lake Allegan, possibly due to benthic algal
uptake. During the summer, the two reservoirs had decreases in the outﬂow calcium
concentrations that affected alkalinity. Silica uptake during the summer was more
marked and different timing in Lake Allegan than in Morrow Lake, and may have

resulted in silica limitation of diatoms. Lake Allegan outﬂow waters exhibited potential

silica and nitrogen limitation in the late summer while Morrow Lake did not, which
may explain the undesirable algal blooms in Lake Allegan. The longer residence time
allows phytoplankton to build up to undesirable levels within Lake Allegan, but not in
Morrow Lake. Ammonium, phosphorus and silica are the main nutrients potentially
regulating species composition, but concentrations of these nutrients remain above
limiting levels for the most part. An internal ammonium source possibly favors non-N
ﬁxing algae and if so, reducing the total phosphorus concentration may not directly

affect the harmful algal blooms.

Introduction

Globally 60% of the world’s rivers have been affected by dams and diversions (WCD
2000), and reservoirs are estimated to have a combined storage capacity of as much as
100,000 cubic kilometers (Chao 1991). Michigan has over 2,500 dams and of those 103
are hydroelectric dams that impact 49 river systems (www.michigan. gov).
Irnpoundrnents yield many important beneﬁts to society by providing ﬂood control,
hydroelectricity, and water storage for agriculture, industry, and municipalities
(Vorosmarty 1997). However, dams have multiple effects that extend downstream. A
few major environmental impacts of dams are (1) changes in downstream river
hydrology, morphology, and water quality, (2) reduction of biodiversity, (3) increased
habitat fragmentation, and (4) trapping of riverine sediment and nutrients (McCully

2001).

This chapter will discuss the changes in river nutrients and major solutes as the water
passes through two reservoirs on the same river and evaluate the potential for nutrient
limitation of phytoplankton growth in the reservoirs. The inﬂow and outﬂow of each
reservoir were sampled during spring and summer for two years. Summer was the most
active period for algal grth because of the relatively long residence times reaching,
11 days for Lake Allegan and 7 days for Morrow Lake. I showed here that the DlNzTP
molar ratio suggested potential N-limitation in both reservoirs, while silica limitation
only occurred potentially in Lake Allegan. A phosphorus Total Maximum Daily Load
was established to control harmful algal in Lake Allegan. However, other nutrients such

as internal ammonium production and silica depletion may also inﬂuence in Lake

Allegan. Nevertheless, ultimately residence time controls the ability of phytoplankton to

grow within Lake Allegan and nutrients are of secondary importance.

Literature Review." Effects of impoundments on river hydrology, biogeochemistry and
ecology
Impoundments change the characteristics of a river from a ﬂuvial environment to a
more lacustrine environment, affecting physical, chemical and biological
characteristics. Some of the main changes upon impoundment are increased water
residence (also called retention time), sediment accumulation, nutrient transformations,
and increased autochthonous primary production (Friedl and Wuest 2002). Longitudinal
gradients in sedimentation, biological activity, and reservoir hydrology (residence time

and water discharge) determine the fate of nutrients in a reservoir.

A longitudinal gradient develops in a reservoir as a result of basin morphology and the
reservoir inﬂows and outﬂow. Basins are generally narrow and elongate with the
deepest part located at the dam. Reservoirs may receive little or no inﬂuence from the
surrounding watershed, with the majority of inputs ﬁ'om the inﬂowing river(s).
Advective currents caused by the river inﬂow and outﬂow distribute nutrients and
sediments within the reservoir. Reservoir longitudinal gradients commonly show three
distinct zones: riverine, transition and lacustrine (Thornton 1980). At the upriver end,
the riverine zone is a narrow, well-mixed entrance with decreasing velocity allowing
coarse organic matter and sand to settle, forming a delta. Light penetration is relatively

low, which limits primary production. Next, in the transition zone clays and silts settle

and light penetration gradually increases. Finally, the lacustrine zone exhibits lacustrine
characteristics with low sedimentation rates, and deeper light penetration promotes

autochthonous primary production; thermal stratiﬁcation may occur during the summer.

Incoming river water forms a plunge point were the water does not mix immediately,
but often sinks to a depth where its density is approximately similar to the reservoir
water (Carmack 1979). From the plunge point, inﬂowing water may be integrated into
reservoir waters as overﬂow, interﬂow or underﬂow currents (Ford 1990). Nutrients,
organisms, and sediments travel within these currents and can be deposited within the
reservoir. In an unstratiﬁed reservoir, outﬂow waters represent a composite from all
depths, but in a stratiﬁed reservoir vertical mixing is inhibited and outﬂow waters are
restricted to a particular stratum (Ford 1990). Most reservoirs discharge water through
a subsurface outﬂow, which under stratiﬁed conditions leads to a restricted hypolimnion
withdrawal zone, a deeper epilimnion, and increased heat storage (Ford 1999, Martin
1978). Hypolimnetic-discharge reservoirs tends to exhibit higher nutrient concentrations
in outﬂowing waters compared to epilimnetic outﬂowing waters (Martin et a1. 1978).
Changes in water elevation associated with dam operations can enhance nutrient

exchange between littoral and pelagic zones.

Sedimentation acts as nutrient sink in reservoirs, while sediment-water exchange of
solutes can release nutrients in a reservoir. Most of the sedimentation typically occurs
near the inﬂow with minimal sediment deposits at the dam. James et a1. (1987) noted

signiﬁcant losses of phosphorus, nitrogen and carbon in DeGray Lake inﬂow water

resulting from sedimentation. Sediment accumulation varied depending on the season,
with higher deposition during the spring compared to summer. However, sediment
retention depends on water velocity and less may be retained if ﬂushing rates are high
(J ossette et a1. 1990). Clay and silt sedimentation in the transition and lacustrine zones
removes associated trace metals and nutrients ﬁom the overlying waters. Anoxic
conditions in the waters overlying sediments during summer stratiﬁcation can cause the
release of trace metals, phosphorus and ammonium from sediment into the overlying
waters. Reservoir sediments can be either a net sink or source of nitrogen (Sherman
2001). Transition and lacustrine zones are the main zones of nutrient release from
sediments in reservoirs; advective forces in the transition zone distribute released

nutrients within the reservoir (Kennedy and Walker 1990).

Reservoirs are divided into three classes based on residence time (Straskraba 1999). The
ﬁrst class is the through-ﬂowing reservoir with residence times less than two weeks.
The intermediate-residence time reservoir class has residence times between two weeks
and one year. The long-residence time reservoir class has residence times greater than
one year. Long residence time reservoirs behave much like a stratiﬁed lake. Nutrient
availability is affected by reservoir residence time. Reservoirs with residence times
greater than 120 days retain much of total phosphorus in inﬂowing waters, whereas at
short residence times (less than 10 days) there may be no phosphorus retention due to
the high ﬂushing rates (Soballe 1987, Straskraba 1999). However, nitrogen retention is
not affected as much by reservoir retention time, but more by reservoir morphology.

More nitrogen is retained in shallow reservoirs where sediment-water interactions

(including dentriﬁcation) have more inﬂuence on overlying waters, compared with deep
reservoir systems (Howarth 1995, Straskraba 1999, Scheffer, 1998). Silica is
replenished in short-residence time reservoirs by river inputs, whereas systems with
long residence times serve as a sink for silica, especially when they have high nitrogen

and phosphorus inputs (Conley, 1993).

A shift from allochthonous to autochthonous energy sources supporting food webs is
common in reservoir systems. Phytoplankton are able to ﬂourish in reservoir systems
with sufﬁciently long enough residence times due to constant inputs of riverine
nutrients, increased light penetration and warming water temperatures. The longitudinal
gradient establishes primary production in the lacustrine zone. Phytoplankton
concentrations peak with a reduction in turbidity and velocity but where nutrient
availability is still high (Gloss et a1. 1980, Kennedy et a1. 1982). During the summer,
reservoirs usually increase in water temperature relative to inﬂowing river waters,
promoting biological activity (Carmack 1979). Internal recycling of nutrients by
phytoplankton partially controls the amount of nutrients available in a reservoir. J ossette
et a1. (1990) concluded from a biogeochemical mass balance that 60% of phosphorus
inputs either were lost by sedimentation or retained by algae, and that silica was
deposited in reservoirs as a result of diatom uptake. Total nitrogen and phosphorus
budgets in Sulejow Reservoir indicated that these nutrients were assimilated by

phytoplankton (Galicka and Penczak 1989).

Primary production affects calcium carbonate (C3CO3) formation in reservoirs by algae
for growth, and by regulating dissolved carbon dioxide concentrations through
photosynthesis. High algal photosynthetic rates, deplete dissolved CO; and raise pH; as
a result, CaCO3 may precipitate in alkaline waters. Increased water temperature also
contributes to CaCO3 supersaturation. CaCO3 precipitation decreases calcium and
alkalinity concentrations (Schlesinger 1997) and can remove available phosphorus

through sorption (Otsuki and Wetzel 1972, Bostrom et a1. 1988).

Denitriﬁcation is a microbial respiratory process that reduces nitrate to nitrogen gas
(N 2). Denitriﬁcation occurs in aquatic sediments under hypoxic or anoxic conditions, is
favored by warm temperatures, and may be limited either by nitrate or labile organic
carbon (Seitzinger 1988). A correlation exists between nitrogen inputs and nitrogen
retention in reservoirs, yet nitrogen retention can depend on changes in residence time
and water volume (sediment-water interaction) (Tomaszek and Koszelnik, 2003).
Nitrate inputs via river ﬂow into reservoirs form a longitudinal gradient with high
nitrate concentrations at the riverine end and lower concentrations at the darn end;
denitriﬁcation may increase towards the dam as temperatures increase and oxygen
concentrations in water overlying the sediments decrease (Wall 2005). The highest
denitriﬁcation rates occur at the end of the spring or summer when oxygen
concentrations are lowest (Tomaszek and Czerwieniec 2003, Wall 2005). Nitrogen
retention gradually declines in autumn (Tomaszek and Koszelnik, 2003, Wall 2005)
reaching the lowest retention in the winter when low temperatures limit denitriﬁcation

rates (Wall 2005).

Rooted macrophytes and periphyton often have limited primary production in reservoirs
due to turbidity and water level ﬂuctuations. However, if water levels are stable with
clear water, macrophyte communities can establish (Barko 1981), and smaller shallow
reservoirs can support abundant periphyton grth as well. Submerged vegetation
serves as habitat for ﬁsh and provides a surface for periphyton growth (Kimmel et. a1.
1990), and detrital inputs from vegetation represent a slow release nutrient source for
the overlying waters (Miner 1974). Tropical and subtropical reservoirs often develop
extensive stands of ﬂoating emergent plants (Thomas et a1. 1999). Light penetration,
nutrients, substratum composition and stability impact benthic algal community
development (Stevenson 1996). These same factors also affect nutrient uptake by
benthic algae. Phytoplankton have more ready access to water column nutrients than
benthic algae. However, benthic algae have another nutrient source beside the overlying
waters; benthic algae utilize nutrients within and released from the sediments and
benthic algae can thereby restrict nutrient movement from the sediments into overlying
waters (Hasson 1988). Benthic algae can be favored by shallow waters and short

residence times that restrict the growth of phytoplankton.

Study Site

The Kalamazoo River watershed is located in the southwestern Michigan, with a
watershed area of approximately 5,231 kmz. The Kalamazoo River runs 260 km through
10 counties of variety of land uses (developed areas, farmland and forest including the
Allegan State Game Area) (Figure 1). Morrow Lake and Lake Allegan are shallow and

non-stratifying run-of-the-river impoundments located on the Kalamazoo River. The

water discharged at the dam is essentially drawn from the entire water column, with a
spillway to accommodate excess discharge. Water levels are kept constant behind the
impoundment wall. Morrow Lake is located 69 km upstream of Lake Allegan, and there
are no major tributary inputs between the impoundments, although groundwater inputs

are substantial. The morphometric features of both reservoirs are listed in Table 1.

Consumers Power Company created Morrow Lake in 1939 for the Bryce E. Morrow
Power Plant in Comstock, Michigan. The plant was ﬁreled by coal, which supplied
energy to the boiler to produce steam. Morrow Lake’s water was pumped through
condensers, which condensed hot steam from the boilers to hot water, which was then
pumped back into boilers. The two electric generators were powered by steam turbines,

which produced 35,000 kilowatts each.

In 1969, the plant was converted to natural gas power, and in 1971 was rebuilt to use
oil. Consumers Power closed Morrow Plant in July 1982 due to high operating costs
and reduction in power consumption. STS Consultants Ltd. purchased about 1,400 acres
surrounding Morrow Plant (excluding the building and equipment) to construct a new
hydroelectric facility. The hydroelectric plant now generates about 1,000 kilowatts of
electricity. Currently, Morrow Irnpoundment is owned by STS Hydropower and is not

licensed by the Federal Energy Regulation Commission (FERC).

10

Calkins Dam was constructed by the city of Allegan from 1931-1936. The city’s
municipal utility operated the darn from 1936 to 1968. In 1968, Consumers Energy

purchased the dam and to date operates the dam.

There are also several decommissioned hydropower dams and diversion dams for a
mill race, all located between Morrow Lake and Lake Allegan. Chapter Two describes

these dams in more detail.

Total Maximum Daily Load ( T MDL) for Lake Allegan

The United States Environmental Protection Agency conducted a National
Eutrophication Survey in 1972 and classiﬁed Lake Allegan as hypereutrophic (U SEPA
1975). The source of Lake Allegan’s hypereutrophication was deemed to be phosphorus
based on the well-documented tendency for other Michigan lakes to be phosphorus
limited. The Michigan Department of Environmental Quality (MDEQ) monitored Lake
Allegan from April through September of the years 1988, 1994, 1996 and 1997, and
determined that total phosphorus concentrations in Lake Allegan averaged 96 pg/L and
ranged from 69 to 125 pg/L (Heaton 2001). In 1998, Lake Allegan remained classiﬁed
as hypereutrophic, exhibiting high nutrient and chlorophyll a concentrations (67 pg/L),
excessive turbidity (0.6 m Secchi depth), low dissolved oxygen, and an unbalanced ﬁsh
community dominated by carp and channel catﬁsh (87% community average) (Heaton

2001).

In 1999, MDEQ developed a phosphorus Total Maximum Daily Load (TMDL) for

Lake Allegan. A Total Maximum Daily Load (TMDL) is an estimate of the total daily

11

input of a pollutant stressor (from point, non-point, and natural background sources)
that may be allowed within a segment of receiving water without exceeding applicable

water quality criteria.

A reduction of total phosphorus in Lake Allegan should improve water quality
conditions if it is indeed the main factor controlling algal growth. Morrow Lake, an
impoundment located upstream, served as a reference in setting Lake Allegan TMDL
parameter goals. Morrow Lake has morphometry similar to Lake Allegan, but with
better water quality: no nuisance algae blooms, lower chlorophyll a (23 pg/L), higher
transparency (Secchi depth average 1.0 m), a balanced non-carp-dominated ﬁsh
community (39% carp and catﬁsh by number), and 58 pg/L total phosphorus. Morrow
Lake’s water quality characteristics were considered a realistic and desirable target Lake
Allegan. Therefore, the Lake Allegan total phosphorus TMDL goal was set at 60 pg/L
for the inﬂow in the expectation that Lake Allegan would become more like Morrow

Lake with this lower phosphorus load.

Considering their spatial proximity and the fact that Lake Allegan and Morrow Lake are
both shallow lakes located on the Kalamazoo River without any major tributary inputs
directly into or between them, the question arises as to why there are major differences
in the total phosphorus concentration and in algal blooms and ﬁsh communities between

the reservoirs.

12

Objective and Hypotheses

The objective of this research was to conduct a comprehensive biogeochemical analysis

of inﬂow and outﬂow waters of Morrow Lake and Lake Allegan. The analysis will help

develop an understanding of the differences and similarities between Morrow Lake and

Lake Allegan and to explain why only Lake Allegan has reported problems with

excessive algal grth and poor water quality.

I hypothesized that the following critical biogeochemical processes may alter elemental

ﬂuxes and inﬂuence algal growth in Morrow Lake and Lake Allegan:

Residence time limits the time for algal growth within the reservoirs.
Phosphorus forms change within the reservoirs by phytoplankton uptake/release
and sediment/water exchanges.

Algal uptake and denitriﬁcation remove nitrate within the reservoirs.
Calcium carbonate precipitation decreases concentrations of calcium and
alkalinity within the reservoir.

Diatoms measurably reduce available silica concentrations during the spring.

Nutrient ratios (N :P and Si:N) shift seasonally in the reservoirs during periods
when residence time is long enough for biological uptake to impact
concentrations, resulting in shifts in the potentially limiting nutrient for algal

growth.

13

Methods
Field Sampling

The Lake Allegan inﬂow sampling location was the historical downtown bridge on
Bridge Road, and the outﬂow site location is just below the Caulkins Dam on Lake
Allegan Dam Road; both sites are located in Allegan County, Michigan. The Morrow
Lake inﬂow sampling location was where E. Michigan Avenue crosses the Kalamazoo
River in Galesburg; the outﬂow sampling location is Merrill Park in Comstock about 2
km below the dam. Morrow Lake is in Kalamazoo County, Michigan.

In 2003, samples of inﬂow and outﬂow waters were collected in early spring (13
March 2003) and weekly during summer (14 May-19 August 2003). In 2004, inﬂow
and outﬂow waters were sampled once during ice—cover in early spring (10 Feb 2004)
and monthly during summer (26 May-20 September 2004). The right and left banks
were sampled periodically for differences in nutrient concentrations, since the Morrow
Lake outﬂow was sampled from left bank. Lake Allegan inﬂow and outﬂow waters and
Morrow Lake inﬂow waters were sampled with a Van Dom Sampler and Morrow Lake
outﬂow waters by an extendable hand-held dipper. Temperature, pH, conductivity, and
dissolved oxygen were measured at each sampling site with a Hydrolab Sonde.

One diel cycle of temperature, oxygen, pH and conductance was recorded with a YSI
multiparameter sonde for Lake Allegan on 19-20 August 2003 and Morrow Lake on 23-
24 August 2003. In Lake Allegan the sonde sensor probe was suspended from the
impoundment wall between two intake gates; in Morrow Lake the sonde was positioned

in water of 0.7m depths off an island in the center. Both locations represent the surface

14

mixed layers, although persistent thermal stratiﬁcation has not been documented in
these reservoirs.

In late summer 2004, vertical proﬁles were measured from a boat in each reservoir
near the impoundment wall, at the deepest point. At that time when maximum vertical
differences would have existed. Depths were determined with Hummingbird sonar
depth ﬁnder. The Morrow Lake vertical proﬁle was measured on 27 August 2004,
taking 7 samples at l-meter depth intervals. The Lake Allegan vertical proﬁle was
measured on 20 September 2004, taking 10 samples at l-meter depth intervals. Secchi
depths were recorded in each reservoir. Temperature, pH, conductivity, dissolved
oxygen were measured in each vertical proﬁles at l-meter intervals with the Hydrolab
Sonde.

Laboratory Analyses

Water samples were ﬁltered through 0.45pm membrane ﬁlters and refrigerated
(nutrients, anions) or acidiﬁed with 8 N HNO3 (cations). Ammonium was analyzed
colorimetrically by the phenylhypochlorite method (Aminot et a1 1997). Soluble
reactive phosphorus (SRP) was measured colorimetrically by the acid molybdate
method; silica was analyzed colorimetrically by the ammonium molybdate method
(Wetzel and Likens 2001). Total soluble phosphorus (in ﬁltered water) and total
phosphorus (unﬁltered water) were determined after persulfate digestion in a pressure
steam sterilizer by colorimetric analysis of the resultant orthophosphate (V alderrama
1981, Langner and Hendrix 1982). The sterilizer was operated at 20 psi for two hours
followed by a gradual cool down period. Standards included ATP to ensure efﬁcient

oxidation of organic matter. Reagent and water contributions to the analytical blank

15

were determined by varying the reagent amount and only the reagent contribution was
subtracted from sample absorbances (this was also routinely done for ammonium
analyses). Nitrate, sulfate, and chloride were measured with an ion chromatograph.
Calcium, magnesium, sodium and potassium were measured with a ﬂame atomic
absorption spectrophotometer. Alkalinity was determined by Gran titration with 0.3 N
HCl. Sestonic chlorophyll a was ﬁltered onto Type A/E glass ﬁber ﬁlters and frozen.
The ﬁlters were later halved and one half was extracted with 95% ethanol, and

chlorophyll a was measured by ﬂuorometry (Welschmeyer 1994).

Data from inﬂow and outﬂow waters were analyzed by linear and multiple regression

using SYSTAT 9.0

Water residence time was calculated from USGS discharge records and reservoir
volumes. For Morrow Lake the gauging station was Comstock and for Lake Allegan
the gauging station was Trowbridge. Lake Allegan and Morrow Lake volume and area
were recorded from critical infrastructure information provided by the Federal Energy
Regulatory Commission. The maximum depth was recorded from the vertical proﬁles.
A time-integrated residence time was calculated as follows, to reﬂect short-term
changes in river discharge. First, the daily residence time for each sampling day was
calculated from the daily discharge and reservoir volume. Once the daily residence time
was determined for that sampling day, I started with that sampling day and counted
back the number of days equal to the residence time estimate. I then calculated the mean

daily discharge residence time over that preceding interval.

16

Results

Climate and River Hydrology

Discharge varied throughout the season with the highest discharge during February
through May and the lowest discharge during June through September. The river at
Lake Allegan had higher discharge than at Morrow Lake (Figure 2). Discharge was
higher overall in 2004 than in 2003. The mean annual discharge for March through
September over 72 years (1931-2003) was 26.38 m3/sec. The mean for March through
September 2003 was 20.6 m3/sec and for March through September 2004 it was 29.72

m3/sec.

Residence times in the two reservoirs varied seasonally and were shorter during
February through May than in June through August. Beginning in June residence times
increased. Residence time varied inversely with discharge and thus was longer in 2003
than in 2004 (volumes of each reservoir were constant). Lake Allegan had a longer

residence time than Morrow Lake (Figure 3).

The climate of the region is humid and temperate. Air temperatures in 2003 and 2004
were low during January through April and started gradually increasing in May. The

highest temperatures occurred in July and August (Figure 4).

Statistical predictors of algal growth in the reservoirs
Simple linear and multiple regression analyses were used to determine what factors
predict algal growth. In 2003 (Table 2), residence time was a good predictor of algal

grth in Morrow Lake (p <0.05) and Lake Allegan (p <0.05). Outﬂow total

17

phosphorus predicted algal grth only in Morrow Lake (p <0.05), and was not a
signiﬁcant predictor in Lake Allegan (p=0.061). However, combining the residence
time and outﬂow total phosphorus yielded better prediction of algal grth in Morrow
Lake (p <0.05) and Lake Allegan (p <0.05). In 2004, when residence times were
shorter (Table 3), p-values were not signiﬁcant for either of these factors predicting
algal growth. Combining the 2003 and 2004 data (Table 4), residence time predicted
algal growth in Morrow Lake (p <0.05) and Lake Allegan (p <0.05). Addition of the
total phosphorus concentrations yielded a better prediction in Morrow Lake (R2 =0.62, p

<0.05), but did not improve the prediction in Lake Allegan (R2 =0.37, p <0.05).

18

Lake Allegan

The residence time of water in Lake Allegan was relatively long during March 2003,
then became shorter as discharge increased in April and May. Beginning in July
residence time gradually increased (Figure 5A). However, in 2004 the residence time
did not increase seasonally, but remained short all summer (Figure SB). Residence time

was longer in 2003 than in 2004, reﬂecting the discharge in those years.

Chlorophyll a concentrations were variable during March and in early July 2003 and
2004, but were usually higher in the outﬂow. In July, there was a steady increase in the
outﬂow chlorophyll a concentrations. Also in mid July the inﬂow chlorophyll a
concentrations increased above the outﬂow, then declined sharply below the outﬂow
(Figure 6A and 6B). Chapter 2 examines patterns in chlorophyll in the river between the
two reservoirs and investigates the origin of the high chlorophyll concentrations in the

Lake Allegan inﬂow waters.

The outﬂow concentrations of total soluble phosphorus were usually lower than the
inﬂow concentrations during April through July 2003and 2004. Starting in mid-July the

inﬂow concentrations ﬂuctuated (Figures 7A and 7B).

The outﬂow concentrations of total phosphorus were usually lower than the inﬂow

concentrations during April through mid July in 2003 and 2004, but in August outﬂow

concentrations exceeded the inﬂow concentrations (Figures 8A and 8B). Soluble

l9

reactive phosphorus concentrations in 2003 and 2004 remained low in the outﬂow, but

ﬂuctuated in the inﬂow (Figures 9A and 9B).

Concentrations of soluble organic phosphorus (measured as the difference between total
soluble phosphorus and soluble reactive phosphorus) were usually higher in the outﬂow
than in the inﬂow. In July 2003, the inﬂow concentrations fell below detection (Figure
10A). In 2004, the outﬂow concentrations were usually higher than the inﬂow, but the

inﬂow did not reach zero during the summer (Figure 10B).

Ammonium concentrations were variable during March through July 2003. From July
on there was an increase in the outﬂow ammonium concentrations relative to the inﬂow,
peaking in August (ﬁgure 11A). However, March-June 2004 inﬂow and outﬂow
concentrations were constant, there was a peak in outﬂow concentration in early July
followed by a decline starting in late July (Figure 11B). Nitrate concentrations in the
inﬂow and outﬂow were similar from March through May 2003, but after June there
was a consistent decline in nitrate concentrations, almost reaching undetectable levels
(< 15 pg N/L) at the outﬂow in late July through mid-August (ﬁgure 12A). The pattern
was the similar in 2004, except that outﬂow concentration did not reach undetectable

levels in July (Figure 12B).

From March through August 2003, outﬂow concentrations of silica were lower than in

the inﬂow. The ﬁrst marked decline was in April 2003 followed by a second decline in

July, and the outﬂow concentrations fell to nearly undetectable levels in late July

20

through mid August (Figure 13A). Outﬂow concentrations of silica declined in April
and July 2004 (Figure 13B). The July 2004 outﬂow concentration decline was not as

marked as it was in July 2003.

Redﬁeld ratio is based on Liebig’s law of the minimum, which states the smallest
quantity of a nutrient relative to grth needs will become the limiting factor. The ratio
for algal biomass is C:N:P = 106:16:l. In the case of diatoms Si:N = 1:1. From March
through June 2003, ratios of available N:P (DIN:TP) indicated that the outﬂow waters
shiﬁed from potential phosphorus limitation to potential co-limitation between nitrogen
and phosphorus, while inﬂow waters remained potentially phosphorus limited(F i gure
14A). From July through August, the inﬂow remained potentially phosphorus limited,
but the outﬂow became potentially nitrogen limited. The 2003 pattern was similar in
2004 except the outﬂow waters never show potential nitrogen limitation (Figure 14B).
These ratios reﬂect potential nutrient limitation because in most samples the

concentrations exceeded those known to be physiologically limiting to algal growth.

In April 2003, diatom grth in both inﬂow and outﬂow waters was potentially silica
limited (Figure 15A). Beginning in May, inﬂow and outﬂow waters shifted to potential
nitrogen limitation, and in July inﬂow and outﬂow waters were potentially silica limited
and shiﬁed back to potential nitrogen limitation during mid August. In contrast, the
inﬂow waters were only potentially silica limited in April and remained potentially
nitrogen limited for remaining months. The outﬂow pattern was similar in 2004 with

potential silica limitation in June and August (Figure 15B).

21

In 2003, the inﬂow waters were mainly potentially phosphorus limited or silica-
phosphorus limited, while the outﬂow waters were potentially phosphorus limited, co-
limited between phosphorus and nitrogen, or silica-nitrogen limited (Figure 16A). In
contrast, 2004 outﬂow waters were slightly potentially silica-nitrogen limited and there

was no co-limitation between phosphorus and nitrogen.

In 2003 and 2004, water temperatures were similar between the inﬂow and outﬂow
from March through June, but starting in July temperatures gradually increased in the

outﬂow compared with the inﬂow (Figures 17A and 17B).

Transparency was not measured in this study. Secchi depth measured by the Michigan
Department of Environmental Quality (MDEQ) from 1998-2003 averaged 0.68 m. The
compensation point depth above which net algal photosynthesis could occur was thus
approximately twice this, or 1.37 m. The mean depth of Lake Allegan is 1.80 m and the
maximum depth is 7 m. Sufﬁcient light to support algal growth could therefore

penetrate 76 % of the water column.

The total suspended solid concentrations were generally higher in the outﬂow than the

inﬂow (Figures 18A and 18 B). There was no consistent difference in 2004. The

particulate matter usually appeared to be mostly algal biomass.

In 2003 and 2004, oxygen concentrations were usually higher in the outﬂow than in the

inﬂow (Figures 19A and 19B). In 2003, The difference was greatest during May

22

through July (Figure 19A), when the outﬂow concentrations noticeably increased, but
then in August the inﬂow and outﬂow concentrations were similar. The outﬂow was
generally supersaturated, especially during June through mid July 2003, and the inﬂow
remained undersaturated (Figure 20A). However, in 2004 the inﬂow and outﬂow were
undersaturated from March through June, but in mid-July the outﬂow shifted to
supersaturation and inﬂow generally remained undersaturated (Figure 203). Very high
oxygen superatsauration occurred in the outﬂow on several dates during the summer,

indicating intense algal photosynthesis.

A diel cycle of temperature and dissolved oxygen was measured off the dam on 19-20
August 2003 (Figure 21A) at the depth of l m. A vertical proﬁle taken at the beginning
showed the water column to be well-mixed. Temperature and oxygen concentrations
paralleled each other with the lowest values recorded in the early morning hours, and a

gradual increase followed by a peak in the late aﬂemoon and a decline in the evening.

The pH did not change consistently from inﬂow to outﬂow but the outﬂow pH was
most often slightly elevated in comparison to inﬂow pH (Figure 22A). Inﬂow and
outﬂow pH were similar from March through July 2004 including one sampling date

when maximal pH was observed, corresponding with very high oxygen supersaturation

(Figure 223).

Calcium concentrations were lower in the outﬂow than in the inﬂow, and from mid-

May through August 2003 there was a gradual decline in the outﬂow calcium

23

concentrations (Figure 23). Likewise, the alkalinity did not change until July 2003 after
which a decline in the outﬂow was observed (Figure 24). The calcite saturation index
suggested than calcite potentially precipitated in both the inﬂow and outﬂow waters,
with calcite saturation in the outﬂow lower than in the inﬂow on most dates from June

through August (Figure 25).

The reduction in calcium and alkalinity support the conclusion from the calcite

saturation index that calcite precipitated as water resided in Lake Allegan

Magnesium (Figure 26), sodium (Figure 27), potassium (Figure 28), chloride (Figure
29), and sulfate (Figure 30) concentrations showed some changes detectably as water
passed through Lake Allegan from March through August in both 2003, but these were

not large and will not be dealt with in this study.

Lake Allegan vertical proﬁles

Lake Allegan had a well-mixed water column on one date in late summer when thermal
stratiﬁcation would have been maximal. Chlorophyll a and total phosphorus
concentrations were high throughout the water column (Figure 31). Soluble reactive
phosphorus and total soluble phosphorus concentrations were high at the surface, and
then high declined throughout the water column (Figure 32). Ammonium and nitrate
concentrations were increased slightly with depth in the water column (Figure 33).
Concentrations of total soluble and soluble reactive phosphorus as well as ammonium in

the reservoir were lower than in inﬂow waters. Temperatures were uniform from the

24

surface to bottom. Oxygen decreased below 2m (Figure 34). Conductance increased

slightly and pH decreased slightly with depth in the water column (Figure 35).

25

Morrow Lake

As in Lake Allegan, the residence time of water in Morrow Lake was long during
March 2003, and shorter in April and May. Beginning in June residence time gradually
increased (Figure 36A). However, in 2004 the residence time did not change seasonally,
but remained low (Figure 36B). Residence time was longer in summer 2003 than in

summer 2004.

In 2003 and 2004, chlorophyll a concentrations in the Morrow Lake outﬂow were

generally much higher than in the inﬂow (Figures 37A and 37B).

In the Morrow Lake outﬂow, concentrations of total soluble phosphorus were usually
lower than inﬂow concentrations during April through July 2003(Figure 38A).
However, in 2004 the difference between inﬂow and was less consistent and a much

higher outﬂow concentrations was recorded on one date in July (Figure 38B).

The total phosphorus concentrations did not change much as water passed through
Morrow Lake during March through June 2003, but then after July total phosphorus
increased in the outﬂow relative to the inﬂow (Figure 39A). In 2004 outﬂow total
phosphorus was lower in concentration on 5 of 7 sampling dates, but much higher on
one date in July (Figure 39B). This contrasts with the net phosphorus loss observed in
both years in Lake Allegan (Figure 8A). The soluble reactive phosphorus concentrations
were consistently lower in the outﬂow than the inﬂow in 2003, especially in late

summer (Figure 40A). On one date in July 2004 a different pattern was observed with

26

an increase in soluble reactive phosphorus concentrations in the outﬂow compared to
the inﬂow (Figure 403); this peak in outﬂow concentrations corresponded with

exceptionally high total and total soluble phosphorus concentrations.

The soluble organic phosphorus concentrations did not change consistently from inﬂow
to outﬂow in 2003 (Figure 41A). Starting in June 2003 the inﬂow and outﬂow
concentrations gradually declined approaching zero in July. This pattern was not
observed in 2004 when the outﬂow dissolved organic phosphorus concentrations were

always higher than in the inﬂow (Figure 41B).

Ammonium concentrations were variable but were most often lower in the outﬂow
(Figures 42A and B). From mid July through August 2003 and 2004 there was a larger
and more consistent decline in ammonium concentrations. This decline in ammonium
contrasts with the increase in ammonium observed in Lake Allegan (Figure 11A).
Nitrate concentrations did not change as water passed through Morrow Lake from
March through May 2003, but after June there was a consistent decline in nitrate
concentrations, reaching nearly zero at the outﬂow in late July-mid August (Figure
43A). The similar pattern was observed in 2004 except the outﬂow nitrate

concentrations did not reach nearly zero in July and August (Figure 43B).

Silica concentrations did not change from March through June in 2003 and 2004

(Figures 44A and 443). Starting in July 2003 (Figure 44A) there was a consistent

decline in the silica outﬂow concentrations relative to the inﬂow. In contrast to 2003, in

27

2004 outﬂow concentrations of silica only slightly declined in late summer relative to

inﬂow (Figure 44B).

From March through July of 2003, ratios of available N:P (DIN:TP) indicated that
inﬂow and outﬂow waters were both potentially phosphorus limited. From mid-July
through August 2003 the inﬂow remained phosphorus limited but the outﬂow became
potentially nitrogen limited (Figure 45A). The pattern was similar in 2004 except the
outﬂow waters were only potentially phosphorus limited in early July and shifted back

to potential co-limitation in August (Figure 45B).

In March 2003 diatom growth in both the inﬂow and outﬂow waters was potentially
silica-limited. Beginning in April, the inﬂow and outﬂow waters were potentially
nitrogen limited (Figure 46A). In contrast, inﬂow and outﬂow. waters in 2004 did not

showed potential silica limitation only nitrogen limitation (Figure 46B).

In 2003 and 2004, Morrow Lake inﬂow and outﬂow waters were mainly potentially
phosphorus limited or nitrogen limited (Figures 47A and B). This contrast with Lake
Allegan where the waters were potentially silica-phosphorus limited and outﬂow waters

were silica-nitrogen limited (Figure 16A).

In 2003 and 2004, water temperatures did not vary from March through June, but

starting in July the outﬂow temperatures increased compared with the inﬂow (Figures

48A and 483).

28

Transparency was not measured in this study. Secchi depth measured by the Michigan

Department of Environmental Quality (MDEQ) from 1998-2003 averaged 0.97 m. The
compensation point depth was thus approximately twice this, or 1.9 m. The mean depth
of Morrow Lake is 1.66 m and the maximum depth is 5 m. Therefore, sufﬁcient light to

support algal could penetrate the entire water column.

In 2003, outﬂow concentrations of total suspended solids were generally higher than
the inﬂow concentrations (Figure 49A). However, in 2004 inﬂow concentrations were

more often higher than in the outﬂow (Figure 49B).

Oxygen concentrations in 2003 and 2004 were generally higher in the outﬂow than in
the inﬂow, except early in the Spring (Figures 50A and 50B). Oxygen concentrations

started gradually increasing in July 2003 (Figure 50A) and in May 2004 (ﬁgure SOB)

relative to the inﬂow. Also in 2003 and 2004, the outﬂow waters were mainly

supersaturated while the inﬂow waters were undersaturated (Figures 51A and 51B).

A diel cycle of temperature and dissolved oxygen was measured on 23-24 August 2003
along the Indian mound island (located south of the DNR launch site) at the depth of
0.39 m. The surface waters were well-mixed. Temperature and oxygen concentrations
parallel each other with the lowest values recorded in the early morning hours, a gradual
increase followed by a peak in the late aﬁemoon and a decline in the evening

(Figure 52). Oxygen was supersaturated throughout the diel cycle.

29

The outﬂow pH was almost always higher than inﬂow pH in 2003 and 2004 (Figures
53A and 53B), Starting in July 2003, pH gradually increased in the outﬂow relative to
the inﬂow (Figure 53A). This contrasts with the decrease in outﬂow pH during the

summer of 2003 in Lake Allegan (Figure 22A).

Calcium concentrations did not change as the water passed through Morrow Lake from
March through July 2003, but after mid-July there was a decline in the outﬂow
concentrations relative to the inﬂow (Figure 54). Like calcium, alkalinity did not
change until July 2003, after which there was a decline in the outﬂow (Figure 55). The
saturation index suggested that calcite potentially precipitated in the inﬂow and outﬂow,
with calcite supersaturation in the outﬂow higher than inﬂow starting in late May 2003

(Figure 56). In contrast, Lake Allegan had a higher calcite saturation index in the inﬂow

(Figure 25).

Magnesium (Figure 57), sodium (Figure 58) potassium (Figure 59), chloride (Figure
60), and sulfate (Figure 61) concentrations change little as water passed through

Morrow Lake from March through August in 2003 and 2004.

Morrow Pond Vertical Profile

Morrow Lake had a well-mixed water column on one date in late summer when thermal
stratiﬁcation would have been maximal. Chlorophyll a and total phosphorus
concentrations were high from the surface to the bottom but were lower than in Lake

Allegan (Figure 62). Total soluble phosphorus concentrations were uniform throughout

30

the water column, while soluble reactive phosphorus concentrations were lower at the
surface (Figure 63). Ammonium concentrations gradually increased with depth and
nitrate concentrations decreased slightly with depth (Figure 64). Compared to the inﬂow
concentrations, the vertical proﬁles showed considerable production of ammonium and
some loss of soluble phosphorus. Temperatures were uniform throughout the water
column. Oxygen started to decrease slightly at 5-meter depth (Figure 65). Conductance

was uniform and pH decreased with depth in the water column (Figure 66)

Comparison of P forms above and below each reservoir

The mean concentration of phosphorus during the 2003 and 2004 sampling periods in
Lake Allegan and Morrow Lake inﬂow and outﬂow waters are summarized in Figure
67 . Particulate phosphorus was calculated as the difference between total and total
soluble phosphorus. Particulate phosphorus was the predominant form in all sites.

In 2003 Morrow Lake usually increased in particulate phosphorus from the inﬂow to
the outﬂow, compared with no change or decrease in Lake Allegan (Figure 67 A).
Soluble reactive phosphorus decreased from inﬂow to outﬂow in both reservoirs.
Soluble organic phosphorus changed less from inﬂow to outﬂow. However, in 2004
(Figure 67 B), Morrow Lake did not show as large of an increase in particulate
phosphorus from inﬂow to outﬂow, and soluble reactive phosphorus did not change
from the inﬂow to the outﬂow. Lake Allegan decreased in particulate phosphorus and

soluble reactive phosphorus from the inﬂow to the outﬂow.

31

Discussion

Morrow Lake and Lake Allegan are shallow, well-mixed (non-stratifying), eutrophic
reservoirs, with short residence times (less than 11 days for both). Temperatures
increased over the summer with the outﬂow temperature generally slightly warmer than
inﬂow (Figures 17 and 48). Net oxygen production was apparent during the summer,
and there is no evidence for persistent thermal stratiﬁcation or anoxic bottom waters. In
the 2004 season (March-September) discharge was higher, and in the 2003 season
discharge was lower, than the 72-year annual season mean of 26.3 m3/sec at the
Trowbridge gauge (above Lake Allegan) (Figure 2). Lake Allegan always had a higher
discharge than Morrow Lake. Due to its larger volume, however, Lake Allegan had a
longer residence time than Morrow Lake (Figure 3). My sampling period for both years

spanned the typical seasonal variation in discharge and residence time (Figures 2 and 3).

The nutrient concentrations of the Kalamazoo River make these reservoirs eutrophic by
Midwestern United States lake standards. There are two substantial wastewater
treatment plants that inﬂuence my sampling reach. The Battle Creek wastewater plant is
23 km upstream of the Morrow Lake inﬂow sampling location and the Kalamazoo
wastewater treatment plant is 10 km downstream of the Morrow Lake outﬂow sampling
location and 63 km above Lake Allegan. These efﬂuents together with a number of
industrial efﬂuents that are discharged directly into the main channel likely explain the
fairly high concentrations of soluble reactive phosphorus concentrations in the river

(Figures 9 and 40).

32

Comparisons between reservoirs

During the two summers of sampling, Morrow Lake was a source, while Lake Allegan
was a sink, for total phosphorus (Figure 67). In 2003 there consistently tended to be an
increase in particulate phosphorus from the inﬂow to the outﬂow in Morrow Lake
(Figure 67A). The highest total phosphorus concentrations occurred during summer and
corresponded with the highest chlorophyll a concentrations. Lake Allegan was a sink
for total phosphorus mainly during the summer when chlorophyll a concentrations were
high, perhaps due to phytoplankton sedimentation. Referring to the regression statistics
(Table 2), both residence time and total phosphorus are a signiﬁcant predictors of algal
growth in Morrow Lake. It is notable that more light reaches the bottom in Morrow
Lake, which could promote the grth of benthic algae. Benthic algal mats uplifted
from the bottom were observed during the summer and may be a major source of
particulate phosphorus leaving Morrow Lake. During the spring and summer these
benthic algal mats grow and once a maximum biomass is achieved, sloughing and lift
off can occur (Stevenson 1996). Thus the apparent production of phosphorus in Morrow

Lake could actually reﬂect seasonal uptake followed by release.

Residence time was the only predictor of algal growth in Lake Allegan; total
phosphorus was not signiﬁcant. Lake Allegan’s residence time ranged from 3 to 11
days in 2003 (Figure 5A) and 3 to 8 days in 2004 (Figure 5B), depending directly on
discharge, since the volume did not change. Chlorophyll a concentrations were the
highest when residence time was the longest. The 2003 sampling season had higher

chlorophyll a concentrations compared with 2004 probably because during 2003

33

discharge was lower and residence time was longer (Figures 6A and B). In 2004, the
longest residence time in Lake Allegan was eight days, compared with 11 days in 2003.
Residence times of around seven days or less limit phytoplankton production and
species composition (Thornton 1980). Dickman’s 1969 study of Marion Lake
concluded that short residence times (less than 2.5 days) greatly reduced phytoplankton
by ﬂushing them via an outlet. Morrow Lake’s residence time ranged from 2-7 days in
2003 (Figure 37A) and 2-5 days in 2004 (Figure 37B). Phytoplankton grth was thus
likely to always be restricted by residence time. Compared to Lake Allegan,
phytoplankton in Morrow Lake was more often ﬂushed from the system before
populations could accumulate. Benthic algal growth is not dependent upon residence
time, but is controlled by light and nutrients. Since the phytoplankton is more often
ﬂushed from Morrow Lake perhaps, shading is prevented and more light is able to reach
the lake bottom, allowing more benthic algal growth. In Lake Allegan phytoplankton
may be the dominant form of algae, while in Morrow Lake benthic algae may be more

important due to its shallower depth and higher ﬂushing rate.

In the summer when algal growth was the highest in both reservoirs, nutrient
concentrations changed from the inﬂow to the outﬂow. Morrow Lake was a variable
either a sink or source for ammonium while Lake Allegan produced ammonium at least
in the summer. Nitrate concentrations declined by the outﬂow in both reservoirs during
the summer. However, in Morrow Lake nitrate concentrations approached zero in late
summer (Figure 43), while in Lake Allegan they did not fall as far (Figure 12). Morrow

Lake’s very low summer nitrate concentrations may have resulted from benthic algal

34

uptake as well as denitriﬁcation. Lake Allegan’s ammonium source may be from
sediment mineralization of organic nitrogen and its low nitrate concentrations may have

resulted from phytoplankton uptake and well as denitriﬁcation.

Nutrient ratios show that both reservoirs are potentially nitrogen and phosphorus limited
during the summer, but there was a difference in the degree of limitation (Figures 14
and 45). The greater degree of potential nitrogen limitation in Morrow Lake could have
been caused by ammonium and nitrate uptake by benthic algae. The Morrow Lake
vertical proﬁle showed that ammonium production was greatest at deeper depths
(Figure 64). Benthic algae are able to take up nutrients directly from the sediments and
from overlying water (Hasson 1988). At the same time in Lake Allegan the potential
nitrogen limitation was not as extreme due to ammonium production within the
reservoir. Ammonium is preferred over nitrate as a nitrogen source for phytoplankton
(Reynolds 1984). Based on N:P ratios, nitrogen was never potentially limiting in the
inﬂow waters of either reservoir, although it was potentially limiting in the outﬂow

waters during late summer.

Lake Allegan has an established phosphorus Total Maximum Daily Load to control
algal growth. The undesirable algal blooms reportedly occur during the summer when
residence time is longer, and at that time nitrogen limitation may be as or more
important than phosphorus limitation. These environmental conditions can promote N-
ﬁxing cyanobacteria (“blue-green algae”), which are able to survive in nitrogen limited

systems. Cyanobacteria ﬁx atmospheric nitrogen when dissolved inorganic nitrogen

35

concentrations are low, but phosphorus is available. Cyanobacteria take advantage of
high phosphorus inputs through the ability to ﬁx nitrogen from the atmosphere;
(Schindler 1977). Eutrophic lakes tend to have low TNzTP ratios and are commonly
dominated by N-ﬁxing cyanobacteria (Downing 1992). Lake Allegan is classiﬁed as a
hypereutrophic by USEPA and with average inﬂow total phosphorus concentrations of

84 pg/L in summer 2003 and 67 pg/L in summer 2004 (from my results).

During the summer, Lake Allegan produced ammonium as indicated by higher
concentrations in the outﬂow than in the inﬂow. The ammonium is a source of
dissolved inorganic nitrogen for algae. The vertical proﬁle did not show an ammonium
increase at deeper depths, in contrast to Morrow Lake (Figure 33). I am not aware of
any quantitative information on the composition of the phytoplankton in these
reservoirs. Lake Allegan’s undesirable phytoplankton population could be composed of
non N-ﬁxing algae. Blomquist et. a1. (1994) hypothesized that dominance by non-
nitrogen ﬁxing cyanobacteria depends on the form in which the inorganic nitrogen
source is present; when ammonium is present or internally recycled at sufﬁcient rates,
phytoplankton growth favors the development of non-nitrogen ﬁxing cyanobacteria. N-
ﬁxing cyanobacteria dominate only when both epilimnetic and benthic dissolved

inorganic sources are inadequate to meet the demand (F eber 2004).

36

The role of Silicon
Silicon is another element that inﬂuences the nature and abundance of phytoplankton.
In lakes, silicon concentrations are particularly important for spring diatom blooms. But

how important is it for silicon to remain available throughout the summer?

Silicon uptake varied in each reservoir with Lake Allegan having the earliest and most
persistent silicon uptake, approaching depletion (Figure 13). However, in Morrow Lake
outﬂow waters silicon depletion did not occur until late summer (Figure 44). In Morrow
Lake potential limitation by silicon occurred only in April, presumably when benthic
diatom blooms occurred (Figure 46). However, in Lake Allegan silicon limitation
occurred twice, ﬁrst in April with spring diatom blooms and again in July when there
were increased chlorophyll a concentrations (Figure 15). Diatoms can be silicon-
limited when the available Si:N ratio falls below 1:1 (Turner 2003). In July 2003 in
Lake Allegan, the Si:N ratio fell below 1:1 at the same time the chlorophyll a
concentration peaked. One assumption from the silicon depletion hypothesis is that an
increase in nutrient loading causes an increase in phytoplankton production, especially
in diatoms (Conley 1993). Diatom grth depends on the presence of dissolved silica.
When dissolved silica concentrations become limiting relative to N and P availability,
other types of algae that do not require dissolved silicon can dominate the
phytoplankton community and decrease diatom abundance, and these other algae

include noxious bloom-forming species (Turner 2003).

37

Ratios of N: T P and Si:N as indicators of potential nutrient limitation

The NzTP and Si:N ratios are potential predictors of phytoplankton population shifts
towards less desirable forms. By combining the two ratios one could predict which
nutrients are potentially limiting in a system. Lake Allegan’s outﬂow waters showed
potential limitation of algal growth by phosphorus, nitrogen or silicon/nitrogen

(Figure 16). Morrow Lake’s outﬂow waters are potentially limited by only nitrogen or
phosphorus (Figure 47). Morrow Lake’s outﬂow was never potentially silicon-nitrogen
limited. Silica-nitrogen limitation leads cyanobacteria] dominance and hence to noxious
phytoplankton development. Lake Allegan only showed potential silicon-nitrogen
limitation during the summer (Figure 16). It is important to note that nutrients ratios
only show the potential for limitation; concentrations may remain above limiting levels

and this is often the case in the reservoirs under study here.

Implications for the T MDL

The Lake Allegan TMDL is based on the assumption that reducing point and non-point
sources of phosphorus would impact the phytoplankton population and reduce hannful
algal blooms. The TMDL goal for Lake Allegan is to attain a total phosphorus
concentration of 60 pg/L in the inﬂowing river water. A main conclusion from this
study is that Lake Allegan has a residence time that is marginally long enough to permit
much algal growth. Nutrient concentrations within Lake Allegan are usually high
enough to sustain high concentrations of phytoplankton, and phosphorus concentrations
are not the most important factor regulating phytoplankton. Residence time is

paramount in limiting phytoplankton biomass in Lake Allegan; nutrients are secondary

38

importance and P, N and Si are each potentially signiﬁcant. The same conclusion
applies to Morrow Lake, where the residence time is even shorter, remaining below the

threshold for substantial accumulation of algal biomass for more of the summer.

When residence time is long enough for signiﬁcant algal growth, nutrients become
potential limiting factors. The existing elevated total phosphorus concentrations cause
the current low DlNzTP ratio, and by lowering the total phosphorus concentrations, the
goal of the TMDL, Lake Allegan may shift toward greater phosphorus limitation. But
this does not address the summertime ammonium production, which may be important
as a nutrient supply along with total phosphorus for phytoplankton growth, and in turn
may lead to silicon depletion. Ammonium and silicon could be important as total

phosphorus for controlling Lake Allegan’s phytoplankton population.

Morrow Lake and Lake Allegan are spatially separated reservoirs on the same river
system. Morrow Lake is imperfect as a reference site to establish the Lake Allegan
TMDL parameter goals. Morrow Lake’s residence time (less than 8 days) is not
sufﬁcient for phytoplankton populations to establish, and benthic algae may be more
important due to shallower depth and greater light penetration. The nutrient ratios of
Morrow Lake are different during the summer, favoring nitrogen and phosphorus
limitation and never silica limitation. Ultimately, residence time is allowing
phytoplankton to build up to undesirable levels within Lake Allegan, but not in Morrow
Lake. Ammonium, phosphorus and silicon all potentially inﬂuence algal abundance and

species composition. The internal ammOnium source possibly favors for non-N ﬁxing

39

algae and if so, reducing the total phosphorus concentration may not directly affect the

trophic state until concentrations reach physiologically limiting levels.

40

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43

 

 

 

 

 

 

Morrow Lake Lake Allegan
Reservoir Area (ka) 4.0 6.4
Volume (m0 7.471106 2.1x107
Mean Depth (m) 1.85 3.3
Maximum Depth (m) 5.4 7

 

 

 

Table 1. Morphometric features of Morrow Lake and Lake Allegan.

44

 

 

 

 

Morrow Lake Lake Allegan
Outﬂow Outﬂow

Chlorophyll a Chlorophyll a
RT R2 = 0.59 R2 = 0.59

p <0.01 p <0.01
R2 = 0.715 RI: 0.263
Outﬂow TP p <0.01 p = 0.061
Rf: 0.77 R2 = 075

RT &TP P <0-01 p <0.01

 

 

 

 

Table 2. Regression coefﬁcients and p-values for residence time (RT) and/or outﬂow total
phosphorus (TP) as predictors of outﬂow chlorophyll a for the spring and summer 2003
sampling period (15 weeks).

 

 

 

Morrow Lake Lake Allegan
Outﬂow Outﬂow

Chlorophyll a Chlorophyll a
RT RT: 0.694 R2 = 0.428
p=0.20 p=0.111
Outﬂow TP R2 = 0152 R7 = 0.064
p = 0.387 p = 0.564
R2 = 0.705 R2 = 0.428
RT &TP p = 0.087 p = 0.327

 

 

 

 

Table 3. Regression coefﬁcients and p-values for residence time (RT) and/or
outﬂow total phosphorus (TP) as predictors of outﬂow chlorophyll a for the spring
and summer 2004 sampling period (7 weeks).

45

 

 

 

Morrow Lake Lake Allegan
Outﬂow Outﬂow
Chlorophyll a Chlorophyll a
RT R2 = 0. 533 R2 = 0. 602
p <0.01 p <0.01
18:0. 652 R2=0. 368
Outﬂow TP p<0.01 p<0.01
R2 = 0.767 R2 = 0.602
RT “P p <0.01 p <0.01

 

 

 

 

Table 4. Regression coefﬁcients and p-values for residence time (RT) and/or
outﬂow total phosphorus (TP) as predictors of outﬂow chlorophyll a for the
combined spring and summer 2003 and 2004 sampling periods (22 weeks).

46

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9.3 26:22 II M

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49

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ro

 

now

 

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row

 

row

(a) arnuadulel

50

Average residence time

 

 

 

2 .-
0 j ,
‘5 '5 '5
Q9 Q96 (‘99 (965 (1965 065 065 065 065 065 00": 065 065 065
450 «\ '9‘ a a «.9 a” N99 {50 «0 \0 .9 a» «0
a; a“ -.\ 9'" ‘0 «,0 6 a «\" " a“ o-\"
Sampling perlod

12-

10‘

84

Average residence time
c»

2+

 

 

yardage-era eyes-o“

«0' (390516 690' 59' $0 \0’
,9!» &\Q (My 69" «\ «\N «(5 $5 6", Q\\

Sampling period

'9“?

Figure 5. Lake Allegan residence time (days) preceding each sampling date in,
A) 2003 and B) 2004.

51

Chlorophyll a (pg/L)

Chlorophyll a (,ugIL)

 

 

80W
70.
60'
50-
40-
30-
20-

10-

 

 

Sampllng period

;--o-inﬂow—7l

I
! -o-ouﬂogj

 

T

-,\ 3°“
8 o)

o“
'8} «\

0‘" c“ d" o“ o“
a «\'<\\'\\'5\\"&®

e? o“ o°“o°‘ o‘" o‘"
«9"? 9N6 ”99 (03} 60> $6

Sampling period

Figure 6. Lake Allegan inﬂow and outﬂow chlorophyll a concentrations,
2003 and B) 2004

52

Total Soluble Phosphorus (pg/L)

Total soluble phosphorus (pglL)

4o-

35‘

30-

25-

20-

 

A

-o- ’iSﬂBCv' -
\
‘,'°', , PEWQWJ

 

 

0°.)

'5
Q
a)“ a"?

40-

35‘

30<

25-

 

'» r5 r5 '5 '5 0.-
Q Q Q Q Q Q
o\ u} q} q) 6 \
ii" 59’ ‘°\ 6'" 8 6'9

'5 n.- n; n.- '5
Q Q Q Q Q
n.) «\ \\ b) 9)
‘\ «\N «<5 <8" .50

65

NN

<:>\
Sampling period

i+inﬂow -
i
‘0', , outﬂowj

 

 

go“

$0 «>80

96"

o
'lv

6 b-

a“ 9'”

00b. 00b. $5. 0°“ §
6» «3“ 6’” s” x
‘o\ (00 g“ <5

’\

go“
\"’ u
«\ %\N

“:09 «(‘9
«\N

Sampling period

Figure 7. Lake Allegan inﬂow and outﬂow total soluble phosphorus concentrations,

A) 2003 and B) 2004.

53

Total Phosphorus (Mg/L)

Total Phosphorus (,uglL)

$49

120-

80-

  

60 -
"ii—"mm -
{-O-Outﬂow‘-
4o - * W * 8 * *

20‘

 

 

o I I I I I I I I I I I T

 

"b '5 '5 '5 ’5 '5 '5 '5 '5 '5 '5 '5 '5 ’5
\o \o \0 so \0 o \o \o o \o \o \o \o \o
«3" «9‘ 9““ s” 6" 49> 6°” 6‘“ «‘9 «V‘ «\“J‘ st“ «3'9 :5“

Sampling period

120 -

i-o- inﬂow i
, do 703mg”;

100‘
80 <

60‘

 

4o-

20‘

 

 

0 I I I I I 1 I I I I I I I

b-
Qor «9°? $0 (198‘ moe“ woo“ (too? ‘90 00“ my “99> (so
«\ a a o q> a s {50 «\ ~\
",0 s" 59' ‘3 a” 6 a“ « «V s“

Sampling period

0"“ o‘"
{19 '19
\

x b) ‘8
«<5 <6" ‘8'"

Figure 8. Lake Allegan inﬂow and outﬂow total phosphorus concentrations,
A) 2003 and B) 2004.

54

40-

A

-o- inﬂow ‘
30 ‘ 79:99.99!)

35--

25s

20.

15'

Soluble reactive phosphorus (pg/L)

 

 

25-

20‘

15-

10-

Soluble reactive phosphorus (pg/L)

5-

 

 

 

 

0 v

(as s (as “as as 49°: as Mas s « s

(a s as (as as

$0 «\‘bsss‘

Sampling period

Figure 9. Lake Allegan inﬂow and outﬂow concentrations soluble reactive phosphorus,
A) 2003 and B) 2004.

55

30-

  
 

 

 

 

 

 

3 25-
a
3
5
o 20-
S
o.
0
O
E 15-
0
'2
§
0 10-
2
.g ,-- -- ,
3 ‘-O-inﬂow ‘
‘" 5‘ LTCZ'PUW‘PW,
O I I I l I I 1' I I I I I
'b '5 '5 '5 'b "o ’5 ’b '5 '5 '5 '5
Q Q Q Q Q Q Q Q Q Q Q Q 0
as"? «0° 89° s 99° (19° 59 99° 69 «0° $9 s9 s9 «<9
ss’is s”bs¢bs‘i«\‘<bs“s‘i\"
Sampling period
30- B
g 25~ Finﬂowi
1 Lﬁ-pqtﬂgc‘
3
3 20-
.C
0.
§
n. 15‘
.2
C
N
9
o 10-
2
.D
2
O
in 5.
o I I l I I I l I
ewo°><v°x°oqgv\o<v§°°h°°h $08k
hm
03"" 49 \"° ,9 ‘0\ 66m (9 «)5 «(30' «<9 (‘5 Q9?“ 09"

Sampling period

Figure 10. Lake Allegan inﬂow and outﬂow soluble organic phosphorus concentrations,

A) 2003 and B) 2004.

56

Ammonium Lug/L)

200-

130 ' iio- inﬂow .
.jﬂﬂﬂmﬂ

140- A

120 -

Ammonium (pg NIL)
é

 

 

 

200-

1804

160 4

140 -

120 -

100-

801

60-

4o-

204

 

 

 

0

 

ﬁr

¢¢¢¢¢¢¢
a; «\ “go ,0“ 6‘9 49> be

0" o“ o“ o“ o“ o“
a «5» *“ «<9 «9“ In“ a“ a?

6
Sampling period

g\

Figure 1 1. Lake Allegan inﬂow and outﬂow ammonium concentrations,
A) 2003 and B) 2004.

57

Nitrate (mg NIL)

Nitrate (mg NIL)

3
A
[lirifiozvﬂi
2.5- / iﬂ‘ﬂqvﬂ
24
1.5-/
1‘ O
0.5« . . ° . .
01...r....°°.vw..t

 

 

 

 

 

 

'b '5
0° we 0° 96‘" .96” so” {90" as” 06" é” 0° 065 so” a”
.35" .136 No“ ,9)" 399 (0.99 6'" .99 {50’ .30 .9“ <2? N
'5‘ '9 v) \ ‘3 \ «\ «\ 6'0 ‘8'"
Sampling period
3.
|+iﬁﬁ3ﬁ
2.5-J +ouﬂog}
2a
1.5-
1.
0.5- \/\
o I I I I I T I I
¥@@¢¢@¢@@¢®‘Nﬂ®‘®“x¢@

Sampling period

Figure 12. Lake Allegan inﬂow and outﬂow nitrate concentrations,
A) 2003 and B) 2004.

58

 

 

 

    

 

 

5 37mm]
A i79109‘901‘0
5-1
A 4-
=1
i7:
5!
15, 3-
§ °
9:,
2.
1' o
o I I I I I I I I I I I I I
965 065 065 055 055 065 365 oéb oQ?’ 065 055 055 95: 065
a,“ «0 o0 is” o” «.9 s30 90 of” «\"v «0 db 9,9 \0
«5950‘? new 66" i«\“«\’5s\‘%\¢o‘
Sampling period
6 B
5 ..
A 4-
.l
h
I!)
U!
E 3‘
II
.2
in 2.
{imam
1' l-z-MEMJ
0 l l l l I I I I I I l I l
we eoeoeooe
49 «0° 00° $9 69 69 «30° <59 {59° «0° «9 9‘9 99° 69
o‘own‘nmﬁéiée‘ic‘Wo‘qﬁ ‘

Sampling period

Figure 13. Lake Allegan inﬂow and outﬂow silica concentrations,
A) 2003 and B) 2004.

59

DlNzTP (molar ratio)

DlNzTP (molar ratio)

120 -

11° ' A I-O-inﬂow q
100 - ' ‘IQZOBtfPlNl
90 a
80 i
70 +
60 i

 

 

Sampling period

120 1

110 4 B rim;
100 a L—g—outﬂowj
90 ~
80 4+

 

 

 

‘90?

09' 00“ 00“ [19'0“ 0.0“
0.559 49“ $9M 9,89 499$ @609 :Légcng «(596‘ 09¢

Sampling period

Figure 14. Lake Allegan inﬂow and outﬂow dissolved inorganic nitrogen (DIN) to total
phosphorus (TP) ratio. Dashed lines show the thresholds of potential nitrogen limitation

(DIN:TP less than 10) and phosphorus limitation ( DIN :TP greater than 20),
A) 2003 and B) 2004.

60

Si:DIN (molar ratio)

Si:DlN (molar ratio)

2.5 -

 

{-0- inﬂow ?
L-°-___29.tﬂ9_u9

 

 

 

Sampling period

2'51

21

  
 
  

.3
(Ii
1

A
4

 

 

05$

0 U I U V U T V U I I 1 U
c“ 0" e e“ a? e“ o“
$9 «50$ «0° $9 «30° «299 9’9 69°“ 90° 49 «0° £9 £9
«9‘5 9" i9 " oi” e a l «0 6 9}" e’5 o)"

Sampling period

Figure 15. Lake Allegan inﬂow and outﬂow silica (Si) to dissolved inorganic nitrogen
(DIN) ratio. Dashed line shows the threshold of potential silica limitation
(less than 1), A) 2003 and B) 2004.

61

 

 

 

 

 

 

3‘7— i""'"'""""'""""""""""'""""_':_:"‘
| Oinﬂow : I
o l ooutfiow I
4 A I FM" '
2.5
I I
I I
I I
a 2* r I
E I '
a I o‘ : :
° 15 I 0 '
g | ‘ i
E I o 0 o i
g. I o o q I
U) 11F I — - u r o - I — ————————————————————— — —-I
8 : . '
o
0.54 8 'I I
o l |
I . |
I J
o — ‘ _I_ -_ __ j r j I W —— —_ -—--___ U
0 1O 20 30 4O 50 60 7O 80 90 100 110 120
DIN:TP (molar ratio)
3' l"""‘""""""'"'"""""""""T ----- i
I omﬂow I
I ooutﬂow i
I I .
2.5 B | I
o l
i I
I
A 21 C . O I
o I l
“‘5 ' 0 . l
5 : I
o s I
515 b I
_ i . l
(E!) 1 I O l
o : o I
I o
0.5I : I
. I
l l
0 —- . r .—— . i - . r T- . . --'.
0 10 20 30 40 50 60 70 80 90 100 110 120

DIN:TP (molar ratio)

Figure 16. Lake Allegan inﬂow and outﬂow dissolved inorganic nitrogen (DIN) and
Silica (Si) ratio versus dissolved inorganic nitrogen (DIN) to total phosphorus (TP)
ratio. Nitrogen limitation is represented by the solid-line square, phosphorus limitation
represented by dashed line, and silica limitation represented by dotted-dashed line,

A) 2003 and B) 2004.

62

deg. C

 

 

 

0 U I U I U I f ﬁ I I V U U I

"b ‘5 '5 ‘5 '5 '5 ‘5 ‘5 '5 '5 '5 ’5 ‘b '5
(90 «\Q 6° $Q $9 (90 69 $Q (9Q «\Q $0 $0 ‘99 I\\0
r9“ 50 a“ v.0 ‘3 «ii 6 e" I‘ «\" «<5 «3“ «ii a“
Sampling period

30-

25-

20-

15‘

deg.C

 

10‘

 

 

e“

N»)
6 «case

age

’\
e“ e

h
f ifﬁffﬁﬁfﬁﬁ

VI
b9

Sample period

Figure 17. Lake Allegan inﬂow and outﬂow temperatures, A) 2003 and B) 2004.

63

50 -
A +ow
4o - ‘:°-°I{tﬂ°wi
35 .
30 -
25 -

20‘

Total suspended solids (mgIL)

 

 

I l v v I I l I l l I

0
0 0 '5 0 0 0 0 0 0 '5 0 0
0° 0° 0° 0° 0° 0° 0° 0° 0° 0° °
(L 00 59 99 $1! (00 90 ,va «(iv \{1'
0" u” ‘0‘ oi” a e" 4‘ 0“ «9’

"b '5
Q Q
Q Q Q
.39 (1?? (‘0!
It} 9} <2)

Sampling period

50-
B

45 «
40 <

F" 7” ’ a
35 . i-O-Inﬂow i
itoytﬂwg‘

Total suspended solids (mgIL)
N
U!

 

 

 

0 l I l I I r I v I I I I I

v. u b. v. 9.
0° 0° 0°h 0°“ 0° 005. 0°“ 0°“ 0°“ 0° 0°“ 0° 0°“ 0°“
,be «\W Q9 £14 ‘60 ,5]; (00 CD0 .50 «(to ,\\'Ir 5‘} $0 \{I’

e“ 00’ 0‘ ii” a a” \" 0‘ «9 «<5 \" e” 0}“

Sampling period

Figure 18. Lake Allegan inﬂow and outﬂow total suspended solids concentrations,
A) 2003 and B) 2004.

Oxygen (mg/L)

Oxygen (me/L)

20*

 

 

 

 

 

 

 

 

(firm—03;“!

18* £0:ny

16-

24

O 1 I T I I I U I U I I I V

0 0 I5 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 \0
0\ «\ 0\ s 0\ 6 0\ I9 «\ x u q) \
rs“ «.9 a“ 0 309966" «‘«i‘ébe‘ .3990

Samplingperiod
201 B
18- _.._L_____,,
+inﬂow1

164

14-

12«

101

8d

5.

4d

2.

o I V I I I I I I l I j I I
2909's" .966 %e «e «\ e 0 o>

Sampling period

Figure 19 Lake Allegan inﬂow and outﬂow oxygen concentrations,
A) 2003 and B) 2004.

65

Percent saturation

Percent saturation

250 -

‘ +inﬂow I;
l
L ,_'°; 1 01‘1“?! J

200 -

 

 

 

o I I I I I I I I I I I T I

 

 

"b "b ’5 '5 “J ‘b '5 "b "b "b '5 '5 ‘5 ‘b
o\o\o§\oo\o\o%\o,\\o\\ob§o§¢o
«$3 49 9'9 99’ 69’ a"? 6'" 6'9 4‘ e" «<5 e“ :6” \"
Sampling period
250 -
3 {3336367}
Leo-outflowI .
200 -
O
150 - ° '
100 a
O
O
50 .
o I I I r I I I I I I I I I
°‘ o“
«9‘5 ,9 e" .9 6" 69> 6 e" *‘ e" «<5 e“ e” \"

Sampling period

A) Figure 20. Lake Allegan inﬂow and outﬂow percent oxygen saturation,
A) 2003 and B) 2004.

66

Oxygen (mgIL)

25 --

 

 

 

 

”-O-oxygen’

[TM ‘7 30
204 ....o°+-29
_. . --29
15A . . °. -.." ‘Pza
‘ '.° °. «~28
10d \,. --27
-L27
5'- --26
«P26
0 1 : : : a r 25

12:00 PM 4:00 PM 8:00 PM 12:00 AM 4:00 AM 8:00 AM 12:00 PM

Time

Figure 21. Lake Allegan diel cycle on 8-9 August 2003.

67

deg. C

pH

 

 

7 I I I I j' I I I I I I I ﬁ
\Q‘b \be \be o” 55 $65
(L

eaobiqi
o‘e'iu‘u’i'o‘e

’5
Q
6"}

"b e '5 '5 '5 '5 '5
o o o o o o o
o} *9 «\ \\ v) G
N
6 ’\\ «N «9’ it)" 29’ e

Sampling period

90

 

[:0- inflow—7i

[10: outﬂow '

 

7

 

T I

o“

,3

’5‘ 9\

5y $0» we

@@®“®“®“°’®“\°‘\°‘®°‘
'3’ «0‘9 0'3 0"“ 69’ 0'9 e” e’s’ «‘5 «<3 0

Sampling period

Figure 22. Lake Allegan inﬂow and outﬂow pH, A) 2003 and B) 2004.

68

Calcium (mglL)

90

80

704

604

50-

40-

30‘

20s

104

 

‘F-o- inﬂow i

-0-outﬂow 1

 

I I j

"J '5 '5 '5 ".9
\0 \° \° 0 \P

I r I I I I I I

'5 '5 '5 '5 '5 '5 ‘5
\Q \Q «\Q \\Q &Q 0 Q0
6\9 «<5 «\N «<5 %\ (‘6 (SN

Sampling period

Figure 23. Lake Allegan inﬂow and outﬂow calcium concentrations for 2003.

69

AlkalinitymquL)

 

 

 

6000 -
2000 «
3330377
I l
1000 . imﬂi
O I I I T I I I II I I I T I
“a ‘5 '5 "b ‘5 '5 ’b ‘5 ‘b “J ‘b ‘5 ‘b ‘5
\° 0° 0° 0° 0° ° \° 0° 0° 0° 0° 0° 0° 0°
0"” 0° 0" 0° ‘0‘ 0°") 6” 0" °\ 0" 0° 0" 0° 0‘

Sampling period

Figure 24. Lake Allegan inﬂow and outﬂow alkalinity concentrations for 2003.

70

Calcite saturation index

1.8-

 

 

 

°-4 ‘ ?-°-._._M9_w;
0 . 2 '
0 e o I I I I I j I I I T I I
“J ‘5 '5 '5 ’5 "b ‘5 '5 '5 ‘5 ‘5 '5 '5 ’5
($0 «\Q 6° $0 $0 0 6° $9 (90 «\Q Q0 $9 $0 \9
a)" 0" 0" 0'” ‘°\ 09> °\ 6" ’\\ :0" '0” ‘0‘ «0” 0)"

Sampling period

Figure 25. Lake Allegan inﬂow and outﬂow calcite saturation index for 2003

71

Magnesium (mglL)

a)

30-

 

 

Ewe-WW!
mwj

 

o r I I I

'5 ‘5 '5 ’5 "b '5
\o 0 \o 0 0 o
“'5 09 0"0 0°" 6% 0°“)

I I I I I I I I

’b ‘b ‘b ’5 '5 '5 "b '5
\° \° \° \° \° \° \° \°
66" 6\9 «(b «('6 «(b\ 65“ Grub cb\'\'\
Sampling period

Figure 26. Lake Allegan inﬂow and outﬂow magnesium concentrations for 2003.

72

Sodium (mg/L)

45

404

35*

304

25‘

20-

154

10-

5d

 

0

   

? +infiow E
|

|
', -O-outﬂow r

 

“a
o
,{0

\
<9

65

I I T I I r j ' r 1 *‘r I '

’b '5
\ \° °

b-\

0'!) Q“:
'13" \
0 e

0., 0
\° \° \°
63 0'9 “(5 «<6 «(5"

Sampling period

Figure 27. Lake Allegan inﬂow and outﬂow sodium concentrations for 2003

73

Potassium (mg/L)

 

 

 

 

:4— inﬂow
[-o-outﬂow:
1 .
o I I I I I I I I I I I T I
‘5 ‘5 ‘5 ’5 ‘5 ‘5 ‘5 ‘5 ‘5 ‘5 ‘5 ‘5 ‘5 ‘5
‘90 «\0 $0 $0 $0 Q \Q 99 (90 «\Q Q0 $0 $0 \\Q
° 0° 0° 0° P‘ 0’9 0° 0" 0‘ 0° 0° 0" 0° 0"

Sampling period

Figure 28. Lake Allegan inﬂow and outﬂow potassium concentrations for 2003.

74

Chloride (mg/L)

100
90
80'
70-4
6%
50.
401
30-4
20-

10‘

   

l-O-i inﬂow 1
if .2300!

 

 

‘5 ‘5 ‘5 ‘5 ‘5 ‘5 ‘5 ‘5 ‘5 ‘5 ‘5 ‘5
0 \0 o 0 0 0 \o \o .00 \o o ,0

I I I I I I I I I I I

hi
0 0 0" 0

Sampling period

Figure 29. Lake Allegan inﬂow and outﬂow chloride concentrations for 2003.

75

Sulfate (mglL)

801

401

30‘

20“

 

 

T—a—TnioTi
'_:'°'__9“_W’1V.f

 

I r I I j I I

‘5 ‘5 ‘5 ‘5 ‘5 ‘5 ‘5 ‘5 ‘5 ‘5 ‘5 ‘5 ‘5
Q Q Q Q Q Q Q Q Q Q Q Q Q
0 0 0 0 0 0 0 0 0 0 0 0
0° 0N 0° ‘3‘ 0°» 6 0" 0‘ 0" 0° 0" 0° 0°
Sampling period

Figure 30. Lake Allegan inﬂow and outﬂow sulfate concentrations for 2003.

76

Total Phosphorus (,ug/I)

 

 

 

 

 

O 25 50 75
0 l l /’
1-— -\ ~
2—

ss-

.C

5.4"

(D

o 5_ r
6*- \
7...-
8 l l l J
0.0 10.6 21.2 31.8 42.4 53.0

Chlorophyll a (,ug/L)

Figure 31. Lake Allegan vertical proﬁle concentrations of total phosphorus (solid line)
and chlorophyll a (dashed line). The inﬂow total phosphorus concentration for the day
44.8 ug/L was and the inﬂow chlorophyll a concentration was 2.8 ug/L.

77

TSP (,LLg/L)

 

 

 

 

0 10 20 30

0 l l

1— / ~

2- 1’ / -
E 3- f -
.c —- ~
0“ f

6— \ —

7:- - ..

8 l l l l

0 2 4 6 8 10
SRP (,ug/L)

Figure 32. Lake Allegan vertical proﬁle concentrations of total soluble phosphorus
(TSP) (solid line) and soluble reactive phosphorus (SRP) (dashed line). The inﬂow total
soluble phosphorus concentration for the day was 32 ug/L and the inﬂow soluble
reactive phosphorus concentration was] 8.2 ug/L.

78

Ammonium (,ug NIL)

 

 

 

 

0 30 6O 90
0 I \
1r I _
2P \ '—
:e: s- \ -
'c .— —.
a4 i
o 5_ T _
6* t r
7' ' ~
8 l l

0 240 480 720
Nitrate (,ug N/L)

Figure 33. Lake Allegan vertical proﬁle concentrations of ammonium (solid line)
and nitrate (dashed line). The inﬂow ammonium concentration on the sampling
day was 16 ug N/L and the inﬂow nitrate concentration was 1320 pg N/L.

79

 

 

 

 

 

O 8 16
0 I f
1_
2—

E 3—

.C

a 4’

(D

D 5-
6....
7— e
8 l l
O 5 10 15

Oxygen (mg/L)

Figure 34. Lake Allegan vertical proﬁle of temperature (solid line) and oxygen
(dashed line). The inﬂow temperature for the day was 19.5 C and the inﬂow
oxygen concentration was 9 mg/L.

80

Conductance (,uS/cm @ 25 C)
0 90 180 270 360 450 540 630

 

 

 

 

0 I I I I I m
1* /
2* /
E 3* /
5 4_
§ 5_ l
6_ 7
7— e
8 I I l
7.0 7.5 80 8.5 9.0

pl-l

Figure 35. Lake Allegan vertical proﬁle of conductance (solid line) and pH
(dashed line). The inﬂow conductance for the day was 689 uS/cm and the inﬂow
pH was 8.4.

81

 

Average residence time

 

 

Sampling period

Average residence time
&

 

o I I I I I I I I I I I I

0 0 0 0 0 0 0
09°“ 0°° 40°? 09¢ 0°§ 0°" 0°° 0°° 0°° 0°° 0°
0" ‘5 0 3 \" "‘ '0" '0'” 0" "

Sampling period

Figure 36. Morrow Lake residence time (days) preceding each sampling date in,
A) 2003 and B) 2004.

82

70-

 

 

 

A Poi-inﬂoiwil
60 - $910140?!»
50
3 1
B:
3
2 4o-
3.
i
e 30«
2
5
20«
10-
O I I I I I I I I I I I I I
00000000000000
Q Q Q Q Q Q Q Q Q Q Q Q Q Q
00000 <0\\\00\0
0‘ 0° 0° 0° 6‘ 0°“) 0 0°‘3 0‘5 08 0° 0° 0°" °
Samplingperiod
70-
60- hie-Inflow]
Lfoumow;
.. 50-
.1
a, B
3
a 40-
3.
S
g 30<
.0
5
20«
10-
0 I I I I l I I l I I I I I

 

 

0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 \ \ \ 0 0 0 \ 0
0° 0° 0" 0° ‘0 0°”> ‘3" 0“)“ “‘6 0° 0° 0° 0°Q’ 0‘

Sampling period

Figure 37. Morrow Lake inﬂow and outﬂow chlorophyll a concentrations,
A) 2003 and B) 2004.

83

90 -
i-o-inﬂow“ I
8°' ‘:°,‘9“Iﬂ‘lwr

70-
A

60-

50-

Total soluble phosphorus (pg/L)

 

 

o I v I l I I I I I r I I ﬁt

'5 '5 '5 '5 '5 ‘5 '5 '5 '5 '5 '5 '5 '5
o o o o o o o o o o o o
q'\\ o\ qr) ‘b\ ,0) 30 <0 P} ’\\ ,{0 0 $0 \\
\ 00" I0 ‘5 0 0" ’\\ «\N ’\\ It)" ‘5\ 9"

‘5
Sampling period

90-

80 : 3:15.13; I
;-0-outﬂow ‘
70 - 7* 7 , 7'"

60‘

50-

40-

Total soluble phosphorus (pg/L)

 

 

 

0 I 1 r v I I I I v v I

(@QF '59“
<0

0 0 0 0 0 0 0 0 0 0 0 0
r5\ 0 0 0 \ \ \ \ \ \
0" 0° 0" 0° 6“" 0°“ 0° 0°" 0"” 0°“ 0'" 0"k 0

Sampling period

Figure 38. Morrow Lake inﬂow and outﬂow total soluble phosphorus concentrations,
A) 2003 and B) 2004.

84

Total phosphorus (Hg/L)

Total phosphorus (irgIL)

0)

\0“\°°‘\°"\°°‘\°°‘°°‘\°”‘
0<5 08 0° 0°“ 6°” 0'£13 0°

160 -

‘Ii-o-aniiciwﬂ1
14° ‘ Ito-Pump!
120 .
100 -
80 -

60-

 

0 I I I T l

'5 '5 '5
Q - Q Q

'5 '5 '5
o o o
(50 ‘9) 66.3

065 «\be
° 0° ‘3 0

P.» '5
o o
o\ 0
N 0'"

b-\ «\

Sampling period

160 -

(Poi-inﬂow I
l ,0 LOE‘ﬂQW.‘

140 «

120 -

100 -

80-

60~

40-

20-

 

0 I l I I I

©(\

Sampling Period

A) 2003 and B) 2004.

85

'5
\°
,9

1

'5
50°
6\

°‘ 0“ 0‘" °‘ 0‘"
\°°‘ \° 0 0 0° \
0’ “<5 0" 0" 0" 0'3,

$0?

\\
q\\

\65

f

Q5

'5
o
(0

 

Figure 39. Morrow Lake inﬂow and outﬂow total phosphorus concentrations,

70-

60q

40-

Soiuble reactive phosphorus (,ugIL)

 

 

 

seessee
o°o°o°o° o°o°

‘iv ‘io ‘lo
00° 0%“ 0'9 Q0 6.0 «(0 «(0°

'5
{19°
0
55"

0° 0°

Sampling period

70-
60-I
50‘
40‘
30‘

20'

Soluble reactive phosphorus (ugIL)

10‘

 

 

 

0 u
M033 008080808080 ¢@;'\0°“.0°\0°‘r

0 0
Sampling period

Figure 40. Morrow Lake inﬂow and outﬂow soluble reactive phosphorus concentrations,
A) 2003 and B) 2004.

86

8

1+ iii—030*}
‘0' -._ BEWQY‘J

8
L
>

Soluble organic phosphorus (,ugIL)
B 8 8 ‘o" 8 5‘

—I
o
n

 

 

 

 

Sampling period

801 B

70‘

    

60 -
F’"_ j—‘Q—"'
i-O-Infiow I
IMP-willow

V.

o I I I I I ‘ I ' I ' '
000000000 00006.00
‘lv :1, @
($90 (566" $0 ”90$" 0‘80 6’0) 09;» 0'90 «(50 05$ «(90. $09, $09} $50
Sampling period

50:

   

40«

30-

20-

Soluble organic phosphorus (,u,gIL)

 

10'

 

 

Figure 41. Morrow Lake inﬂow and outﬂow soluble organic phosphorus concentrations,
A) 2003 and B) 2004.

87

Ammonium (ug NIL)

120 - 7 7 , ,,
A ;I+inflow ‘

-O-outﬂow‘
100- "’"’”‘

Ammonium (,ug NIL)

 

 

 

 

 

 

o l I I I I I I I I I I I

‘5 ‘5 ‘5 ‘5 ‘5 ‘5 ‘5 ‘5 ‘5 ‘5 '5 '5

Q Q Q Q Q Q Q Q Q Q Q Q
0°° 0°° 0°° 0°° (0’9Q 0°° 0°° 0°° 0°° 09 0°° 0°° 0°° \°°
0°0°0°0°°a0°60° 0‘ \°0°\°\°

Sampling period

60-

50<

40-

30-

20-

10-

o l I I I I I I I I I l I I

bx D: 5 5

é,0 (90* '90 mg 0“ Q0 00 $00 .0" (90* 0° $00 $00 090
00000000000000
0°0°0° 0° 990° Qi0“ 00°0°0°0°0°

Sampling period

Figure 42. Morrow Lake inﬂow and outﬂow ammonium concentrations,
A) 2003 and B) 2004.

88

Nitrate (mg NIL)

Nitrate (mg NIL)

 

 

 

‘5 ‘5 ‘5 ‘5 ‘5 ‘5 065
0 0 0 0 0 0° .,°0 90 0° 0 0
0 {1' 0 ° 090 0° 09
009608!» M000 0“; .9. $09®§
Samplingperiod
3.
25. :ihﬁdgj B
-o—outﬂow1
2.
1.5-

 

 

osJ A \

0000000000000
09 0°00” 0M0 0°W0°¢i060° M00000 0

Q

 

 

 

Sampling period

Figure 43. Morrow Lake inﬂow and outﬂow nitrate concentrations,
A) 2003 and B) 2004.

89

7 ‘ 1+ inﬂow, .
A 59:9UEOEJ

Silica (mg SiIL)

 

 

0 I I I I I I r I I I I I T

'5 '5 'b ‘5 ‘5 '5 "5 '5 '5
Q Q Q Q Q Q Q
0‘ 0° 0" 0° ‘3 0° 0 0" 0 0

Sampling period

 
 
 
 

7”,? ,, ﬂ
[-o—Inﬂow ‘
lﬁwﬂpﬂl

  

Silica (mg SiIL)

 

 

o I ' I I I I l I I I V I ﬁr
0 0

0°“ 0 0° 0° 0°“ 0°“ 0°“ 0°“ 0°“ 0
0° 0° 0° 0° 0° ° 0° 0° 0° 0°
'\ 41. N “(1. ¢_,\ 6'03 6 6° \ «\N

0‘" 0“ 0“
r5\ b} ’\

'0 0 ~\
0’5 0‘ 0° 0‘

Sampling period

Figure 44. Morrow Lake inﬂow and outﬂow silica concentrations,
A) 2003 and B) 2004.

90

9° ' “"’.*‘"‘*1
A '-O-|nﬂow ‘

80 - :_-_0_- outﬂow J

DlNzTP (molar ratio)
a:
o

 

 

DlNzTP (molar ratio)

 

 

 

 

Sampling period

Figure 45. Morrow Lake inﬂow and outﬂow dissolved inorganic nitrogen (DIN) to total
phosphorus (TP) ratio. Dashed line shows the thresholds of potential nitrogen limitation
(less than 10) and phosphorus limitation (greater than 20), in A) 2003 and B) 2004.

91

18 -
17 0 ,«ww.-.

16- lf-o-ini‘iow }

15 - ire-3910!! A
14 -
13 0
12 .
11 -
1o -

Sl:DlN (molar ratio)
to

 

 

 

Sampling period

17 - 1 ‘_L___,____]
g-o-inﬂow
16 d l

{-0-outﬂow B

Si:DiN (molar ratio)

 

 

 

Sampling period

Figure 46. Morrow Lake inﬂow and outﬂow silica (Si) to dissolved inorganic nitrogen
(DIN) molar ratio. Dashed line shows the threshold of potential silica limitation relative to
nitrogen (less than 1), A) 2003 and B) 2004.

92

20
18
16
14
121
10 i

31

SlleN (molar ratio)

 

O

201
191
181
171
161
151
141
131
121
111
101

Sl:DIN (molar ratio)

 

[inﬂow 1
Lo outﬂow ‘1

0e

i o co ’
O . Q.

' 0 e 9 09

 

I—hI—ol—l—o-e—l—l—o—lﬁl_o—orl
04%

I — I h -—
' p_.___.__r___.___.__.____7m__

 

O—‘-‘ — -— ——_—- - -
ﬂ—wT———-T—'—_—k_*T—__f—ﬁm'_——T_Ff—ﬁ_—fﬂ "D

10 20 30 40 50 60 7O 80 90 100
DIN:P (molar ratio)

r - :w-L- -------------------------
loinﬂow 1
{992091.

CD

0

l
|
1----..
L
!
l
!e
L
I
I

 

I
.11.

 

 

p
b

 

A
O
N
O
03
O
b
0
(II
C
O,
O
N
O
(D
O

100
DiNzTP (molar ratio)

Figure 47. Morrow Lake inﬂow and outﬂow dissolved inorganic nitrogen (DIN) to Silica
(Si) ratio versus dissolved inorganic nitrogen (DIN) to total phosphorus (TP) ratio.
Potential Nitrogen limitation is represented by solid line square, phosphorus limitation
represented by dashed line, and silica limitation represented by dotted-dashed line

93

deg C.

deg. C

30-

251

201

     
 
  

(SIREN!)

 

 

15 - L'S'PFLWEVL‘

1o -

5 .

o . . . . . . . . . . . .
0365 4990 £90": £90 4&0 4965 0665 60°65 '\ @015 «(365 «0‘65 $590 0&5 $~¢Q15

Sampling period

30 - B
FO—inﬂow i

“(J-outwit!
25 1 r"‘ ’

2011

 

0 F T

I I

I I '7 I ‘1' I

 

I

0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 \ 0 0 x 0
0‘ 0° 0N 0° 6 0°q> ‘3 0“ 1‘ 0° 0° 0‘ 0° 0‘

Sampling period

Figure 48. Morrow Lake inﬂow and outﬂow temperatures,
A) 2003 and B) 2004.

94

80 . ,____ __
1+infiow ‘

7o 0 ire-211m»! i

Total suspended solids (mglL)

 

 

 

45 1 ($7017.? 7
4o -
35 - B
30 ‘
25 "
201

1511

Total suspended solids (mglL)

10-

5c:

 

 

 

O I .

0°0°0° 0‘"
0” 0000000000000
‘59-

{1,

‘11

1:)
Sampling period

Figure 49. Morrow Lake inﬂow and outﬂow total suspended solids concentrations,
A) 2003 and B) 2004.

95

Oxygen (mg/L)

OXYQGN (mglL)

000000000000
0‘9 0'9 0"°\ 0°‘)) 0) 03> $6 0“» «<9 0° 0°"\ 0'";

16 . 901.1110} 1
59: 0,149va ‘1

  

 

 

0 I I I r I I I I I I I ‘F

0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0
0\ '\\ 0\ 10 0\ '13 9} 0} '\\ \\ I) \
0° 00’ I0" 10'" '°\ 90'" 6 0" K (“P

'5
\°
“<5 «\ 10'” 10"

Sampling Period

B 1’ 4:11.110?” '1
14 ‘ ire-outﬂow;

 

 

0 I I r I I

'5
\Q

q\'\

 

 

I ﬁi

,0 0“
0° 0‘
Sampling period

Figure 50. Morrow Lake inﬂow and outﬂow oxygen concentrations,
A) 2003 and B) 2004.

96

I

i" “’_T_———j
‘-O- Inﬂow i
{—03.203995

 

 
 

60-

Percent saturation
on
o

40-

201

 

 

'5 0 0 0 '5 0 0 15 q, 05 .5 .5 ,5 0
°°° Q \°‘° \°°° 0‘90“ 0° 0° 0° 0° °° 0° 0° 0
N N
“965 ‘56} N0 ”’9‘ ‘5?) \‘1' 66" \‘q «<5 0'3 «(5 90“ 6113’ 9\
Sampling period
160 -
14o «
120 -

100 11

 

 

Percent saturation
on
O

 

 

60 1-
4o -
20 -
o 0...,,,"f1"
$0“ (900“ $0“ £0 0°” 0 090 0°“ $0 «(50 «(30 «(5,0 $0 0 ,0 $0

Sample period

Figure 51. Morrow Lake inﬂow and outﬂow percent oxygen saturation concentrations,
A) 2003 and B) 2004.

97

OXYgen (mglL)

 

 

 

 

25 23
- 27
~ 26
L25 E.
0 24

5 ‘ b 1 - 23

o 1 4. .L : 1‘ 4. : ‘r 4 22

0009‘} (650$ 690$ '95.??? .506“ 6§°Q¢ $0§ 6,9"? 39$ {96‘}

Time

Figure 52. Morrow Lake oxygen and temperature diel cycle on 25-26 August 2003

98

A

‘-O- inﬂow .
:0' OU‘IIQWL

 

 

 

7 I I I I I I I I I I I I ‘I

0
0
<9

‘5 '5 '5 “J '5 '5 ‘5 '5 '5 '5 “J
0 0 0 0 o 0 0 0 0 0 0
0 0° 0No 0° 0‘" 0°“) 6” 0“” *‘n’ 0‘“ 0° 0‘“

‘5 ‘5
0° 0°
0° 0"

Sampling period

pH
(D

1+ inﬂow .
1'0', Sling“ ‘

 

 

7 I I I I

I I I I I

0‘"
N»)

b-
\"J\°> (‘9‘ "5°0
'0 1\\ v0

0
\05‘ \0“ \0 0“ 0“ 0°
0° 9,1,0 6% 69> .000 6,9 ,\

0 0
0’3 0° 0

,0 \\0
0° 0

Sampling period

Figure 53. Morrow Lake inﬂow and outﬂow pH concentrations, A) 2003 and B) 2004.

Calcium (mglL)

80-
701
60¢

50 -1
4o , 1330.60":
i-O-outflow“J
30 -1
20 -

10-

 

 

o I r r I U U U U V ‘I' I

‘5 ‘5 ‘5 ‘5 ‘5 ‘5 ‘5 ‘5 ‘5 ‘5 ‘5 ‘5

\0 \0 \0 $0 0 0 \0 0 \0 ,\\0 ”(0

0° 09 0"0 0° 43° 0°?) 6‘6 0'3 «‘9 0° 0° 0"
Sampling period

Figure 54. Morrow Lake inﬂow and outﬂow calcium concentrations for 2003.

100

Alkalinity (,uoqIL)

6000 a

 

 

 

122.0%
2000+
1000 -
0 T T T If l 1* 1 ﬂ f ‘F *U I I
‘5 ‘5 ‘5 ‘5 ‘5 ‘5 ‘5 ‘5 ‘5 ‘5 ‘5 ‘5 ‘5 ‘5
Q Q Q Q Q Q Q Q Q Q Q Q Q Q
«\ \ 10 \ \ \ 10 1\\ 0 0 \ 0
0"”; 0° 0" 0° 6% 0'9) 0° 0’35 4‘ 0‘ 0° " 0” 0"
Sampling period

Figure 55. Morrow Lake inﬂow and outﬂow alkalinity concentrations for 2003.

101

Calcite Saturation index

 

 

 

0.2 1
0.0 1 I V I r T 1
05° 0 0 0 0 0 0 0 0
055 0°n” “(50° W60° «0°60 30° “0° 0° 0° ‘90 0° 00°
0“ 0“ 09° \‘9 £4” <9 (‘0' 0"“ 0‘ ‘6“ 0
10 10 10 “00" ‘0 ’\ 1\\ 0 10 10'" \
Sampling period

Figure 56. Morrow Lake inﬂow and outﬂow calcite saturation index for 2003.

102

Magnesium (mglL)

30-

 

 

iiinﬂoW—i
257 [m
20 -
15 4
10 -
5 .
0 1 j ' ' v u u u 1 , 1 j '
'Sklgéb “9&6: $965 £190 6665 030(965 6665 6'96, «{9th «(663 «(5&ch 3&965 #1395 g\’\'\\65
Sampling period

Figure 57. Morrow Lake inﬂow and outﬂow magnesium concentrations for 2003.

103

Sodium (mglL)

30-

25"

20-

10-

 

  
    

i-O- inﬂow :
i-O- outﬂowﬂi

 

I f l I r f T U I I I I

‘b "b '5 '5 ‘b 'b 'b ‘5
Q Q Q Q Q Q Q Q
(o\ q\ 0} ’\\ \\ ti 2} -\\
6 6" «\ N <5 \" é” o)"

'5 '5 ’5 '5
s is a q>°
’\ hp" 9} (00 I\\ t\ %

Sampling period

Figure 58. Morrow Lake inﬂow and outﬂow sodium concentrations for 2003.

104

Potassium (mglL)

     

 

 

ﬁxinﬂow ’1

J L—g—outﬂow,

24

11

0 I I I f I T I I I I I I j
‘5 ’b “J ‘5 "J "b '5 '5 '5 ‘5 '5 ‘5 ‘5 ’5
0 0 0 0 0 0 0 0 0 0 0 0 0 0
'5‘ ’\\ 0\ s 0‘ \ \ '5‘ ’\\ \\ b} 0\ \\
«9" a” a“ 9‘0 ‘3‘ '9 a” 6'9 «‘ «\“ «<5 a“ «b0 «5"

Sampling period

Figure 59. Morrow Lake inﬂow and outﬂow potassium concentrations for 2003.

105

Sulfate (mg/L)

80-1
70"

60.

 

    

 

50 1
é-o- inﬂow ,

4M 229%?!

30 4

20 '-

10 'i

0 j I I I I I I I I I I I I

'5 '5 '5 '5 '5 '5 ‘5 ’5 '5 '5 '5 '5 ’5 ”J
<99 (£60 \60 (‘90 69 (£99 6° ’90 «(99 ’69 Q’QQ \&0 09 ($5
a .9 a a 6 a «\ «\ a 0 e

Sampling period

Figure 60. Morrow Lake inﬂow and outﬂow chloride concentrations for 2003.

106

Chloride (mglL)

._ lizmmr 9"! W"i¢-m4“3‘ ‘

 

 

 

90!
so F-o-annow'i
« {:23wa
204
10‘
o I I I I I I I I I I I j I
‘b ‘5 '5 ’5 "b "b 'b ‘b ‘b "b "b ’b ‘5
Q Q Q Q Q Q Q Q Q Q Q Q Q Q
®«\0\&$q>¢a\0\r9«\~\9q>~\
«9“ a“ a“ a” ‘0‘ a“ a a“ «‘ «\" «<5 a“ a” a“

Sampling period

Figure 61. Morrow Lake inﬂow and outﬂow sulfate concentrations for 2003.

107

Total Phosphorung/L)
O0 25 5O 75

 

 

 

 

1
1- 1 -
2* /’ ‘

E 3*- / “i

.c r _

a 4 \

D 5- ,\ _
6' ’ "
7.. ~—4
8 l l 4 i
0.0 10.6 21.2 31.8 42.4 53.0

Chlorophyll a (,ug/L)

Figure 62. Morrow Lake vertical proﬁle concentrations of total phosphorus
(solid line) and chlorophyll a (dashed line). The inﬂow total phosphorus
concentration for the day was 44.5 ug/L and the inﬂow chlorophyll a
concentration was 2.7 ug/L.

108

TSP (,ug/L)
o 5 1o 15 20 25
l I

 

 

 

0 \I
1— > ~
2— O
:e:s- -
.C
‘34” '\ \
D 5- )-
/
6— -/ -
7.... _
8 l l l i

 

o 2 4 6 8 1o
SRng/L)

Figure 63. Morrow Lake vertical proﬁle concentrations of total soluble phosphorus
(TSP) (solid line) and soluble reactive phosphorus (SRP) (dashed line) . The
inﬂow total soluble phosphorus concentration for the day was 31 ug/L and the
inﬂow soluble reactive phosphorus concentration was 11.8 ug/L.

109

Ammonium (,ug N/L)
OO 30 60 90
i l

 

 

 

 

 

1..—
2—
5 s-
.C
214"
m
D 5_.
6P
7....- .
8 i i
o 240 480 720

Nitrate (Mg NIL)

Figure 64. Morrow Lake vertical proﬁle concentrations of ammonium
(solid line) and nitrate (dashed line). The inﬂow ammonium
concentration for the sampling day was 37.2 pg N/L and the inﬂow
nitrate concentration was 777 pg N/L.

110

 

 

 

 

 

 

I [i
1" T
2’ I
E 3' I
'c .—
54 7
D 5_ /.
6“ /
7_.— e
8 I i
O 5 1O 15

Oxygen (mg/L)

Figure 65. Lake Allegan vertical proﬁle of temperature (solid line) and oxygen
(dash line). The inﬂow temperature for the day was 23.1 C and the inﬂow
oxygen concentration was 7.8 mg/L.

111

Conductance (,LLS/Ci‘n @ 25 C)
00 90 180 270 360 450 54%630
l

 

 

 

 

 

I I i 7F I
1- /- i ~
2- f 0 —
E 3r 0 -
z \
45.4%- x _
(D
D 5__ /. _.
5— / —
7.. ./ _
8 i 1 i
7.0 7.5 8.0 8.5 9.0

pH

Figure 66. Morrow Lake vertical proﬁle of conductance (solid line) and pH
(dashed line). The inﬂow conductance for the day was 597 p S/cm and the
inﬂow pH was 7.9.

112

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

9°I
80 - A
60 d w ,_ _
ISoiubie I
E 50i i Organic I
340 . Phosphorus I
L ISoluble I
30 ‘ i Reactive
‘ Phosphorus 'e
20 . . EJParticuiate i
l Phosphorus :
104 i- __ W _
o I I j I I
4‘ 4‘ 4‘ 4‘
o o o o
5 Os 5* Os
‘9 0 0° c
x? ‘t- 09 0
4‘ \5’ \‘ 0°
0 4‘ V’ v)‘
06 60 $° 0
§ *0 o y
9° I
B
80 .
70 .
60 u
s so q EISoiubie Organic;
5 | Phosphorus .
:i. 40 . I
‘ISolubie f
30 4 I Reactive l
Phosphorus 'I
20 - i . I
i Ci Particulate I
10 , Phosphorus l
i L___- mg
0 T I I I I
4‘ 4‘ 4‘ 4‘
o o o o
53‘ 53‘ «3‘ s“
o O o O
é" ° .5? e
4‘ ‘9’ § \09
#960 06° J? *9
t} 4’

Figure 67. Morrow Lake and Lake Allegan mean phosphorus concentrations,
A) 2003 and B) 2004.

113

Literature Cited

Aminot, A., D. S. Kirkwood, and R. Kerouel, 1997. Determination of ammonia in
seawater by the indophenol-blue method: evaluation of the ICES NUTS I/C 5
questionnaire Mar. Chem. 56: 59-75.

Blomoqvist, P. A. Pettersson and P. Hyenstrand. 1994. Ammonium-nitrogen: A key

regulatory factor causing dominance of non-ﬁxing cyanobacteria in aquatic
systems. Arch. Hydrobiology. 132 (2): 141-164.

Bostrom, B., J .M. Anderson, S. Fleischer and M. J ansson. 1988. Exchange of
phosphorus across the sediment-water interface. Hydrbiologia. 170:229-244.

Carmack, E.C., C. B]. Gray, C.H. Pharo and R.J. Daley. 1979. Importance of lake-
River interaction on seasonal patterns in the general c irculation of kamloops
lake, British Columbia. Limnology and Oceanography 24 (4): 634-644.

Conley, D.J., C.L. Schelske, E. F. Stoermer, 1993. Modiﬁcation of the biogeochemical
cycle of silica with eutrophication. Marine Ecology Progress Series. 101:179-
192.

Dickman,M. 1969. Some effects of Lake Renewal on phytoplankton productivity and
species composition. Limnology and Oceanography. 14(5): 660-667.

Downing, J .A. and E.McCauley. 1992. The nitrogen: phosphorus relationship in lakes.
Limnology and Oceanography 37(5): 936-945.

Ferber,L.R., S.N. Levine, A. Lini and GP. Livingston. 2004. Do cyanobacteria
dominate in eutrophic lakes because they ﬁx atmospheric nitrogen. Freshwater
Biology. 49:690-708.

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Hasson, L-A. 1988. Effects of competitive interactions on the biomass development of
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balance (C,N, P, Si) in three large reservoirs of the Seine Basin (France).
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Kennedy, RH and W.W. Walker, 1990. Reservoir Nutrient Dynamics p 109-118 In
Thornton, K.W, B.L. Kimmel and F .E. Panye (eds) Reservoir Limnology:
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_ up; .Féésngfgw; '

Chapter 2. Longitudinal biogeochemical patterns in river water passing through
impoundments of varying residence times

Abstract

The Kalamazoo River (Michigan, USA) has six run-of-the-river dams (four small
decommissioned ones and two larger ones producing hydropower). The hydropower
reservoirs’ residence times vary from 2 up to 11 days during the year. The
decommissioned impoundments residence times vary from a quarter of day to 1.5 days
during the year. Three longitudinal river surveys from Morrow Lake inﬂow to Lake
Allegan outﬂow were conducted at varying discharges. Special emphasis was placed on
above and below Plainwell, Otsego, Allegan City and Trowbridge decommissioned
impoundments. Despite their spatial proximity a Total Maximum Daily Load for
phosphorus G3) was deemed necessary for Lake Allegan to control summer algal
blooms. High algal abundance was observed in Lake Allegan inﬂow, which may have
resulted from Morrow Lake’s algae transported downstream or algal biomass build-up
as the river passed through semi-impounded reaches. The average river total phosphorus
concentration was 79 ug/L during these surveys. Chlorophyll a concentrations declined
below Morrow Lake by benthic ﬁlter feeders. The decommissioned impoundments
greatly enhance algal biomass during low discharge below the Lake Allegan. The algal
biomass would peak above and within Lake Allegan. The removal of some or all of
those impoundments to restore a free-ﬂowing river channel would seem likely to
diminish the problem of excessive algal grth in Lake Allegan, converting the

impounded reaches from a source to a sink of river phytoplankton.

117

Introduction

The sources of phytoplankton in rivers are (l) periphyton sloughing due to physical

disturbances or (2) a supplied source of phytoplankton from lakes, reservoirs or still

waters. Compared with other aquatic systems, algal abundance counts (per unit total

phosphorus) followed this sequences: rivers<impoundments<natural lakes (Soballe et.

al. 1987). Abiotic factors regulate the presence of phytoplankton within the river. Light

and temperature control growth but ultimately river discharge limits phytoplankton

persistence (Allan 1995). River discharge and phytoplankton abundance are inversely

related. Similarly, horizontal ﬂow controls the available time attached or suspended —

algae interact with transport materials, such as nutrients (Soballe et. a1. 1987).

Structural modiﬁcations in river channels ultimately usually result in decreasing river
velocity. This decrease in velocity corresponds to an increase in water residence time
within the river. Natural lakes (Hynes 1970) and man-made reservoirs (Coutant 1963)
can supply plankton to the downstream river. In some cases, reservoirs can function as a
sink for river algae (Soballe et. a1. 1984), and algae released from the hypoliminion into
the rivers immediately below the dam are unsuited for the lotic environment (Coutant

1963). However, this may not be true for natural lake outﬂows.

Water ages as it ﬂows down the rivers and phytoplankton abundance will increase
downstream (Hynes 1970). Phytoplankton will spend longer in the river and thus have
time to reproduce especially in eddies and pools. Benthic algae can prosper in a river

due to a mixture of biotic and abiotic factors. The balance between biomass accrual and

118

 

losses controls benthic algal abundance within the river (Bi ggs 1996). Biomass losses
due to high water ﬂows, abrasion and grazing by scrapers transform benthic algae to

suspended algae.

In this chapter, I examine longitudinal patterns of phytoplankton abundance and nutrient
availability in the lower Kalamazoo River, between the two larger reservoirs (Morrow
Lake and Lake Allegan). The roles of these reservoirs as well as several smaller

impoundments as sources of algae to the river are emphasized.

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Study site

The Kalamazoo River watershed is located in the southwestern Michigan, with a
watershed area of approximately 5,231 kmz. The Kalamazoo River runs approximately
260 km through 10 counties of variety of land uses (developed areas, farmland, and
forest including Allegan State Game Area). Six run-of-the-river impoundments (four
small decommissioned ones and two larger ones producing hydropower) are located on
the Kalamazoo River. A decommissioned impoundment is a remnant of an active dam
where the turbines, gates and spillway were removed. The only remaining structures are
the concrete walls that may be lowered and the foundation that forms the sill.

The order of impoundments starting upstream heading downstream are (1) Morrow
Lake, a hydropower reservoir, (2) the Plainwell impoundment, a decommissioned
impoundment, (3) the Otsego impoundment, a decommissioned impoundment, (4) the
Trowbridge impoundment, a decommissioned impoundment, (5) Allegan City Dam, a
non-hydropower dam, and (6) Lake Allegan, a hydropower reservoir. Table 1 lists the
impoundments’ morphometric characteristics. Morrow Lake is located 69 km upstream

of Lake Allegan.

Consumers Power Company created Morrow Lake in 1939 for the Bryce E. Morrow
Power Plant in Comstock, Michigan. The plant was fueled by coal, which supplied
energy to the boiler to produce steam. Morrow Lake’s water was pumped through
condensers, which condensed hot steam from the boilers to hot water, which was then
pumped back into boilers. The two electric generators were powered by steam turbines,

which produced 35,000 kilowatts each.

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In 1969, the plant was converted to natural gas power, and in 1971 was rebuilt to use
oil. Consumers Power closed Morrow Plant in July 1982 due to high operating costs
and reduction in power consumption. STS Consultants Ltd. purchased about 1,400 acres
surrounding Morrow Plant (excluding the building and equipment) to construct a new
hydroelectric facility. The hydroelectric plant now generates about 1,000 kilowatts of
electricity. Currently, Morrow Irnpoundment is owned by STS Hydropower and is not

licensed under the Federal Energy Regulation Commission (FERC).

Michigan Paper Company built the Plainwell Dam in 1902, as a part of Foote’
hydroelectric facility. In 1965 operations at the Plainwell Darn were terminated and in
1967 Consumers Power Company deeded the dam to the Michigan Department of
Natural Resources for recreational purposes. The dam was ofﬁcially decommissioned in

1970-1971.

Otsego Dam was built in 1903-1904 as a part of Foote’ Trowbridge darn hydroelectric
facility downstream. In the 1980s, the dam was deeded to Michigan Department of

Natural Resources and decommissioned.

Trowbridge Dam was constructed in 1898 and was Michigan’s ﬁrst high voltage
hydroelectric generation and transmission system. The dam was designed by James
Foote. In 1910 the darn operations were terminated and in 1965, the dam deeded to the

Michigan Department of Natural Resources. The dam was decommissioned in 1986.

121

Allegan City Dam was constructed in 1837 and served as the central growing point for
Allegan, Michigan. The dam water wheel provided energy for various mills in the area.
In 1996 Allegan City purchased the darn from Imperial Carving Company. The current
purpose of the dam is to maintain the water levels of the Kalamazoo River above the

impoundment, where the pool is adjacent to city of Allegan downtown waterfront

property.

Calkins Dam was constructed by the city of Allegan ﬁom 1931-1936. The city’s
municipal utility operated the dam from 1936 to 1968. In 1968, Consumers Energy

purchased the dam and to date operates the dam.

A decommissioned impoundment is a remnant of an active dam where the turbines,
gates and spillway were removed. The only remaining structures are the concrete walls

that may be lowered and the foundation that forms the sill.

Total Maximum Daily Load ( T MDL) for Lake Allegan

The Michigan Department of Environmental Quality (MDEQ) monitored Lake Allegan
from April through September of the years 1988, 1994, 1996 and 1997, and determined
that total phosphorus concentrations averaged 96 ug/L and ranged from 69 to 125 ug/L
(Heaton 2001). In 1998, Lake Allegan remained classiﬁed as hypereutrophic, exhibiting
high nutrient and chlorophyll a concentrations (67 ug/L), excessive turbidity (0.6 m
Secchi depth), low dissolved oxygen, and an unbalanced ﬁsh community dominated by

carp and channel catﬁsh (87% community average) (MDEQ 2001). In 1999, MDEQ

122

 

 

 

 

developed a phosphorus Total Maximum Daily Load (TMDL) for Lake Allegan. A
reduction of total phosphorus in Lake Allegan should improve water quality conditions

if it is indeed the main factor controlling algal growth, which is the premise of the

TMDL

Objective and Hypotheses

This research was prompted by observing high algal abundances in Lake Allegan inﬂow
water, and wondering if the algae exiting Morrow Lake were the same algae observed
entering Lake Allegan. I hypothesized that the higher algal abundance in Lake Allegan

was due to either or both of the following:

(1) Phytoplankton from Morrow Lake are transported 69 km downstream into Lake

Allegan

(2) The higher algal biomass at the Lake Allegan inﬂow is due to the algal biomass
build-up between Morrow Lake and Lake Allegan as the river passed through semi-
impounded reaches caused by decommissioned impoundments (Plainwell, Otsego,
Trowbridge and Allegan city dam), which decrease stream ﬂow allowing for algal

growth.

123

 

 

 

Methods

Field Sampling

Three longitudinal surveys were conducted over a two-year period (2003-2004) with
one at a low discharge on 18 August 2003, one at a medium discharge on 3
September2004, and one at a high discharge on 2 July 2004. The surveys began at the
Morrow Lake inﬂow and concluded at the Lake Allegan outﬂow. Table 2 shows the
sampling locations with distances from the Morrow Lake inﬂow at E. Michigan Ave.
Special emphasis was placed on sampling above and below the Plainwell, Otsego and
Trowbridge decommissioned impoundments in addition to above and below Morrow
Lake and Lake Allegan, the two active hydropower reservoirs. A longitudinal survey
within Morrow Lake was conducted on 27 August 2004; the survey started at the

riverine zone and progressed toward the impoundment wall.

Laboratory Analyses

Water samples were analyzed for total phosphorus. Total soluble P (in ﬁltered water)
and total P (unﬁltered water) were determined after persulfate digestion in a pressure
steam sterilizer by colorimetric analysis of the resultant orthophosphate (V alderrarna
1981, Langner and Hendrix 1982). The sterilizer was operated at 20 psi for two hours
followed by a gradual cooldown period. Standards included ATP to ensure efﬁcient
oxidation of organic matter. Reagent and water contributions to the analytical blank
were determined by varying the reagent amount and only the reagent contribution was
subtracted from sample absorbances (this was also routinely done for ammonium

analyses). Sestonic chlorophyll a was ﬁltered onto a Type A/E glass ﬁber ﬁlter and

124

 

 

 

frozen. The ﬁlters were later halved and one half was extracted with 95% ethanol, and
chlorophyll a in the extract was measured by ﬂuorometry (Welschmeyer 1994).

Water residence time was calculated from USGS discharge records and reservoir
volumes. For Morrow Lake the closest gauging station was Comstock, for the Otsego
and Plainwell impoundments the gauging station was Plainwell, and for Trowbridge
impoundment, Allegan City Dam, and Lake Allegan the gauging station was
Trowbridge. Morrow Lake and Lake Allegan residence times represent the average
residence time preceding each sampling date. To calculate the average residence time
over days. First, the daily residence time for each sampling day was calculated from the
daily discharge and reservoir volume. Once the daily residence time was determined for
that sampling day, I started with that sampling day and counted back the number of
days equal to the residence time estimate. Then the discharges for those proceeding
days were summed and divided by the sampling day residence time. This yielded a
more accurate estimate of the average residence time over the interval proceeding
sampling, when discharge was variable. Residence times of the Plainwell, Otsego and
Trowbridge decommissioned impoundments represent the residence time on the
sampling date for 2003 and 2004, calculated ﬁ'om the mean daily discharge and the
volumes of water behind each impoundment. Volumes were determined from digital
elevation models of bathymetry obtain from Cynthia Rachol of the US. Geological

Survey.

125

 

 

 

Results

Discharge varied throughout the season with the highest discharge during February
through May and the lowest discharge during June through September (Figure 2).
Discharge was higher overall in 2004 than in 2003. The mean discharge for March
through September over 72 years (1931-2003) was 26.38 m3/sec. The mean for March

through September 2003 was 20.6 m3/sec and 2004 it was 29.72 m3/sec.

Kalamazoo River longitudinal survey conducted at low discharge

On the low-discharge survey date (18 August 2003), The mean daily discharge at the
Comstock gauge was 9 m3/sec and at the Trowbridge gauge it was 20 m3/sec. River
water temperature increased within Morrow Lake and ﬂuctuated little as the river
passed though the decommissioned impoundments, until the temperature increased
again within Lake Allegan (Figure 3). Oxygen concentrations increased within Morrow
Lake and slightly declined downstream, then gradually increased as the river passed

through the decommissioned impoundments, peaking at the inﬂow to Lake Allegan

(Figure 3).

Conductance declined within Morrow Lake, increased shortly thereafter, and remained
constant downstream through the decommissioned impoundments into Lake Allegan,
followed by declined in the Lake Allegan outﬂow (Figure 4). The pH increased within
Morrow Lake and declined downstream, then gradually increased through the
decommissioned impoundments, and peaking at the inﬂow to Lake Allegan followed by

a decrease in the outﬂow (Figure 4).

126

 

 

 

Total phosphorus concentrations increased within Morrow Lake and gradually declined
downstream, remained constant as the river passed through the decommissioned
impoundments, then decreased within Lake Allegan followed by an increase in the
outﬂow (Figure 5). Chlorophyll a concentrations increased considerably in Morrow
Lake, followed by a marked decline downstream, then gradually increased again as the
river passed through the decommissioned impoundments, until the concentration peak

within Lake Allegan follow by a noticeable declined within Lake Allegan (Figure 5).

Kalamazoo River longitudinal survey conducted at medium discharge

On the medium-discharge survey date (3 September 2004), The mean daily discharge
at the Comstock gauge was 25 m3/sec and at the Trowbridge gauge it was 41 m3/sec.
River water temperature remained constant throughout the entire reach (Figure 6).
Oxygen concentrations slightly decreased within Morrow Lake and remained fairly
constant as the river passed though the decommissioned impoundments and Lake

Allegan, except for a marked peak at one sampling station (Figure 6).

Conductance was fairly constant throughout the entire reach (Figure 7). The pH
declined within Morrow Lake and ﬂuctuated as the river passed through the
decommissioned impoundments, there was a the pH peak before Lake Allegan
(corresponding with the oxygen peak), followed by a noticeable decline above and

within Lake Allegan (Figure 7).

127

 

 

 

Total phosphorus concentrations decreased within Morrow Lake, remained constant as
the river passed through the decommissioned impoundments and decreased within Lake
Allegan (Figure 8). The chlorophyll a concentration increased considerably within
Morrow Lake followed by a decrease as the river passed through the decommissioned

impoundments, then increased again within Lake Allegan (Figure 8).

Ammonium concentrations showed no pattern through out the river (Figure not shown).
The nitrate concentrations decreased within Morrow Lake and gradually increased and

remain steady through the river and declined within Lake Allegan (Figure not shown).

Kalamazoo River longitudinal survey conducted at high discharge

On the high-discharge survey date (2 July 2004), The mean daily discharge at the
Comstock gauge was 56 m3/sec and at the T rowbridge gauge it was 85 m3/sec. River
water temperature increased slightly within Morrow Lake and decreased immediately
downstream, then remained fairly constant as the river passed through the
decommissioned impoundments, and slightly increased within Lake Allegan (Figure 9).
Oxygen concentrations increased within Morrow Lake and gradually increased as the

river passed through the decommissioned impoundments, peaked within Lake Allegan

(Figure 9).

Conductance was fairly constant throughout the entire reach (Figure 10). The pH

increased within Morrow Lake and gradually increased as the river passed through the

128

 

 

decommissioned impoundments until the concentration peaked above Lake Allegan

followed by a declined in the outﬂow (Figure 10).

Total phosphorus concentrations increased between the Morrow Lake inﬂow and
outﬂow and remained constant as the river passed through the decommissioned
impoundments, until concentrations declined above and within Lake Allegan (Figure
11). Chlorophyll a concentrations were variable across the reach with an increase in
Morrow Lake and through the decommissioned impoundments, peaking at the inﬂow to

Lake Allegan with a large decline in the outﬂow (Figure 11).

Ammonium concentrations showed no pattern through out the river (Figure not shown).

Morrow Lake longitudinal survey

The river discharge at Comstock was 26 m3/sec when the longitudinal transect within
and just below Morrow Lake was sampled on 27 August 2004. Morrow Lake total
phosphorus concentrations gradually increased in the riverine zone, yet chlorophyll a
concentrations were low there (Figure 12). Chlorophyll a concentrations increased in
the lower half of the reservoir and peaked at the dam. Downstream from the darn, total
phosphorus concentrations were constant, whereas the chlorophyll a concentrations

declined at ﬁrst, then leveled out (Figure 12).

A graph of three measured forms of phosphorus shows that particulate phosphorus (total
minus dissolved phosphorus) and soluble organic phosphorus (total dissolved minus

soluble reactive phosphorus) were roughly equal in importance (Figure 13). Soluble

129

 

 

 

reactive phosphorus concentrations were low throughout the entire reservoir and
downstream. Downstream from the dam, total phosphorus, total soluble phosphorus,

and soluble reactive phosphorus concentrations were constant (Figure 13).

130

 

Discussion

The nutrient concentrations of the Kalamazoo River make the river eutrophic by lakes
and reservoirs standards (V ollenweider 1975, Rechow and Chapra 1983). There are
many point-source discharges, including substantial wastewater treatment plants, at
Battle Creek and Kalamazoo that inﬂuence my sampling reach. Nonpoint sources of

phosphorus are also thought to be important because the sum of known point sources

 

can only account for less than half of the river’s phosphorus load (MDEQ 1999). The

water quality problems associated with excessive nutrient loading into the river are

 

largely due to phytoplankton growth, which is most evident in the impounded reaches.
This study indicates that the smaller decommissioned impoundments are sites of
signiﬁcant algal growth, at least at low discharge, and thus they appear to exacerbate the

water quality problems.

The 18 August 2003 survey was conducted at low discharge, the 3 September 2004
survey was conducted at medium discharge, and 2 July 2004 survey was conducted at
high discharge. Longitudinal differences were most marked at low discharge. The
average river temperature for the three surveys was 26 C. Water temperatures
sometimes increased within Morrow Lake and Lake Allegan, but remained constant
through the decommissioned impoundments. On 2 of the 3 dates, there was net oxygen
production during the summer in the active reservoirs and gradual increases in oxygen
as the river passed through the decommissioned impoundments. River conductance
averaged 630 uS/cm with slight decreases on 2 of the 3 dates during the summer within

Morrow Lake and Lake Allegan, whereas the decommissioned impoundments had no

131

effect on conductance. The river pH increased during the summer within the active
reservoirs and showed gradual increases on 2 of the 3 dates as the river passed through

the decommissioned impoundments.

Total phosphorus concentrations were relatively high throughout the reach independent
of river discharge. The active reservoirs either serve as a sink or a source for total
phosphorus. The average total phosphorus concentrations for the surveys were

80 ug/L for the 18 August 2003 survey, 79 ug/L for the 2 September 2004 survey, and
79 ug/L for the 2 July 2004 survey. The decommissioned impoundments had a slight
effect on increasing total phosphorus concentrations, possibly though sediment

resuspension or bank erosion, regardless of discharge.

Algal Growth in the River

The surveys began at the Morrow Lake inﬂow and ended 69 km downstream at the
Lake Allegan outﬂow. It is known that reservoirs prompt algal growth by increasing
water residence time. Morrow Lake and Lake Allegan are shallow, well-mixed (non-
stratifying), reservoirs with short residence times (less than 11 days for both; See
chapter 1 for more detail. These two reservoirs are clearly sites of substantial algal

growth, especially at lower discharge.

Phytoplankton was always present at high amounts in the reservoirs over the summer
sampling periods and reservoir discharge may affect the algal abundance downstream.
However, at least at low discharges, algae exiting Morrow Lake do not appear to be

transported to Lake Allegan. Instead, that algae largely disappears and new algal growth

132

 

 

appears. A noticeable phytoplankton decline occurred during low discharge below the
Morrow Lake outﬂow, between 15-35 km river sampling distance (Figure 5), but this
was not apparent at medium discharge (Figure 8). During the high discharge survey, the
D Ave bridge sampling location was closed for construction and thus data are
incomplete in this reach. Possible loss processes that could account for the
disappearance of algae below Morrow Lake include consumption by benthic ﬁlter
feeders and ﬂocculation out of the water column. An invasive clam, Corbicula
ﬂuminea, was observed at high densities in this reach, and this species is capable of
ﬁltering phytoplankton from the river. Net-spinning cadisﬂies (Hydrosychidae) were
also abundant. At low discharge such benthic ﬁlter feeders would be expected to reduce

algal densities more effectively.

The ﬁve decommissioned impoundments (Plainwell, Otsego City, Otsego, Trowbridge
and Allegan City) lie between the 40-65 km river sampling distances and their
cumulative effect on water residence time could reestablish the algae population within
the river. Decommissioned impoundments in the Kalamazoo River decrease river
velocity and cause pooling behind the impoundments. For the 2003-2004 discharge
year, each impoundment’s residence time varied 0.01-0.73 days (Table 1), the
cumulative residence time within the ﬁve decommissioned impoundments was only 1.5
days at low discharge and less than quarter of a day at high discharge. The
decommissioned impoundments would thus not seem to encourage much additional
phytoplankton growth by their effects on residence time. Yet, Figure 5 clearly showed a

stepwise increase in chlorophyll a concentration as the river passed through the

133

 

 

 

decommissioned impoundments, until concentrations peaked above and within Lake
Allegan. Lake Allegan’s residence time varied from 3-11 days, and during the summer
of 2003 the residence time was as high as 11 days, which was long enough for algae to
thrive. Retention times of around 7 days or less limit phytoplankton production and
species composition (Thornton 1990). It is possible that the impoundments encourage
algal growth not only by increasing water residence time, but also by discouraging
benthic ﬁlter feeders, perhaps because of ﬁner sediments and lower velocities. Another
possibility is that within the impounded reaches there are signiﬁcant off-channel waters
with much longer residence times, and these supply algae to the rivers. My estimates of

residence time assume thorough mixing of impounded waters.

During the summer even at relatively high discharge, the decommissioned
impoundments increased chlorophyll a concentrations within the river, until
concentrations peaked above Lake Allegan (Figure 11). It is unusual to observe algae
abundance increasing at high ﬂows, but the ﬂows occurred during the summer when
conditions are prime for algae. Lake Allegan’s longest residence time for 2004 was 7
days. The Lake Allegan outﬂow had a noticeable decline in chlorophyll a, which
suggested algae were reduced in abundance in the reservoir, perhaps via loss to
zooplanktonic grazers. Zooplankton require a somewhat longer residence time than
phytoplankton, and only Lake Allegan may provide sufﬁcient time for zooplankton

reproduction.

134

 

 

Implications for the T MDL

Net algal growth seems to be promoted by pools and backwaters created by the
decommissioned impoundments. Therefore, removal of some or all of those
impoundments to restore a free-ﬂowing river channel would seem likely to diminish the
problem of excessive algal growth in Lake Allegan, converting the impounded reaches
from a source to a sink of river phytoplankton. This is especially true during the
summer at a low discharge, which is when algal blooms in Lake Allegan are most likely

to be a problem.

 

 

135

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Biggs, B.J.F. 1996. Patterns in benthic algae of streams pp 31-56 In Stevenson, R.J.,
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Coutant,C. 1963. Stream plankton above and below Green Lan reservoir. Proc. Penn
Acad. Sci. 122-126

Heaton, S. 2001. Total Maximum Daily Load (TMDL) for total phosphorus in
Lake Allegan. MDEQ Surface Water Quality Division Report.

Hynes, HE. 1970. The Ecology of Running Waters, University of Toronto Press,
Toronto.

 

Soballe, D.M. and BL Kimmel. 1987. A Large-scale comparison of factors inﬂuencing
phytoplankton abundance in rivers, lakes and impoundments. Ecology 686 (6)
1943-1954.

Soballe, D.M. and R.W. Bachmann. 1984. Inﬂuence of reservoir transit on river
transport and abundance. Can. J. Fish Aquat. Sci. 41 1803-1813.

Rechow,D and SC. Chapra. 1983. p 222 In Engineering approaches for lake
management. Butterworth publishers. Boston,MA

Thornton, K.W. 1990. Sedimentary Processes p57-63 In Thornton, K.W, B.L. Kimmel
and F .E. Panye (eds) Reservoir Limnology: ecological perspectives. John Wiley
and sons, Inc. New York, NY.

Vollenweider,R. 1975. Input-Output models with special reference to the phosphorus in
Lake Eutropohication. Swiss Journal of Hydrology. 37 53-84

 

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Location Distance (km)
Above Morrow Lake 0
Below Morrow Lake 9.3
Mosel Rd near Parchment 11.3
D Ave bridge (between Kalamazoo and
Plainwell) 27.7
City of Plainwell, Railroad bridge 40.7
Below Plainwell Dam and above Otsego 45.0
Farmer Rd in Otsego (below Menasha) 47.5
River Rd. below Otsego Dam 52.5
26th St. Bridge (below Trowbridge Dam) 60.1
Williams Rd. bridge above Allegan 67.1
Allegan city waterfront, above Lake
Allegan 73.9
M89 Bridge at upper Lake Allegan 81.7
Outﬂow from Lake Allegan dam 89.5

 

Table 2: Longitudinal river sampling locations on the Kalamazoo River

139

 

 

The distance

 

 

 

 

 

 

 

 

 

 

 

 

Mean Volume Residence from Morrow
Reservoirs Area (m2) depth (m) (103m3) Time (days) Dam (km)
Morrow Pond H 4,451,542 1.66 7,401 2 - 6 0

Plainwell 0 407,257 1.30 529.00 0.05 - 0.73 34.70
Otsego ° 129.737 0.88 114.00 0.01-0.15 42.98
Trowbridge 0 431,054 0.75 322.00 0.02 - 0.21 50.39
Allegan City Dam 0 546,326 1.80 986.00 0.08085 84.83
Lake Allegan H 6,422,361 3.30 21,200 3 - 11 80.177

 

Table l. Morphometric data: Hydropower Reservoir H and Decommissioned

Irnpoundments D

140

 

Figure 3. Longitudinal river survey of temperature and oxygen at low discharge

(18 August 2003). The solid line boxes represent the active hydropower reservoirs
(Morrow Lake and Lake Allegan) and dashed line boxes represent the decommissioned
impoundments (Plainwell dam, Otsego dam, Trowbridge dam and Allegan City dam).

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Figure 5. Longitudinal river survey of total phosphorus and chlorophyll a at low
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Figure 6. Longitudinal river survey of temperature and oxygen at medium discharge

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147

 

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Figure 7. Longitudinal river survey of conductance and pH at medium discharge

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149

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Figure 8. Longitudinal river survey of total phosphorus and chlorophyll a at medium
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Figure 9. Longitudinal river survey of temperature and oxygen at high discharge

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153

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Figure 10. Longitudinal river survey of conductance and pH at high discharge (2 July
2004). The solid line boxes represent the active hydropower reservoirs (Morrow Lake
and Lake Allegan) and dashed line boxes represent the decommissioned impoundments
(Plainwell dam, Otsego dam, Trowbridge dam and Allegan City dam).

155

 

 

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Figure 11. Longitudinal river survey of total phosphorus and chlorophyll a at high
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impoundments (Plainwell dam, Otsego darn, Trowbridge dam and Allegan City dam).
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Figure 12. Longitudinal river survey of total phosphorus and chlorophyll a within
Morrow Lake and downstream in the river (27 August 2004). The solid line box
represents Morrow Lake.

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Figure 13. Longitudinal river survey of total phosphorus (TP), total soluble phosphorus
(TSP), and soluble reactive phosphorus (SRP) within Morrow Lake and downstream in
the river (27 August 2004). The solid line box represents Morrow Lake.

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