" ufilialLmjggmnmnflngmmjnjnjn1| '

,. J h- l". .
MALL-u '1

 

This is to certify that the

dissertation entitled

A MODEL FOR
CONCENTRATION OF TOTAL PHOSPHORUS AND CHLOROPHYLL A
IN A SMALL, EUTROPHIC LAKE

presented by

Bette J. Premo

has been accepted towards fulfillment
of the requirements for

PhD degree in Limnology

 

 

MA Ml

‘jorpjmssor

Due October 13, 1982

 

MS U is an Aflirnum'vc Action/Equal Opportunity Institution 0-12771

 

 

RETURNING MATERIALS:
IVIESI_J Place in book drop to
remove this checkout from
4::::;:::i_ your necord. FINES will
be charged if book is
returned after the date
stamped below.

 

 

 

 

 

 

 

 

A MODEL FOR
CONCENTRATION OF-TOTAL PHOSPHORUS AND CHLOROPHYLL A
IN A SMALL, EUTROPHIC LAKE

BY

Bette J. Premo

A DISSERTATION

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

DOCTOR OF PHILOSOPHY

Department of Fisheries and Wildlife

1982

ABSTRACT
A MODEL FOR

CONCENTRATION OF TOTAL PHOSPHORUS AND CHLOROPHYLL A
IN A SMALL, EUTROPHIC LAKE

BY

Bette J. Premo

Measurements were made on Skinner Lake, in Noble
County, Indiana, over an annual cycle in 1978—79, to
determine the relationship between incoming total phos-
phorus concentration and in-lake phosphorus and chloro-
phyll a concentration. Total phosphorus concentrations
([TP] ) were measured in samples from atmospheric fallout
and inlet streams. Flow measurements of inlets and the
lake's outlet were taken and hydrographs were constructed
to determine annual and seasonal discharge into and out
of the lake. Upper and lower pelagial portions of the
lake were sampled at two-week intervals in the ice-free
period and analyzed for [TP]. Internal loading of TP
was estimated from lake mass balance budgets. [Chl a} was
analyzed in pelagial samples of the upper photic stratum.

Total nitrogen:total phosphorus determined in the
epilimnion of Skinner Lake ranged from 19 to 220 indicating
that algal yield in the epilimnion was likely phosphorus

dependent. Approximately 90% of annual TP loading was

Bette J. Premo

delivered to the lake via streamflow, and 93% of this
occurred during snowmelt and spring-overturn periods
(February - May). During this same interval the lake
was flushed 2.4 times by incoming water. Atmospheric
loading amounted to 0.04 9 TP m"2 yr-l; 1.4% of the annual
TP load of streams. Internal TP loading occurred during
the summer stratification interval. Phosphorus was appar-
ently released across the anaerobic sediment surface
that existed in the hypolimnion, causing hypolimnetic
[TP] to be twice that of the epilimnion. Mean [chl a]
for the ice-free period was 15.15 mg mf3, in the range
eXpected for eutrophic lakes.

Data from 1978-79 were used to develop a model for
the Skinner Lake system. The model was based on that
of Vollenweider and Kerekes (l980),which stated that mean
epilimnetic total phosphorus and chlorophyll a concentra-
tions were predictable from mean total phosphorus concen-
tration in streams and residence time of water in the
lake determined from measurements during the periods
of spring overturn and summer stratification. The model
was tested in 1982 and it closely predicted observed
mean epilimnetic [TP] and [chl a] for the ice-free period.
Use of the lake-specific model for making watershed manage-

ment decisions was considered.

ACKNOWLEDGEMENTS

I wish to express my sincere gratitude to Dr. Clarence
D. McNabb for his conscientious review of this manuscript.
I am especially appreciative of Professor McNabb's thought-
ful advice and encouragement throughout my_graduate program.

I would also like to thank members of my graduate
committee, Dr. Boyd G. Ellis, Dr. Donald J. Hall, Dr. Niles
R. Kevern and Dr. Robert G. Wetzel for their review of my
work. My research greatly benefitted from data collected
as a result of federally supported studies of Skinner Lake
granted to the Limnological Research Laboratory. In this
regard I am indebted to Fred C. Payne, Robert P. Glandon,
Ted R. Batterson and Kevin Williams for their experimental
design, and collection and compilation of data during 1977-
1979. I would like to thank the Laboratory Director, John
R. Craig, and Mehdi Siami, Paul R. Roettger, Wayne M. Swaney
and R. Brent Glenn for their work on the projects during
1979-1982.

It is difficult to adequately express my appreciation
to my husband, Dean Barrette Premo. This manuscript bene-
fitted from pertinent discussions with Dean and from his
graphic and editorial contributions. Dean's moral support

and patience were unending.

ii

Financial support for this work was provided by the
U.S. Environmental Protection Agency, Clean Lakes Program,
under Grant No. CR 80504601, and by Noble County Soil and
water Conservation District, under Cooperative Agreement

with Michigan State University.

iii

LIST OF TABLES
LIST OF FIGURES
INTRODUCTION .
METHODS . . .
RESULTS . . .

DISCUSSION . .

LITERATURE CITED

APPENDICES

APPENDIX I
APPENDIX II

TABLE

OF CONTENTS

iv

12
27
42
56

60
82

Table

LIST OF TABLES

Concentrations of nitrogen and phosphorus
(mg 1"1 ) in Skinner Lake during the ice-
free period in 1979 . . . . . . . . . . . . .

Atmospheric bulk loading of total phosphorus
on Skinner Lake during the interval 9/6/78 -
9/17/79 0 o o o o o o o o o o o o o o o o o o

Flushing coefficients (9) of Skinner Lake
during periods of 1978-79 . . . . . . . . . .

Concentration of chlorophyll 3 (mg m_3) (in
Skinner Lake during summer of 1979 and 1982 .

Pit of Skinner Lake data of 1978- 79 to
Vollenweider and Kerekes (1980) estimates of
in-lake [TPL calculated from [TP] =

[TP. 1/(1+W ) where [TP. ] is from stream

dis harges except for IIB . . . . . . . . .

Comparison of the predictions of [TPL] from
[TPi ]1 and tw using three models . . . . . .

Estimated interval discharge (m3) of inlet
streams and outlet of Skinner Lake during
1978-79 0 o o o o o o o o o o o o o o o o o

Analytically determined [TP] (mg m-3) in
samples from.in1et streams and outlet of
Skinner Lake during 1978-79 . . . . . . . . .

Estimated interval discharge (m3) of inlet
streams and outlet of Skinner Lake during
1982 O O O O I I O O O O O O O O O I I O O O

Analytically determined [TP] (mg m-3) in
samples from inlet streams and outlet of
Skinner Lake during 1982 . . . . . . . . . .

28

32

36

41

44

52

82

83

84

85

Figure

LIST OF FIGURES

Temperature isopleths (°C) for Skinner
Lake during the ice-free season of 1979 . .

Dissolved oxygen isopleths (mg 1-1) for
Skinner Lake during the ice-free season
Of 1979 O O O O C O O O I O O O O O O O O

The Skinner Lake watershed in Noble County,
Indiana. Section boundaries form the grid
Show 0 O O O O I O I O O O O O O O O O O I

Bathymetry of Skinner Lake; contours are in
meters. In-lake sampling stations are shown
by asteriSks O O I O O O I O I O O I O O 0

Land management practices applied to the
Skinner Lake watershed during 1979-1981 .

Total phosphorus concentration (mg 1'1) in
Skinner Lake during the ice-free season of
1979 . . . . . . . . . . .-. . . . . . . .

Stream flow hydrograph for the Rimmell
inlet during 1978-79 . . . . . . . . . .

Concentration (mg 1-1) and mass (kg) of
total phosphorus (TP) delivered to Skinner
Lake by the Rimmell inlet during 1978-79 .

Diagramatic representation of the Skinner-
specific model (modified from Vollenweider
and Kerekes, 1980) . . . . . . . . . . . .

Stream flow hydrograph and precipitation
record for the Hardendorff inlet (1978-79)

Stream flow hydrograph and precipitation
record for the Riddle inlet (1978-79). .4.

Stream flow hydrograph and precipitation
record for the Croft-Sweet inlet (1978-79)

Stream flow hydrograph and precipitation
record for the Weimer inlet (1978-79) . .

vi

ll

14

24

30

35

39

50

61

63

65

67

Figure
A-S

A-lO

A-ll

LIST OF FIGURES (continued)

Stream
record

Stream
record

Stream
record

Stream
record

Stream
record

Stream
record

Stream
record

flow
for

flow
for

flow
for

flow
for

flow
for

flow
for

flow
for

hydrograph and precipitation
(1978-79)

the Croft Drain

hydrograph and precipitation

the Rimmell inlet (1982)

hydrograph and precipitation
(1982)

the Hardendorff inlet

hydrograph and precipitation

the Riddle inlet (1982)

hydrograph and precipitation
the Croft-Sweet inlet (1982)

hydrograph and precipitation

the Weimer inlet (1982)

hydrograph and precipitation

the Croft Drain (1982)

vii

73

75

77

79

81

INTRODUCTION

Sawyer (1947) was among the first to use the concept
of nutrient loading in his studies of effects of agricul-
tural and urban drainage on the fertility of the Madison,
Wisconsin, lakes. He observed that lakes which received
the greatest quantity of phosphorus and nitrogen experienced
the most frequent and most severe algal blooms. Rawson
(1955) and Edmondson (1961) emphasized the importance
of mean depth to the productivity of water-bodies. This,
parameter took into account the degree of dilution of
nutrients entering from the watershed. Vollenweider
(1968) quantitatively defined the relationship between
nutrient loading and planktonic algal response. This
relationship showed that lakes of similar planktonic
production had similar ratios of total phosphorus loading
(mg P m-2 yr-l) to mean depth. Dillon (1974, 1975) was
the first to report water-bodies which did not fit Vollen-
weider's original phosphorus loading scheme. Dillon
explained the anomolous fit of his lakes as due to their
rapid flushing rates. Vollenweider (1975, 1976) pointed
out that nitrogen limitation was known to occur in lakes,
and such water-bodies would not be expected to fit his

phosphorus loading models. Sakamoto (1966), Chiaudani

and Vighi (1974), and Smith and Shapiro (1980) showed
that examination of [TfilllTP] in the photic zone was
a useful procedure for separating N-limited and P-limited
systems. Their work predicted that if [TNl/[TP] was .
greater than 10, algal production in the majority of
lakes was likely phosphorus rather than nitrogen dependent.
In an attempt to allow for effects of fast or slow
flushing rates and sedimentation of phosphorus on nutrient
loading - trophic response relationships, Vollenweider
(1975, 1976) modified his phosphorus loading model to
include hydraulic residence time and phosphorus residence
time. Based on the data from 200 lakes in 50 countries
participating in the Organization for Economic Cooperation
and Development (OECD) Cooperative Program on Lake Eutro-
phication, Vollenweider and Kerekes (1980) found that

residence time of water and phosphorus in lakes were

key factors and were related in the following manner:

 

[TPL] l
t /t = =
P w ('1? 1 1 + t5
J. W
and
__ [fiil
(1) [TPLl = ——3;
1 + tw

where tp was the residence time of phosphorus, tw was
the hydraulic residence time, [T51] was the mean incoming
phosphorus concentration and [TPL] was the mean lake

phosphorus concentration. This relationship between a

3

water-body's mean in-lake phosphorus concentration and
incoming phosphorus concentration was the same as that
developed by Larsen and Mercier (1976) and was similar
to those developed by Kirchner and'Dillon (1975) , Chapra
(1975), Reckhow (1977) and walker (1977). Pram data

of the OECD lakes, Vollenweider and Kerekes (1980) also
presented a relationship between concentration of total
phosphorus in a lake and algal production as measured
by chlorophyll §_concentration. The relationship was

expressed as:
(2) log [c'h'l—g'] = 0.99 log [TEL] - 0.57

where [EEIIE] was mean chlorophyll a concentration and
[TPL] was mean in-lake total phosphorus concentration.

The Vollenweider and Kerekes (1980) model was empiri-
cally derived from temperate lakes of all trophic cate-
gories with wide ranges of flushing rates. It therefore
represented a starting point for examining the effects
of inflow phosphorus on specific phosphorus limited lakes.
In this study, relationships in the Vollenweider and
Kerekes (1980) model were tested on Skinner Lake in Noble
County in northeastern Indiana.

Skinner Lake has an average depth of 4.4 m, a maximum
depth of 10 m and a surface area of 49.4 ha. One hundred
twenty-five permanent residences.1ine.. the shore of the
lake. Lake level is controlled by a concrete sill dam

that was constructed in 1962. The lake discharges to

-the Croft Drain that enters the South Branch of the
Elkhart River some 8.3 km downstream.

Thermal stratification of Skinner Lake existed from
mid-May through mid-October in the years 1978 and 1979.
Figure 1 shows the 1979 temperature regime for the ice-
free season. The hypolimnion approached anaerobic condi-
tions rapidly as stratification became established (Figure
2). Relative areal oxygen deficits, calculated for the
interval 1 May to 15 May in 1978 and 1979 were in the
range of 700-900 mg m'2 day‘l. Lakes with areal oxygen
deficits greater than 550 mg 111"2 day"1 are considered eu-
trophic or highly fertile by Hutchinson (1957). Other
expressions of eutrophy for Skinner Lake included extensive

growth of aquatic macrophytes, such as Nymphaea odorata,

Ceratophyllum demersum, and Myriophyllum spicatum, and

 

blooms of blue-green algae (Aphanizomenon sp.). The

 

dominant fish in Skinner Lake included small sunfish
(Lepomis spp.) and crappies (Pomoxis spp.), and a large
rough fish population composed of the white sucker (Cata-

stomus commersoni) and the golden shiner (Notemigonus cry-

 

soleucas). The lake's turbidity, algal blooms, macrophytes

and low oxygen conditions were blamed for a general decline

in fishing quality over the last two decades (Pearson, 1978).
The area of Skinner Lake watershed is 3649 hectares,

68% of which is used for agriculture. The remaining 32%

is in woodlands and wetlands. The Rimmell inlet is the

most important continuously discharging surface flow

.mhma mo common cumulmow may omenso
mxmq Hoccwxm MON .00. mnumamomw musumquEoB .H ousmwm

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

23%

 

 

 

 

 

 

 

 

 

 

.mhmH mo acmmmm omum1o0fl ecu ocfiHso
oxen Hoccwxm “Om AHIH me. mnuoamomfi cwmaxo oo>aommflo .N ousmwh

duo ego: CHOP—.00 gram hm§<. >42. mza.

L11 . .E. .. . . .. NV.

._.E<

 

 
   

e

   

 

 

 

nvoohomg

,,
/
/
/ ,.
., ,
,
(\‘llrrt

\.\/ 1)

  
 

 

 

L

V. __, /
.1 4/ ._

'—

2

 

 

_ i I?

 

(W) HidBO

-N

to Skinner Lake. Eighty-two percent of the entire Skinner
Lake watershed (3091 ha) is within the Rimmell drainage
system (Figure 3). Land is put to varied crop and live-
stock use. Subsurface tiles are widely employed for drain-
age. Three smaller streams carrying tile and surface run-
off enter the lake from agricultural land: the Hardendorff
system draines 180 ha, the Riddle stream 107 ha, and the
Weimer stream drains 42 ha of the watershed. The overflow
from nearby Sweet Lake runs along a 0.8 km channel through
a woodland to Skinner Lake. The Croft-Sweet system drains
229 ha of the watershed.

Measurements were made on the Skinner Lake system
over an annual cycle in 1978-79 to derive variables in
the Vollenweider and Kerekes model (equations (1) and
(2)). Their model was then modified to fit states of
the variables measured at Skinner Lake. A model specific
for the Skinner system was the result. The validity
of this new model was tested by changing the [T51] of
equation (1). The change was accomplished by implemen-
tation of agricultural land management practices on the
watershed during 1979-1981. In 1982, measurements were
made on the system to test the fit of the Skinner-specific

lake model.

10

.c3onm owum ecu EH0“ mmwumocson cowuomm
.mcmwocH .xucsoo manoz cw oonmumuoz oxen Hmccflxm one

.m musmflm

 

 

 

 

 

4
2L»; ’ n// I.

‘19. .. gag—"magma _[.Ilrfl

 

 

ll

 

\/\/.

 

 

 

22.5.
. .35

I\/

., /
1......

who».
Lid um’O p.523

  

 

 

 

 

 

 

 

/ .)\
(l

 

 

, .. as 3.. r
/\ /Ia\\l/r\I/lH\ull lies/.8. 8%“ gifts.—

METHODS

Studies were conducted at Skinner Lake in the interval
September 1978 - September 1979, to determine [TEL],
[TEL], [T51], tw and [EST—E] of the Vollenweider and
Kerekes (1980) model. Water samples were collected at
two-week intervals in the ice-free period to determine
[TEL] and [Tit]. A volume-proportional scheme was used
to obtain representative samples of upper pelagial and
lower pelagial portions of the lake. During summer strati-
fication, these zones were the epilimnion and hypolimnion
respectively. Volumes of water within layers of the

upper and lower zones were calculated from:

(3) V =

on:

(A1 + A2 + (A1A2)%)

where h was depth of a layer of water, A1 was area

of the upper surface of that layer, and A2 was area

of the lower surface of that layer (Wetzel, 1975).' A
bathymetric map of the lake was used to obtain areas.
Three strata within the upper pelagial water were sampled
at four stations on the lake (Figure 4), and combined

to form volume-proportional composites. Similarly, water
was combined from three strata in the lower pelagial

zone. Composite samples were obtained in duplicate.

12

l3

.mxmflumumm >9 :3onm mum mcofluoum mcmeEom mxoach
.mumuofi ca mum mucoucoo «oxen chsflxm mo auumewnumm

.v ousmwm

14

 

H.593 IV

 

   

euusmntoro \ . 52...; \ Ar memoezuecaz

15

Samples were processed utilizing adaptations of pro-
cedures described in U.S. EPA Methods for Chemical Analysis
of Water and wastes(l97l, 1979a). Total phosphorus deter-
mination used persulfate oxidation followed by colorimetric
determination of the antimony-phospho-molybdate complex.
Total nitrogen was taken from the sum of nitrate-nitrite
nitrogen and Kjeldahl nitrogen. Nitrite-nitrate-N was
determined using the cadmium reduction method. In order
to analyze for amounts of total Kjeldahl nitrogen, water
samples were heated in the presence of concentrated sul-
furic acid, K2804 and 39504, and evaporated until 803
fumes were obtained and the solution became colorless.

The cooled residue was diluted, and made alkaline with
addition of a hydroxide-thiosulfate solution. The ammonia
was determined spectrOphometrically after distillation
and Nesslerization. Spectrophotometric determinations
were made with a Varian SuperScan 3, UV-visible spectro-
photometer with a band width of 2-4 nm.

[TEL] and [TPt] for Skinner Lake were calculated

with the following equation:
(4) [NLl = [(Vup '[Nlupl + (Vlow'mllowq / VL

where Vup was volume of the upper pelagial at sampling

time, [N]up was nutrient concentration determined from

upper pelagial composite sample, Vlow was volume of the
lower pelagial at sampling time, [N]low was nutrient

cOncentration determined from the lower pelagial composite

16

sample, and VL was volume of Skinner Lake (2.157 x 106 m3).
Ratios of total nitrogen to total phosphorus ([TNLJIITPL1)
were calculated using these values. Mean in-

lake concentrations over the ice-free period were cal-
culated by finding the average of the nutrient values

as calculated by equation (4).

Measurements of atmospheric loading, stream loading
and internal loading to Skinner Lake were made to estimate
[T51] for the model. [TP] in atmospheric fallout was
determined at intervals of two to several weeks. Tripli-
cate lexan containers (23 cm deep, area = 0.26 m2) in
a stand 1 meter above the surface of the lake, were used
to collect fallout. At the beginning of each period,
acid cleaned containers were filled with six liters of
distilled deionized water. One liter was withdrawn from
each. These were combined and analyzed for beginning
concentrations of TP. After exposure, interior surfaces
of containers were cleaned into the water. Water from
all containers was combined and mixed. Volume was
measured, and one liter was withdrawn for analysis
of [TP]. Loading was calculated from increase in mass
of TP during the period of exposure.

Stream loading of total phosphorus between September
1978 and September 1979 was based on a water budget calcu-
lated for that interval. Continuous hourly stage height

records were available for the two streams in the watershed

17

with greatest discharge: the Rimmell stream and Croft
Drain. Largest fluctuations of discharge occurred
during spring. On the basis of these data, daily flow
measurements were made during the spring of 1979 to
estimate discharge for streams without recorders. During
the rest of 1978-79, when fluctuations in discharge were
small, flows on these streams were measured at two-week
intervals. Discharge rates were determined according to
the U.S. Dept. of Interior Water Measurement Manual (1967)
using a pygmy Price-Gurley current meter.

Hydrographs, which represented continuous plots
of discharge over time, were constructed for all streams.
Hydrographs for the Rimmell stream and Croft Drain were
constructed from continuous stage height records. During
summer, fall, and winter, daily records of discharge
were not available for inlets other than the Rimmell
stream. Consequently, an indirect method for hydrograph
construction between bi-weekly discharge measurements
was developed from other analyses. Barnes (1940) found
that after peak response to a rain event, discharge of
a stream declined at a constant geometric rate character-
istic of the stream. This rate, the recession constant

(K), can be calculated as:

 

(5) _K =

18

where q1 is discharge at day l, qn is discharge at day

n, and n is the time between q1 and qn in days. K was
calculated for the Riddle, Croft-Sweet, Weimer and Harden-
dorff inlets from the hydrographs of spring when daily
flow measurements were available. The shape of the inlet
streams' hydrographs for rain events of summer and fall
was determined from these recession rates. A heated,
recording precipitation gauge installed on the watershed
provided a continuous record throughout the study period.
The time of rain events was given by its record. Lag-
time (time from start of event to peak discharge) was
determined during storms of early summer to be less than
two days for all inflowing streams. The total discharge
for an event was calculated based on the continuous record
of discharge of the Skinner Lake outfall. Base-flow
discharge from the lake and input due to rainfall on

the lake were subtracted from the continuous discharge
values provided during an event. Results were then plotted
giving the hydrograph for total stream inputs during

a precipitation event. This input was consigned to
individual streams on the basis of the percentage of

the total input they contributed to the lake during the
most recent gaging studies. A shape, enclosing estimated
discharge, was then given to the hydrograph of each stream
knowing the lag-time and the slope of the recession line
(K). Stream discharges for the whole year (9/6/78 -

10/3/79), and intervals of snowmelt-spring overturn-summer

19

stratification (2/6 - 10/3/79), spring overturn-summer
stratification (3/20 - 10/3/79) and summer stratification
(5/21 - 10/3/79) were determined by planimetry of the
stream.hydrographs.

[TP] was measured in stream.samples collected daily
during spring of 1979. Aliquots from each stream's samples
were composited over two-weeks according to a discharge-
proportional scheme (Glandon et al., 1981). Volume of
aliquots was determined by considering that each sample
(e.g., collected at time t1) represented the volume of
water discharged from the time halfway to the previous
sample collection (t1 - t0/2) to halfway to the following
sample collection (t2 - t1/2). Volume of discharge over
the interval was calculated using the following equation:

Q +30 30 +0
0 1 1 2
(6) v = 3 (t1 - to) + 8 (t2 - t1)

 

 

where V is the volume of water discharged, and Q is the
discharge rate measured at time 0, 1 and 2. Composite
samples were refrigerated and acidified (2 ml conc.
HZSO4/l), and submitted to the laboratory at two-week
intervals for total phosphorus analysis. During summer,
fall and winter, individual samples were collected for
[TP] analysis at two-week intervals.

Mass of TP for each inlet was calculated by multi-
plying concentration by the total discharge of the inlet
over intervals represented by water samples. Mean concen-

tration of total phosphorus in stream flow discharged

20

to Skinner Lake ([TPil) was calculated by adding amounts
of TP in discharge of five inflows to the lake and dividing
by total volume of discharge of those streams over the

interval in question.

Internal loading of TP was estimated from:

(7) TP A Lake Storage - (TPi - TP )

Load n out

where TPLoad was mass of TP internally loaded to Skinner
Lake during an interval, TPin was the mass of TP entering

in stream flow, TP was mass of TP exiting the lake,

out
and A Lake Storage was the difference in mass the lake
contained between the beginning and end of an interval.

TP calculated for the ice-free season up until mid-

Load

July was zero or negative. TP calculated for the

Load

remainder of the stratification period (7/16 - 10/3)

was large and positive. Solving the equation for the

interval 7/16 - 10/3/79 allowed for determination of

the mass of TP in the lake due to internal loading.
Vollenweider eutrophication models consider lake

basins to be completely mixed reaction vessels. Thermal

stratification in summer commonly provides a barrier

to this expectation. Year around distribution of tempera-

ture and dissolved oxygen was measured in Skinner Lake

to mark the times of occurrence of overturn and depths

of the epilimnion, metalimnion, and hypolimnion during

summer stratification. Dissolved oxygen and temperature

were measured at two-week intervals at each of four lake

21

sampling stations during the ice-free season (Figure 4).
These measurements were taken at 0.5 m depth intervals
with a YSI Model 54 A oxygen meter.

Flushing coefficient (a) and residence time of water
(tw) were calculated for Skinner Lake. The flushing

coefficient was determined as:

(3) o = Vo/VL

where Vo was volume of outflow from the lake, and VL
was volume of the lake. Planimetry of the hydrograph
of the Croft Drain outlet yielded lake discharge. Flushing
coefficients were calculated for intervals of the year and
for a whole year (9/6/78 - 9/17/79). The flushing coeffi-
cient for the epilimnion (to 4 m depth) during summer
stratification was also calculated. Residence time (tw)
was the reciprocal of the flushing coefficient.
Concentrations of chlorophyll a in Skinner Lake
were obtained to calculate [EKT a] for use in the Vollen-
weider and Kerekes expression of equation (2). Upper
pelagial composite samples were collected at two-week
intervals during the ice-free period of 1979. Chlorophyll
a was determined as outlined in Strickland and Parsons
(1965). Approximately 500 ml of water were filtered
through Gelman Metricel Filters. Chlorophyll was extracted
by grinding the filters in 90% aqueous acetone. Samples
were then centrifuged. Supernatant was scanned with

a_Varian SuperScan 3 spectrophotometer for absorbance

22

from 800-400 nm. The sample was acidified with HCl and

rescanned from 800-400 nm. Absorbance recorded at 665 nm

before and after acidifying allowed for determination

of chlorophyll a in mg mf3.
Land management practices were put in place on the

Skinner Lake watershed during 1979-1981 with cost-sharing

funds provided by the US EPA under the Clean Lakes Program

(U.S. EPA, 1979b), and US Department of Agriculture, Soil

Conservation Service. The particular practices used

were chosen from the data and experience generated by

the nonpoint-source pollution study of Black Creek in

nearby Allen County, Indiana (Christensen and Wilson,

1979; Lake and Morrison, 1977). These included settling

basins, conservation tillage, group tile mains, terraces,

livestock exclusion, planting vegetation on critical

sites, diversions, and grassed waterways. The work accom-

plished is shown in Figure 5. The purpose of these prac-

tices was to decrease nutrient runoff in the direction

of Skinner Lake. The goal was to diminish the development

of obnoxious blue-green algae that occurred each summer,

and to improve the quality of the recreational fishing.

An anticipated result was reduction of nutrient loading

to the lake, specifically reduction of [TPi].

During 1982, measurements were made of [TPi] due

to streams, t

w’ [TPL] and [chl a]. Data from 1978-79

showed that [T51] and tw calculated over the spring over-

turn-summer stratification interval determined [TPi] in

23

Figure 5. Land management practices applied to the
Skinner Lake watershed during 1979-1981.

 

 

24

 

Mlninun tillage
Pasture a hay seeding:
Settling 8 lake bash:
Tile .

Terrace

Diversion

Watershed boundaries

Watercantral strum

Animalwaeteph

25

 

26

the ice-free period, and that algal production in the
ice-free period was related to [Tit] by equation (2).
Because of this, the period 3/24 - 8/10/82 was used for
making measurements to test a Skinner-specific lake model.
water samples from each inlet were collected daily during
3/24 - 6/30/82 using the same methods of compositing
and TP analysis as in 1978-79. From 6/31 - 8/10/82,
daily sampling was deleted and water from each inlet
was collected and analyzed at two-week intervals. [TPi]
from streams was determined in 1982 from measured [TP]
and a water budget from the interval 3/24 - 8/10/82.
The water budget was obtained using the techniques of
1978-79. Measurements of discharge from.the lake were
used to calculate residence time of water in Skinner
Lake (tw).

Samples from the lake's outflow were taken from
3/24 - 9/13/82 to determine [TPL] and [SET 3]. Mean
[TP] of the epilimnion during summer of 1979 (T = 44

3, s = 0.016) was essentially the same as that of

Skinner Lake's outflow (E = 45 mg m-B, 8

mg m-

0.027). This
followed the prediction of Chapra (1975) that the concen-
tration in outflowing water will be equivalent to that

in surface water at mid-lake in small well-mixed systems.

RESULTS

Concentrations of nitrogen and phosphorus in Skinner
Lake in 1979 are reported in Table 1. Total nitrogen
concentrations diminished from high values in the spring
to low values in later summer and fall. The pattern
of decrease in [TN] was much the same for concentrations
calculated for the whole lake volume and for the epilimnion
only. The range observed of [TN] was 5.88 - 1.19 mg 1'1.
Regarding [TP], a range of 0.021 - 0.199 mg 1"1 was ob-
served. High whole-lake [TP] in the interval July 30 -
October 3 resulted primarily from high TP concentrations
in the hypolimnion. They ranged from 0.154 - 0.221 mg 1-1
during that time. Phosphorus was apparently released
across the anaerobic sediment surface that existed in
the hypolimnion (Figure 6). It can be noted from Table 1
that concentrations of TP in the epilimnion from July 30 -
October 3 were approximately 50% of whole-lake concentra-
tions during that time. Whole-lake [TP] changed abruptly
in October with initiation of fall overturn; concentration
fell from 0.120 to 0.043 mg 1‘1. Coincidence of overturn
and decrease in [TP] suggest that phosphorus, particularly

that in the hypolimnion, fell out to the sediments (Figure

6). Solving equation (7) for phosphorus mass balance in

27

28

.m “coauoo nwaou5u am so: omquauauuo axed .H

 

 

«a Nac.c He.~ arc.c aa.m acne:
oh aac.c ec.m NH nonaoooc
«m onc.c rm.e as ecoao>oz
on mac.c m~.e am noooooo
nu ch.c c~.H c~e.c ~m.e m noooooo
mm mao.c co.e HNH.c ao.~ as nonaooeom
nN ano.c ma.H oce.c ea.e AN Leanna
ae ~oo.c aH.H eme.c aa.a me banana
ace amc.c on.m Hrc.c m~.m cm seas
Hue aNo.c ca.~ ~ac.c me.~ as sane
ca coo.c aa.~ eco.c ma.~ N sane
och euc.c ~a.~ emc.o ~a.m we once
cum emc.o Ho.a omc.c em.m m once
one Hmc.c no.a mnc.c am.a am an:
oa eac.c cm.a e an:
no aoc.c Ho.m mu Hane<
rm mac.c ~a.m me Hanna
on NHH.o mm.m H Hanna
an aaH.c mm.m as roan:
_ea_\.ze_ "my. .29. _ee_ H29. once
ecoecaaeeam ores odor:

 

one weenie weaken axed ofiona new cm>aw one HmH_\_ze_
ecu maausv axed umcsfixm :« Aala wav msuocimoai use cowouufic mo acoquauuamucou .H manna

.aouuauwuuuauuo unease wcauav coficsqawio use mcuauuo>o Hana
.mnaa ca moaned oeumlooa

29

.mhmn MO
common weanlmoa on» mcwuso oxag Hmccwxm

cfi AHIH mew cowumuucoocoo manocimosi Hobos

.o musmwm

30

 

a 0

20.55.55 a

 

20.72303: c .

Duo >02 .50 mum . 03‘ . .53 22. >32 an?
a q q u -

O O O
O

.93.. mmzzim mum.

l

00.

O
O
N
(EM/6w) SnaOHdSOHd “(V101

 

00m

31

the lake basin for the period when fall overturn was -
initiated (October 3 - October 24) supported this sug-
gestion.

Estimates of internal phosphorus loading were cal-
culated for intervals of the ice-free period of 1979
(equation (7)). These were negative for intervals of
measurement after ice-out until mid-July. By these calcula-
tions, a net loss of phosphorus occurred during that
time. For the interval July 16 - October 3, internal
loading to the water column was calculated to be 120 kg TP.
From the perspective of the Vollenweider and Kerekes
(1980) model, this phosphorus influenced the magnitude
of [TPi] in the Skinner Lake system.

Total nitrogen:total phosphorus for the epilimnion
of Skinner Lake ranged from 19 to 220 (Table l). The
work of Sakamoto (1966), Chaiudani and Vighi (1974), Allen
and Kenny (1978), and Smith and Shapiro (1980) predicts
that at [TNl/[TP] greater than 19, nitrogen limitation
did not occur in Skinner Lake, and that algal yield in the
epilimnion was likely phosphorus dependent.

Atmospheric bulk loading measurements of TP on Skinner
Lake for the study interval of 1978-1979 are given in
Table 2. Atmospheric loading amounted to 0.04 g TP in-2
per year. While this measurement fell within the range
predicted for the region by Chapin and Uttormark (1973),

it constituted only 1.4% of the annual stream loading.

32

'Table 2. Atmospheric bulk loading of total phosphorus on Skinner
Lake during the interval 9/6/78 - 9/17/79.

 

 

Rate of Input to
Period Fallout Lake

(mg m’2 day-1) (kg day-1)
9/6 - 9/25/78 0.099 0.049
9/25 - 10/9/78 0.045 0.022
10/9 - 10/23/78 0.117 0.058
10/23 - 11/6/78 0.066 0.033
11/6 - 11/27/78 0.050 0.024
11/27 - 12/14/78 0.092 0.045
12/14 - 1/16/79 0.041 0.020
1/16 - 2/6/79 0.023 0.011

2/6 - 4/2/79 0.074l . 0.0361
4/2 - 4/23/79 0.125 0.061
4/23 - 5/7/79 0.107 0.052
5/7 - 5/21/79 0.378 0.185
5/21 - 6/18/79 0.145 0.071
6/18 - 7/2/79 0.108 0.053
7/2 - 7/16/79 0.059 0.029
7/16 - 7/30/79 0.126 0.062
7/30 - 8/13/79 0.607 0.298
8/13 — 8/27/79 0.222 0.109
8/27 - 9/17/79 0.163 0.080

 

1. Sampling disrupted: values are the average between the previous
and following intervals.

33

hence, the influence of atmospheric loading on model
[TPi] was small at Skinner Lake.

Stream hydrographs were developed for the annual period
of study in 1978-79. Seasonal patterns of discharge
observed at Skinner Lake are shown for the Rimmell stream
in Figure 7. Other hydrographs made in this study are
in Appendix I. These hydrographs were divisible into
periods of fall and winter runoff, runoff due to melt
of snowpack, discharge during spring overturn, and discharge
during summer stratification. Discharges of streams
during these periods are reported in Appendix II (Table
A-l). Total discharge associated with melt of the snowpack
amounted to 53% of the annual stream discharge to the
lake in 1978-79. Stream discharge from rains during
spring overturn accounted for 35% of annual discharge.

In 1979, hydrographs for inflowing streams remained near
base flow during summer stratification. Base flows of
summer, fall and winter provided 12% of annual runoff

to the lake.

Flushing coefficients (0) for Skinner Lake for 1978-79,
given in Table 3, are broken down by periods of the year.
‘High observed coefficients during snow melt and spring rains
and low coefficients for other times of the year are likely
typical of small-volume temperate zone lakes with relatively
large watersheds. It can be noted that runoff from snow-

melt tended to displace the volume of water in the lake

34

.aenceafl cognac coach
HHoEEwm ecu How nimumouoas 30am Eamuum

.h musmfim

35

V

r0

N

(w°)NOLLV.lel33<‘:ld

OD< 1.23 Z

 

 

 

25 ><§. mi< . $32

. mm.”—

23. 0mo >02 .50

 

(<3

2\

 

 

 

:.

 

Amsumhm: 1.4%/.2.”—

._____.

 

 

 

L1 1

L
k .

OOON

000v

000m

000m

 

( 1.3 ' l) BOHVHOSIO

36

Table 3. Flushing coefficients (p) of Skinner Lake
during periods of 1978-79.

 

Period (0)

 

Fall Overturn and Winter 0.02
9/6/78 - 2/6/79_

Snow Melt 1.30
2/6 - 3/20/79

Spring Overturn 1.06
3/20 - 5/22/79

Summer Stratification 0.17
5/22 - 9/6/79

Whole Year 2.55
9/6/78 - 9/6/79

 

37

basin, which occurred during the period of ice-off from
the lake. Subsequent runoff from rains diluted the
lake during spring overturn. Coincident with relatively
low stream discharges to the lake in summer, the flushing
coefficient during stratification was small.
Concentrations of TP measured in inlet streams during
1978-79 are reported in Appendix 11 (Table A-2).
Spring runoff of phosphorus dominated stream.[TPi]
during the 1978-79 annual interval. For example, Figure
8 for the Rimmell stream can be used to demonstrate that
approximately 90% of the annual loading of TP from that
watershed was delivered to Skinner Lake during snowmelt
and spring overturn periods (February - May). For the
five inlets to the lake taken collectively, 93% of annual
TP loading occurred during this interval. For the year,
calculated stream [TPi] was 231 mg m-3.
Data given above for 1978-79 were used to develop
a model for the Skinner Lake system. It was conceptually
similar to that of Vollenweider and Kerekes (1980). The
model stated that [TPi] and [EFT a] in Skinner Lake in
the ice-free period were predictable from tw and [TPi]
from streams derived for the period of spring overturn
and summer stratification, rather than for the entire
year, or a period that included runoff during melt of
the snowpack.
Measurements to test the Skinner-specific model

were made in the post-land-treatment year of 1982.

38

.mblmhma mafiuso uoacw HHmEEflm ecu
an oxen Hoccwxm ou omum>waoo Ame. mononimonm
Hauou mo Amx. name one Aala OE. cowuauucmocoo

.m oucmflm

TP (kg)

175‘

150.

125-

 

39

 

 

 

 

 

T“
R - RIMMELL
1978-79
-0.600
3. -0.400
7' \ b
" \ p -0200
.t-or’o‘v-e-d’p-d' k \\ 9’04, \h‘ -

 

o'N‘DrJ'F‘M'AfM'J'JIArs

TP (mg/l)

40

Discharge and [TP] in streams measured in 1982 are
reported in Appendix II (Tables A-4 and A-S). During the

interval of measurement (4/20 - 8/10/82), tw was 0.65,

3

[T51] from.streams was 99.6 mg m-' 3

, and [TPL] was 54 mg m- .

For the comparable interval in 1979, tw was 0.63, [T131]

3 3

from streams was 127 mg m- and [TPi] was 63 mg m? .

By the relationship of equation (2) [chl a] in the ice-
free period was expected to be less in 1982 than in 1979.

Chlorophyll data for these years are given in Table 4.

3 3

A depression in [chI a] from 15.15 mg m- to 9.58 mg m-

occurred between years.

41

Table 4. Concentration of chlorophyll a (mg mf3) in Skinner
Lake during summer of 1979 and 1982.

 

 

 

1979 1982
Date [chl a] Date [chl a]
4/23/79 24.80
5/7/79 11.59 5/4/82 7.48
5/21/79 6.27 5/18/82 4.01
6/18/79 12.05 6/2/82 8.01
7/2/79 18.96 6/18/82 9.35
7/16/79 9.36 6/28/82 5.34
7/30/79 13.26 7/14/82 16.02
8/13/79 12.21 7/28/82 16.02
8/27/79 20.42 8/10/82 9.35
9/17/79 16.70 9/13/82 10.68
10/3/79 21.00
:7 - 15.15 SE- 9.58

 

 

DISCUSSION

The Vollenweider and Kerekes model was applied to
the Skinner Lake system.to quantify the relationship
of [TPi] to [TPL] and [SET—E]. From the 1978-79 data of
this study, the model was specifically modified to fit
the conditions of Skinner Lake. To make modifications,
the following were considered: major sources of [TPi]
to Skinner Lake, seasonal differences in [TPi] and tw'
and differences in epilimnetic and hypolimnetic [TPL]
and their relation to [EFT—E].

Vollenweider and Kerekes (1980) did not specify
sources of [TPi] measured to derive the empirical basis
for their model. Atmospheric loading, septic tank loading,
internal loading, and stream loading can be important
sources of [TPi] for lakes. The influence of atmospheric
TP loading on [TPi] of Skinner Lake was found in this
study to be negligible. Septic tank loading was estimated
using the constant, 0.08 kg TP caput-1 yr_1, reported
by walker (1979). There were 125 cottages and approxi-
mately 375 people served by septic tanks around Skinner
Lake. By Walker's constant, these contributed 30 kg TP Yr—lo
This septic tank loading comprised 2% of the 1978-79 annual

total TP load. Internal phosphorus loading during summer

42

43

has been found to be an important contributor to [TPi]
in some eutrophic lakes (Nurnberg, 1982). In Skinner
Lake during summer of 1979, the estimated 120 kg of in-
ternal TP loading comprised 8% of the 1978-79 total TP
load. Of the potential sources, stream loading was the
major component of [TPi] at Skinner Lake, comprising
90% of the annual total TP input.

There is inference in their work that Vollenweider
and Kerekes calculated [TPi] and [TEL] by averaging data
over an annual period. However, in the Skinner Lake
system there was great seasonal variation in both [TP11
and tw over a year. These variations effected the model
predictions of [TPL] in ways that are shown in Table 5.

A comparison of rows I and II in Table 5 shows that base-
flow conditions of streams in fall and early winter (9/6/78 -
2/5/79) had little effect on determining the magnitude

of annual [T51] and tw. For the whole year and for the
interval including snowmelt, spring overturn, and summer
stratification, the Vollenweider and Kerekes model greatly
overestimated [TPL]. A comparison of rows II and III

in Table 5 shows the importance of the snowmelt period

for determining the magnitude of annual [TPi] and tw’

During that interval (2/6 - 3/20/79) both [TP] and discharge
of inlet streams were high (Figure 8). In contrast,

the large mass of TP delivered during snowmelt did not
greatly influence observed [TPL] as given in rows I,

II, and IIIA. [TPi] and tw taken for the period of spring

44

Table 5. Fit of Skinner Lake data of 1978-79 tg_Yollenweider and
Kerekes (1980) estimates of in-lake [TP] calculated from:

__ [I51]

1 + t.w

where [TFi] is from stream discharges except for III B-

 

Predicted Observed

 

Period [TP1] tw [TPL] [TPL]
(“18 f3) (m8 r3) (mg m'3)
1. Whole Year 231 0.39 142 85
9/6/78-10/3/79
II. Snowmelt-spring 234 0.41 143 98
overturn-summer
stratification
2/6-10/3/79
III. Spring over- (A) 127 0.63 71 88
turn-summer
stratification
3/20-10/3/79 (B) 1631 0.63 91 88
(C) 127 0.63 71 632
IV. Summer 89 3.38 31 80

stratification3
5/22-10/3/79

 

1. Internal loading was added to stream loading to calculate [TP1].

2. Observed [TP ] was calculated by averaging whole lake [TP ]
for the perigd of spring-overturn that constitutes one flkshing
time prior to stratification and epilimnetic [TPL ] during summer
stratification.

3. Whole-lake volumes and concentrations were used to calculate [TPL].

45

overturn and summer stratification provided a better:
prediction of [TEL] in the Vollenweider and Kerekes model
than annual estimates of these variables, or estimates
using other periods of the year. .This is shown in sec-
tion III of Table 5. [EL] predicted from [iii] and

tw during summer stratification grossly underestimated
observed [TEt] (Table 5, row IV).

The Vollenweider and Kerekes (1980) model assumes
that lakes are mixed reactors in which [TP] is homogeneous.
Skinner Lake was an exception to this in that hypolimnetic
[TP] was more than twice that of epilimnetic [TP] during
the last one-half of the summer stratification period
(Figure 6). In this Study, whole-lake [TEL] was calculated
for the spring overturn-summer stratification period
using TP mass and volume of water in both the epilimnion
and hypolimnion. This yielded a [TEL] for the interval
of 88 mg m-3. Row IIIA of Table 5 shows that whole-
lake [TEL] was underestimated using the Vollenweider
and Kerekes model with measured values of [TEi] and tw'

A closer prediction of whole-lake [TEL] was achieved

by including internal TP load with stream TP load in

the [TEi] term (Table 5, Row IIB). Specifically, this

was achieved by adding 120 kg of internal load to TP

mass from stream load and dividing by stream discharge.
The better fit obtained suggests that [TEi] should include
both stream and internal loading when predicting whole-

lake [TEL] for Skinner Lake during the spring-summer interval.

46

A major goal of this study was to predict [BETTE] in
the ice-free period from [TEi] and [TEL]. Use of whole-
lake [TEL] measured in the spring-summer interval in
equation (2) of the Vollenweider and Kerekes model pre-
dicted [SKI—E] in Skinner Lake at 22.65 mg m-B. Observed
[EFIEE] during 1979 was a relatively poor fit at 15.15
mg m-3. It is likely that algae grow in response to
[TP] of the epilimnion (Smith and Shapiro, 1981). On
this basis, an alternate method of calculating [TEL] was
considered. It averaged whole-lake [TP] during spring
overturn and epilimnetic [TP] during summer stratification
(Table 1). From measurements of this study, the resulting
[TEL], designated [fifiepilss’ was 63 mg m-3. Using this
value in equation (2), predicted [EETEE] at 16.27 mg m-3.
This result was close to the observed value given above.
Thus, while’ including internal loading in [251] for the
spring-summer period yielded a close approximation between
predicted and observed whole-lake [TEi], [EFT—E] was
best predicted by [TE] in the lake at overturn and the
epilimnion (rather than whole-lake) in summer. In row

IIIC of Table 5, it is shown that [TEi] for streams in
]

sprlng-summer at eXlstlng tw predlcted observed [TPepi ss

relatively well. From these considerations, [TEi] of
Vollenwelder and Kerekes was treated as [TPstreamlss and

] for purposes of modeling the effect

[TPL] as [TPepi as

of incoming phosphorus and algal yield in Skinner Lake.

Further, a spring overturn period was used in the study of

47

1979 to coincide with the interval of time prior to strati-
fication during which the flushing coefficient of the

lake approximated 1.0 (Table 3). The spring period as
applied to variables (e.g. [TEstreamlss):h1the Skinner-
specific model was defined by this. Records of the U.S.
Weather Bureau for 1979 showed it was a relatively dry
year at Skinner Lake. Basing a model on a spring period
where p = I appeared appropriate for this system.

The Skinner-specific model based on above considerations

took the form:

 

[TE ]
tream ss
(9) a. [TP .1 = 5
epl ss 1 + tw 8
ss
b. log [ch13]ss = 0.99 log [TPepi]SS - 0.60
where [TEepi]ss was mean TP concentration of the epilimnion

over the spring-summer stratification (ss) interval,
[TPstreamlss was mean TP concentration delivered to the

lake from the inlet streams over the ss interval, tw
83

was residence time of water in the lake over the ss interval,
and [EEI—Elss was mean chlorophyll a concentration in
the epilimnion over the 33 interval. The constant in
the Vollenweider and Kerekes relationship for [EHITE]
and [TEt] given in equation (2) was changed (0.57 to
0.60) to fit the observed conditions of Skinner Lake

during 1978-79.

48

Following land treatment during 1979-1981, the

Skinner-specific model proved to be an accurate predictor

]

as compared to 127 mg m'3 in 1979. Concomitant

of [T epi ] was 100

and [c—‘hl‘a'lss. In 1982, [fi' SS

33 stream

mg m'3

decreases in [TPepilss and [chl alas were expected as pre-
dicted by equations (9a) and (9b). Predicted [TEépi]
3

for 1982 was 55 mg m- ; observed was 54 mg m‘3. Predicted

 

[chl a] was 13.02 mg m'3; observed was 9.58 mg m‘3.

ss
Figure 9 is a graphical representation of the Skinner-
specific model modified from Figure 8 of Vollenweider and
Kerekes (1980). This figure illustrates that given residence
time (yr) of lake water during the spring-summer interval

I

predicted. Lines of equal [Tfiepi]

(y-axis), [TE ] is

(x-ax13) and given [TP epi ss

stream SS

are represented by

l

of each curve designated on the left. Corresponding value

1

is designated along the right end of each curve. Included

38

the curves running across the figure with the [TPepi 33

of [chI 3153 associated with [T epi via equation (9b)

55
on Figure 9 are plots of Skinner Lake data for 1979 and 1982.
The figure also shows boundaries of trophic categories
(ultraoligotrophic to hypertrophic) as presented by Vollen-
wieder and Kerekes (1980). These represent the synthesis of
opinions of OECD investigators as to the trophic classifi-
cation of their study lakes, based on [TEL] and [EFT—i].

In the use of models such as have been discussed, a
range of uncertainty exists within which predicted values

vary from observed. This uncertainty may reduce the power

Figure 9.

49

Diagramatic representation of the Skinner-
specific model (modified from Vollenweider
and Kerekes, 1980) . .represents plot of
Skinner Lake coordinates of 1979; ||repre-
sents plot of Skinner Lake coordinates of
1982; ‘a probable case for Skinner Lake with
diversion of Rimmell stream around lake to
outlet stream. ,- ‘13 probable case for Skinner
Lake if settling basin on Rimmell stream
removed 100% TP in stream discharge.

50

 

 

 

 

 

(000 g

d

4

d

1

d

vo- I001

E a

\ d

0 cl

E ..

.8 .‘
fl

g -(

It; ‘
L—_—l

IO-j

d

d

.4

-(

q

q

I r I ITIITI' F I Ilrlul l frrriri
DJ I I0 IOO

RESIDENCE TIME (twss)

51

of conclusions which are based on lake modeling schemes
(Reckhow, 1979). In order to calculate confidence limits
of model predictions, it is necessary to determine standard
error from the variation among lakes used to construct the
particular model. Two current lake models (Reckhow, 1977
and Walker, 1979) consider the statistical uncertainty of
predictions of lake phosphorus concentrations, and both
give a method by which confidence limits can be calculated.
Confidence intervals for predictions made by these models

can be estimated from:

2
(10) S2 = P _ 10log Pe 2 sm
t e
where S is the total.prediction error in mg 1-1, s is

t
the standard error of the estimate for the model, and Pe

m

is the predicted lake concentration (Reckhow, 1981). Table
6 compared predictions made by the Skinner-specific, Reckhow
(1977) and Walker (1977) models for phosphorus in Skinner
Lake in 1979. For the purpose of this comparison, [TEi]

was taken as [TP ] , and [TPL] as [TPepi

stream ] in the

SS SS

Reckhow and Walker models. Table 6 also presents the pre-
dicted confidence intervals of these models. In both cases,
the confidence intervals are wide, and it is difficult to
apply them to a particular lake for management decision
purposes. It should be noted that error terms were estimated
from least squares analysis on a data set from many lakes.
Thus, much of the error results from variability between

these lakes (Reckhow, 1977). When a model is applied to a

52

 

 

 

 

.amaeu canoe: Haow Haas usaa> man» who mean we nmo .0.« “pound pudendum use A .n
nauhv axed can cw nouns «a mafia cocoofioou I so one coaumuuaoocoo nanosecond
Seamaaouuo owouu>a I name. .coauauuaoocoo nanosecond axed mwouu>o I "Ammg muon3 .a

.Heooe any new duodenum one we wanna pudendum I 3m .m
.msaa magnet oxen moccaxm new mmHAQom9_ oo>uomoo .N
Am)... as R: 22 .88... oeeeooennuocfixm of acne $.83:me no 1mm. 4
. u. a
.— 43.} can. + H 4 HS
83v. mmvemv as h u _ a: :3: node:
_ a: l.
. a
a an 2. +24 a a: .. c
any. $.7an 2: a u H on: £33 Boredom
_ E
. ran 1. H a
IIIII an (IJUIII.I ”.mw_ ofimuooomluoccfixm
_ he
Anna may nuwaau A Anna may «coaumsvm new new
88328 _ as announced Honor Honor

 

.MIE N3 MO I GOHUQHUGOUQOO 03¢." UOEQQQO .mHO—voa OOHSU

mean: 3a one Hmwmw_ Menu Hjmwu mo meowuouooun emu mo conquoiaoo .o canoe

53

particular lake, the model error term should only include
that lake's variability. -For example, if the Skinner-
specific model was applied to Skinner Lake for several
years, a series of predicted and observed values would
allow determination of the certainty expected for the model
on Skinner Lake. This would provide more appropriate con-
fidence estimates for management decisions at Skinner Lake.
When a model can be calibrated to fit a specific
lake's characteristics using data from several years, it
then becomes a powerful management tool. Use of this model
could predict the effectiveness of potential management
schemes, and costly projects which predict only little
improvement in lake quality could be avoided. For example,
one treatment considered by planners of the Skinner Lake
reclamation project was diversion of the Rimmell stream
directly to the lake's outlet. Contours of the existing
landscape favored such an approach, but compensation for
disrupting intervening land use would have been costly.
The Skinner-specific model can predict the effect of this
project if, for example, it had been implemented in 1979.
Figure 9 shows that diversion of the Rimmell would not have

lowered [TE ]

stream appreClably. Other lnlets were lmportant

SS

in determining total [TE' ] Because the Rimmell

stream 35‘

provided a large percentage of inflow water to Skinner Lake,
diverting the stream would have increased twss from 0.63

to 2.35 yr. The net effect of diverting the Rimmell would

3 3

have been to reduce the [TE ] from 63 mg m- to 45 mg m-

epi ss

54

and [EFT—Ejss from 15 mg m.-3 to 11 mg m-3. This project
would not have provided substantial benefit toward impro-
ving lake quality.

As a second example, a settling basin was constructed
on the Rimmell inlet just above Skinner Lake during 1980-81
(Figure 6). This basin was intended to slow Rimmell water
velocity and promote settling and removal of suspended
particulate material. However, designers of the basin did
not account for hydrologic relationships which dictate
appropriate design. The Rimmell settling basin was too
small and its effect was much less than optimum (McNabb et
al., 1982). On the basis of 1979 data, if the basin removed

100% of particulate phosphorus from the water, [TE ]

stream SS

would have been reduced from 127 mg m"3 to 52 mg m'3,

__. -3 -3 .___.
[TPepi]SS from 63 mg m to 20 mg m , and [chl 313s from
15 mg m-3 to 7.5 mg m-B. As shown in Figure 9, this would

represent a considerable improvement in quality at Skinner
Lake. Considerations such as these, with lake-specific
models, can focus attention of planners on management al-
ternatives most likely to achieve the intended goals.

In summary, calibrating a general lake model for a
single lake requires knowledge of the lake's specific
hydrologic and limnological variables. Even though data
from Skinner Lake did not fit the basic form of Vollen-
weider and Kerekes' model, this did not discredit the
relationships they described. Rather, it indicated the

Skinner Lake system had specific attributes requiring

55

attention. Total phosphorus loading for Skinner Lakewas
predominantly from inlet streams. Other sources, such

as atmosphere and septic tanks, had a negligible impact
on relationships in the model. Flushing coefficients (0)
during snowmelt and ice-off were > 1.0 at Skinner Lake

in the years of this study. Coefficients in subsequent
spring overturn periods were also > 1.0. [TEL] in the
ice-free period was determined during the period of
spring overturn just prior to stratification when 0 = 1.0,
and continuing through the time of stratification. Other
temperate zone lakes with high watershed area:lake area
relationships may follow this pattern. Internal phosphorus
loading influenced whole-lake [TP]. However, algal pro-
duction in Skinner Lake was related to the [TP] of the

epilimnion. [TE

epi] was related to stream [TPi] in

SS

the the manner described by the Skinner-specific model.

The addition of internal TP load to [TEi] was not necessary
in modeling the system. In other stratified, eutrophic
lakes, similar considerations might be appropriate. Results
of this study call attention to the need for site specific

information on which to base cost-effective land management

decisions.

LITERATURE CITED

LITERATURE CITED

Allen, R.J. and B.C. Kenney. 1978. Rehabilitation of
eutrophic Prairie lakes in Canada. Verh. Internat.
Verein. Limnol. 20:214-224.

Barnes, 8.8. 1940. Discussion of analysis of runoff
characteristics by O.H. Meyer. Am. Soc. Civ. Engng.
Trans. 105:1-106.

Chapin, J.D. and P.D. Uttormark. 1973. Atmospheric con-
tributions of nitrogen and phosphorus. Tech. Rep.
Wat. Resources Ctr. Univ. Wis., Madison. 35 pp.

Chapra, S. 1975. Comment on: "An empirical method of
estimating the retention of phosphorus of lakes" by
W.B. Kirchner and P.J. Dillon. Water Resour. Res.
11:1033-1034.

Chiaudani, G. and M. Vighi. 1974. The N:P ratio and
tests with Selanastrum to predict eutrophication in
lakes. Water Res. 8:1063-1069.

 

Christensen, R.G. and C.D. Wilson. 1976. Best management
practices for non-point source pollution control A
report on a seminar. US EPA, Chicago, Illinois.

323 pp.

Dillon, P.J. 1974. A critical review of Vollenweider's
nutrient budget model and other related models.
Water Resources Bull. 10:969-989.

Dillon, P.J. 1975. The phosphorus budget of Cameron Lake,
Ontario: the importance of flushing rate to the
degree of eutrophy in lakes. Limnol. Oceanogr. 19:
28-39 0

Edmondson, W.T. 1961. Changes in Lake washington following
an increase in nutrient income. Verh. Internat.
Verein. 14:167-175.

Glandon, R.P., F.C. Payne, C.D. McNabb and T.R. Batterson.
1981. A comparison of rain-related phosphorus and
ntriogen loading from urban, wetland, and agricultural
sources. Water Research. 15:881-887.

56

57

Hutchinson, G.E. 1957. A Treatise on Limnology. 1.
Geography, Physics, and Chemistry. New York, John
Wiley & Sons, Inc., 1015 pp.

Kirchner, W.B. and P.J. Dillon. 1975. An empirical
method of estimating the retention of phosphorus in
lakes. Water Resour. Res. 11:182-183.

Lake, J. and J. Morrison. 1977. Environmental impact
of land use on water quality. Final Report on the
Black Creek Project (Summary). U.S. Environmental
Protection Agency, Chicago, Illinios. 94 pp.

Larsen, D.P. and H.T. Mercier. 1976. Phosphorus retention
capacity of lakes. Jour. Fish. Res. Ed. Canada.
33:1742-1750.

McNabb, C.D., B.J. Premo, J.R. Craig and M. Siami. 1982.
Project Report. A cooperative project to determine
the effectiveness of land treatment in reducing the
trophic state of Skinner Lake, Indiana. Submitted
to US EPA,Corvallis, Oregon, Project Officer Dr. Spencer
A. Peterson, for review.

Nurnberg, G.K. 1982. The prediction of internal phosphorus
load in lakes with anoxic hypolimnia. A contribution
to the Limnology Research Centre, McGill University,
Montreal, Quebec, Canada.

Pearson, J. 1978. Fish management at Skinner Lake, Noble
County, Indiana. Indiana Department Of Natural
Resources. Division of Fish and Wildlife.

Rast, W. and F. Lee. 1978. Summary analysis of the
North American OECD Program on eutrophication (U.S.
Portion) U.S. Environmental Protection Agency 600/3-
78-008. Ecol. Res. Ser. Corvallis, Oregon.

Rawson, D.S. 1955. Morphometry as a dominant factor in
the productivity of large lakes. Verh. Internat.
Verein. Limnol. 12:164-175.

Reckhow, K.H. 1977. Phosphorus models for lake management.
Ph.D. dissertation. Harvard Univ., Cambridge, Mass.
304 pp.

Reckhow, K.H. 1981. Lake data analysis and nutrient
budget modeling. U.S. Environmental Protection Agency,
EPA-600/3-8l-011. Corvallis, Oregon.

Sakamoto, M. 1966. Primary production by phytoplankton
' community in some Japanese lakes and its dependence
on lake depth. Arch. Hydrobiol. 62:1-28.

58

Sawyer, C.N. 1947. Fertilization of lakes by agricultural
and urban drainage.- Jour. New Engl. Water Works Assoc.
61:109-127. '

Smith, V.H. and J. Shapiro. 1981. Chlorophyll-phosphorus
relations in individual lakes. Their importance to
lake restoration strategies. -Environmental Science
and Technology. 15(4):444-451.

Strickland, J.D.H. and T.R. Parsons. 1965. A manual of
sea water analysis. 2nd edition. Fish Res. Board,
Ottawa, Canada.

U.S. Environmental Protection Agency. 1971. Methods for
Chemical Analyses of Water and Wastes. Environmental
Monitoring and Support Laboratory Office of Research
and Development. Cincinnati, Ohio.

U.S. Environmental Protection Agency. 1979a. Methods for
Chemical Analyses of Water and Wastes. Environmental
Monitoring and Support Laboratory Office of Research
and Development. Cincinnati, Ohio.

U.S. Environmental Protection Agency. 1979b. Limnological
and socioeconomic evaluation of lake restoration
projects: approaches and preliminary results.
Corvallis Environmental Research Laboratory, Office
of Research and Development. Corvallis, Oregon.

Vollenweider, R.A. 1968. Scientific fundamentals of the
eutrophication of lakes and flowing waters, with
particular reference to nitrogen and phosphorus as
factors in eutrophication, 192 p. Annex, 21 pp; Biblio-
graphy, 61 pp. Rep. Organization for Ecomonic Coopera-
tion and Development, DAS/CSI/68.27, Paris.

Vollenweider, R.A. 1975. Input-output models with special
reference to the phosphorus loading concept in limno-
logy. Schweiz, Z. Hydrol., 37:53-84.

Vollenweider, R.A. 1976.. Advances in defining critical
loading levels for phosphorus in lake eutrophication.
Mem. Ist. Ital. Idrobiol., 33:53-83.

Vollenweider, R.A. and J.J. Kerekes. 1980. Background
and summary results of the OECD cooperative program
on eutrophication. p. 25-36. Proc. International
Symposium on Inland Waters and Lake Restoration. U.S.
Environmental Protection Agency. 440/5-81-010.
Washington, D.C.

 

 

59

Walker, W.W., Jr. 1977. Some analytical methods applied
to lake water quality problems. Ph.D. dissertation.
Harvard University, Cambridge, Mass. 528 pp.

Walker, W.W., Jr. 1979. Use of hypolimnetic oxygen deple-
tion rate as a trophic state index for lakes. water
Resour. Res. 15(6):1463-1470.

Wetzel, R.G. 1975. Limnology. W.B. Saunders & Co.,
Philadelphia. 743 pp. ,

APPENDICES

 

APPENDIX I

60

.Amblmhmflv peace mwuoocooumm
on» HON oucomu cowuauwmwooum can niaumonoms 3on Eoouum

.HI¢ ousmflm

61

 

034. (:5 22. >32

E4 mg). mle_ 23.. DMD >02 #00
a d a q . -

 

v

IO

(”49) NOllVlldIDBHd

9‘

 

   

 

 

 

 

 

Tr __ -

 

Amhlmhm: Limoozwom<r

1;

 

 

 

boom

LLl

00m

1 1

hooh

JOOO

 

(l-S' l) BOHWOSIO

hook .

62

.Amhlmhmflv uoHcH oaoowm
on» uOM ouooou coflumuflmflooui one nimumouo>o 30am Emonum

.NI¢ ousmflm

63

q-

[‘0

N

1

(w9)NOIlVlld133tld ,

 

cod .2. 22. as
<l

 

 

 

 

q

Ed. 232

 

 

mmE 2.3.

_a\

 

TP. :.

 

owe >02

lwfllll .

POO

armed: ”1.59m .U.

 

 

a; _ TE

0 .
IO

LO
(C
(.94) BOHVHOSIO

o
9.

no
SE

00—

 

 

 

64

.xaeamnmfl. peace boosmubeouo
one “Ow ouooou cowpmuwiwooui one niaumouo>o 30am anwum

.mu¢ musmwm

65
re a.

(”43) NOIlVildlDBtld

 

 

02 (5.. 22. >32 mi< 245. mm“. 23. omo >02 .50
d q q 4 a a .. _

 

   
 

 

94

 

 

 

 

 

 

 

 

 

 

 

q .Jlll A
l
(on
armamsemmsméuomo moo.
. G
U (S
. m
hon. V
. no
A m
MOON”
I ..
- homm(
- Room
T
__ r __ :fiE

66

.Amblmnmav umacw umemz
mnu new Uncomu :0flumuwmwomum flaw :mmumounwn 30am Emwuum

.wlfi musmflm

67

q-

M

N

(”43) NOLLVildIDEHd

re? 5.. 22,

__ ___L

 

 

 

 

 

 

 

>52 mm< as). mm... 266 owe . >02 . .50 .

85¢th mmgmg

 

 

 

 

 

_. :. Li. E

In
N

O
10

‘19
(15' l ) ESHVHOSIG

0
92

mm—

Om—

 

68

.Amhlmhmav Gamma uwouo
man new Uncomu coaumufimflomum can :mmumOH©>5 30am Emmuum

.mn4 9.33m

69

v .

['0

(”49) NOLLVildIDBBd

9‘

 

Q3 42. 22. >32 . an? . KS2

r

I

 

 

 

 

fimm... 23.

3

 

 

AmNnmNm: 2320. Hmomo

—_ D

 

owe >02 .50

2

 

 

 

000—

000m

000m

000V

coon

0000

 

( $5“ I) EQHVHOSIG

70

.ANmmH. umacw oEEH
wan How ouoomu coaumuflmwomum can namumouc»: 30Hmafimmuww

.ou< musmfim

71

(W9) NOLLVLIdIOBHd

CO

N

F

 

{Fr—E. _ _ :Fl

.5... 23.. >52 In; :52

 

L

4
L
.U 00.0w

Nomw Adm—25:1

In:

000?

l

0000

 

 

 

 

 

(Sn) BSHVHOSIO

72

.AmmmH. umacw mwuoucmoumm map
How choomu coflumuwmwvmum Dam smuumouv>n 30Hw Emmuum

.hld munmwm

73

('3

(m9) NOLLVJJdIOSHd

 

N

 

IL? _ LE

5.. 22. ><2 $2 5.2
moo.
«2: mmmoozmog: .loou

noon

 

 

 

 

 

(Sm seam-109:0

74

.Ammmav umacfl macowm
mnu Hem Choomu cofiumuflmflomum cam nmmnmouvmn 30Hm Emmmum

.mu¢ musmflm

IR. .2... i.il.::a..,.:..,!! L.

(“33) NOILVLIdIOSHd

 

 

[LEE _

42. 22.. ><§ mm< :32

.2}

 

 

N00?
m...DD.E

 

 

 

A

I A n A

A A

L411 LA

 

2F.

 

mm

on

ms

00p

 

(9m asaVHosm

76

.Ammmdv umacw ummsmuumouo
mnu How ouoomu sowumuwmfiomum cam nmmumouc>n 30Hm Emwnum

.ml¢ musmflm

77

N 0

(“35) NOLLVJJdIOBHd

 

.53 22. >52 mm< m<s.

 

 

00

00..

00..

com

 

 

 

.

J

L
. «mm. M
I pmmzmutomo .U
H. m
r L E _ r: _ _._ ._.__.

 

(Sll) ESHVHOSIG

78

..mmma. umacfl umEam
03» MOM GHOUGH GOHHMHHQflOQHQ 02m SQQHOOHUNS 3OHM Emmwum

.OHI< mHDmHm

79

(“19) NOILVLIdIOSHd
'- N 0')

LI I IF11

JUL

 

 

 

“T'I‘ IWWFF
WEIMER 1982
JUN

MAR APR MAY

 

IIIIAILJIAIAA
l0 0 IO
N If) N

(S/I) BSHVHOSIO

 

80

..~mm.. gamma amouu may
new nuoomu coflumuflmfiomum can nmmumoucmn 30Hm Emmuuw

.Halm musmflm

81

(”9) NOLLVJJdIOSHd

 

 

42.. 23.. >52 ma< :52

 

 

“one.
. hooow
o ,. 32 22mg taco
Nr ”0000
.- hoooc
.

 

 

 

(sll) BSHVHOSIO

APPENDIX I I

€32

.a~u>uou:« omega uo>o omuazuauv gonad cuuuoasou use aqua o» vanes ace euuauuufl an: aucuaq Ada noun ouuasuuua .~

.olqu saga uguuav umuaaoaqv o: uuuuoaecu .u

 

 

 

 

Gama #ONNG mh\n\cnlmdxa

Nana Necccu ah\sd\alcu\¢

owhan Ndénnd an\hN\mI€~\Q

OnNah cdcnwfl ahxnuxmlun\n

names doa0~ a~\0n\hlh~\h

th¢~ sauna ah\0~\sln\h

unn$h NNncn GN\N\~IO~\0

accun names o~\¢~\olo\o

23a 23... $33.23

N50<Md «name on\~N\ntn\n

whence aoncan mh\h\mlcm\¢

humans ancNN ON\MN\¢Ind\e

:«uuo amouo «ouucsuuue.uoucu vuuuoonloo
00¢o¢0~ cumdn such ncnuu ancmo ONNOom m~\nd\¢tu\e
occaucu Gamma nNhnA ohan manna Ownhno ah\n\clcu\n
mNmunOd cacac NNNGd hNhNn Gamma namnuo Oh\ad\nlo\n
onuooce Osooaq @nnan hGfiAOd nmaueu acnno~a Oh\o\nlh\u
women 000d law {Ne snn {New QN\0\NIOH\A
«chad “650 III NNHN 0&0 docau mh\0M\~InN\NH
aqua Ouon III «don Donn chncn Os\c~\NdlcN\dd
acucn nan III Maud nan Amman DN\NN\~AIh\nn
«god III {II nnnu coca heNNA Oh\o\dnlh~\0H
-3 2... an..- 8: 22 :32 23.372...
such: uuouo nouamuuuouu nun—o: caucus uuuovumvuaz udoaaum ~a>uoucn

 

.anlnsmu saunas «so; uo=cusm no uouuao ecu alumnae gods“ uo Anlv ouuasuoqv ua>uousu euuwluuom .~I< annoy

813

._mb_ uou weak—ace as: uuuaomlou can «nauseous cu usueuouuu auuuuomlou cum: auwawaum a laumawwwmmwm um

 

 

 

 

as“. auzu ya u v a:
do and anxnxcd
um no o~\h~\a
2 3 222a .
an Nun ahxnnxo
am aa m~\on\~
0N do mh\o~\n
NM 00 anxu\h
0“ «n m~\mn\o
5N en . onxnxo
ucd Ow mm\au\n
an nu as\h\n
as so . ¢~\MN\¢
such: nacho undulaa none“ acuunOQIOu
Ha «NH no GNN emu man am\n—\c
hug an we sun ea. mnu oh\~\<
mod no an mud new and ah\m~\n
3 RN 2: . as an a: 22>”
an ac Inl ne cn and mh\o\u
an can III . Na no #5 ouxom\~
an nN III 0c @0— no QN\QA\N~
en MN til hm «ed no Q~\NN\~u
en III til mm was no asxcxun
i- ...... -E 2 . 8. 2 33:2
--- -l m.-- 3 _ 2: an at»;
3:: 886 326.386 3:3. «2.3.. 332.35. 22.5. 33

 

osnosa— saunas can; nosauum uo uu—uao van alaouuu uoucu loam coda-Lu :« A :- ml. .ma. coca-nouwv aquuuuuaqa=< .~u< snack

841

.oauu aqsu ”sumac owuasuuuv o: concouvcn .a

 

 

«Noon n~¢¢ q--- mafia «can owqwo ~u\c~\o . a~\~
~a¢~n~ goon. uuu «fine nanu. ~e~¢a ~a\u~\~ . «~\~
neeusa «none on cnoag o-~m ~ce~o~ ~¢\m~\~ ‘ a~\o
noncou mane. can «Nae “Nan“. «nwueu Na\a~\o . e.\o
asamhn choc" «can ages. saga~ andaon ~a\n~\c . «\o
ooc-n ammo“ ~c~n canes caudn moons" «u\~\o - ad\n
omcuad ”moms No.“ agonu agnog o-a- ~oxogxn - «\n
ceonmod «once snnn cocoa wens" “ahahn ~a\n\n u o~\e
acsconu «mason ~h-~ chfinou c~ean occan_~ ~a\a~\e . “\e
Macadam ansnn a... oneafi ohoos anunna ~o\e\e a ¢~\n
and»: uuouu unasauuuouu waldo: .ouuenu uuuoeconuuz duollqa ~c>u0usu

 

.Noon nauuae 03.4 nocaqu uo uouuso as. allouun uoncu uc Ami. «mango-«v no>u0ucu scan-quau .n|< munch

85

.aawu nusu an umua:ua«v a: nouauuecm .u

 

 

 

on me gun: «a on mad ~o\c~\a
nq co all: on an deg ~c\c~\~
no no cc Now can co ~axnuxn
an no on we «a mag ~o\o~\c
on «s «9 mm cc no ncxnnxc
me an «N ecu «ca Qua Noxus¢
an no on co ¢n an uo\a~\n
as on mg an an on Noxmxn
add «a as mom nun «cu ~a\a~\¢
.5 8 3 c: a: :N . $3:
a: «.2 2 3a «2 a: 2:2.”
cunuauuuouo uooamyuuouu amigo: aunt‘s uuuouaoau-a amullus «an:
.~oan usuuae can; nocuuxm no uomuao as. alumnus nousu roan noun-ac an Anni cl. —mh. song-nouov auauuquauo=< .¢i< awash