:. "’ -. . .n. ‘ “A . :3"- ‘ ‘23."; 14.; 4:9; f“ 1‘4 ~ >‘Tr.’ ' ’ it.‘ ~ ”1%: ”WA-‘ can t“ ..» ., ryéaxg‘zfi‘? '3 ?‘ :fiigfi‘“: 5:3: at 7‘1!“ ' “a ~r'. \ ‘ a u ¢ .53» . u‘.‘ u a. ‘3 at 1:.“ ‘ .. ifiafiwx; ":5 ' ‘ 505121253?“ 3., .. » ndfifiF-au' 1 r we, § . . 9k§€5¥$ ;::PL‘~§’§$§’ . wk fizé‘figf ‘ ' ink}... , , “$48: * mm .. 332% I-fih “ .‘Jw‘n'v‘ n r . ,n . - If» ‘ ~.‘ 3"}.5?“ 3‘.‘ ‘5. I I“ \ ‘-‘ u . THEsis \lllllll\llllllllll This is to certify that the thesis entitled The Impacts of Cultural Nutrient Inputs on Townline Lake presented by Julie Helen Tsatsaros has been accepted towards fulfillment of the requirements for Master of Science degree in Fisheries and Wildlife "/ £10 z? @tkémc/ Major professor V3 .5, 0-7539 MS U is an Affirmative Action/Equal Opportunity Institution LIBRARY Michigan State Unlverslty PLACE IN RETURN aoxui man than Momma. your mom. To AVOID FINES Mum on or baton um duo. DATE DUE DATE DUE DATE DUE , ”twig 33 Y ! .99!”le «a. WEE—T bit: [—th flEEJ rfifi MSU In An Affirmative ActloNEqunl Opportunity lmthlon m m1 THE IMPACTS OF CULTURAL NUTRIENT INPUTS ON TOWNLINE LAKE BY Julie Helen Tsatsaros A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Fisheries and Wildlife 1993 ABSTRACT THE IMPACTS OF CULTURAL NUTRIENT INPUTS ON TOWNLINE LAKE . BY Julie Helen Tsatsaros Townline Lake, located on the northern edge of Montcalm county in Michigan, is a lake heavily used for recreation. Townline Lake has an abundance of nutrients, primarily phosphorus and nitrogen, contributing to an excess growth of aquatic plants. The main tasks of this study were to assess current trophic conditions of Townline Lake, examine current land uses in the watershed, locate nutrient sources from the watershed, and examine the impacts of aquatic plant growth on the riparian residents. A water analysis program on Townline Lake was undertaken, watershed land use was examined, and a personal interview questionnaire was administered to all riparian residents on the lake. Also, a phosphorus loading model was utilized to allocate phosphorus loading rates from the Townline Lake watershed. Results from this study have indicated lakeside septic systems may be a major contributor of nutrients into Townline Lake. ACKNOWLEDGEMENTS First of all, I would like to thank Dr. Niles Kevern, my major professor, who asked me during fall term 1991 if I would like to study Townline Lake. I have enjoyed working on this project with him, and have appreciated all of his guidance and interest in my graduate studies at Michigan State. I would also like to thank my committee members Dr. Peyton and Dr. Witter for their help with the project. As well, I would like to thank Dave Speas, who assisted me with the limnological survey of the lake. I also appreciated all the help and encouragement I received for this project from the residents on Townline Lake. I would also like to thank my family who have supported my interests through-out my undergraduate and graduate studies, and I would like to thank the good friends I have made in the Fisheries and Wildlife Department. I have appreciated their friendship and sense of humor during the past few years. Finally, I would like to thank Greg Claesson who has always been supportive of me, and has been a great shoulder to lean on, through-out all phases of my masters program. iii TABLE OF CONTENTS Page LIST OF TABLES...O......OOOOOOOOOOOOOOOOOO0......0...... Vi LIST OF FIGURES.. ........ .............. ...... ......... viii BACKGROUND......................................... ..... 1 INTRODUCTION..... .......... . ....... .. ................... 5 RESEARCH OBJECTIVES.... ............................... .. 8 STUDY SITE DESCRIPTION ............. . .................. .. 9 METHODS...O..0.........OOOOOOOOOOOOOOOOI.O.......O...... 12 Limnological Survey of Townline Lake... ........ ....... 13 On-Site Inspection of the Watershed................... 23 The Personal Interview Questionnaire. ................ . 27 Phosphorus Loading Model........... ................ ... 33 RESULTSOOOOOOO ...... ......OOCOOOOOOO‘OOCOOO0.00.00.00.00. 37 Limnological Survey of Townline Lake.................. 37 On-Site Inspection of the Watershed................... 42 The Personal Interview Questionnaire.................. 45 Phosphorus Loading Model........... ................. .. 58 DISCUSSION............................. ......... . ..... .. 62 Limnological Survey of Townline Lake.................. 62 On-Site Inspection of the Watershed................... 65 The Personal Interview Questionnairel................. 66 Phosphorus Loading Model........................ ...... 72 iv RECOMENDATIONS O O O O O O O O O O O O O O O O O O O O O O O OOOOOOOOOOOOO O O O O O 75 APPENDIX A. O O O O O I O O O O O O O ....... O I O O O O O O O O O O ...... O ..... O 78 APPENDIX B O C O O O O O O O O O I O O O ..... O O O O O O O O O O O I ....... O ..... O 87 LITERATURE CITEDOOI.......OOOOOOO......OOOOOOOOOOOO ..... 92 Table Table Table Table Table Table Table Table Table Table Table Table Table 1. 2. 11. 12. 13. LIST OF TABLES Page Morphological Dimensions of Townline Lake.... 9 Mean Secchi Disk Readings of Visibility...... 37 Measurements of Total Phosphorus (mg/L) at the Surface, Mid-depths, and Bottom Of Townline LakeOOOOOOOOOOOOOOOOOOO00.......0 40 Mean and Total Zooplankton Densities in Townline Lake (#lL).......................... 41 Land Use Activities in the Townline Lake waterShedOOOO.....IOOIOOOOOOOOOOOOO0.0.0.0... 44 Mean Number of Days Seasonal and Permanent Reside at their Home or Cottage.............. 46 Approximate Number of Guests at Cottages/ Residences, and their Length of Stay......... 47 Resident Responses to Townline Lake Water Quality For Their Uses of the Lake........... 48 Responses for Improving Water Quality in Townline LakeOOOOOOOOOOOOOOOOOOOOOOOOO0000 48 Recreational Activities the Respondent, the Respondents Family, or Guests Participate in at Townline Lake............................. 49 The Most Important Recreational Activities Respondents Participate in at Townline Lake, and the Recreational Activity Respondents Would Miss Most.............................. 50 Location and Type of Lakeside Septic Systems for Permanent Residences..................... 51 Location and Type of Lakeside Septic Systems For Seasonal Residences...................... 52 vi Table Table Table Table Table Table Table Table Table Table 14. 15. 16. A-3 O A-4. A-S. A-6. A-7. Mean Septic System Age, Distance From the Lake, and Frequency of Septic System Pumpings For Permanent Households......................... 53 Mean Septic System Age, Distance From the Lake, and Frequency of Septic System Pumpings for Seasonal Households.......................... 56 Phosphorus Concentration As Linked to Trophic State and Potential Lake Use Attributes (From: Simpson and Reckhow 1979).................... 59 Years Permanent/Seasonal Residents Have Owned Their Cottages/Residences on Townline Lake... 78 The Percentage of Weekdays and Weekends Permanent/Seasonal Residents Spend at the Lake From January-March........................... 78 The Percentage of Weekdays and Weekends Permanent/Seasonal Residents Spend at the Lake FromApril-June.0.00.00.00.00....0.......0... 78 The Percentage of Weekdays and Weekends Permanent/Seasonal Residents Spend at the Lake FromJuly-septemberOOOOO......OOOOOOOOOO..... 79 The Percentage of Weekdays and Weekends Permanent/Seasonal Residents Spend at the Lake From October-December........................ 79 Depth of Lakeside Wells...................... 79 Resident Responses to Contamination Problems in their weJ-ISOOOOOOOOOOOOO......OOOOOOOOOOOOOOO 80 vii Figure Figure Figure Figure Figure Figure LIST OF FIGURES Page StudyArea.........OOOOOOOOO......O.......... 6 Hydrographic Map and Sampling Stations on Townline Lake............................. 10 Townline Lake Watershed Area................. 24 Temperature Isopleths (0C) For Townline Lake. 39 Land Use Activities in the Townline Lake waterShedOOOOOOOOOO......OOOOOOOOOOO......... 43 Frequencies of Septic Systems That Have Never Been Maintained Through Pumping........ 54 viii B CKG OUND The term ‘eutrophication’ has been frequently used to describe waterbodies with artificial and undesirable additions of plant nutrients, primarily phosphorus and nitrogen. Excessive inputs of plant nutrients can stimulate nuisance growths of algae and higher aquatic plants in a lake, decrease the clarity of the water, limit light penetration, and contribute to stunted populations of fish (Ryding and Rast 1989). Eutrophic lakes commonly have high levels of productivity and biomass at all trophic levels, frequent occurrences of algal blooms, and anoxic bottom waters during periods of thermal stratification. These lakes often have fewer types of plant and animal species, enhanced growth of littoral zone aquatic plants, and poor water quality for many uses (Ryding and Rast 1989). Natural eutrophication refers to the natural, gradual accumulation of sediment and nutrients in a lake (Simpson and Reckhow 1979). When this over-enrichment stems from human activity, it is called cultural eutrophication. Many of the eutrophication problems in Michigan lakes are cultural. 2 Unfortunately, the eutrophication problem often worsens as long as human population and activity intensify around a lake (Williamson 1990; Ryding and Rast 1989; Simpson and Reckhow 1979). . Excessive algae and aquatic plant growth in lakes are highly visible, and can interfere significantly with the uses and aesthetic quality of a waterbody. The effects of cultural eutrophication are usually considered negative and often reflect human perceptions of good versus bad water quality (Ryding and Rast 1989). Phosphorus, an essential nutrient for plant growth, is often in short supply naturally in aquatic systems. Human activities including use of fertilizers, and discharge of sewage greatly increase the availability of phosphorus in many lakes, resulting in undesirable increases in plant and algae growth (Kevern 1989). Phosphorus often originates from human sources outside the lake, and it's amount is typically higher from humanactivities than other nutrients. Phosphorus removal from water is possible, and non-point phosphorus pollution may be eliminated with proper land use practices. Cultural eutrophication problems developed most rapidly in the last 50 years, due to piped water supplies and the flush toilet, which became common to households. The volume of waste from septic systems greatly increased, speeding phosphorus towards waterbodies (Williamson 1990). 3 Septic systems at lakefront homes or cottages can leach phosphorus into groundwater, which can then travel into a waterbody such as a lake (The Michigan Department of Natural Resources (MDNR) 1990; Williamson 1990). Wastewater seepage from septic tank/drainfields is especially important for many lakes, as these septic systems of shore areas are often inadequate to protect lakes from phosphorus (Williamson 1990). A waterbody undergoing cultural eutrophication can be treated so it will again exhibit an ‘aging’ rate more characteristic of natural eutrophication. Top priorities for the management of phosphorus include limiting or reducing nutrient inputs into the waterbody from sources in the drainage basin contributing the largest quantities of the biologically available forms of nutrients (Ryding and Rast 1989). The best solution to lake water quality problems is to try and prevent them from happening in the first place, a less satisfactory way is to attempt to correct them after ' they occur. It is possible to restore deteriorated lakes in some circumstances (Yanggen 1983). One approach towards the mitigation of cultural eutrophication and it's effects is to initiate intensive lake restoration activities. However, this method is used to attack the symptoms, rather than the causes of cultural eutrophication. A more logical approach is to curtail 4 excess nutrient inputs from the source through conscientious watershed planning and management (Simpson and Reckhow 1979). Lake conservation begins with grass roots recognition of the needs of the watershed (Balsamo 1984). Each waterbody is unique, and study and understanding of the unique features of a watershed are essential for good planning, yet‘there are also characteristics of a watershed and lake behavior that are, if not universal, shared by many lake systems. INTRODUCTION Townline Lake, located in the northern edge of Montcalm county, Michigan is a lake heavily used for recreation (Figure 1). The shoreline of this lake is somewhat irregular, providing bays and inlets for increased recreation and development. A 1991 limnological survey determined that Townline Lake has an abundance of nutrients, primarily phosphorus and nitrogen (Kevern et a1. 1991). Nuisance growth of algae and aquatic plants, and an excessive number of small sunfish have created water quality problems for residents on Townline Lake. Subsequently, the economic value of Townline Lake may diminish for waterfront property owners. Some property owners have become frustrated over how to address this problem. The residents of Townline Lake have been spending over $20,000 a year for over twelve years on herbicide treatment of algae and aquatic plants with little or no long term relief. Unfortunately, this situation is typical of many other inland lakes in Michigan, as these lakes have been developed with permanent homes or seasonal cottages around their 7 shorelines. Most of these residents are serviced by septic systems, and many lakes have activities in their watersheds resulting in nutrient enrichment of lakes. According to US Environmental Protection Agency maps (Omernik et al. 1988), Townline Lake is in an area of low natural soil fertility. The authors of a 1991 Limnological Survey of Townline Lake state the basic fertility of the watershed is probably not responsible for the continued problem of excess algae and plant growth in the lake. Therefore, land use activities in the watershed must be examined as being potential sources of nutrients. RESEARCH OBJECTIVES There are four research objectives for this project: 1) Assess the current trophic conditions and general water quality of Townline Lake. 2) Examine current land uses in the Townline Lake watershed. 3) Locate nutrient sources from the watershed contributing to excessive algae and macrophyte growth in Townline Lake. 4) Examine the results of excessive algae and macrophyte growth on the riparian residents of Townline Lake. In the past, there has been only one approach towards management of cultural eutrophication in Townline Lake. This approach has been an annual intensive use of chemical aquatic plant control. However, this method has only treated the symptoms, rather than the causes of the eutrophication problem. As long as the lake continues to receive nutrient loading from the watershed, internal practices alone will not eliminate cultural eutrophication. STUDY SITE DESCRIPTION According to the U.S. Public Land System, the location of Townline Lake is T.12N, R.7-8W in sections 1,6,7 and 12. The dimensions of Townline Lake are given in Table 1. The lake has an area of 99 hectares, with a maximum west to east length of 2,212 meters. The maximum depth of Townline Lake is nearly 15 meters. The Michigan United Conservation Club (MUCC) 1954 map of Townline Lake reveals the lake has an elongated shape with the long axis lying directly west to east, in the direction of the prevailing winds from the west (Kevern et al. 1991)(Figure 2). Table 1. Morphological dimensions of Townline Lake*. Selected Parameters Dimensions Surface Area 99.72 (Hectares) Maximum Length 2,212.00 (Meters) Maximum Depth 15.00 (Meters) Shoreline Length 6,436.00 (Meters) 'iievern et al. 1991. There is a marshy area at the extreme east end of Townline Lake. This area serves as a nursery area for raising northern pike by the Michigan Department of Natural Resources (MDNR) for stocking into the lake (Kevern et al. 1991). Approximately 35-40% of the lake is over 4.5 meters 10 0x3 0:35.59 :0 35% 2.2535 mafia—sum can no: ofisnmumouchm .N 950?" Z N N mcowumum mafiamfimm 11 deep, and there are 2 deep holes in Townline Lake. One hole is 11 meters deep in the west half of the lake, and the other hole is 15 meters deep in the east half of the lake. The depth of the water between the two deep areas is at least 6 meters deep, (Figure 2),(Kevern et al. 1991). A channel enters the lake from the north, just to the west of the center of the lake. This channel has been dredged and used for boat access for cottage owners along the channel. In the upper section of the channel, there is an intermittent creek that flows in the spring and fall following heavier rains. This waterway may bring some nutrients into the lake from the watershed, although the watershed is well vegetated (Kevern et al. 1991). The outlet for Townline Lake is located on the south side of the lake just to the east of the mid section of the lake. The shoreline of the lake has been developed for cottages and permanent residences for many years. On the north side of the lake, a small subdivision has been established and continues a few blocks back from the (shoreline. The irregular shoreline, and location of Townline Lake in Michigan has given the lake a greater development potential for homes and cottages. Unfortunately, the presence of these homes and cottages along the shoreline may have helped change the natural eutrophication process of the lake in a dramatic way. MEIEQD§ Before beginning the technical studies providing the data and calculations necessary to reach the objectives for this project, it was important to assess research methods that could be used successfully. The following research methods were selected: 1) A limnological survey of Townline Lake, during the spring, summer, and fall of 1992, would incorporate physical, biological, and chemical parameters to assess current trophic conditions and general water quality in the lake. 2) On-site inspection of the watershed during the spring, summer, and fall of 1992, to examine activities in the watershed that may be contributing significant sources of nutrients to the lake. 3) A personal interview questionnaire was developed to gather information on probable sources of nutrients from riparian residences (specifically septic systems and fertilizer use on lawns) on Townline Lake. Lakeside septic system information, fertilizer use, and other aspects of riparian residence usage, were needed for incorporation into a phosphorus loading model used in this study. The impacts 12 13 of the excessive plant and algae growth on the riparian residents, and their recreational activities was also an important aspect of the questionnaire. 4) Finally, a phosphorus loading model designed by Simpson and Reckhow (1979) for north temperate lakes, was used to quantify the effect of watershed characteristics, including land use, on lake trophic status and water quality for Townline Lake. Information taken from the questionnaire including septic system usage by lakefront homes provided critical information for the phosphorus model. 0 o ' a u ve o l' e e The determination of trophic state and general water quality of a lake represents the core of any assessment or classification of a lake. Trophic descriptions are used to denote the nutrient status of a waterbody, or otherwise to describe the effects of the nutrients on the general water quality and trophic conditions of a lake (Ryding and Rast 1989). A water sampling or monitoring program can be used to assess the impacts of excessive nutrients on the aquatic environment with respect to plant growth, deteriorating water quality, fishery development, and general effects on the aquatic ecosystem (Ryding and Rast 1989). 14 Williamson (1990), states for any surface water quality program, lake surveys should be conducted during spring overturn and summer stratification periods. Lakes should be sampled in the major deep basins for the selected chemical, physical, and biological parameters. In regard to spatial location of sampling stations, if a waterbody has no significant arms or sub-basins, and is well mixed horizontally, a single sampling station at the deepest part of the waterbody is usually adequate to characterize the eutrophication-related water quality of the lake (Ryding and Rast 1989). Water samples should be taken at the surface, mid-depth and bottom of a waterbody. Water samples taken from the lower levels of a stratified waterbody reflect water quality characteristics of a longer period of time, compared to a sampling scheme which only samples the epilimnetic upper layer (Ryding and Rast 1989). Macrophytes are important as they provide food, cover, and substrate for many aquatic organisms, and contribute to the survival of young fish by providing refuge areas which hamper predators. At the same time, however, excessive macrophyte growth can lead to stunted populations of fish, as in the case of Townline Lake (Kevern 1989). A water quality sampling plan was initiated in May 1992, and continued until October 1992 to determine the trophic state and general water quality of Townline Lake. 15 Using a depth finder, sampling stations were located over the two deepest holes in the lake, and sampled every three weeks beginning May 28th and ending October 2nd. Station 1 was located over the 15 meter hole, and station 2 was located over the 11 meter hole (Figure 2). In total, there were 7 water sampling periods in 1992, on Townline Lake. The MDNR (1990), states measures to indicate levels of eutrophication in lakes should always include Secchi disk readings of transparency, and total phosphorus readings. These two measurements reflect the productivity a lake. As nutrients are the leading cause of eutrophication, phosphorus concentrations can be measured from water samples, and used as a direct measure of eutrophication. Chemical, biological, and physical parameters of water quality in Townline Lake were included in the sampling program. Measurements taken at both stations included Secchi disk readings, temperature profiles, total phosphorus, and zooplankton counts. Physical Parameters: Light provides the means for photosynthesis to occur in terrestrial and aquatic plants. Kevern (1989), states the degree of light penetration in water is a function of the incident sunlight, and the type and amount of suspended and dissolved material in the water. Transparency of light in the water column has important implications for aquatic organisms. For example, algae as 16 phytoplankton need light in order to grow, however; excess growths of algae can decrease the clarity of the water and limit light penetration (Kevern et al. 1991). Measurements of transparency or visibility can indicate the degree of algal growth, and the presence of other suspended material in a lake. A Secchi disk, (a black and white disk approximately 20 cm in diameter), is an inexpensive measure of water quality. The Secchi disk can indicate on a seasonal basis whether water quality in a lake is remaining stable, decreasing, or showing improvement over time. It is used to measure water transparency or visibility, but it is not an actual measure of light penetration. Kevern (1989), states a Secchi disk is a useful index of visibility if used under standard conditions, and can be measured easily without the need for expensive equipment. At both stations, a Secchi disk attached to a calibrated line was lowered into the water, and depths noted where it disappeared from sight and then upon retrieving, where it first reappeared. The Secchi disk readings were taken for both stations on the lake, and the two readings of the Secchi disk averaged at each station. These readings were the transparency of the water or limit of visibility at each station. Kevern (1989), states water temperature plays an important role in physical, chemical, and biological 17 processes in lakes, including regulation of chemical reactions and metabolic rates, to regulation of spawning events and egg hatches. Temperature influences the types of fish that can survive, and seasonal temperature differences influence the amount of oxygen and nutrients at different depths of the water column (MDNR 1990). At higher temperatures, the solubility of gases, particularly oxygen and carbon dioxide decreases, and affects the type of life that can exist. The rate of metabolism in organisms is also influenced by temperature as is the rate of decomposition of organic materials in the water (Kevern et al. 1989). Water temperature profiles of Townline Lake were included in this study as they are an important indicator of whether the lake is thermally stratified or undergoing turnover. Temperature profiles were taken using a . thermistor and meter. The thermistor cable was calibrated at 1 meter intervals, allowing temperature readings at each consecutive meter of depth, from the surface to the bottom of the 2 deep holes in Townline Lake. Chemical Parameters: - The three most important factors influencing aquatic plant growth in freshwater lakes are the essential nutrients, phosphorus, nitrogen, and carbon. Simpson and Reckhow (1979), state of the three nutrients, phosphorus is considered the most manageable nutrient for the following 18 reasons: 1) Phosphorus is added primarily from allochthonous sources, it originates outside the lake, and unlike nitrogen and carbon, it is not transported across the air/water interface. 2) For lakes that have been developed for cottages and permanent residences, the proportion of the total supply of phosphorus directly attributable to man_is typically higher than for any other growth limited element. 3) Non-point phosphorus pollution may be restricted with proper land use practices. Although nitrogen and carbon are also considered important nutrients in lakes, these nutrients were not measured for this study as phosphorus is the most manageable nutrient. Phosphorus in septic system wastes absorbs to soil in the drain field and is "locked" there until the system becomes overloaded. This occurs in time, when the adsorption sites on the soil particles become saturated with phosphorus thus ending the soils adsorption capacity. Additional phosphorus then migrates downward into the ground water or laterally into a surface water body (MDNR 1990). A water sampling interval of approximately 14-28 days is considered to be a good general guideline for determining phosphorus concentrations of freshwater lakes. In various eutrophic studies on lakes, Reckhow et al.(1980), states the 19 standard error of an annual phosphorus flux varied between 10% and 20% of the true flux based on a water sampling interval of 14-28 days. Due to the readily changing nature of phosphorus, only total phosphorus was analyzed for this study. Phosphorus occurs in a variety of chemical and biological forms through-out the year; it may be recycled by biological, chemical, and physical processes, or remain in sediments. Most strategies to control phosphorus (P) input into lakes have been based on total phosphorus data. This has been for realistic as well as practical reasons. Total P gives the greatest overall information, and is easily measured, whereas the measurement of biologically available P, which would be the most useful determinant is problematic (Marsden 1989). Whole water samples on Townline Lake were collected using a Kemmerer water sampler. These samples were then transferred into polyethylene bottles containing a preservative, and stored in an insulated cooler until analysis could be conducted in the lab. These water samples were taken at the surface, mid-depths and bottom of the lake, for both stations on the lake. As phytoplankton and marl drift down towards the bottom of a lake, it is common by the end of the summer to find phosphorus concentrations high at mid—depths, and highest near the bottom. As phosphorus may occur in combination 20 with organic matter, a digestion method to determine total phosphorus was utilized to oxidize organic matter effectively to release phosphorus as orthophosphate (Standard Methods APHA 1989) Total phosphorus was measured following acid digestion of the water samples, and included reactive plus non- reactive phosphorus. The samples were first acid digested to hydrolyze any condensed phosphates, digesting any organic material, leaving the phosphorus in a reactive phosphate form which was then measured with an ascorbic acid procedure (Standard Methods, APHA 1989). A set of standards were also utilized for analysis. According to the Beer-Lambert Law, in natural waters, there is a linear relationship between color intensity as measured by spectrometry and the actual concentration of a sample. In order to determine the total phosphorus concentration in each of the samples, the standard curve was generated in which the intensity of color (absorbance) is related to the known concentrations of the substance (Kevern 1989). Using a statistical software package (Lotus 1-2-3), a standard curve (regression analysis) was created to convert absorbance to concentration of P in mg/L. Biological Parameters: Water quality affects the abundance, species composition, stability, productivity, and physical condition of indigenous populations of aquatic organisms. Therefore, 21 the nature and health of aquatic communities is an expression of the quality of the water (Standard Methods, AHPA 1989). In freshwater lakes, zooplankton are very small or are microscopic in size, and comprise a collection of invertebrate animals that are swimming or are suspended in the water column. However, zooplankton species and their abundance can vary greatly from each season, and from one lake system to another (Kevern 1989; Kevern et al. 1991). Zooplankton are extremely important in a lake's food chain as they provide important sources of food for larval and juvenile fish and larger invertebrates., As well, zooplankton are primary consumers feeding on algae. Zooplankton were collected in Townline Lake to provide an indicator of the health of an important aquatic community in the lake. The presence of large zooplankton in Townline lake gives a good indicator of an important food source for fish and invertebrates. Plankton nets are preferred to bottles and traps for sampling where qualitative data, or large biomass is needed for analysis. Vertical tows are preferred to horizontal tows, as they collect a composite sample in an integrated water column (Standard Methods APHA 1989). Vertical tows with a Wisconsin net were used to collect zooplankton from stations 1 and 2. Two vertical tows were taken for each station. Zooplankton samples were taken near 22 the mid to lower depths of the lake, at a 9 meter vertical tow at station 1, and 6.5 meter vertical tow at station 2. The samples were then transferred into polyethylene bottles containing a small amount of formalin, and stored in a cooler until they could be analyzed in the lab. In the lab, each bottle containing zooplankton was adjusted with distilled water to a volume of 100 ml. Then, a 10 ml subsample of the zooplankton from each polyethylene bottle was taken, and placed into a grided counting dish. A dissecting microscope was used to count and sort the zooplankton by order and size. Two counts of each zooplankton subsample were then taken and averaged. The total number of zooplankton per liter of lake water was then calculated using the following formula (Standard Methods, APHA 1989): number (liter) = TN x CV/SV Q where: TN = Total number of organisms in a subsample counted CV = Volume of concentrated sample (mL) SV subsample of volume taken from a concentrated sample (mL) Q = volume of lake water sampled (liters) 23 On-Site Inspection of the Watershed Thorton and Ford (1985), state an obvious and too often ignored step in interpreting water quality patterns is visiting the watershed, inspecting the point sources, septic systems, drainage patterns, vegetative cover, and other watershed activities. In understanding lake conditions, it is important to realize the entire watershed and not just the lake, or the lake and it’s shoreline, is the basic ecosystem unit. It is also important to note the aquatic portion of a watershed is downhill from the terrestrial portion. Dissolved and particulate materials from the land are transported by geological proCesses to the water, and eventually to aquatic sediments (Dillon and Rigler 1975). As part of this study, land use practices and soil types were examined and recorded for the Townline Lake watershed. At various times during the spring, summer, and fall of 1992, on-site visual observations were made of the watershed. A MDNR (1984) map of the Townline Lake watershed was used to delineate the boundaries of the watershed (Figure 3). Utilizing Soil Surveys for Montcalm and Mecosta County, (The U.S. Department of Agriculture 1989, 1984), soil types in the watershed, and their rates of water transmission were recorded and analyzed for this study. As well, visual observations of the presence of steep slopes and low lying 24 SCALE 1 : 24,000 v\"/ Q Townline Lake V‘a P“ Figure 3. Townline Lake Watershed Area. 25 areas near the lake were noted. During the past 40 years, there has been a noticeable increase in the construction of cottages and residences -around lakes including Townline Lake. Most of these dwellings use individual septic tank disposal systems, and these systems are often installed at the minimum distance above the water table, and the minimum distance from the shore permitted by the law at the time of installation (Chen 1988). At most Michigan lakes, septic tanks and drain fields are the normal method of household sewage disposal. On-site septic systems may be the only economically viable wastewatertreatment option in rural areas (Cogger 1988). A drainfield may plug up and fail within twenty years, and it can ooze sewage onto the surface, and thus pass phosphorus into a lake (MDNR 1990). Also, depending on the type, soils eventually become phosphorus saturated and again pass phosphorus laterally to lakes. Lawn and crop fertilization can also be significant sources of nutrient pollution. These fertilization practices may contain nitrogen, phosphorus, potassium, plus other ingredients that could eventually reach the lake. Natural factors can influence the degree of eutrophication in lakes. These factors include location, climate, hydrology, and soils. But, human alterations and disturbances can result in greater nutrient exports to a 26 receiving waterbody than can natural factors (Ryding and Rast 1989). For this study, it was important to determine if algal and aquatic macrophyte growth in Townline Lake may partially be the result of nutrients discharged from natural occurring sources, or more likely from septic tank disposal systems, lawn and crop fertilization, or other activities in the watershed. Therefore, on-site visits of the watershed were needed to inspect potential point sources, non-point sources (including septic system locations), drainage patterns, vegetative cover, and other watershed characteristics. 27 The Personal Interview Questionnaire Social survey instruments including questionnaires can be helpful in acquiring water quality and sociological information that could not be obtained from a limnological survey alone. The questionnaire survey is the most widely used method in social studies, this technique relying heavily on personal answers to specific questions (Filion 1980). Most measurements of water quality in lakes involve only the determination of physical, chemical, and biological characteristics. These parameters may or may not bear a relationship to changes in demand for and use of water recreational purposes. What is needed is more information on user perceptions of water quality in lakes. When the aquatic flora and fauna of a waterbody are affected, there is a good chance the recreational values of the lake will also be affected (Nicolson and Mace 1975). Interested citizens can give insight about the extent of a given eutrophication problem, and can be an asset in the development of feasible and accurate eutrophication projects. Knowledge gained through lifetime observations of a waterbody can be documented for use in developing management programs. Persons encouraged to participate in eutrophic studies of lakes are more likely to become advocates of water quality programs (Ryding and Rast 1989). 28 The relationship between a limnologist's judgement of water quality and user's perceptions of water quality may be strikingly different (Klessig and Bouwes 1983). Kooyoom et al. (1974), state perception of water quality by different user groups on a lake can offer insight for researchers studying the effects of water quality on the public. The importance people place on recreational pursuits may significantly influence their responses to existing water quality conditions. A limnologist usually uses lake quality criteria that can be measured and communicated with other scientists. But, riparian residents or cottage owners on lakes may not think of water quality in biological or chemical terms. They may respond to what they see in the water, and on the shoreline. Therefore, it is not surprising to find water quality means different things to a limnologist than to a property owner on a lake. Therefore, public evaluation of the water quality of the lake should be recognized as distinct from the experts criteria, and both should be recognized as equally important in determining the water quality of a lake (Klessig and Bouwes 1983; Hines and Willeke 1974). A personal interview questionnaire was developed by the author, with guidance from Dr. Kevern, and Dr. Peyton, and was reviewed and approved by the Michigan State University Committee on Research Involving Human Subjects. The 29 questionnaire addressed the following two research needs for this project. 1) To gather riparian household information on Townline Lake. The data were then utilized using Simpson and Reckhow's (1979) phosphorus model to help estimate phosphorus loading in Townline Lake. 2) To assess riparian residents (permanent and seasonal) opinions regarding Townline Lake's water quality. As well, to examine the impact of algae and macrophyte growth on the recreational activities of riparian residents. The questionnaire and accompanying cover letter (Appendix A) was administered by personal interview to the riparian residents on Townline Lake. Approximately 86% or 153/177 people were surveyed from May to July 1992. Barrager (1974) states water quality of a lake will greatly affect owners of properties located at the water's edge, but may have no measurable effect on the owners of properties located some distance away. For this study, it was assumed septic systems of lakeside dwellings may significantly impact the water quality of Townline Lake through groundwater transport, as these systems are located close to the waters' edge. If the septic system is incorrectly sited, used, or maintained, it 30 may fail and cause accelerated eutrophication by discharging high levels of phosphates and nitrates into the lake. Simpson and Reckhow (1979), state a common source of phosphorus in lakes is from the shoreline septic tank-tile field system. A personal interview was used for this study to obtain a high response rate, and to probe for detail that might be difficult in telephone or mail surveys (Peyton 1992). The accompanying cover letter prepared and involved the respondents for the survey, explained the nature of the survey, the utility of the research, and the important role of the respondent in the survey (Appendix A). Close ended or structured questions were used in the questionnaire. Minnis (1992), stated providing distinct answer categories may more accurately tap differences among respondents, and ease in the analysis of the survey instrument. However, open-ended questions were also used in this study where appropriate. Bradburn and Sudman (1979), stated when the full range of pertinent response categories is not known, and the salience of a topic is being assessed, open-ended questions should be utilized in a questionnaire. Non-response bias was minimized in the questionnaire as 86% of residents were interviewed for the questionnaire. The first section of the questionnaire dealt with general questions pertaining to ownership of the residence, number of years the residence has been owned/rented, 31 permanent/seasonal occupancy of the lakeside dwelling, number of household members, and usage of the residence by family and guests. The next set of questions dealt with participation in water-based recreational activities by the respondent on Townline Lake. The respondent was also able to rank their most important recreational activities on the lake. The following question, using a likert scale, allowed the respondent to rate the water quality of Townline Lake for their uses of the lake. The final set of questions dealt with septic system information including location, age, and maintenance of the system. As well, fertilizer use on lakeside lawns was included, and contamination problems in lakeside well waters was addressed. The personal interview questionnaire was essential for providing lakeside residence information for the Simpson and Reckhow (1979) phosphorus loading model. Information used in the model from the questionnaire included: number of lakeside cottages/residences, number of permanent and seasonal residents, average number of persons per living unit, and the number of days spent at the unit per year by the residents. As well, lakeside septic system type and age, were incorporated into the model. The personal interview questionnaire was also important for gathering residents opinions of the water quality of Townline Lake. Lant and Mullens (1991), state accurately 32 assessing the recreational and intrinsic values of lakes is of increasing importance as the demand for water based recreation continues to increase. The questionnaire data were collected, coded, and stored on disk. The Statistical Package for the Social Sciences (SPSS), was utilized for analysis of the survey. For each variable in the survey, a special code was entered in the program for values that were missing. Norusis (1990), states data that are missing are called user- missing, and SPSS will not use missing values in carrying out analysis commands. Statistical information including frequencies, means, tests of significance (Pearson's chi- square, Fisher's exact test, and T-tests of means), and cross tabulations were used in analysis of the questionnaire. 33 Phosphorus Loading Model Phosphorus has been demonstrated to be the nutrient most frequently controlling production and trophic status in north temperate lakes. Therefore, any approach to predict water quality from a trophic status must take into account the importance of phosphorus (Reckhow et a1. 1992). A watershed model, an approximation or simplification of a real world system, is particularly useful for estimating non-point source nutrient inputs into a lake. However, prediction from a model is inherently uncertain (Reckhow and Chapra 1983). The broad objective of watershed models in eutrophication control efforts is to provide estimates of the nutrient loads reaching a lake (Ryding and Rast 1989). Human activities, watershed characteristics, and climate are general determinants of phosphorus mass transport to lakes (Reckhow et al. 1980). Calculations estimating non-point source pollution can reveal sources contributing to water quality impairment. Those watershed areas contributing the greatest percentage of the nutrient load can then be identified so these loads can be reduced (Thornton and Ford 1985; Dillon and Rigler 1975; Marsden 1989). Simpson and Reckhow (1979), developed a simple phosphorus loading model for the prediction of lake 34 phosphorus concentration associated with activities in a lake's watershed. The phosphorus loading model then considers modifications by environmental factors and yields an output that approximates the lake's average phosphorus concentration. Simpson and Reckhow (1979), estimated phosphorus concentration in a lake may then be related to trophic state, water quality, and lake use features predicted for that concentration. This model was developed from 47 temperate lakes included in the Environmental Protection Agency's National Eutrophication Survey (Simpson and Reckhow 1979; Reckhow and Chapra 1983). Simpson and Reckhow's (1979) model was utilized for this study to estimate Townline Lake's phosphorus concentration associated with land uses in the watershed. The estimated phosphorus concentration was then related to the trophic state of the lake. To validate the model, the estimated phosphorus concentration was compared to total phosphorus concentrations over the spring, summer, and fall 1992 limnological survey. The phosphorus model, based on unit area nutrient loads or export coefficients, combines water runoff and nutrient concentration to estimate nutrient loading as a single term. The variables in the model were estimated in the following order: 35 a. areal water loading (qs), b. areal phosphorus loading, c. lake phosphorus concentration (p), and d. phosphorus prediction uncertainty (st). Simpson and Reckhow’s (1979), model states phosphorus concentration (P, in mg/L) is a function of phosphorus loading (L, in g/mZ-yr), areal water loading (q8 in m/yr), and apparent phosphorus settling velocity (V8 in m/yr) in the form: vs+qs Simpson and Reckhow (1979), state the apparent settling velocity (v3) of the model was found to be a weak function of areal water loading (93): using least squares regression. Therefore, the model was modified by the authors to incorporate these changes, and the final form of the model becomes: 11.6 + 1.2 q,3 The model standard error (5111109): 0.128 in logarithmically transformed concentration units (Reckhow and Chapra 1983). 36 Phosphorus concentration measurement error was also included in the model, and was expressed in terms of confidence limits representing the prediction plus or minus the prediction uncertainty. Confidence limits were set at the 95% level bounding the "true" phosphorus concentration level of the lake. Simpson and Reckhow's (1979), phosphorus model provides information on the impact of watershed characteristics and activities on phosphorus concentration, which is a measure of lake trophic quality. This information can be important for lake management strategies aiming to control eutrophication problems in lakes. BE§HLI§ Limnological Survey of Townline Lake: A water analysis plan was initiated in May 1992 and continued until October 1992. Measurements taken included Secchi disk readings, temperature profiles, total phosphorus, and zooplankton counts. Water Transparency or Visibility: By the end of May 1992, Secchi disk readings showed good water clarity, averaging over 4 meters at both stations on the lake. After July 9th, however, Secchi disk readings showed a decrease in water clarity. By the middle of September, Secchi disk readings revealed even less transparency of the water, averaging 1 1/2 meters less visibility than readings taken at the end of May (Table 2). Table 2. Secchi Disk Readings of Visibility. Depth (meters) Date Station 1 Station 2 May 28 4.1 4.0 June 18 3.5 3.5 July 9 4.2 4.2 July 30 3.0 3.5 August 20 3.4 2.8 September 11 2.6 2.3 October 2 2.8 ‘2.8 37 38 Temperature: Temperature profiles were taken at 1 meter intervals from top to bottom over the deep holes of Townline Lake. Surface temperatures averaged 16°C for both stations at the end of May, while bottom temperatures averaged 11.5°C. The thermocline, characterized by a rapid drop in temperature with increased depth, was located between 3-4 meters at station 1, and between 5-6 meters at station 2 (Figure 4). By July 9th, surface temperatures averaged 22.5°C at the surface, while bottom temperatures averaged 13.5°C. The thermocline was located between 4-5 meters at station 1, and between 3-4 meters at station 2 (Figure 4). At the end of August, surface temperatures averaged 22°C, while bottom temperatures averaged 13°C. The thermocline was located between 5-6 meters at station 1, and between 6-7 meters at station 2. By the beginning of October, surface temperatures averaged 16°C, while bottom temperatures averaged 14.5°C (Figure 4). Total Phosphorus: Total phosphorus values increased from May to the beginning of October 1992, reaching it's highest values from August 20th to October 2nd (Table 3). Phosphorus concentrations at the end of May showed values of 0.021 mg/L at the surface, and 0.16 mg/L at the mid and bottom depths for stations 1 and 2. By August 20th, 3 2 3 23 22 ‘ 4 \j 5 21‘\\\\——’//// 6 - 2O 1 9 7 18 1t) \0 Depth(m) (D co \_. )3 M ..L ..L 00-4 N .101 < 11 ‘12 May Junefi Jul Aug Sept Oct Sampling Period (05/28/92-10/02/92) Figure 4. Temperature Isopleths (°C) For Townline Lake. 4O phosphorus values had increased to 0.025 mg/L at the surface, 0.046 mg/L at the mid depths, and 0.086 mg/L at the bottom of the lake. By the beginning of October, phosphorus values decreased to 0.014 mg/L at the surface, reached a high concentration of 0.055 mg/L at the mid depths, and maintained a high concentration of 0.059 mg/L near the bottom (Table 3). Table 3. Measurements of Total Phosphorus (mg/L) at the Surface, Mid-depths and Bottom of Townline Lake. Date 47§fi?face Mid Bottom Total 05/28 0.021 0.016 0.016 0.053 06/18 0.022 0.033 0.033 0.088 07/09 0.008 0.010 0.059 0.077 07/30 0.025 0.009 0.028 0.062 08/20 0.025 0.046 0.086 0.157 09/11 0.101 0.014 0.065 0.180 10/02 0.014 0.055 0.059 0.128 Zooplankton: Zooplankton samples were taken at a 9 meter vertical tow at station 1 and a 6.5 meter vertical tow at station 2. Results have shown the majority of zooplankton sampled from both stations were less than 2mm in size (Table 4). Zooplankton in Townline Lake were quite numerous and included copepods (Copepoda), immature copepods (Nauplis larvae) and cladocerans (Cladocera). The highest counts of 41 zooplankton were found from May to June, and then generally decreased to the end of August (Table 4). Table 4. Mean and Total Zooplankton Densities In Townline Lake (#IL). Cladocera Copepoda Nauplii Date Station <2mm >2mm <2mm >2mm larvae Total 05/23 1 * * * * * * 2 34.5 4.2 78.8 6.3 0.0 123.8 05/13 1 * * * * * * 2 34.5 3.2 70.9 5.0 0.0 113.6 07/09 1 14.1 1.0 19.5 2.0 0.0 36.6 2 9.6 0.7 27.7 1.4 0.0 39.4 07/30 1 6.0 1.5 18.3 3.4 0.0 29.2 2 6.4 1.3 18.8 1.1 0.0 27.6 08/20 1 9.6 0.0 13.8 0.1 1.0 24.5 2 21.4 0.0 24.2 0.0 1.5 47.1 09/11 1 10.4 0.0 26.0 0.0 1.1 37.5 2 14.0 0.3 40.0 1.0 2.8 58.1 10/02 1 15.0 0.5 25.5 0.3 1.7 43.0 2 9.3 0.7 27.5 0.5 2.4 40.4 * not available 42 Zooplankton numbers then increased at the beginning of September and remained fairly high through the early part of October. Zooplankton from both stations were dominated by small Copepoda, 2mm or less in size, including Qiappmus sp., and ngIOps sp., being the most abundant. Nauplii larvae (immature Cyclops sp.) were also found in small numbers. Small cladocerans, (2 mm or less in size), were abundant in Townline Lake and were dominated by Lepgogopa sp., Daphnia sp., Bospina sp. and Qiaphanosoma sp. Qp-Sigg Ipspegtiop of the Watershed; USDA Soil Survey maps for Montcalm County (1989), and Mecosta County (1984), indicated the majority of the watershed is underlain by deep dry Grayling sands having poor water holding capacity and low natural nutrient content. On-site visual observations reveal Townline Lake has a well vegetated watershed. Approximately 68% of the watershed is heavily vegetated, with low lying forested areas. Agricultural activities comprise approximately 13% of the watershed, while approximately 5% of the watershed is comprised of rural residential areas (Figure 5)(Table 5). Approximately 5 farms are operating within the . watershed. Farm fields consisted of pasture land, corn fields, old fields, hay and Conservation Reserve Program 43 SCALE 1: 24,000 Townline Lake @ Corn I Residential Hay Forest Orchard I Pine Plantation Old Field Pasture Figure 5. Land Use Activities In The Townline Lake Watershed. 44 lands or CRP. These fields are located over a mile from Townline Lake, are not easily erodible, and would probably not contribute large amounts of nutrients through runoff or groundwater transport. There does not appear to be any industries, sewage treatment facilities, or other point sources in the Townline Lake watershed (Figure 5). The watershed did not appear to have extensive impervious surfaces such as roads, and parking lots. As well, most storm water runoff would infiltrate the ground or vegetation before reaching the lake. Table 5. Land Use Activities in the Townline Lake Watershed. Land Use Area (10°m2) Total Watershed 7.167000 Agricultural lands 0.931710 Forest lands 4.873560 Rural residential 0.358350 Townline Lake 0.997000 There are Some small marshy areas in the watershed that may contribute some nutrients into the lake. But, streams carrying this sediment load are intermittent, and flow into the lake only on a seasonal basis. .The shoreline of Townline Lake appears to have been developed for cottages and permanent residences for many 45 years. On-site visual observations conclude there are approximately 177 lakeside residences on Townline Lake serviced by septic systems. Approximately 36 (20%) of riparian residences are located on steep slopes, and 31 (18%) riparian residences are situated on low lying lots. As well, there appeared to be some fertilizer use on a number of lakeside lawns. There was also a lack of vegetative buffer strips for reducing runoff on most lakeside lawns. The Personal Interview Questionnaire: A questionnaire and accompanying cover letter was administered to all riparian residents on Townline Lake beginning in late May 1992 (Appendix A). In this study, it was asSumed septic systems of lakeside dwellings might significantly impact the water quality of Townline Lake. Approximately 86% or 153/177 of the lakeside households were surveyed from May-July 1992. Of the respondents interviewed, 100% (153) owned their lakeside residence, 43.1% (66) were permanent households, while 56.9% (87) were seasonal residences. Permanent households had a mean value of 2.1 regular household members, while seasonal residents had a mean value of 3.6 regular household members. The greatest number of days spent by permanent and. seasonal residents at their cottage/residence was between the months of July to September. Permanent residents spent 46 a mean of 91.5 days at their home, while seasonal residents spent a mean of 39.4 days at their cottage (Table 6). Table 6. Mean Number of Days Seasonal and Permanent Residents Reside at their Home or Cottage. Time Period Mean Days Mean Days Seasonal Residents Permanent Residents January-March 8.4 65.5 April-June 19.8 82.0 July-September 39.4 91.5 October-December 10.5 77.6 The least number of days spent at Townline Lake was between the months of January to March. Permanent residents spent a mean of 65.5 days, while seasonal residents spent an mean of 8.4 days during this time period (Table 6). The months between July-September had the highest mean number of guests (7.4 guests) for permanent and seasonal households, and the mean number of days these guests stayed was 4.0 days (Table 7). Respondents were asked to describe the water quality of Townline Lake for their uses of the lake. Over 60% of permanent residents, and 45% of seasonal residents rated the water quality of Townline Lake as less than satisfactory (Table 8). Pearson's chi-square (x2=4.18 df=1 P=0.04088) 47 Table 7. Approximate Number of Guests at Cottage/Residence, and Length of Stay. Time Period Mean # of Guests Mean # of Days January-March 2.3 1.0 April-June 5.6 2.0 July-September 7.4 4.0 October-December 2.1 1.2 was utilized to test if there were significant differences between permanent and seasonal residents based on their responses to water quality. Satisfaction levels were rated on a likert scale of 1-5, with 5=excellent, 4=very satisfactory, 3=satisfactory, 2=slightly satisfactory, and 1=unsatisfactory. If the respondents rated the water quality as 3,4,5, the response was classified as satisfactory. If the response was rated as 2 or 1, the response was rated as unsatisfactory. Results showed seasonal residents significantly (0.05 level or less) rated the water quality of Townline Lake as satisfactory more than permanent residents (Table 8). Respondents were asked how they would improve the water quality of Townline Lake. Approximately 38.7% stated they did not know how they would improve the water quality, 20% stated a sewer system around the lake would improve the water quality of Townline Lake, while 14.7% stated they 48 would improve the herbicide treatment currently used on the lake (Table 9). Table 8. Resident Responses of Townline Lake Water Quality For Their Uses of the Lake. I 77Permanent Seasonal Response Frequency (%) Frequency (%) Unsatisfactory 21 31.8 19 22.4 Slightly unsatisfactory 19 28.8 19 22.4 Satisfactory 24 36.4' 40 47.1 Very satisfactory 1 1.5 4 4.7 Excellent 0 0.0 3 3.5 No Opinion 1 1.5 0 0.0 Table 9. Responses To Improving Water Quality in Townline Lake. Response Frequency Percent(%) Sewer system 30 20.0 Improve herbicide treatment 22 14.7 Maintain herbicide treatment 16 10.7 Dredge channel 14 9.3 Do not know 58 38.7 Other 10 6.7 49 Recreational activities for respondents, the respondents' family, or guests at Townline Lake included boating (90.8%), fishing (86.1%), and swimming (84.7%) (Table 10). Pearson’s chi-square was used to test if there were any significant differences in residents' responses to Townline Lake's water quality based on the recreational activities they chose to participate in. Using Pearson's chi-square analysis, no significant differences existed (at the 0.05 level of significance or less). Table 10. Recreational Activities the Respondent, the Respondent's Family, or Guests participate in at Townline Lake. Activity Frequency Valid Percent(%) Boating 139 90.8 Fishing: 130 86.1 ice fishing 66 43.4 bass/pike 104 68.4 bluegill 121 79.6 yellow perch 99 65.1 crappie 74 48.7 other 26 17.2 Swimming 127 84.7 Waterskiing 91 59.9 Other 115 76.7 50 Residents stated boating, fishing, and swimming were the most important recreational activities they participated in at Townline Lake (Table 11). The recreational activity residents would miss most if they could not participate in a recreational activity at Townline Lake included boating (32.5%), fishing (30.5%), swimming (18.5), other activities (11.2%), and waterskiing (7.3%)(Table 11). Pearson's chi-square was used to test if significant differences existed for residents responses to Townline Lake's water quality based on the recreational (activity respondents would miss the most. Using Pearson's chi-square analysis, no significant differences existed at the 0.05 level of significance or less. . Table 11. The Most Important Recreational Activities Respondents Participate in at Townline Lake, and the Recreational Activity Respondents Would Miss Most. A 77v‘ Miss s Activity Frequency Frequency ‘Valid Percent(%) Boating 98 49 2 32.5 Fishing 85 46 30.5 Swimming 63 28 18.5 Other Activities - 41 17 11.2 Waterskiing 35 11 (7.3 51 Cross tabulations were made of septic system location and types of septic systems by permanent and seasonal households. Approximately 77.3% of permanent households had a septic tank and a drainfield, 19.7% had a dry well, and 3.0% did not know what type of septic system they had (Table 12). Approximately, 41% of permanent households had a septic tank with a drainfield located between the house and the road, 15% had a septic tank and a drainfield located between the house and the lake, 15% had a septic tank and drainfield at the side of the house, and another 15% had a dry well located between the house and the road (Table 12). Table 12. Location and Type of Household Septic Systems For Permanent Residences. Location . Septic Tank Dry Well Do w/Drain Field Not Know In between house/road 27 10 1 In between house/lake 10 1 1 At side of house 10 1 0 Across the street 1 0 0. Under house/deck 2 I 1 0 Do not know 1 0 0 For seasonal households, approximately 79.3% had a septic tank with a drain field, 13.8% had a dry well, and 6.9% did not know the type of septic system they had 52 (Table 13). Approximately 48.3% of seasonal households had a septic tank with a drainfield between the house and the road, 14.9% had a septic tank with a drainfield between the house and the lake, 12.6% had a septic tank and a drainfield at the side of the house, and 6.9% had a dry well between the house and the road (Table 13). Cross tabulations were taken of mean septic system age, distance from the lake, and mean frequencies of septic systems pumpings for permanent and seasonal households. Table 13. Location and Type of Lakeside Septic Systems for Seasonal Residences. Location SepticTank Dry Well Do w/Drain Field Not .1 Know In between house/road 42 6 4 In between house/lake 13 3 0 At side of house 11 2 1 Across the street 1 1 0 Under house/deck 1 0 0 Do not Know 1 0 1 For permanent households, septic systems located closest to Townline lake (25-100 feet) were generally older systems that were pumped out less often than septic systems located further from the lake (110-300 feet). Approximately, 59.4% of permanent residents had septic systems located between 25-100 feet from the lake (Table 53 14). Septic systems located between 77-300 feet were pumped more frequently than septic systems closer to the lake, although, 18.8% of permanent residents had septic systems between 110-200 feet that had never pumped out their systems. Over 40% of permanent households had septic systems located 110-300 feet from the lake (Table 14). There were 23 (36%) permanent households that had never pumped out their septic systems. Of these permanent households, 10 had septic systems located 25-100 feet from the lake, and 3 of these systems were older than 20 years old. Approximately, 12 households that had never pumped out their septic systems had systems located 110-200 feet from the lake, and one household had a septic system located 225- 300 feet from the lake (Table 14) (Figure 6). Table 14. Mean Septic System Age, Distance From the Lake, and Frequency of Septic System Pumpings for Permanent Households. Distance Mean Mean Mean f of Systems (Feet) Distance Age Pumpings Never Pumped (Feet) (Years) (Years) 25-45 38.0 17.7 10.8 (5)‘1 2 50-75 60.3 26.4 11.4 (12) 4 77-100 94.0 24.1 5.2 (11) 4 110-200 152.5 16.0 7.0 (10) 12 225-300 287.5 11.5 5.3 (3) 1 a=number of systems ( ) 54 Age of Septic System (YearS) unknown Seasonal Residents - 33-47 , , , , , . . 7 1° 21-30 _ 11-20 _ 8 8 Ion ~ ,_ ,, _ ...;- d 6 a i- " o ._ 4 g _ 3 ------------- _ 22' Ifisuuum 5*;45329 _ 77-100 Rom Lake (Feet) 110.200 0 Age of Septic System Permanent Residents (Years) .1 10 unknown a - 33-47 a 2 E; 2 11-20 g III 040 6 a: I- o 4 S 3% 2 IHsuuuw FTontLake(Feefl 0 Figure 6. Frequencies of Septic Systems That Have Never Been Maintained Through Pumping. 55 Fisher's Exact Test (expected frequencies were < 5) was used to determine if there were any significant differences for permanent resident responses to water quality based on the age of the septic system, and if the septic system had ever been pumped out. Variables used included permanent residents that had septic systems 20 years old, or older that had never pumped out their septic systems, compared to permanent residents that had septic systems less than 20 years old, that had pumped out their septic systems. Using Fisher's Exact Test, no significant differences were found at the 0.05 level or less. Results showed seasonal households had septic systems located closer to Townline Lake (25-100 feet) that were as old, or older than seasonal septic systems located 110-300 feet from the lake (Table 15). Septic systems located between 25-100 feet from the lake (78.2% of respondents) generally had septic systems that were pumped out less frequently than septic systems located further from the lake. Approximately 21.8% of seasonal residents had septic systems located between 110-300 feet from the water’s edge (Table 15.) There were 41 (47.1%) seasonal households that had never pumped out their septic systems. Of these residences, 32 (78%) had septic systems located 25-100 feet from the lake, and 9 of these residences had septic systems older 56 than 20 years old. There were also 9 households that had septic systems between 110-200 feet from the lake that had never been pumped out (Table 15)(Figure 6). Pearson's chi-square was used to test if significant differences existed in seasonal residents responses to water quality based on the age of their septic system, and if the system had ever been pumped out. Variables included seasonal residents that had septic systems 20 years old, or older that had never pumped out their septic system, compared to seasonal residents that had septic systems less than 20 years old that had pumped out their septic system. There were no significant differences at the 0.05 level or less. Table 15. Mean Septic System Age, Distance From the Lake, and Frequency of Septic System Pumpings for Seasonal Households. Distance Mean Mean Mean # Of Systems (Feet) Distance Age Pumpings Never Pumped (Feet) (Years) (Years) 25-45 30.0 24.0 6.0 (2). 3 50-75 66.0 28.3 8.0 (14) 17 77-100 96.7 22.0 10.0 (20) 12 110-200 158.1 22.0 8.0 (9) 9 225—300 225.0 2.0 1.0 (1)* 0 a=number of systems ( ) * 1 respondent in this category 57 Overall, there were more seasonal residents (78.2%) than permanent residents (59.4%) that had septic systems located between 25-100 feet from Townline Lake. As well, there were more seasonal residents (78.2%) having septic systems located between 25-100 feet from the lake that had never pumped out their septic systems than permanent residents (43.5%). Pearson's chi-square was used to test if there were significant differences between permanent and seasonal residents that had never pumped out their septic systems. No significant differences were found at the 0.05 level of significance or less. The mean distance of septic systems for permanent households was 117 feet from Townline Lake, mean septic system age was 20.2 years, and mean number of years for pumping out septic systems was 8.1 years. The mean distance of septic systems for seasonal households was 96.1 feet, mean septic system age was 24.1 years, and mean number of years seasonal residents pumped out their septic systems was 8.7 years. T-tests of means were used to determine if there were significant differences between permanent and seasonal households for mean distance of septic systems from the lake, mean age of the septic systems, and mean years of septic system pumpings. No significant differences were found at the 0.05 level of significance (2 tail probability) 58 for any of the variables tested. Approximately, 26.8% (40) of respondents (permanent and seasonal) used fertilizer on their lawns at Townline Lake. However, the majority of the residents 73.2% (109) stated they did not use fertilizers on their lawns. One respondent did not know if they used fertilizer on their lawn. Additional information from the questionnaire can be found in Appendix A. Phosphorus Loading Model Simpson and Reckhow's (1979) phosphorus model for lakes in the north temperate climatic zone was used to predict present phosphorus concentrations in Townline Lake, based on estimated phosphorus loading, lake, and watershed characteristics. Simpson and Reckhow (1979) state the estimated phosphorus concentration of a lake from the model can then be related to trophic state and lake use features including expected water quality characteristics (Table 16). Steps for calculating the phosphorus concentration in Townline Lake using the model are located in Appendix B. The application of this model resulted in a "most likely" phosphorus concentration of 0.021 mg/L. According to Table 16, based on the estimated phosphorus concentration of 0.021 mg/L, Townline Lake has just entered a eutrophic state, able to support a productive warm water fishery, but having decreased water quality values. 59 Table 16. Phosphorus Concentration As Linked To Trophic State and Potential Lake Use Attributes (From: Simpson and Reckhow 1979). Phosphorus Trophic State Lake Use Concentration (mg/L) < 0.010 Oligotrophic Suitable for warm water based recreation and propagation of cold water fisheries, such as trout. Very high clarity and aesthetically pleasing. 0.010-0.020 Mesotrophic Suitable for water based recreation but not for cold water fisheries. Clarity less than Oligotrophic lakes. 0.020-0.050 Eutrophic Limited total body contact suitability, based upon either loss of aesthetic properties or possible health hazards. Generally very productive for warm water fisheries. >0.050 Hypereutrophic A typical "old aged" lake in advanced succession. Some fisheries, but high levels of sedimentation and algae, or macrophyte growth may be diminishing open water. 60 Using 68% confidence limits, as demonstrated in the model, the "true" phosphorus concentration is bound between: 0.011 mg/L < P < 0.035 mg/L. By widening the confidence limits to 95% confidence, doubling the total prediction uncertainty of the model, the "true" phosphorus concentration of Townline Lake is bound between: 0.002 mg/L < p < 0.050 mg/L. The "most likely" phosphorus concentration of 0.021 mg/L was then compared to mean phosphorus concentrations from surface water samples of Townline Lake from the end of May to the end of August 1992. The comparison between the "most likely" estimated phosphorus value from the model (0.021 mg/L) and the actual mean surface phosphorus concentrations from Townline Lake (0.020 mg/L) was similar during the stratified period. The model was also used to predict an expected phosphorus concentration in Townline Lake, based on the absence of lakeside septic systems as a phosphorus source for the lake. The resulting "most likely" phosphorus concentration was calculated to be 0.015 mg/L. According to Table X, this phosphorus concentration would result in the lake being a mesotrophic lake, characterized as supporting a warm water fishery, and having good water quality for various recreational activities. Using 68% confidence limits, the "true" phosphorus concentration would be bound between: 0.009 mg/L < P < 0.024 61 mg/L. By widening the confidence limits to 95% confidence, doubling the total prediction uncertainty of the model, the "true" phosphorus concentration would be bound between: 0.002 mg/L < P < 0.033 mg/L. DISCUSSION Limnological Survey of Townline Lake:' Water Transparency or Visibility: The decrease of water clarity after July 9th as indicated by the Secchi disk readings could be due to an increase in algal blooms from the regeneration or release of nutrients from decaying macrophytes. Decaying macrophytes from herbicide treatments on the lake contribute to the regrowth of weeds and summer phytoplankton densities. Normally, in lakes, there is an early summer bloom of phytoplankton following the spring overturn which brings up nutrients from the bottom. These cells settle out and the water usually clears in mid to late summer followed by another lesser bloom when the lake mixes in the fall (Kevern 1989). Townline Lake appeared to have a continuing phytoplankton bloom into the late summer as indicated by the Secchi disk depth. Temperature: At the end of May 1992, Townline Lake was thermally stratified or layered. The surface water of Townline Lake had become less dense as it was warmed separating it from the colder more dense water at the lower depths. Thermal stratification between the upper, middle, and lower levels in the lake was maintained throughout the 62 63 summer. By the end of August, the lake was still thermally stratified. However, by the beginning of October, the lake was turning over, causing the temperature of the lake to be nearly uniform from top to bottom. Thermocline profiles, characterized by a rapid drop in temperature with increased depth, revealed Townline Lake had temperature readings of a typical, normal, temperate zone lake, supporting warm water fish such as bass, pike, and sunfish. Total Phosphorus: Kevern et al.(1991) state since plankton and marl drift downward towards the lake bottom, it is common from August until the fall turnover to find total phosphorus concentrations high at the mid-depths and highest at the bottom of a lake. The high phosphorus values in Townline Lake after July 30th are probably a combination of an increase in summer use of septic systems, and the release of phosphorus from decaying macrophytes due to herbicide treatments throughout the early part of the summer. The 1991 Limnological Survey on Townline Lake, (Kevern et al. 1991), stated unpolluted lakes in the upper half of the lower peninsula of Michigan generally have total phosphorus concentrations averaging below 0.015 mg/L in surface waters. Total phosphorus concentrations in Townline Lake over the 1992 sampling period averaged 0.031 mg/L, or double the value for unpolluted lakes. United States 64 Environmental Protection Agency Maps reveal soil fertility for lakes in the northeastern section of Montcalm county have low natural phosphorus fertility. Thus, Townline Lake, located in the northeastern section of Montcalm County should have low phosphorus concentrations from natural sources. However, high phosphorus values in Townline Lake . in 1991 and 1992 reveal there must be phosphorus input into the lake from other sources or other activities in the Townline Lake watershed. Zooplankton: The lack of large zooplankton in Townline Lake could be due to heavy grazing pressure on large zooplankton from small fish. Grazing on zooplankton by fish was evident as the highest numbers of zooplankton were found from May to June, and then decreased to the end of August. Zooplankton numbers increased at the beginning of September and remained fairly high through the early part of October. The increase in zooplankton numbers is perhaps due to reproduction and algae blooms for food in late summer and early fall. Zooplankton abundance can be a good indicator of the presence of toxic conditions in a lake, as zooplankton are often intolerant of toxins. Therefore, the abundance of zooplankton in Townline Lake indicates the lake does not appear to have toxicity problems. 65 On-Site Inspection of the Watershed Visual observations of land use practices reveal the Townline Lake Watershed to have a well vegetated watershed. There does not appear to be any industries, sewage treatment facilities, or other point sources in the watershed. Although lawn and crop fertilization, storm water, and impervious surface runoff can be significant sources of nutrient pollution in a watershed, they do not appear to be significant contributors of nutrients into Townline Lake. However, the shoreline of Townline Lake has been developed for cottages/residences for many years, and all of these residences are serviced by septic systems. As well, some of these residences are located on steep slopes and low lying lots. The majority of the Townline Lake Watershed is underlain by deep, dry Grayling sands having poor water holding capacity and low natural nutrient content. Riparian septic systems built in these sandy/gravely soils will not completely remove nutrients such as phosphorus and nitrogen, and these wastes may drain rapidly through to the groundwater and eventually to the lake (MDNR 1990, Williamson, 1990). Soil and water conditions near the shoreline may make these systems less efficient in treating waste (MSU WQ13 1987). Otis (1978) states as much as 68% of the total land area of the United States has soils unsuitable for septic 66 tank systems. Phosphate movement is evident in some sandy soils with limited phosphate fixation capacity especially around old or heavily loaded septic systems with high water tables (Cogger 1988). Studies have shown phosphorus passes into lakes through some Michigan soils from as far away as 300 feet (MSU E-891; Rodiek 1978). Septic systems are designed to effectively accept and treat liquid wastes from households, and to prevent biological and nutrient contaminants from getting into wells or nearby lakes (MSU W014 1987). Maintaining septic systems on shoreline property requires more care and work than maintaining similar systems in other places. 0 n 'e u s '0 Phosphorus contributions into lakes from shoreline septic systems depend upon on a number of considerations including the fraction of the year the system is in use and the occupancy rate of the dwelling unit (Reckhow and Chapra 1983; Reckhow et al. 1980). The greatest number of days permanent and seasonal residents spent at their cottage/residence was between the months of July to September. Analysis of water samples revealed the highest values of total phosphorus were from August to the beginning of October 1992. Common septic systems in Michigan are the septic tank 67 and drain field, septic tank and tile bed, and the dry well. These septic systems are soil-based wastewater treatment systems, and all of these systems have inherent shortcomings with respect to lake communities (Cogger 1988; Gibson and Humphrys 1979). Approximately 78% of resident households on Townline Lake had a septic tank with a drainfield. Septic tanks with drainfields are a non-point source that must be considered, as these systems may not always be effective in trapping and preventing nutrients from entering a lake via groundwater transport (Reckhow et al. 1980; Ryding and Rast 1989). Canter and Knox (1985) state the general advantages of septic tank systems include the following: 1. minimal maintenance is required for the system, with potential pumpage of the septic tank required every three to five years, 2. the cost of individual or community septic tank systems is less than the cost of central wastewater collection facilities, 3. the septic tank system represents a low technology system, thus the possibility for long term operation without extensive periods or shutdown is enhanced, and 4. the energy requirements of septic tank systems are low in comparison to centralized wastewater treatment facilities. According to Canter and Knox (1985), the general 68 disadvantages of septic tank systems include: 1. the potential for groundwater pollution depending on the soil characteristics and density of systems in a given geographical area, and 2. system overflows and pollution of adjacent water wells and surface water courses if the systems are not properly maintained. Reckhow and Chapra (1983) state the estimated nutrient loading from septic systems will also depend upon the location of the system with respect to the surface water body. Approximately 59% of residents stated their septic system was situated between the house and the road, 18% of residents had septic systems at the sides of their residences, and 18% of respondents had septic systems located between the house and the lake. Ideally, septic systems should be located as far from the lake as possible, the greater the distance between the septic-tile field and the water table, the greater the likelihood phosphorus will be immobilized and not transported to a surface water body via groundwater. A zone of aeration should exist between the septic tile field and the water table at all times of the year, as this zone functions as a chemical and physical filter for phosphorus (Reckhow et al. 1980). Nutrients or biological contaminants encountering soil 69 saturated with water can move greater distances, in some instances as much as several hundred feet. As well, septic systems on shoreline property are often close to the water, and can sometimes become saturated during high water periods, leaking wastes into lakes (MSU W013 1987). Phosphorus contributions from groundwater via septic systems may also be a function of septic system age and frequency of septic tank pumpings for seasonal and permanent households (Reckhow and Chapra 1983). Otis (1978) states septic tank failure is often due to it's misapplication and misuse. Permanent households with septic systems located closest to Townline Lake (59.4%) were generally older systems that were pumped out less often than septic systems located further from the lake. As well, seasonal households with septic systems located closest to Townline Lake (78.2%) were generally as old, or older systems pumped out less often than seasonal systems located further from the lake. Most septic systems will fail sometime, and after a while, as long as 20 to 30 years under the best conditions, the soil around the drain field becomes "filled up" with phosphorus making the system unusable. Therefore, any additions of phosphorus then moves through the drain field into the lake (MSU W014 1987; Williamson 1990; MDNR 1990). Soils have only a finite capacity for phosphorus adsorption. Phosphorus-saturated soils in a watershed will 70 no longer remove phosphorus from septic tank effluent. The majority of the Townline Lake watershed is underlain by deep dry Grayling sands having poor water and nutrient holding capacity. Therefore, old septic systems may provide less soil retention of phosphorus than do new systems.’ Overall, the greatest risk of phosphate pollution for lakes comes from surface failing on-site systems or from the direct discharge of septic tank effluent into the surface water (Cogger 1988). In the tank, the phosphorus adsorbs strongly to particles, when the tank is pumped out, this load is very high in phosphorus, and the material doesn't go out into the drainfield. Therefore, by pumping the tank out on a regular basis, some of the phosphorus is prevented from reaching the lake, and the life of the drainfield is extended (Kevern personal communication 04/93). The most common reason for early failure of septic systems is improper maintenance by homeowners. When a system is poorly maintained and not pumped out on a regular basis, sludge builds up inside the septic tank, then flows into the adsorption field clogging it beyond repair (MSU W014 1987). Septic systems should be pumped out every 3-5 years for seasonal households, and more frequently for permanent households. Nicolson and Mace (1975) state water quality standards are written primarily in chemical and biological terms, but 71 some consideration must be given to the aesthetic perceptions of sight, smell, taste and touch. Seasonal residents significantly rated the water quality of Townline Lake as satisfactory more than permanent residents. This may indicate seasonal residents may not be as affected by water quality problems as permanent residents who reside at the lake on a year round basis. Townline Lake is heavily used for recreation. Residents stated boating, fishing and swimming were the most important recreation activities they participated in at the lake. The development of a long-term strategy to improve water quality of the lake can result in decreased nuisance growths of algae and aquatic plants, increasing the clarity of the water, and improving opportunities for water based recreation including the sport fishery on the lake. Limitations With The Questionnaire: The effects of question wording and clarity are unclear and difficult to predict. Minnis (1992) states subtle differences in wording may alter responses, whereas substantial changes in wording may have no apparent effect at all. Questions in the survey requiring recall (Appendix A) may have been problematic in some instances, as respondents may have had difficulty in accurately remembering their actions. An open-ended, hypothetical question (Question 19. If 72 you could improve the water quality of Townline Lake how would you improve it?) was used at the end of the survey to assess salience. However, response bias may have been introduced in this question, as interpretation of some residents opinions may have been difficult to accurately assess . Pppsppopus Loadipg Model Simpson and Reckhow (1979) state phosphorus loading models provide information on the impact of watershed characteristics and activities on phosphorus concentration in a lake. These watershed models are simplification of real world systems, and their broad objectives are to estimate non-point source nutrient inputs reaching a lake or reservoir (Ryding and Rast 1989). Prediction of phosphorus concentrations in Townline Lake using Simpson and Reckhow's (1979) model are inherently uncertain, but still provide a reasonable estimate. Phosphorus export coefficients were used to estimate non-point phosphorus loads. As well, an estimation was made of the soil retention coefficient. The selection of appropriate export phosphorus coefficients and soil retention coefficient was a subjective task, and a poor choice of these values may contribute to errors in use of the model. Reckhow (1992) stated judgmental bias is part of 73 the error in selecting export coefficients from a table. For the purposes of this study, the model did not include an estimation of numbers of guests at a cottage or residence and their length of stay. This would result in a conservative (low) estimate of phosphorus loading. The model only estimated the average number of persons per living unit, and number of days spend at the unit per year, for permanent and seasonal residences. Guest usage may have been an important factor for contributing to nutrient loading into Townline Lake. The months from July to September had the highest mean number of guests (7.4), and the mean number of days these guests stayed at Townline Lake was 4.0 days. Total phosphorus values reached the highest values from August to the beginning of September 1992. Therefore, if guest usage of lakeside residences was included in the model, estimated phosphorus concentrations in Townline Lake may have been greater than the predicted "most likely" concentration of 0.021 mg/L. An estimate of the recirculation of phosphorus from sediments at the bottom of the lake into the water column (internal loading) was not included in the model. The main tasks of the model and this study focused on the external sources of phosphorus from the watershed and not the 7 internal recycling of phosphorus in the lake. The phosphorus model demonstrates riparian septic 74 systems are important non-point sources leading to water quality impairment. The presence of these systems in the Townline Lake watershed appears to contribute the greatest percentage of the phosphorus load to the lake. If the residents on Townline Lake invested in a small, sanitary sewer system to replace existing septic systems, the sewer system would be an effective long-term strategy eliminating most of the phosphorus sources into the lake. Absence of septic systems from the watershed produced a "most likely" phosphorus concentration of 0.015 mg/L, resulting in mesotrophic conditions, characterized by good water quality. Presently, Townline Lake has entered a eutrophic state, characterized by decreased water quality conditions. RECOMMENDATIO S Results of this study demonstrate riparian septic systems are the most likely and important sources of cultural nutrient inputs into Townline Lake. These inputs have led to cultural eutr0phication conditions, impairing the water quality of Townline Lake. Over 60% of permanent residents, and 45% seasonal residents rate the water quality of Townline Lake as less than satisfactory. Almost 40% of residents stated they did not know how they would improve the water quality of the lake, 20% stated they would put a sewer system around the lake, and approximately 15% would improve the herbicide treatment currently used to control aquatic plants and algae. In the past, there has only been one approach to managing excessive macrophyte and algae growth in Townline Lake. This approach has been an annual intensive use of chemical aquatic plant control. However, this method has only treated the symptoms, rather than the causes of the eutrophication problem. As long as the lake continues to receive nutrient loading from the watershed, internal practices alone will not eliminate cultural eutrophication. As phosphorus is an essential nutrient for the growth of macrophytes and algae in a lake, one of the most effective long-term strategies for controlling cultural eutrophication of lakes, is to reduce the quantity of the 75 76 nutrients entering the lake (Nordin 1983; Ryding and Rast 1989). A small, sanitary community sewer system, installed around Townline Lake to replace existing septic systems, could improve the water quality of the lake by eliminating septic contamination. It may take a number of years (5 or more) for significant improvements to occur in the water quality of the lake, after the sewer system is installed. As well, in-lake methods such as harvesting would help to remove in-lake nutrients, while chemical aquatic plant control may contribute to the improved appearance of the water. The US Environmental Protection Agency (1980) states, treating the sources of lake degradation may be expensive and results not as dramatic as hoped for, but the effects are likely to be long lasting, and more cost effective in the long run. Unless phosphorus loading from the watershed is reduced, intensive internal measures such as weed harvesting, will only be as permanent as lawn mowing. Also, chemical treatments might have to be repeated frequently, and will be a recurring expense. Placing water quality management techniques into action is a local responsibility. Lake associations can provide informal settings where lake issues can be discussed by the residents. The MDNR (1990) states lake boards are important institutions for improving inland lakes. These boards have 77 the legal authority to propose lake improvement plans, hold public hearings, and proceed with the plans. As well, there may be federal, state, and local programs offering financial and technical assistance for water quality improvement activities. Townline Lake is typical of many other inland lakes in Michigan, as these lakes have been developed with permanent and seasonal cottages around their shorelines. The residents on Townline Lake may choose to initiate a watershed approach for improving water quality in their lake. They may also continue with current herbicide treatments or try other in-lake treatments. However, the decision to improve water quality of Townline Lake using a watershed management approach is a decision that must be made by the residents on this lake. APPENDICES AEEEHDIX_A Homeowners and Cottagers: Table A-1. Years Permanent/Seasonal Residents Have Owned Their Cottage/Residence on Townline Lake. Years Owned Frequency Percent(%) 0.515 44 28.8 5-10 32 20.1 11-15 22 14.4 16-20 21 13.7 > 20 34 22.2 Table A-2. The Percentage of Weekdays and Weekends Permanent/Seasonal Residents Spend at the Lake From January-March. DE§§_§pent at Lake Weekdays(%) Weekends(%) 1-30 14.0 86.0 31-60 40.0 60.0 90-> 100.0 100.0 78 Table A-3. The Percentage of Weekdays and Weekends Permanent/Seasonal Residents Spend at the Lake From April-June. Days Spent atSLake Weekdays(%) Weekends(%) 1:157 36.2 63.8 16-30 17.8 82.2 31-60 44.4 55.6 61-80 45.5 54.6 90-> 100.0 100.0 Table A-4. The Percentage of Weekdays and Weekends Permanent/Seasonal Residents Spend at the Lake From July-September. Days Spent at Lake Weekdays(%) Weekends(%) ‘1315 64.2 35.8 16-30 20.4 79.6 31-60 33.3 66.7 61-85 53.3 46.7 90-> 100.0 100.0 Table A-5. The Percentage Of Weekdays and Weekends Permanent/Seasonal Residents Spend at the Lake From October-December. Days Spent at Lake Weekdays(%) Weekends(%) 1-15 2775 72.5 16-30 5.6 94.4 31-60 50.0 50.0 90-> 100.0 100.0 80 Table A-6. Depth of Lakeside Wells. DEEEE_TFeet) Frequency Percent(%) 3-40 47 30.9 42-90 44 28.9 120-180 5 3.3 Do not know 56 36.8 Table A-7. Resident Responses To Problems With Contaminants In Their Wells. Response Frequency Percent(%) Yes 5 3.3 NO 145 94.8 Do not Know 3 p 2.0 81 MICHIGAN STATE UNIVERSITY DEPARTMENT O? m AND WILDLIFE EAST LANSING 0 MICHIGAN 0 0824-1222 NATUIAL was IUILDING ' (117) 335-4477 FAX: 517-596-1699 April 29, 1992 Dear Townline Lake Residents, I am conducting a survey for a masters thesis at Michigan State University in the Department of Fisheries and Wildlife. The object of my thesis is to examine watershed nutrient input into Townline Lake over the 1992 spring, summer, and fall period. The survey information will help to determine the effect of increased nutrients into Townline Lake, and it's impact on homeowners, cottagers, and recreationlists. Hopefully, the survey will also gain some understanding of the values, perceptions, and actions of the people who use Townline Lake. The interview will take approximately 20 minutes to complete. Please note your responses are strictly confidential. No one will be able to identify you or your answers. Your participation is strictly voluntary, and your contribution to this survey would be greatly appreciated. Thank you for taking a few minutes to help with this study. Sincerely, Julie Tsatsaros Dr. Niles Kevern Investigator Major Professor (517) 353-9276 (517) 353-1737 82 INTERVIEW QUESTIONS: This Questionnaire Was Administered As A Personal Interview. Homeowners and Cottagers: 1. Do you own or rent this cottage/residence? own rent 2 . How many years have you owned/ rented your cottage/ residence on Townline lake? years 3. Are you a permanent resident? a. Yes b. no 4. How many persons are regular members of your household? I’m going to ask you a couple of questions dealing directly with your use of the lake, your family's use of the lake, and guest use of the lake. I am also interested in your opinion regarding the water quality of the lake. As well, I'm going to ask you a couple of questions dealing with your septic system. 5. Approximately how many days/weeks per year do you spend at the lake? January - March days weeks April - June days weeks July - Sept. days weeks Oct. - Dec. days weeks 83 6. Of the days/weeks per year you spend at the lake, please indicate what percentage of weekends/weekdays you spend at your cottage/residence? weekdays(%) weekends(%) January - March April - June July - Sept. Oct. - Dec. 7. What is the approximate number of guests, usually at your cottage/residence, and how long do they stay at your cottage/residence? no. of persons length of time January - March days weeks April - June days weeks July - Sept. days weeks Oct. - Dec. days weeks 8. I'm going to list several recreational activities. Please indicate which activities you, your family, or your guests participate in while at Townline Lake? Boating Fishing: a. ice fishing b. bass/pike c. bluegill d. yellow perch e. crappie f. other Swimming Waterskiing Other(explain) 84 9. Of the above listed recreational activities, please indicate 3 of the most important activities you personally participate in at Townline lake. 10. If you were unable to participate in the recreational activities you just listed, which one would you miss the most? 11. How would you describe the water quality of Townline Lake for your uses of the lake? unsatisfactory slightly unsatisfactory satisfactory very satisfactory excellent no opinion 12. Do you know where your septic system is located? yes no 85 * Septic System Features: distance from the lake location of the system use of fertilizers on the lawn physical features of the lot 13. Could you describe your septic system? Is it a septic tank with a drain field or tile bed, or a dry well? 14. How old is your septic system? 15. How often is your septic system pumped out? 16. Do you have a well? How deep is it? 86 17. Have you ever had any problems with contaminants in your well? If so, please go to question 18. yes no 18. What kind of contaminants have you.had in your well water? 19. If You Could Improve the Water Quality of Townline Lake, How Would You Improve It? Comments: Appendix B Steps To Calculate Phosphorus Concentration In Townline Lake Using Simpson and Reckhow's (1979) Phosphorus Loading Model. Step 1: Estimation of qa (areal water loading) 0 = (A13 x r) + (A.L x pr) (1) .836483 10°m3/yr qs = Q/AL (2) = .8389 m/yr Where: q8 = areal water loading (m/yr) 0 = inflow water volume to lake (m3/yr) AB = watershed area (10°m2) AL = Lake surface area (10°m2) r = Total annual unit runoff (m/yr) Pr= Mean annual net precipitation (m/yr) Townline Lake data necessary for the estimation of q8 Yamaha Estimate AB= Watershed area 7.167000 10°m2 r= Total annual unit runoff 0.0 m/yr AL= Lake surface area 0.997 10°m2 Pr= Mean annual net precipitation 0.839 m/yr Step 2: Estimation of L (areal phosphorus loading) Step 2A: Estimation of Areaf, Area .Area ag' u Land use areas in the Townline Lake watershed: use Area 0°m2 Agriculture 0.93171 Forest 4.87356 Urban 0.358350 87 Step 28: 88 Estimation of Ece, Ecag, Ecu, Ecp, and Ec8t (export coefficients) Phosphorus export coefficients (units are Kg/10°m2-yr;. except septic tank: High Forest 40 Agriculture 50 Urban 150 Precipitation 60 Input to Septic 1.5 Tanks Step 2C: Permanent capita-year: = average # of persons per living unit (2.08) Sgasopal capita-year: Average # of persons x # days spent Most Likely pr 20 2 20 10 9O 50 40 15 0.7 0.4 Estimation of # of capita-years. x # of living at unit per year units (316.6) (66) 365 x # days spent x # of living per living units at unit per year units (3.57) (78.12) (87) 365 Permanent Seasonal Total # of capita = 119.0 + 66.47 years = 185.57 Step 2D: Estimation of S.R. (soil retention coefficient) A most likely S.R. coefficient of .50, a low of .75, and a high of .25 were selected to represent the soils surrounding Townline Lake. Step :3: Estimation of PSI (point source input) 89 Currently, there are no known point sources in the Townline Lake watershed, therefore PSI= Step 2F: 0 Kg/yr. Calculation of M (total phosphorus mass loading) Total mass loading (M) may be expressed as (in Kg/yr): Where: M (high) (m1) M (low) Step 26: Lihigh) = M = (ch x areaf) + (Eca area“) + (Bo capita-years s3 ch Ecag Ec u ECp Ecst Areaf Areaag Areau A #Lof capita years S.R. PSI a9 x area 89) + (Ecu x x AL) + (Ec at x # of x (1- S. R. ) + PSI. export coefficient for forest land (Kg/ mz-Yr) export6 coefficient for agricultural land (Kg/106 m 2-Yr) export6 coefficient for urban area (Kg/10 6mZ-yr) export6 coefficient for precipitation (Kg/10° m 2'Yr) export coefficient to septic tank systems impacting the lake (Kg/capita- yr) area area area of forest land (10°m2) of agricultural land (10°m of urban land2 (106 m2 ) area of lake (106 m2 ) # of capita-years in watershed serviced by septic tank/tile field systems impacting the lake soil retention coefficient (dimensionless) point source input 2) 576.76725 Kg/yr 258.92 Kg/yr (most likely) 72.2138 Kg/yr Calculation of L (annual areal phosphorus loading) L (9/m2/Yr)= M (Kg/yr) 1000 x AL (10°m2) .5785028 g/mz/yr I'(ml) (low) stop 3: 90 .2596991 g/mz/yr .0724311 g/mZ/yr Calculation of P (lake phosphorus concentration) 11.6 + 1.2 qB 11.6 + 1.2 q8 11.6 + 1.2 qa For Townline Lake: P (high) P (low) (m1) stop 4: 43: 4b: .0458886 mg/l .0057455 mg/l .0206001 mg/l Estimation of sT (prediction uncertainty) Calculation of log Pun) = -l.6861307 Estimation of sm+ ("positive" model error) sm+=antilog [longn + smIOQJ-Pml) = .007061 mg/l Estimation of sm-("negative" model error) sm-=antilog [logP (m1 ) -sm1°g] -P (m) = .-.0052585 mg/l Estimation of sL +("positive" loading error) 51." = P(high)-P(ml) 2 46: 4f: 91 = 0.0126443 mg/l Estimation of sL-("negative" loading error) SL‘ = P(ml)- P(low) 2 = 0.0074273 mg/l Estimation of sT+(tota1 "positive" uncertainty) (sT+)2 = (sm+)2 + (sL+)2 = 0.0144845 mg/l Estimation of sT-(total "negative" uncertainty) (51")2 = (Sm-)2 + (sir)2 = 0.0091049 mg/l Calculation of 68% Confidence Limits (Paul) 'S'r') < P < (Paul) + sT +) = 0.0114952 mg/l < P < 0.0350896 mg/l Calculation of 95% Confidence Limits = 0.0023903 mg/l < P < .0495791 mg/l LITERATURE CITED LITERATURE CITED A.P.H.A. 1985. 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