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Lewis Lake, a quiet lake sun-ounded by cattail marshes, forest, and cabins, is a paradise for its residents. Members of the Lewis La1~e Association would like to keep it that way. Concealed about excess algae and weed growth on the htlie; they contracted with the University to Ie~u~l mope about the nutrient inputs, the phulis growing in the water, and options for land management. With fiuiding from. the Connnuuit5~ Assistance Program at the University's Center for Urban and Regional Affairs; I was hired by the Association to shady their lake. I have been taking bi-weel~ly ivater~ samples, perfonlling aquatic vegetation stuveys, aucl researching land-use options. The water samples ~u-e t~lken at sever~~1 sites in and around the lake, and are being analyzed for phosphors, nitrates; and chlorophyll-ce. I will use the results of these analyses to detenline the nnaQni- tude of ]andsc~q~e mrtrient inputs and the amotult of internal recycling of nutrients that OCCLlrs. With the help of sev eral vohmteers, I have also conducted the first of t<vo aquatic plant surveys. The result of these surveys will be a cat~dog of plants in the lake, estimates of their relative abundance, and specific inlfonnation about each spe- cies. The first survey has indicated a mod- erately diverse plant comm~uinT domi- nated by coontail, a common aquatic pl~mt in Mimiesota. The Lake also has a healthy Phosph®r~as continued from page 1 Agnicttlturll watersheds ~dso tended to have high deliberate exports, in the form of animal products. Phosphorus retention in the watersheds vaned from eight to 8~ percent of input. Phosphorus retention; as a percentage of total input, was highest for watersheds with little agriculhu'al activ- ity. Stream export of phosphors to lakes varied fi~om one to 68 percent. The mass balance approach used shows that phosphorus retention often comprises a major fraction of phosphorus input to watersheds. In other words, roost of the phosphorus entering ~vatershecls is being retained witlin those watersheds. Over the short term, retention of phospho- population of white water lily, yellon~ wa- form, however, and so I am iu the process ter lily, several native pondweed species; of compiling a list of fiinding options and and water celery. Urlforttmately, Ialso shoreline restoration information. follllCl a Srllall population of curly-Ieaf poncl~veed, ~, ~ an exotic; ,~ , invasive spe- cies that can ~ ' grow lll thrck, extensive plats. Curly-leaf pondjveed doesn't always cause problems- sometimes the ~ population remains shall Sarah Roley collects a sample o and unobtru_ project to reduce algae and wee live-but it often does well in lakes with poor water quality. Bec~aise of tlis nosh, it becomes even more important that Lewis La1se maintain or improve its water quality. This can be achieved tlu~ouQh land management projects, including shoreline restoration, septic system improvements, and erosion prevention. Some Le~~-is L<tlce residents have installed shoreline rip-rap, ~md most understand the importance of shoreline vegetation buffers. These projects can be expensive and tecluically difficult to per- pis is desirable, but we hypothesize that phosphous retention is not sustainable for soils that receive very high phosphors loads; such as fanrr fields and lawns that have received high phosphorus inputs over time, ~md septic leach fields. This hypoth- esis is supported by theoretical consider- ations Auld some published field studies. A potential problem for Mimiesota may be the 600,000 septic systems, which are sig7ificant sites of phosphorus retention often located very near lakes. Our research suggests the potential ef- fectiveness of reducing phosphorus inputs or increasing outputs to reduce watershed phosphorus retention. The cun-ent lawn phosphorus restriction in Nlirlnesota is a f Lewis Lake's aquatic vegetation as part of a d growth and improve water quality in the lake. I will be presenting this informa- tion, along ~a=ith the results of my ~arater sampling and aquatic vegetation surveys. at the Association meeting in September. My research and presentation will help the Lewis Lake Association better understand how their htlie fimctions, and give them several options for improved land manage- ment With help from my advisor, Ray Newmal7 (I'ishelies, Wildlife, and Conser- vationBiology), this project will lead to my M.S. in Conservation Biology. good example of input-side phosphous m~magement. nor some fauns, improve- ments in animal nutrition could reduce phosphorus inputs and therefore reduce the annount of phosphorus iti m~mnre. For lakes that are heavily developed; seweruig the laheshore would remove sewage phos- phorus from the watersheds of import~ult recreational lanes, thereby reducing the potential for eutroplication. This watershed phosphonis mass balance approach was reported as a M. S. thesis by Johanma Schussler. The study ~a,as supported by the U.S. Forest Service's North-Central Research Station. The filll report will be av~ulable in 2006. Mir~r~~~r~m ~