Large Scale Lake Planning
Lake Virginia is located approximately two miles east o f Reedsburg, Wisconsin in Sauk County. The 35 acre lake is created by an earth embankment dam approximately 800 feet in length. The dam was constructed in 1970. The watershed has a total drainage area of 1,190 acres and consists mainly of agricultural land including three barnyards. Figure 1 shows a map of the watershed. An aeration system was installed prior to 1985 t o maintain oxygen levels in the lake. Two fish kills of unknown cause occurred in 1991. In the past several years, weeds have spread throughout the lake and are becoming a nuisance. Also, water levels have been three feet below normal pool level . Water quality issues include nutrient loadings, dissolved oxygen levels, water clarity, and weeds(macrophytes) . Phosphorus and nitrogen have been introduced to the lake from agricultural runoff, septic systems, and other sources and have led to water quality deterioration such as algae and weeds. Water quality is often measured by concentrations of total phosphorus and chlorophyll a and by Secchi depth readings. Secchi depth measures the clarity of the water by measuring the depth at which a black and white disk is visible . Chlorophyll a is a measure of algae present in the water. Water samples were taken periodically at the north and south shores by the DNR in 1991 and analyzed for several water quality parameters. Figure 1 shows the locations at which the samples were taken. Table 1 shows selected data that were obtained through laboratory analyses of the samples. Complete results of the sampling and analyses are contained in Appendix B.
1) Prepare a generalized hydrologic budget. Review historical and recently collected water quality data. Develop a lake water quality model for dissolved oxygen to compare to historical oxygen depletion in lake.2) Inspect dam to identify leaks or potential leaks and conduct flow measurements to see if this contributes to low lake levels.3) Develop water budget to identify potential lake water losses. 4) Generate report summarizing findings and making management recommendations.5) Disseminate information to the public by newsletter mailing.
Water Quality Modeling
Data analysis, report production
Hydrologic Budget Development