Assessment of the Hydrology, Water Quality, and Phosphorus Loading of Silver Lake, Barron County, Wisconsin
Project Number: 9KB38
Project Chief: Dale Robertson
Project Topics: Water quality
Cooperators: Barron County
Period of Project: October 2007-2011
At top: Silver Lake at high water level. At bottom: Silver Lake low water level.
The Lake Studies team is investigating the lake's hydrology to understand why the water level in Silver Lake has fluctuated several feet over periods of several years and perhaps as much as 10 ft in the last 10-15 years. Decreased lake water quality in recent years appears to be associated with high water level.
The water level in Silver Lake has fluctuated several feet over periods of several years and perhaps as much as 10 ft in the last 10-15 years. Decreased lake water quality in recent years appears to be associated with high water level. Coincident with rising water level and decreased water quality has been increased residential development in the near-lake area. It is not clear how or if deteriorated water quality is related to rising water level. There is evidence of shoreline slumping as a result of high water levels. A better understanding of the hydrology of the lake and the magnitude and sources of nutrient loading to the lake is needed.
The objectives of this proposed study are to:
- Develop a detailed water budget for the lake by measuring all major inflow and outflow sources and estimating the magnitude of minor sources.
- Develop a ground-water model for the area around Silver Lake and use it to determine ground-water contributing areas and flow paths from recharge to discharge into the lake.
- Determine a detailed phosphorus budget by quantifying the phosphorus loading associated with each water inflow and outflow source, including contributions from the wetlands.
- Map shoreline erosion and estimate the importance of this erosion to the phosphorus budget.
- Evaluate the current lake-water quality (trophic state) relative to long-term trends.
- Evaluate current relations between water quality and measured water and phosphorus loading through the use of selected models in WiLMS (J. Panuska, Wisconsin Department of Natural Resources, Written commun., 2002) and the WDNR's Seepage Lake Model.
- Use the calibrated model or models to simulate the likely response of Silver Lake to phosphorus-loading changes associated with various lake-management actions that might be implemented.
- Relate historical lake-water quality (from available measured data and inferred from sediment-core analysis) with historical precipitation and lake-stage records to assess the effect of climatic (non human) factors on lake water quality.
- Evaluate the hydrologic and water-quality response to possible scenarios at modifying the water level of the lake.
Data collection for the development of water and phosphorus budgets for Silver Lake will continue through Oct. 31. Instrumentation will be dismantled and piezometers removed. Second-year monitoring data will be compiled and published. Water and phosphorus budgets for the two monitoring years will be constructed and finalized. Phosphorus-loading/lake quality-response modeling will be completed. The first draft of the study report will be completed.
Publications and Reports
Robertson, D.M. and Rose, W.J., 2011, Response in the trophic state of stratified lakes to changes in hydrology and water level: potential effects of climate change: Journal of Water and Climate Change, vol. 2. No. 1, p. 1-18.
Robertson, D.M., Rose, W.J., and Fitzpatrick, F.A., 2009, Water quality and hydrology of Silver Lake, Barron County, Wisconsin, with special emphasis on responses of a terminal lake to changes in phosphorus loading and water level: U.S. Geological Survey, Scientific Investigations Report 2009–5077, 38 p.