INVESTIGATING THE INTERPLAY BETWEEN WATER LEVELS AND CLARITY IN NINE NORTHWEST WISCONSIN LAKES OVER MULTIPLE YEARS

Precipitation is a primary contributor to lake water level fluctuation across seasonal and annual timescales. Runoff attributable to precipitation is expected to decrease water clarity as organic compounds, nutrients, and sediment enter a lake. Therefore, water clarity is expected to decrease as water levels increase. We investigated the interplay of water level fluctuation, water clarity, and algal abundance amongst nine lakes in northwestern Wisconsin. Lake morphometry and dissolved organic matter concentrations varied between the study lakes, whereas precipitation was likely similar across all lakes given their close proximity on the landscape. Lake stage and light attenuation (photosynthetic active radiation and Secchi depth) were used to evaluate the association between lake level and water clarity with measurements from the open water period over 5-9 years. In general, water clarity decreased as water levels increased. However, the extent to which water clarity changed varied between clear and stained lakes. For example, a greater shift in light attenuation (1.9-4.3 m^-1) occurred in a stained lake with less water level fluctuation (0.8 m) than a clear-water lake, which had less light attenuation (0.4-0.9 m^-1) despite a larger change in water level (1.1 m). Oscillations in water clarity as a result of water level variation may affect lake food web dynamics across trophic levels. The results of our study will support the development of well-informed management decisions, particularly as global climate change affects precipitation event frequency and intensity.

Primary Presenter: Cayla Cavey, Mary Griggs Burke Center for Freshwater Innovation (ccavey@northland.edu)

Authors:

Cayla Cavey, Mary Griggs Burke Center for Freshwater Innovation  (ccavey@northland.edu)

Peter Levi, Mary Griggs Burke Center for Freshwater Innovation  (plevi@northland.edu)

Matthew Hudson, Mary Griggs Burke Center for Freshwater Innovation  (mhudson@northland.edu)