USGS reports decades of Wind Lake monitoring; warns rising salt levels may exceed EPA chronic thresholds

Mrs. Oliver, a representative of the U.S. Geological Survey, told the Wind Lake Management District at its April 28 meeting that USGS has monitored Wind Lake for about 40 years and that the lake ranks among the top 1% of regional lakes for historical data coverage. She said monitoring includes phosphorus, chlorophyll, salts (chloride and sodium), metals and full-depth profiles for temperature, oxygen and pH.

Mrs. Oliver noted that alum treatments in 1997 and 2011 "correspond with a notable improvement in water quality," but she cautioned that watershed inputs and spring runoff remain significant drivers of the lake's condition. She warned that increasing salt levels are a major concern and reported that Wind Lake is among the highest in the region, "approaching or exceeding EPA chronic thresholds for aquatic life." She said road salt from winter use is the primary source and that once in the lake salt is costly and generally impractical to remove; prevention via reduced application is the most effective approach.

To better target management, Mrs. Oliver recommended conducting a full water/phosphorus mass-balance study and additional sediment phosphorus analysis to inform whether another alum treatment would be effective. She said additional monitoring (for example, at inflows or stormwater pipes) is possible but of limited value unless the measurements are tied to actionable management steps.

Board members did not take formal action on the presentation. The USGS's long-term dataset, Mrs. Oliver said, makes more detailed trend analysis—particularly looking at post-2011 conditions—valuable before committing to costly interventions.