Phosphorus is a nutrient that fuels algae blooms and reduces water quality. This project aims to reduce phosphorus levels in Oak Knoll Pond/Wood Lake by applying spent lime, which binds to phosphorus.
Water quality monitoring is ongoing to determine project impact.
Funding for this effort was provided by VLAWMO and the City of White Bear Lake.
Stormwater ponds are a valuable tool for collecting pollutants such as phosphorus and sediment before they flow into a larger waterbody. However, these ponds require maintenance over time to remove accumulated pollutants so the ponds stay functional. Dredging is a common technique for improving pond performance, removing pollutants, and increasing storage capacity, but it can be costly and disruptive to the environment.
Spent lime, a byproduct of drinking water treatment, is a practical alternative to dredging. Spent lime binds to phosphorus, which fuels algae blooms and reduces water quality. The overarching goal of the demonstration project in Oak Knoll Pond/Wood Lake is to address the effectiveness of spent lime in a larger waterbody and determine the longevity of the treatment.
Oak Knoll Pond/Wood Lake was selected for this study due to its size, depth, and location. Spent lime slurry was applied to the pond in summer and fall of 2023, with the final spent lime application completed in summer of 2024. Monitoring took place throughout 2025 and will be ongoing in 2026.
Monitoring continues to gauge project effectiveness.
Project partners appreciate the support and access granted by residents around the pond/lake.
