The CRWD applied for and received a $351,906 grant from the Minnesota Board of Water and Soil Resources to construct a stormwater treatment systems near the City of Watkins (official grant title: 2015 - Watkins Area Stormwater Treatment - C15-1978). An additional $231,909 in local match was also provided to complete this project. This grant is funded through the Clean Water Land and Legacy Amendment. Total project cost was estimated at $583,815.
This project targets a 796 pound annual phosphorus reduction by treating runoff from 6,500 acre urban and agricultural drainage area that flows to the Clearwater River and Lake Betsy. The project treats runoff from about 30% of the drainage area to the DO and bacteria impaired Clearwater River, and about 15% of the drainage area to nutrient impaired Lake Betsy. The project represents a 10% reduction of the non-point source phosphorus load to Lake Betsy, while improving water quality in the Clearwater River and several donstream lakes in the Clearwater River Chain of Lakes. The project is also project to provide 10% of the water load reduction for nitrogeneous oxygen demand for the Clearwater River.
The projects target treatment of the 1.25 inch event through filtration/ infiltration. Low flows will be diverted from two streams through a treatment train which includes a sedimentation basin for particulate treatment and a limestone filter for dissolved phosphorus treatment. Soils in the area are generally sandy, so if project area soil borings show infiltration is possible, the basins will infiltrate treated stormwater to recharge shallow groundwater which discharges locally to the Clearwater River and deeper aquifers. Because low flows are treated and infiltrated, peak flows are reduced, returning the system to something closer to native hydrology than the current ditched drainage system. Shallow groundwater resources are also recharged and runoff volume reduced.
This project is being completed due to the cooperation between the Clearwater River Watershed District, the Minnesota Board of Water & Soil Resources, the City of Watkins and local property owners.