City of Kimball Stormwater Treatment Phase II

The City of Kimball and surrounding area drains into Willow Creek, a designated trout stream and important park space for the area. The creek itself empties into the Clearwater River Chain of Lakes. This water, when left untreated, is detrimental to the health of the creek and the downstream waters due to high temperatures and excessive nutrients. Such factors can cause algal blooms, loss of habitat, and poor water quality.

To correct this problem, the Clearwater River Watershed District applied for and received a $738,750 grant from the Minnesota Board of Water and Soil Resources to construct additional stormwater treatment systems in the City of Kimball (official grant title: 2012 - Clearwater Water Assistance - C12-72). An additional $246,500 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 $985,000.

Two treatment basins were constructed to provide treatment of stormwater, and a storm sewer extension was completed to move more stormwater from the east side of the city to these treatment areas. These changes will improve water quality and temperature in Willow Creek and reduce nutrient loadings to downstream lakes, and improved the treatment capacity of previously-installed stormwater treatment areas (i.e. phase I). The project is estimated to provide 1,175 lbs. of nutrient removal per year, resulting in improved water quality and temperature in Willow Creek and downstream lakes. Smaller additions to the principal construction were included to address addition stormwater runoff challanges, including constructing a sediment forebay and installing riprap to protect a stormwater outlet from further erosion.

This project is Phase II of the CRWD's plan to reduce nutrient loading to sensitive and impaired downstream waters, and to protect high value recreational resources by managing stormwater from one of two urban areas within the watershed draining to the impaired waters. Phase I, also funded by a Clean Water Land and Legacy Amendment grant, treated a portion of runoff from the City of Kimball through stormwater reclamation and reuse. Phase II provides treatment for the 1.25 inch event for the remainder of the drainage areas to Willow Creek near the city (about 108 acres), while enhancing function for Phase I by allowing it to treat a higher volume from a smaller drainage area.

The project was completed concurrently and in cooperation with the City of Kimball while they upgraded their street design in order to optimize designs for both stormwater treatment and street improvement, and to minimize costs. The District also worked in cooperation with other regulator authorities and partner agencies on this project, such as the US Army Corps of Engineers, MN Board of Water and Soil Resources, MN Department of Health, MN Department of Natural Resources, MN Department of Transportation, Stearns County Environmental Services, Stearns County Highway Department, and Stearns County Soil and Water Conservation District.