Thompson Lake Sediment Removal and Stormwater Improvement Project

About the Program

Category: Parks and Recreation (Best in Category)

Year: 2020

Dakota County, the City of West St. Paul and the Lower Mississippi River Watershed Management Organization, completed a two-year, $2.6 million project to restore and protect Thompson Lake by addressing the lake’s contamination and preventing the problem from happening again to maximize public interaction with the lake and surrounding County park.Thompson Lake received decades of direct, untreated stormwater discharge, depositing sediment and pollutants which degraded water quality and habitat. The lake is a critical resource for Thompson County Park as it enhances recreation and provides scenic views. The project removed more than 6,000 cubic yards of contamination from Thompson Lake. It restored over an acre of degraded wetland by removing invasive plants and restoring native wetland plant species; and improved the trail and boardwalk. It installed a stormwater treatment infrastructure with two underground hydrodynamic separators, an irrigation re-use system, raingarden, and a stormwater forebay that protects the lake by cleaning stormwater before it enters the lake; and reduced pollution to the lake, with an estimated annual decrease of 48.4 lbs. of phosphorus and 12.9 tons of total suspended solids. It informed and educated park visitors and the public through a variety of education and communications tactics.