The Prior Lake-Spring Lake Watershed District recently completed a major maintenance project on the Prior Lake Outlet Channel.

The pipelining project may not look like much from the outside, but it has doubled the lifespan of the only outlet for Prior Lake’s 30-square-mile watershed. The outlet channel and its pipe are crucial for flood mitigation in the area. Without it, Prior Lake would have flooded 11 additional times over the past 33 years, according to Danielle Studer, Water Resource Specialist.

In 2022, annual monitoring revealed longitudinal and circumferential cracks forming in the outlet pipe, indicating a need for serious maintenance. A cured-in-place pipelining was selected as a solution that could be installed through existing manholes, extend the pipe’s life and smooth its interior walls for faster water flow.

With a total estimated cost of over $950,000, the watershed district pursued available opportunities for grant funding. Residents wrote letters of support and lobbied at the State Capitol for capital bonding, which ultimately fell through. The district continued applying for state grants and in the fall of 2024, was awarded more than $856,000 in grant funding by the Minnesota Pollution Control Agency, finally making the project possible. The grant required a local contribution of 10% to the project cost.

Construction began during the last week of April and was finished in mid-May. The pipe lining was completed in four sections. A resin-infused fabric liner was fed through the manholes, some as deep as 40 feet. Steam was used to cure the resin, bond it to the walls of the pipe, and create a hard, smooth surface. Minor site restorations around the manholes have been completed, grass is growing in, and it is anticipated the project will come in under budget, Studer said.

The project reflects years of community advocacy and planning. While water levels in Prior Lake will always fluctuate, the pipelining will allow water to continue flowing out of the lake for the next 50 years when it reaches an elevation of 902.5 feet, according to Studer.

The Prior Lake-Spring Lake Watershed District covers approximately 42 square miles in Scott County, including portions of the cities of Prior Lake, Shakopee and Savage, and the townships of Sand Creek and Spring Lake.