Leak Sends 70,000 Gallons Of Sewage Into Thompson Lake: Officials

WEST ST. PAUL, MN —The City of West St. Paul on Monday evening provided an update about a wastewater sewage leak that forced the temporary closure of Thompson County Park and led to a call for the public to avoid direct contact with Thompson Lake water.

City officials said they were called to Thompson County Park earlier Monday about the leak, and they determined the sewage was coming out of a valve designed to let out air buildup.

Officials said they believe a gasket that surrounds the air relief valve failed. The valve had been replaced in 2018 and was well within its lifespan, according to the city.

Sewer staff worked quickly to stop the leak, and no properties were without sewer services as of Monday night, the West St. Paul officials said.

The city originally reported Monday that 50,000 gallons of sewage had entered Thompson Lake over a 24-hour period. Now, officials believe about 70,000 gallons of sewage ended up in the lake.

"For comparison, an Olympic-sized pool holds about 660,000 gallons of water and the sewer main in question moves about 1,200,000 gallons every day," officials said in a statement.

The City of West St. Paul said Monday evening that it was working with the Minnesota Pollution Control Agency, the Minnesota Duty Officer and the Dakota County government to determine if any mitigation needs to be done after the leak.

"In the meantime, we're asking everyone to avoid contact with Thompson Lake for both people and pets until levels can be tested and we know it's safe again. This includes fishing," city officials said.

The city said Dakota County Parks - forever wild has placed signage around Thompson Lake alerting any visitors to avoid contact with the water until given the all-clear.

West St. Paul officials said Monday evening that a new valve had been installed. Though manufacturers no longer produce the exact valve that was previously in place, the city said it acquired the newest version of the valve.

City officials said they don't believe any other water sources or properties will be affected by the leak.

"While 70,000 of anything sounds like a lot, in relation to a body of water the size of Thompson Lake, it's not likely to impact the surrounding area. We're working with the correct agencies to make sure this is the case."officials said.

Earlier Monday, Dakota County Parks - forever wild said updates about the cleanup effort will be available on the department website or by calling 952-891-7000.