Volunteers clean dead fish out of Spring Lake; cause of death under investigation

Prior Lake American

There’s a murder mystery at Spring Lake.

The casualties at the lake, which borders Prior Lake and Spring Lake Township, are in the thousands and the cause of death is under investigation.

The residents who live around Spring Lake would like to know — after all, it’s not every day that they come home to find thousands of dead fish in the water near their homes. They began noticing the fish on Aug. 28.

“It was one of those things where we usually have a fish kill or two, but there’s usually very few fish and it’s usually right after the ice off,” Spring Lake Association President Dan Kelly said. “Each day, we constantly had fish. We went into the Labor Day weekend and that’s when the worst of it was.”

On Labor Day, Kelly sent out emails to anyone he thought might be able to help, or have answers — the Prior Lake-Spring Lake Watershed District, the city of Prior Lake, the mayor of Prior Lake, the Prior Lake Association and more.

From there, the death investigation began.

The working theory is that the fish, which were mostly crappies, died as a result of an oxygen depletion in the lake caused by the weather. Crappies have small lungs, Kelly said he was told, and would have suffered more from having less oxygen than other fish, which were not found in the kill off.

“During this time of year, there is a high biological demand for oxygen in the lake, as many fish and other organisms are active and consuming oxygen, so competition for oxygen is high in the lake,” according to a Prior Lake-Spring Lake Watershed District post regarding the kill off. “Different fish species have varying oxygen needs and tolerance of low oxygen levels.”

The Prior Lake-Spring Lake Watershed District measured oxygen levels on Aug. 28 and found that the bottom six meters of the lake were anoxic, or without sufficient oxygen for a healthy fish population whereas the top four meters of the lake had the minimum required level of oxygen for a healthy fish population.

The district tested the water again and found that the bottom four meters were anoxic, but that oxygen levels had increased in the rest of the lake.

On Sept. 5, the Minnesota Department of Natural Resources collected live samples of the fish to take to the University of Minnesota pathology department for testing, Kelly said. During that time, a researcher with the department told Kelly that there were some visual signs around the gills of the fish of a disease.

The University of Minnesota is currently testing the fish to determine the cause of the kill.

As the week went on and the dead fish began to smell, people began to ask the Spring Lake Association about how the fish could be removed.

Kelly organized a volunteer effort to remove the fish, spreading the word through the Spring Lake Association channels and social media.

Throughout the weekend of Sept. 7-9, about 15 volunteers worked their way along the shoreline, cleaning up as much dead fish as possible and putting the fish in a dumpster, which was donated by Buckingham Companies.

The Organics Recycling Facility, which is owned and operated by the Shakopee Mdewakanton Sioux Community, disposed of the fish at no cost, according to a blog post from the Prior Lake-Spring Lake Watershed District.

Kelly said the volunteers picked up three or four boatloads of fish.

“I know there were a lot of people who did individual efforts, as well,” Kelly said. “The good news is following that, I’d say all signs are that there are no additional fish that are dying off now.”

Kelly said he has been on the lake for seven years and has never seen a fish kill off of that magnitude.

“We’re interested to hear what the results of the study come back with,” Kelly said.