Officials with the Minnesota Department of Natural Resources were in Shoreview, Minn., on Monday to try and determine what killed thousands of fish, including trophy-sized walleye and muskie, in Lake Owasso.
Residents in the area had wondered whether low oxygen levels could be responsible for the fish kill, but tests conducted by the DNR show oxygen levels are normal.
A spokesman for the DNR said there is no evidence of a chemical spill or toxins in the lake, which is managed primarily for muskies and lies within the suburbs of Roseville and Shoreview.
Residents told Fox 9 News they have counted hundreds of dead fish since the lake froze over last Tuesday, and the fish could be seen belly-up beneath the clear ice.
DNR workers say about 90 percent of the dead fish they counted are small panfish, but residents have pulled out a few of the larger muskies and walleyes.
DNR DOUBTS WEED KILLER A CAUSE
The DNR discounted the rumor that herbicides used to treat lake weeds could have been the cause of the fish kill on Monday because the DNR does not treat lakes for weeds. Although individual permits are issued to lakeshore property owners to treat for weeks, the last treatments would have taken place in August.
Although the fish kill is unusual for this time of year, the DNR says they are not alarmed by it.