The complaint alleges manure was not properly mixed with the farmland, and it was able to run into an area drain. The drain leads to the Grand River.
MSU says it is aware of the complaint and is investigating.
The Michigan Department of Environmental Quality is looking into the matter.
Meantime, the Sierra Club is conducting its own tests of the water. The Sierra Club's test results are expected to come back next week.
The Department of Environmental Quality is still investigating.