(ELKTON) -- State officials are working to determine the cause of hundreds of fish deaths in a Michigan river. The Department of Natural Resources says the recent fish deaths were reported from the McMillan Drain in Huron County's Meade and Chandler Townships to the Pinnebog River and on to Port Crescent State Park. Reports say a manure spill at Shupe Dairy Inc. was reported last week near where the fish kill began, but the DEQ is investigating the cause of the fish deaths. Shupe Dairy apologized and said there was an "operational accident with manure." The dairy was blamed for a fish kill last year linked to manure runoff.