MINNEAPOLIS (WCCO) — The United States Fish and Wildlife Service says as many as 200 turtles have been found dead in the Big Stone National Wildlife Refuge near Ortonville.

Big Stone National Wildlife Refuge (credit: CBS)

The discovery was made on April 30 on a half-mile section of the Minnesota River, both on the banks and in the water. Crews are still counting the dead, which include species such as the snapping and painted turtle.

USFWS officials say some of the turtles have been sent to Madison, Wisconsin for testing at the USGS National Wildlife Health Center.