DE SOTO - At the junction of Wisconsin, Minnesota and Iowa, there's a place called Reno Bottoms, where the Mississippi River spreads out from its main channel into thousands of acres of tranquil backwaters and wetland habitat.

For all its beauty, there's something unsettling about the landscape, something hard to ignore: hundreds of the trees growing along the water are dead.

Billy Reiter-Marolf, a wildlife biologist for the U.S. Fish and Wildlife Service, calls it the boneyard. It’s a popular spot for hunting, fishing and paddling, so people have begun to take notice of the abundance of tall, leafless stumps pointing to the sky.

“Visitors ask me, ‘What’s going on, what’s happening here?’” Reiter-Marolf said. “It just looks so bad.”