TRAVERSE CITY — A black, arsenic-tainted muck coated portions of Boardman River bottom after an October breech at Brown Bridge Dam and resulting flood, and one riverfront resident worries the substance might prove harmful to humans.
Dave Downer lives with his wife Sally on land that straddles the Boardman. The Downers’ property sustained only minor damage after an Oct. 6 flood caused by construction crews as they prepared to empty an upstream pond, a step in a massive, multi-million dollar project to remove dams upstream from Boardman Lake and return the river to a more natural state.
But the Downers worried about changes they saw in the waterway, including the post-flood appearance of dense silt.
“This is a river where you could always see the bottom,” Sally Downer said. “It turned black. It smelled.”
The silt has cleared up some, but in mid-December Sally and a friend noticed another change as they kayaked along the river. They found large deposits of black muck — Dave Downer said it resembles tar — settled on river bottom.
In January, Dave Downer collected a sample of the dark, viscous material and sent it to Traverse City-based SOS Analytical lab for testing.
Testing results showed levels of arsenic in the muck that exceed the Michigan Department of Environmental Quality’s cleanup criteria, he said, findings that trouble the Downers.
“If that’s the case, we have lost a tremendous recreational asset,” Dave Downer said. “Hundreds and hundreds of people come down this river every year. When my kids come here, and my grand kids, I don’t know if I’m going to let them swim in the river.”
Dave Downer recently shared results of the lab test with fellow members of the Brown Bridge Advisory Committee, a group that works with local government officials and other agencies on river-related matters. He said he had the muck tested as a private citizen.