The restoration effort suffered a setback Oct. 6 when the contents of the 191-acre Brown Bridge Dam pond were suddenly and unintentionally released into the river, damaging at least 53 properties and sending debris flowing downstream.
Tests one week after the flooding found levels of arsenic, acidity, dissolved oxygen and temperatures all at acceptable levels, said Todd Kalish of the Michigan Department of Natural Resources.
"Based on the water quality samples, it doesn't appear there was any contamination," Kalish said.
The water was murkier than it should be, but that happens periodically on healthy rivers as well, Kalish told the Traverse City Record-Eagle.
"It's basically silt, fine material, within the water," Kalish said. He said the cloudiness should dissipate with the wrapping up of the project in mid-December. Work on sand collectors and river banks contribute to the cloudiness, and river systems occasionally see elevated levels of cloudiness due to natural events.
"It can be elevated every year ... when we have a rain event and spring floods, so fish populations and aquatic populations are accustomed to occasional elevations. They can tolerate occasional elevations of total suspended solids," Kalish said.
Fish surveys on the river below the dam are preliminary. A survey of about 500 feet of the river near Brown Bridge Road yielded 73 fish of 13 different species, including 11 brown trout and one brook trout. Warm-water species recovered included an 18-inch largemouth bass, a northern pike, rock bass and yellow perch.
The flood happened during what was supposed to be a slow draining of the dam, near Traverse City in Grand Traverse County's East Bay Township. The dam blocked the natural flow of river sediment for 90 years and created a sand delta.
Frank Dituri, head of a team overseeing the removal of the Brown Bridge Dam and two others downriver, said the fast draining of the pond and the flooding it caused were "very terrible," adding, "We need to learn from it." A state investigation of the cause is under way.