State: Edenville Dam work will create unstable ice conditions

State officials are warning residents in Gladwin and Midland counties to stay off ice that's formed behind the Edenville Dam as water levels are expected to drop there over the next several weeks. 

The Michigan Department of Environment, Great Lakes and Energy will lower the dam's Tobacco River spillway Feb. 24 by more than 20 feet, which will drop water levels about 12 feet upstream of the dam by mid-March. The decreased water levels will make ice formations hazardous in those areas as the water recedes, according to a department statement.

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The lowering of the spillway will restore the Tobacco River to natural flow, part of emergency work meant to stop potential future floods at the Edenville Dam, which failed under historic rains in May.

The most unsafe ice conditions on the Tobacco River likely will develop between Dale Road and west of M-30, where the remaining portion of the dam stands, according to EGLE. The drawdown also could shift ice and water flow on the Tittabawassee River, upstream of the dam, and the downstream portion of the Tobacco River.

Bottom lands exposed by the receding water also are expected to be unstable; the water drawdown could exposed debris, tree stumps and steep channels.

Map courtesy of: Michigan Department of Environment, Great Lakes and Energy

The Michigan Department of Natural Resources and Gladwin County Emergency Management will alert residents of the potential hazards, according to EGLE's statement. 

The emergency work at the Edenville Dam site, which began in December, aims to stop a second potential flood by restoring both the Tobacco and Tittabawasee rivers to their natural channels. 

The project essentially would lower or breach the Tobacco River spillway to divert water that's been draining east into the lower Tittabawassee River and streaming through the earthen embankment breached in May. The design also would alleviate strain on M-30 bridges, which collapsed during the flood.

eleblanc@detroitnews.com