Today, work crews will begin to lower the Edenville Dam spillway, allowing more water to flow through the structure and downstream. The emergency work on the dam that began in December is expected to help protect against downstream flooding when spring rains and snowmelt occur.
The work: The Tobacco River spillway crest modifications are being made to lower the level of the impoundment and increase the spillway capacity to pass more water during higher flow events, which are common in the spring. This will alleviate dam safety and stability concerns and restore the natural flow of the Tobacco River downstream.
The water levels: Lowering the spillway by 20 feet means Tobacco River water levels directly behind the dam will drop by an estimated 12 feet. The changes in water levels will be less prominent farther up the river, with little to no change upstream of Dale Road.
The ice danger: Changes in water levels and increased water velocity behind the dam and downstream will cause dangerous and unstable ice conditions. This poses a significant risk for residents and recreational users who venture on to the ice and former bottomlands.
The impact: The public is warned to stay off the ice and the newly exposed bottomlands until further notice. Signs and fliers about the dangerous ice conditions have been posted and distributed throughout the area.
The area affected: Dangerous and thinning ice can be expected from Dale Road south to the Edenville Dam. Ice and water conditions may also be affected on the Tittabawassee River above the dam and on the Tobacco and Tittabawassee Rivers south of the dam in Gladwin and Midland Counties.
The timing: The work is being done now in preparation for springtime snowmelt and rains. Without the modifications, a future dam failure could mean water 10-15 feet high would flood downstream areas.
The future: The current emergency work will have no impact on future decisions regarding rebuilding the dam. Four Lakes Task Force, which owns the facility, and local stakeholders will make that determination.
The additional information: An FAQ, story map, webinar and other resources are posted at Michigan.gov/EdenvilleDamFailure.
Photo caption: Crews on Feb. 24, 2021 began lowering the Edenville Dam spillway following about two months of work to increase capacity so the spillway can pass more water during higher flow events, which are common in the spring.