Tobacco River Flow Restored
Work to lower one Edenville Dam spillway has been completed, allowing for the river to follow its natural channel
The major portion of work to restore the Tobacco River to its natural course is now complete. The Tobacco Spillway of the Edenville Dam was partially demolished while the river channel downstream of the dam was cleared of debris to allow a return to a more natural river flow. The emergency work was necessary after the dam in Gladwin County failed in May 2020 following intense storms in Mid-Michigan. The Tobacco River spillway is one of two on the Edenville Dam, the other being on the nearby Tittabawassee River, where a breach drained Wixom Lake and flooded the area downstream all the way to Midland.
Run of river back to normal
The Edenville Dam sits on the Tobacco River, left, and Tittabawassee River, right, in Gladwin County.
The $2.7 million emergency project was approved in October by the Michigan Department of Environment, Great Lakes, and Energy with work on the dam starting in December. A two-week drawdown of water behind the dam was completed on March 10, after portions of the spillway was demolished and stoplogs were removed. Dropping the spillway height by approximately 20 feet allowed the water level upstream of the dam to drop a maximum of 13 feet.
The drawdown was methodical, a drop of about 1 foot per day over the two-week period. The lower water levels have exposed larger portions of the lake and river bottomlands. EGLE will perform a follow-up endangered mussel survey and rescue operation as well as continue to monitor for new erosion or slope stability concerns and address them as appropriate with the dam's owner, the Four Lakes Task Force .
With the help of local officials, the public was warned to stay off the ice behind the dam and up to four miles upstream since the lowering could make for dangerous ice conditions. There were no reports of anyone violating that warning.
“Completing this project on schedule was a collaborative effort between state and local officials, who teamed to make sure it was planned and executed with public safety as a priority. I would like to thank the Michigan Department of Transportation, AECOM engineers and Fisher Contracting for their successful efforts on this emergency work.” EGLE Director Liesl Clark
Why was project important?
There are several reasons why EGLE decided it was critical to perform the emergency work.
- Improve the stability of the remaining dam structure.
- Limit the possibility of a second collapse that could unleash a 10- to 15-foot wave of water that would severely affect properties and infrastructure downstream.
- Lessen negative impacts on natural resources.
- Aid with temporary repair of the destroyed M-30 causeway bridge.
Edenville Dam Upcoming Stabilization Project Update Webinar.
Area residents are noticing changes due to the project’s successful completion. Those living in the area between Dale Road and the dam have seen water levels in the Tobacco River and the impoundment drop at various depths. More debris and natural resources can be seen on the newly exposed bottomlands. Finally, residents along the Tobacco and Tittabawassee Rivers downstream of the dam were seeing increased water flow during the drawdown operation.
Local company does the work
The time-sensitive work plan was developed by engineering firm AECOM , hired by EGLE and the Michigan Department of Transportation (MDOT) to assess the dam’s condition and develop a work plan that can be completed in a short timeframe. EGLE hired Fisher Contracting Co. of Midland to perform the work on the dam and Tobacco River channel. Fisher Contracting employed a crew of approximately 15 staff working six days a week to complete the project on time.
Among the equipment Fisher used on the project:
- A 100-ton crane with a 150-foot boom.
- 50-ton excavator.
- 30-ton excavator on a barge.
- GPS-guided bulldozer.
- 40-ton off-road trucks.
- 40-meter concrete pump.
- Hydraulic demolition saws.
The various equipment used by the contractor at the spillway project site.
Next phase in spring, summer
The emergency work project is not totally finished:
- On the Tobacco River side, spillway stabilization work and site restoration need to be finished. This work is expected to be completed by late spring.
- Also this summer, Four Lakes Task Force, which owns the dam, will begin work on Phase 2 of the emergency project on the Tittabawassee side. This will include demolition of the spillway structure and removal of sediment and debris from the river downstream.
- Four Lakes Task Force will also build a small diversion berm across the breach in the dam to keep flood flows within the river channel.
Spillway stabilization work and site restoration needs to be completed in the spring.
Inaction forced decision
Boyce Hydro Power LLC, the dam’s former owner, refused in September to undertake the critically needed safety measures. EGLE issued on Nov. 19 an emergency conditional permit for the dam work. The dam was breached in May 2020 following a large amount of rain in the region. The breach drained Wixom Lake and the flood of water eventually overtopped the Sanford Dam, which also breached. The two dams are part of a four-dam system in Gladwin and Midland counties. Secord and Smallwood dams north of the Edenville Dam also sustained some damage. Four Lakes Task Force, which now owns the dams, is performing repair work on Secord and Smallwood.
Four dams make up a series of dams in Gladwin and Midland Counties: Secord (top), Smallwood, Edenville and Sanford. The dams were formerly owned by Boyce Hydro Power LLC.
M-30 temporary bridge opens
Concurrent with the work on the Edenville Dam spillway, MDOT installed a temporary bridge east of the dam to reconnect two sections of M-30 after its bridge over Wixom Lake was destroyed in the flood. MDOT recently opened the bridge to traffic after a 10-month closure. The temporary M-30 causeway bridge is a steel structure, prefabricated and assembled onsite. It is intended to be in place for five to seven years and will be removed when a permanent bridge is built. The 230-foot structure cost $4.5 million.
All totaled, MDOT estimated that damages to road and bridge infrastructure from the flood is expected to exceed $100 million. MDOT so far has repaired the US-10 bridge at Sanford Lake, the M-30 bridge over the Tittabawassee River, the Curtis Road bridge over the Tittabawassee River and Saginaw Street in the village of Sanford.
The rebuilt and newly opened M-30 temporary causeway bridge looking east with the Tobacco River impoundment in the foreground.
The M-30 bridge is open to traffic after being destroyed by last May's flooding.
Dam’s future uncertain
The emergency work will have no impact on future decisions on whether to rebuild the Edenville Dam. Four Lakes Task Force and local stakeholders will make that determination. EGLE is fully committed to working with stakeholders to make sure any decisions that are made on the future of the dam are carried out in a safe manner and in accordance with applicable laws.
The Michigan Dam Safety Task Force provided 86 recommendations to Gov. Gretchen Whitmer regarding policies and procedures regarding dam safety throughout the state. An independent forensic investigation funded by the Federal Energy Regulatory Commission (FERC) is continuing its work in determining the cause of the collapse. A report on its findings, which will be made public, is not expected until late this summer.
The Edenville Dam breached in May 2020. Water overtopped Sandford Dam, which also breached. to the south.
