New satellite images show the massive damage caused in mid-Michigan when two dams failed last month, wiping out bridges and roads as water roared out of Lake Huron toward Midland.
The images, provided to Bridge Magazine by Colorado-based Maxar Technologies show the Edenville and Sanford dams in May 2019 and again on May 21, after a storm dumped over 6 inches of rain, swamping the dams and forcing the evacuation of some 11,000 people downstream.
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The images show how the Curtis Road bridge just south of the Edenville Dam was virtually scraped away, as was the M-30 bridge that ran north-south between the Edenville Dam and the Tobacco River to the west.
(Note: Drag black line to see before and after photos. Mobile phone users can get fuller images by turning phones horizontal)
Edenville Dam, Wixom Lake
For decades, federal regulators told the owners of the Edenville Dam (to the right in photo) that it needed to expand spillway capacity at the dam to meet a potential threat from heavy rains.
The photo shows how the existing spillway, lower right, performed as expected during the rains, creating a pathway for high water to safely flow downstream.
The problem was there wasn’t enough capacity. For years, the Federal Energy Regulatory Commission found the dam did not have enough spillway to accommodate a major flood and FERC demanded two additional spillways to the west to act as safety valves to protect the region from flooding.
But the owners of the dams, most recently Boyce Hydro Power LLC, never added the spillways, prompting FERC in 2018 to revoke its license to generate and sell electricity from the dam.
Oversight then reverted to Michigan, but state regulators had not decided on a new design before the dams gave way May 19.
To the right (north) of the dam is Wixom Lake, formed by the damming of the Tittabawassee River. To the left (west) is the Tobacco River. Edenville is just south of the dam and about 17 miles northeast of Midland.
Downstream of the Edenville Dam, the Sanford Dam took the shock of the upstream failure and it too failed, sending water into the town of Sanford where many homes were destroyed and damaged.
The water flowed right down West Saginaw Road, the town’s business district and the surrounding neighborhood.
The town is at the base of Sanford Lake, which runs north to the Edenville Dam. It is 9 miles northwest of Midland.
Just south of the Edenville Dam, Curtis Road takes traffic west toward Clare and east. The western approach to the bridge was wiped out.
The Tittabawassee River overflowed its banks, sweeping around the bridge and eliminating some of the roadway.