Edenville Dam

In a rarely used federal power, the Federal Energy Regulatory Commission (FERC) terminated Boyce Hydro Power's license in 2018, because of its "inability to pass the Probable Maximum Flood (PMF)",[8] as well as seven other failures.[9] The federal government was concerned that "the dam may not have the ability to pass enough water, if a severe flood were to hit, among other issues and violations."[10]

Following the federal government's 2018 license revocation, the Michigan Department of Environment, Great Lakes, and Energy (EGLE) took oversight of the dam.[11] EGLE determined that the dam was structurally sound.[12] Edenville and the other former Boyce dams were taken over in 2019 by the Four Lakes Task Force, a county delegated authority,[13][14][15] with title to transfer in early 2022.[16] The State of Michigan appropriated $5 million for the purchase.[17][18] The Four Lakes Task Force operates under the Four Lakes Assessment District in the State of Michigan,[15] created in May 2019 by Judge Stephen Carras. In 2019, Michigan's 42nd Circuit Court was involved in determining if only the lakefront owners or all area residents would pay tax to the Four Lakes Assessment District.[19]

In October 2018, and again in mid-November 2019, the dam's operator lowered the water level, in what it called "a safety move." It said it had requested a permit to lower the level from Michigan's EGLE, a permit that was not issued. The operator said it acted “due to concern for the safety of its operators and the downstream community,” and went on to sue EGLE in federal court, alleging "its safety concerns were paramount."[20][21]

In December 2019, the Federal Energy Regulatory Commission issued a permit to investigate expanding the hydropower plant with a second powerhouse containing one 1.2 MW turbine-generator unit for a total of 6 MW.[22]

The dam's operator said it began to raise the lake's water level in April 2020, under threat of being sued by Michigan's EGLE, and that it reached "normal pond level" in the first week of May. Michigan's Attorney General Dana Nessel confirmed EGLE had directed the operator to raise the water level, stating: "Michigan EGLE directed Boyce to follow the court-ordered lake level requirements," but challenged that the operator had lowered it for safety reasons.[23]

In April 2020, EGLE sued Boyce, alleging it had lowered the water level without permission in 2018 and 2019, killing thousands of freshwater mussels.[24][25][26][27]

Copernicus Programme image of the dam after failure, showing the new river channel east of the original spillway.

On May 19, 2020, 5:46 p.m., due to massive inflow from heavy rains in the area, the eastern side of the dam collapsed, prompting immediate evacuations in the towns of Edenville and Sanford.[28] The Sanford Dam, about 10 miles (16 km) downstream, subsequently overflowed, requiring evacuations in much of Midland six miles (9.7 km) further downstream.[29] Governor Gretchen Whitmer declared a state of emergency, and announced an investigation into the dam's operators for alleged neglect.[30][31][32] Over 10,000 local residents were ultimately evacuated, as officials cautioned residents to maintain social distancing during the COVID-19 pandemic.[33]

The Tittabawassee River crested at 35.05 feet (10.68 m) late on May 20, resulting in extensive flooding throughout eastern Midland and low-lying parts of its downtown district, and severely damaging most of the village of Sanford.[34][35][36] The extent of the floodwaters was visible from space on May 22.[37] Dow Chemical's Midland operations were threatened by the flooding, but reportedly suffered no serious damage.[38] As of the morning of May 20, no casualties had been reported as a result of the flooding.[39]

In the wake of the flooding, three class-action lawsuits were filed by the victims, of which two named Michigan's EGLE as defendant and two named the dam's operator as defendant.[40] Michigan's Attorney General Dana Nessel is also being sued.[41]