Unprecedented flooding was ongoing Wednesday morning in Midland County, Mich., after a pair of dams collapsed following record rainfall. Thousands of residents have been told to evacuate as floodwaters gush into the communities along the Tittabawassee River, inundating homes and businesses and prompting an emergency declaration from Michigan Gov. Gretchen Whitmer (D). The flooding is threatening a major Dow Chemical plant that lies along the river.

The Edenville Dam was breached Tuesday evening after Midland received 4.7 inches of rain in a 48-hour period, following days of heavy rain across the state. The dam sits about 18 miles upstream of Midland, a city of more than 40,000.

That collapse sent floodwaters gushing into Sanford Lake, where a dam has powered the Boyce Hydroelectric Plant. The Sanford Dam succumbed shortly thereafter, the twin reservoirs of water left with no place to drain but into the city of Midland. A flash flood emergency is in effect for downstream areas of Sanford.

According to the Associated Press, 10,000 residents have been evacuated.

The National Weather Service in Detroit issued a rare flash-flood emergency, the governor warning that downtown Midland could find itself under up to nine feet of water early Wednesday. News reports showed flooded Midland homes and businesses on Wednesday morning. The Weather Service bulletin described a “particularly dangerous situation” and “catastrophic” flood threat.

“This is devastating,” said Whitmer on Wednesday, following an aerial tour of the damage. She said the flood severity is on the order of a 500-year event. A 500-year flood would have a 0.2 percent chance of occurring in any given year.

“Right now, the water is rising, and we won’t know the extent of it for maybe the next 12, 15 hours,” said Whitmer at a news conference Tuesday evening.

Scores of businesses have been shuttered in the fallout of the coronavirus pandemic, which has been particularly severe in Michigan, and are facing serious economic hardship.

“This is unlike anything we’ve ever seen before,” said Whitmer. “I feel like I’ve said that a lot over the last number of weeks, but this truly is a historic event that is playing out in the midst of another historic event.”

Major flooding begins when the Tittabawassee River hits 28 feet; flood stage is at 24 feet. As of 8 p.m. on Wednesday evening, river gauges reported a level of 35.05 feet. That’s enough to flood West Main Street from Main Street to Saginaw Road, with many homes experiencing overland flooding. It’s also more than one foot above the previous record.

It supersedes the historic 33.9-foot flood stage measured on Sept. 13, 1986, which at the time was deemed a “once in 500 year flood.” National Weather Service hydrologists were forecasting a crest four feet higher early Wednesday, though the river fell shy of that prediction.

Dow Chemical Co.’s Midland headquarters was evacuated, with only essential staff remaining on-site to monitor the situation. The facility is associated with a Superfund site due to excess dioxins, which are known to cause cancer, in the riverbed downstream of the plant. New video released by the Michigan State Police showed flooding on the Dow property, though the extent and severity is unclear.

According to a company statement issued Wednesday, at 10 a.m. they received word that “flood waters were commingling with on-site containment ponds.” Dow says it’s working with the Coast Guard and other officials to ensure the safety of the facility and community.

“Dow has activated its local emergency operations center and is implementing its flood preparedness plan which includes the safe shutdown of operating units,” wrote the company on its Facebook page. Dow also filed an “Unusual Event Report” with the Nuclear Regulatory Commission because of the possibility that floodwaters could affect its 300 kilowatt nuclear research reactor, located at the plant, though the reactor was already shut down due to the coronavirus outbreak. That reactor was built in 1967.

The flooding illustrates the challenge that natural disasters, worsened by climate change, poses for cleaning up Superfund and other hazardous waste sites in the country. A Government Accountability Office report released in 2019 found that “About 60 percent of Superfund sites overseen by EPA are in areas that may be impacted by wildfires and different types of flooding — natural hazards that may be exacerbated by climate change.”

“This is a solidly middle to upper class town because of the Dow plant here,” Peter Sinclair, a Midland resident who is a videographer for Yale Climate Connections, said in an interview. He said a 2017 seasonal flood event, combined with this disaster, may cause property values to decline. This includes expensive lakefront property, since these lakes are now being drained by the flooding.

Edenville dam’s previous owners were warned about safety issues

For years, the Federal Energy Regulatory Commission (FERC) has feared a failure at the Edenville Dam. According to The Detroit News, the dam has been of concern to federal overseers since at least 1999, when its owners were warned that more spillway capacity was needed to avoid a potential collapse.

The Edenville dam was constructed in 1924 and was on FERC’s list of “high hazard” dams, meaning that its failure could damage property and threaten lives.

Boyce Hydro LLC, which has owned three other dams along the Tittabawassee River, failed to meet FERC demands for years.

A January 17, 2019 FERC document notes “a history… of Boyce Hydro’s failure to comply with its license for the Edenville Project.”

In January of this year, a two-county authority moved to purchase four dams and lakes from Boyce Hydro LLC, including Edenville and Sanford, for $9.4 million, and expects to spend $100 million to improve the dams. FERC had repeatedly faulted the previous owner for failing to maintain and improve spillways, which help direct excess water around the dam to relieve pressure on the structure.

FERC argued that the Edenville dam “could not handle 50 percent of a probable maximum flood for the region,” the paper reported, whereas in 2018, Boyce Hydro put the odds of a “probable maximum flood” event occurring during the next 5 to 10 years at “5 to 10 in one million.”

FERC revoked Boyce Hydro’s license on September 10, 2018, forcing the company to permanently disable its power generating capacity within the dam. The order, however, did not require Boyce to modify the dam’s structure. Boyce filed for a rehearing, which was denied on January 17, 2019.

“This was a known problem for a while,” Whitmer said of the dams that failed. She said the state may pursue legal action to ensure the state is compensated for the damage.

Sinclair, who is on the dry side of Midland and is sheltering family members who live closer to the flood-affected areas, says this event illustrates what climate scientists have been warning about for years.

“[There is the] Larger issue of aging infrastructure plus incremental climate change, this is a point that all the scientists make that the change is gradual, gradual, gradual until the infrastructure fails.”

Heavy rains are in line with recent climate change trends

Heavy spring rains triggered the disaster. Much of the Midwest has borne the brunt of a wet weather pattern that’s left many areas with an extra 8 to 10 inches of rain when compared to average.

On Tuesday, Gladwin, Mich. picked up 2.53 inches of rain, while Central Michigan University in Mount Pleasant, about 25 miles west of the Edenville Dam, received 2.65 inches. Upwards of three inches fell upstream, pouring into a river that’s been already swollen in recent weeks.

The scene in Michigan after a pair of dams collapsed following record rainfall

May 22, 2020 | Residents clean up debris in the aftermath of the Sanford Dam failure, which flooded the Tittabawassee River and parts of Sanford, Michigan. (Rebecca Cook/Reuters)

Midland received 3.83 inches on Tuesday — its fourth-highest calendar-day rainfall total on record, and its wettest day since September 2015. Records date back to 1970.

During the past several decades, spring rainfall in Michigan has been on the increase, likely tied to warming temperatures and the air’s ability to hold additional moisture. Data point to a roughly 25 percent increase in March through May rainfall since 1970 in Midland, with similar trends observed areawide. Mean springtime precipitation in Gladwin has leapt from 7.1 inches in 1940 to nearly 9.3 inches nowadays. Spring temperatures have warmed a degree and a half there during that same time frame.

According to the U.S. government’s National Climate Assessment, the heaviest precipitation events in the Midwest have increased by 42 percent since 1958, which it attributed in large part to added heat and moisture from human-caused climate change.

The last four years, 2016 through 2019, were all ranked among Michigan’s top 15 wettest on record, and five of the top 10 wettest years have come in the last decade.