How a spring rainstorm became a 500-year flood event in mid-Michigan

MIDLAND, MI - Rainstorms are a typical part of spring in Michigan. The rainstorm that hit mid-Michigan beginning on Sunday, May 17, though, proved one for the history books.

The flooding that resulted from up to 7 inches of rain in Midland, Saginaw and surrounding counties damaged homes and property, forced more than 10,000 people to evacuate and most spectacularly destroyed one power dam and severely damaged another.

It’s being called a 500-year flood event, meaning it is only likely to occur once every 500 years.

How did it unfold?

The story starts with the storm itself. One key ingredient fueled the downpour. MLive meteorologist Mark Torregrossa said the heaviest rain was produced by tropical moisture, as Tropical Storm Arthur was churning off the Mid-Atlantic coast.

In what he called a conveyor belt effect, a mass of moisture traveled from the East Coast westward into Michigan, allowing the ongoing storm to tap into that tropical moisture and cause a substantial increase in rainfall totals.

Total Rainfall

Total storm rainfall for Michigan's Lower Peninsula, from 5/17 to 5/19. Image courtesy of the National Weather Service.

Mid-Michigan received a heavy amount of moisture from the storm, with Midland, Bay and Saginaw Counties floating around 3-4 inches of rain. The heaviest rainfall totals were found to the north, with Au Gres receiving 8.10 inches, East Tawas getting 7.97, and Sterling clocking in at 7.20 inches.

The rainfall itself caused headaches for various municipalities, with Bay City’s wastewater treatment plant requiring the use of an auxiliary pump to keep up with the sudden deluge of water the evening of Monday, May 18.

Numerous roads closed due to the heavy rain, especially in counties in northern mid-Michigan, with Arenac and Gladwin County beginning to see numerous road closures during the night on Monday.

“Many roads have washed away. What may appear to be standing water may be much deeper than you believe. As it gets darker, you will not be able to see the flooded areas. Unnecessary travel ties up resources if you end up stranded. Please stay home if you do not absolutely need to be traveling,” said an alert from the Arenac County Sheriff’s Department that night.

The Arenac County Sheriff’s Department stated that U.S. 23 was closed at the time between M-65 and Standish due to possible bridge damage and water over the road and at Omer. The Sheriff’s Department evacuated the areas around Townline, Pinnacle, Franklin Trail, and Miller roads today due to flooding that same day.

As the floodwaters began to make their way through the watershed, areas downstream on the Tittabawassee River also were advised of potential severe flooding Monday night as all flood gates at the Sanford Dam were being opened due to high water. This action served as a forewarning as the next phase of the disaster started to take shape.

A catastrophic chain of events

Midland County Central Dispatch issued an alert at 12:22 a.m. on Tuesday, May 19, stating residents in Edenville Township needed to leave their homes due to an “imminent dam failure" at the Edenville Dam and that those who live along Sanford Lake and Wixom Lake were to vacate their homes and head to shelters immediately.

Residents were directed to emergency shelters that were setup at Meridian Junior High School in Sanford and Coleman Community High School in Coleman.

At 6:50 a.m. on Tuesday, Midland County Emergency Management determined that the structures such as the Edenville and Sanford dams were structurally sound but that the dams could not control or contain the water flowing through spill gates anymore.

Later that day, things took a turn for the worse. A section of the dike at the Edenville Dam collapsed just after 6 p.m. after it couldn’t hold anymore of the swollen river.

The collapse prompted flash flood warnings from the National Weather Service that read, "Life threatening flash flooding of areas downstream from the Edenville Dam along the Tittabawassee River,” the warning reads. “The nearest downstream town is Sanford Dam...located about 7 miles from the Edenville Dam. Areas downstream from the Edenville Dam along the Tittabawassee River should be prepared for additional flooding.”

Midland County Emergency Management confirmed later on Tuesday, May 19, that water was flowing over the earthen embankment of the Sanford Dam after the Edenville failure sent a torrent of water into Sanford Lake. After overwhelming the Sanford Dam, the water surged south along the Tittabawassee River toward downtown Midland.

The flooding from the event closed roadways such as eastbound and westbound US-10 between River Road and M-30 on Tuesday, per the Michigan Department of Transportation Bay Region Twitter page. The M-30 bridge was destroyed near Stryker’s Marina.

Gov. Gretchen Whitmer issued an emergency declaration late Tuesday and sent the National Guard to help after the dam failure while also urging residents in evacuation zones to get out immediately.

“Please, get somewhere safe now,” she said in a 10 p.m. Tuesday, May 19, press conference.

About 10,000 people were evacuated, in Midland along with the village of Sanford, Edenville and Dow Chemical. Officials also were trying at the time to evacuate areas of Tittabawassee Township, Thomas Township and Saginaw Township, said Whitmer.

The Tittabwasee River was reported to have crested at about 35 feet on Wednesday evening. The crest topped the river’s 1986 all-time record level, but falls short of the dire 38-foot mark that was predicted.

Sanford Dam remains standing but flooding impacts surrounding area

A look at the Sanford Dam on Wednesday, May 20, 2020. After the Edenville Dam failed and the Tittabawassee River flooded surrounding areas, many residents were urged to leave their homes and to brace themselves for the possibility of the Sanford Dam to collapsing. Water flowed over the top of it through the night, but the structure is still in place. (Kaytie Boomer | MLive.com)Kaytie Boomer | MLive.com

While the Edenville Dam fell to the floodwaters, the Sanford managed to hold its ground but did not come out of the situation unscathed. A hole formed at the dam’s brim Thursday, May 21, causing water to flow freely from the lake.

Midland City Manager Brad Kaye on Thursday confirmed that as of 10 a.m. that the structure was still standing. He said that there is water over the top of the earthen berm portion with a substantial washout, but the concrete structure of the dam itself remains standing

More than just a structural failure

The resulting flood from the Edenville Dam collapse displaced about 10,000 people and prompted federal energy regulators to order Boyce Hydro to conduct a third-party investigation.

It was reported in 2018 that federal energy regulators yanked the Edenville Dam operator’s license out of concern the spillway couldn’t pass enough water to avert a failure during a historic flood. Federal Energy Regulatory Commission (FERC) records showed that capacity issues at the Edenville Dam spillway were cited as problematic dating back to the late 1990s.

Gov. Whitmer delivers remarks on mid-Michigan flooding

Gov. Gretchen Whitmer delivers remarks on Midland-area flooding at a press conference in front of Midland High School on Wednesday, May 20, 2020 in Midland, Mich. Gov. Whitmer surveyed flood damage from a helicopter earlier in the morning.Riley Yuan | MLive.com

Michigan Gov. Gretchen Whitmer vowed that the state will pursue every line of legal recourse and she suggested that such critical infrastructure should not be in private hands.

“We can talk about the merits of whether or not private companies should own critical infrastructure or not - I don’t think that they should - but that’s what we’re dealing with here,” she said.

The governor also took an aerial tour of the flood zone along the Tittabawassee River by helicopter on Wednesday and gave a press conference at Midland High School, which is being used as a shelter for residents displaced by flooding.

President Trump also weighed in with a tweet thanking first responders for helping to evacuate people in the danger zone below the dams.

What’s next?

By Friday, homeowners slowly started to return to their homes, as they have been able and as flooding conditions have allowed. Families have been returning home to find muddy and water damaged homes as they work to pickup the pieces together.

Wixom and Sanford Lakes were reported to be nothing more than mud puddles after their contents were swept downstream into the Tittabawassee.

Wixom Lake disappears as water continues to flood through failed Michigan dam

A nearly barren Wixom Lake stands dry after severe flooding forced the failure of Edenville Dam on Wednesday, May 20, 2020 in Edenville Township north of Midland. (Jake May | MLive.com)The Flint Journal, MLive.com

President Trump approved an emergency declaration on Thursday, May 21 for areas affected by the water. Federal assistance will begin to supplement state and local responses starting Saturday, May 16.

The City of Midland will soon begin cleanup efforts, as well. The city will make announcements regarding landfill access and debris collections to help residents with cleanup efforts, said Selina Tisdale, a public information officer for the city. Residents are now able to report damage to their property online here.

The American Red Cross compiled a list of locations in Midland and Saginaw counties where displaced residents may seek shelter, food or other assistance and offers an online service to help friends and relatives to try and contact missing loved ones.

Subsequent downstream flooding occurred in Saginaw County, where the community of Shields was flooded and residents in part of Spaulding Township were told to evacuate after a dike was breached.

Memorial Day weekend in 2020 will be a busy time of cleanup, repair and reflection for those impacted by the flooding. Though remarkably there are no reports of any serious injuries or deaths attributed to the event, the damage to homes, businesses and properties will take time to repair.

One family living in Sanford was busy picking through the muddy debris of their destroyed home, hoping to salvage some family pictures.

“Thirty-one years and our whole life is gone,” Pat Perry said in the early evening of Thursday, May 21. “The thing that bothers me most are things like pictures that you can’t replace. Those are most important. The other stuff is just stuff.”

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