Newly Released Report Details What May Have Caused Historic Midland Flooding

It’s been more than a year since the historic Midland flooding in 2020.

On Monday, a five-member independent forensic team released a 42-page report with what they call “strong evidence” of what caused the 500-year sized flood.

Their finding is weak soil.

The report cites precipitation, lake levels, and gate and power plant operations as contributing factors to saturated soil.

The mass flooding event caused more than $200 million dollars in estimated damages, and forced about 10,000 people to temporarily evacuate.

From May 1 to May 19, the four Boyce hydro dams saw 20 inches of rain, with the majority of the rain falling on May 18, the day before the flooding.

Because of the rain on May 18, levels at the dams started to rise. Gates were opened periodically, but operations stopped after 8 p.m.

On May 19 at 5:35 p.m., the Edenville Dam failed, releasing wasters that overtopped the downstream Sanford Dam.

With no operations at any of the other Boyce hydro dams, it created a ripple effect of dam failures, with the flood waters now pouring into Gladwin and Midland Counties.

The report says that the failure of the Edenville Dam is consistent with static liquefaction, or loose saturated sand. It also says that weak soil led to internal erosion and embankment instability.

According to the preliminary report, a team is still evaluating if human factors contributed to the flooding.

A final report is pending.