In a May 20 statement, Dow said its local emergency operations centre had been fully activated, and it implemented its flood preparedness plan.
It also worked with the US Coast Guard to activate emergency plans when floodwaters mixed with on-site containment ponds.
Managers said all the site's operating units were safely shut down, except those needed to safely manage chemical containment. All rail cars on the site were secured.
'Only essential staff are on site to monitor and manage the situation, with no reported employee injuries,' managers said.
Dow managers said on Facebook that the firm's Midland-based Michigan Operations 'activated their emergency operations centre and will be adjusting operations as a result of current flood stage conditions' shortly after the dams failed.
'Dow Michigan Operations is working with its tenants and Midland County officials, and will continue to closely monitor the water levels on the Tittabawassee River,' they added. 'As always, our first priority is the safety and security of our employees and community.'
In an update issued later on 20 May, managers said that the mixtures of water in the pond and flood water 'does not create any threat to residents or environmental damage'. They added that no product releases have been reported.
Crain's Detroit Business (CBD), a sister publication of UTECH-polyurethane.com and Urethanes Technology International, reported that the ponds cover 200 acres (81 ha) of Dow's 1,900-acre property in Midland. The ponds collect wastewater which is filtered before being discharged into the Tittabawassee River. The river flows into the Saginaw River and then on into Lake Huron.
The emergency began when the 96-year-old Edenville Dam failed after 1800 hrs. on 19 May. Water that had made up Wixom Lake then overwhelmed the 95-year-old Sanford Dam downstream.
CDB also reported that Michigan state had rated Edenville Dam unsatisfactory in 2018. That year, the Federal Energy Regulatory Commission revoked the license of dam operator because it did not comply with current regulations including spillway capacity. The Michigan State rated the 95-year-old Sanford Dam received fair in 2018, according to CDB.
Midland has a population of 42,000, and is located in central Michigan. Dow, one of the world's largest plastics and chemicals makers, has operated in Michigan since 1897.
This is an edited version of a story which first appeared in PlasticsNews.com