Note: This release is based on projections and the most current information from the Army Corps of Engineers. This is a rapidly-evolving situation that may change as more information becomes available.
Gov. Dennis Daugaard announced today that, based on projections by the U.S. Army Corps of Engineers, all residents of Dakota Dunes should immediately begin making plans to evacuate later this week, due to Missouri River flooding.
Residents should have their possessions moved, homes secured and be out of those homes by late Thursday, June 2. They should expect to be away from their homes for as much as two months because elevated releases of water from the mainstem dams will continue for several weeks.
“State and local officials are coordinating to respond to this flooding, and we are considering all possible protective measures,” Gov. Daugaard said. “Every property owner in Dakota Dunes should assume the worst – that protective measures will be impossible or will fail – and should act now to remove their possessions and secure their homes.”
The Corps of Engineers now projects that, once water releases reach a maximum flow of 150,000 cubic feet per second (CFS), water levels in Dakota Dunes will reach 1,098 feet above sea level. That means protective measures should be built to 1,100 feet above sea level.
When will this begin and for how long will it last?
According to Corps’ plans, water releases from Gavins Point Dam Dam will increase gradually beginning today and continue through the end of this week. Beginning next week, water releases will increase more rapidly and will reach a maximum of 150,000 CFS by mid-June.
Explanation of the cause:
Over the past several days, the Corps of Engineers dramatically increased its calculation of water releases required from the mainstem dams on the Missouri River. The Corps believes that this increased water release is necessary to avoid overtopping of the spillways.
Huge rainfalls in Wyoming, Montana, and western North Dakota and South Dakota over the past month have exceeded rainfall in a normal year. This has used capacity of the reservoir system that had been reserved to accommodate the annual snowmelt. In addition, mountain snowpack is 135 percent to 140 percent of normal, and it is melting at a later time. As a result, all the moisture will require the Corps to increase water flows to unprecedented levels.
Source: office of Governor Daaguard