OMAHA, Neb. – The U.S. Army Corps of Engineers announced Tuesday night that water releases from Gavins Point Dam in South Dakota will increase to 160,000 cubic feet per second by Thursday as a result of continued wet weather throughout the Missouri River Basin.
The corps said large, heavy rain system has impacted South Dakota and northern Nebraska in the past 48 hours, with as much as 6-inches falling across part of South Dakota. The heavy rains resulted in high inflows to Oahe, Big Bend and Fort Randall reservoirs. High inflows are also anticipated for Gavins Point.
The impact of an additional 10,000 cfs to the current 150,000 cfs will result in an increase in river stages from 0.7 to 1 foot at Sioux City, Ia., and 0.3 to 0.4 of a foot from Omaha to Rulo, Neb. At St. Joseph, Mo., the river stage rise will be roughly 0.6 foot, and at Kansas City, the rise will be roughly 0.7 foot. Actual stages will depend on tributary inflows.
“Since the end of May, we have been slowly ramping up releases from our reservoirs to buy time for communities and local and state governments to be able to prepare for high water,” said Brig. Gen. John McMahon, commander of the Northwestern Division of the Army Corps of Engineers. “We thought we would be able to hold at 150,000 cfs for an extended period of time. Unfortunately, recent rains have reduced our flexibility, and we must evacuate these floodwaters to manage the remaining flood control storage in the reservoir system. As we’ve stated all along, heavy rain storms could result in major revisions.”
Public safety is the number one concern of the Corps of Engineers. The Corps is working closely with state and local emergency management teams to identify potential flood areas, provide residents with the most current information and help protect vital infrastructure.
“This continues to be a very dynamic situation and dangerous at the same time,” said Gen. McMahon. “We are committed to being open, transparent and timely in our communication.
“People along the river are encouraged to make evacuation plans to protect their possessions and property. Maps for potential flood areas are available at www.nwo.usace.army.mil and from local emergency management offices,” he added.
Flooded areas are expected to be inundated for several months.
“Once more, the amount of rain has nearly filled the reservoirs, doing away with most of the flexibility we had built into operations this year,” said Jody Farhat, Chief of the Water Management Division here. “We will continue to evaluate the amount of water entering the system along with weather events and revise our plans accordingly.”
Releases from Fort Peck will remain at 60,000 cfs for the time being. Releases from Garrison will stay stable at 150,000 cfs for the foreseeable future. In response to high inflows between Oahe and Big Bend, Oahe’s releases have been reduced to 150,000 cfs and will return to 160,000 cfs as soon as conditions at Big Bend permit. Releases from Big Bend will rise to 165,000 cfs tomorrow and remain at that level till the end of June. Fort Randall releases have temporarily reduced to 138,000 cfs and will incrementally ramp up 157,000 cfs. Gavins Point will increase levels to 160,000 over a two-day period, increasing by 5,000 per day. The 160,000 cfs level will be attained by Thursday and remain at that level through August.
Updated inundation maps from Gavins Point to Rulo, Neb., will be available online within 24 hours at the Omaha District Web site at http://www.nwo.usace.army.mil. Inundation maps for south of Rulo will be available by the weekend on the Kansas City District Web site at http://www.nwk.usace.army.mil.