As Fort Peck Dam’s outflow is increased to a historic high of 50,000 cubic feet per second in mid-June, the downstream community of Wolf Point will see flows rise 1 to 1.5 feet above flood stage.
The figures were released on Tuesday by the Army Corps of Engineers, the agency in charge of managing the dam. The calculation takes into account high flows on the Milk River, which enters the Missouri River just below Fort Peck Dam.
According to the Corps, at releases of 50,000 cfs the Missouri River will rise to 14 to 14.5 feet at Wolf Point, an increase of 6 feet from the current level. Flood stage at Wolf Point is 13 feet.
The same discharge past the Culbertson gauge, farther downstream, will result in a rise to 16.5 to 17 feet, an increase of 8 feet from the current river level. Flood stage at Culbertson is 19 feet.
John Daggett, operations manager at Fort Peck, said the town of Wolf Point would largely be spared. The outlying areas would be hardest hit, along with utilities and facilities such as sewage lagoons, he said.
“People need to see where they’re at,” Daggett advised, and prepare for higher water.
The entire Missouri River flood control system is being flushed with record amounts of water thanks to unusual rainfall in Montana. The Yellowstone River has carried a year’s worth of rainfall into reservoirs in the Dakotas and downstream.
Dams said to be safe
In a conference call Tuesday, a North Dakota congressional representative said citizens were concerned that the dams would be unsafe at such high water levels.
“Our dams are sound,” said Col. Robert Ruch, Omaha District commander.
To prepare for the runoff from a record snowpack, the Corps has to make room in its reservoirs. Downstream dams will see record outflows up to 150,000 cfs, causing flooding in the cities of Bismarck, N.D., and Pierre, S.D., as well as outlying areas. The flooding is predicted to last for months.
The Missouri at Fort Peck’s head was flowing at a daily average of 91,000 cfs, thanks in part to record runoff in the Musselshell River that has flooded Roundup. Meanwhile, the Fort Peck Dam is only releasing 10,000 cfs to try to ease the strain on reservoirs downstream.
But that can’t continue, as Fort Peck needs to make room for the Missouri’s spring snowmelt. So by June 14, the outflow will be raised to a record high 50,000 cfs. The previous high release mark was 35,000 cfs in 1975.
Because of the unusual weather, the Corps has had to continually alter its releases. Only last week, the agency said outflows from dams downstream of Fort Peck would top out at 110,000 cfs. That was raised to 150,000 cfs.
Because of the weather’s unpredictability, the Corps said “the possibility of 1.5 to 2 additional feet in the river stage beyond current projections” should be considered.
“Actual releases will be based on conditions on the ground,” said Jody Farhat, chief of Missouri River Basin Water Management.
The Corps advises people living along the Missouri to make evacuation plans to protect their possessions and property and contact local emergency management offices for more information.
Flooding in Dakotas
In South Dakota, residents of the community of Dakota Dunes in southeastern South Dakota, below the final dam on the river, have been told to move their possessions to higher ground and be ready to leave their homes by Thursday. Nearly all of Dakota Dunes, a city of about 2,500, would be subject to flooding if the levee system does not hold.
Several thousand people in Pierre, the state capital, and neighboring Fort Pierre have been working day and night since late last week to lay sandbags around their homes and move to safety. Those forced to leave their homes may not be able to return for two months or more.
Minot, N.D., Mayor Curt Zimbelman ordered a quarter of the city’s residents to evacuate areas along the flooding Souris River. He said the evacuation order affects about 10,000 residents. More than seven miles of levees were being built in Bismarck and another 3½ miles were going up across the river in Mandan.
Officials in western Iowa also were making plans to deal with flooding in Sioux City and other areas. The Nebraska towns of Niobara and Santee are already dealing with flooding from the Lewis and Clark Reservoir, while cities further downstream are preparing for high water over the next month.