Missouri River Basin Runoff Forecast Cut Again

Reservoir inflows in the Missouri River basin above Sioux City, Iowa, were well below average in March, the Corps of Engineers reported April 4. The March runoff of 1.5 million acre-feet (maf.) was 48 percent of average for the month.

The updated 2022 upper basin runoff forecast is 17.8 maf., 69 percent of average, approximately 2.6 maf. less than the March 1 forecast.

“Runoff was well below normal due to dry soil conditions and well below normal precipitation across the entire Missouri River basin,” said John Remus, chief of the Corps’ Missouri River Basin Water Management Division. “Due to the lack of plains snowpack in 2022, below-average mountain snowpack and dry upper basin conditions, we expect upper Missouri River Basin runoff to be below average.” 

The runoff forecast is based on soil moisture conditions, plains snowpack, mountain snowpack and long-term precipitation and temperature outlooks.

“System storage is currently 48.4 maf., which is 7.7 maf. below the top of the carryover multiple use zone. That zone is designed to provide service to the eight congressionally authorized purposes, though at reduced levels, through a long-term drought,” he said. “Water conservation measures, such as minimum winter releases and reduced flow support for navigation, are implemented as the amount of water in the reservoir system declines.”

Snowpack

Mountain snowpack in the upper basin is accumulating at below-average rates. The April 3 mountain snowpack in the Fort Peck reach was 75 percent of average, and the mountain snowpack in the Fort Peck to Garrison reach was 71 percent of average. By April 1, about 95 percent of the total mountain snowpack has typically accumulated. Mountain snowpack normally peaks near April 15.

Currently, plains snowpack in the upper basin is essentially non-existent with only trace amounts in southern North Dakota and northern South Dakota remaining, the Corps said.

Navigation

Gavins Point Dam releases were increased near mid-March to begin flow support for Missouri River navigation. As part of water conservation measures, minimum service flow support for Missouri River navigation will be provided for the first half of the 2022 season, in accordance with the guidelines in the Master Manual. Minimum-service flow targets range from 25,000 cfs. at Sioux City, Iowa, to 35,000 cfs. at Kansas City, Mo.

Flow support for the second half of the navigation season, as well as the navigation season length, will be based on the actual July 1 system storage. The current forecast indicates that minimum service flow support will be required throughout the navigation season, and flow support may be shortened by as much as three weeks.

Spring Public Meetings

Seven public meetings will be conducted throughout the basin April 11–13 and April 15. The purpose of these meetings is to update the region on current hydrologic conditions and the planned operation of the mainstem reservoir system during the coming months. Meeting times and locations are listed below (all times are CDT except Fort Peck, which is MDT):

Fort Peck, Mont.—10:30 a.m. April 11, Fort Peck Interpretive Center, Lower Yellowstone Road.

Bismarck, N.D.—6 p.m. April 11, Bismarck State College, National Energy Center of Excellence (NECE), Bldg. 15, Bavendick Stateroom, 1200 Schafer St.

Fort Pierre, S.D.—10 a.m. April 12, Casey Tibbs Conference Center, 210 Verendrye Drive.

Sioux City, Iowa—4 p.m. April 12,  Lewis & Clark Interpretive Center, Betty Strong Encounter Center, 900 Larsen Park Road.

Smithville, Mo.—11 a.m. April 13, Jerry Litton Visitor Center, Smithville Dam, 16311 DD Hwy.

Nebraska City, Neb.—6 p.m. April 13, Steinhart Lodge, 1888 Steinhart Park Road.

St. Louis, Mo.—10:30 a.m. April 15, VUE 17, 1034 S. Brentwood Blvd., Suite 1700.