Runoff continues to be below average in the upper Missouri River Basin above Sioux City, Iowa. Below-normal precipitation, dry soil conditions in the western portions of the basin, and cooler-than-normal temperatures slowing mountain snowmelt, resulted in a May runoff of 2.7 million acre-feet. While this was 0.4 MAF more than forecast last month, this volume is still 79% of average.

The updated 2022 runoff forecast is 18.3 MAF, 71% of average and 0.5 MAF higher than last month’s annual runoff forecast. If realized, this runoff amount would rank as the 25^th lowest calendar year runoff since 1898.

“A wet April and May in North Dakota resulted in wetter soils in the state, but dry soils remain in the rest of the Basin,” said John Remus, chief of the U.S. Army Corps of Engineers’ Missouri River Basin Water Management Division. “Drought conditions persist but have improved over the last month. Over 20% of the basin is drought-free, and only 8% of the basin is left in extreme drought conditions, mostly in the state of Montana.”  Due to the ongoing drought and the amount of water stored in the reservoir system, water conservation measures will likely continue through the remainder of 2022 and into 2023.

Mountain Snowpack:

Mountain snowpack in the upper Missouri River Basin has been melting at slower-than-average rates due to cooler-than-normal temperatures during the spring and early summer, which has also allowed for additional late season accumulation. On June 1, 60% of the annual peak remains above Fort Peck Dam, and 68% of the annual peak remains above Garrison Dam. The mountain snowpack peaked above Fort Peck on April 29 at 85% of average, while the mountain snowpack in the Fort Peck to Garrison reach peaked on May 3 at 92% of average. Mountain snowpack normally peaks near April 15. The mountain snowpack graphics can be viewed at: http://go.usa.gov/xARQC.

Navigation:

Gavins Point Dam releases will provide minimum-service navigation flow support at all four target locations (Sioux City, Omaha, Nebraska City, and Kansas City) through July 1. Flow targets may be missed to conserve water if there is no commercial navigation in a given reach. Minimum-service flow targets range from 25,000 cubic feet-per-second at Sioux City, Iowa to 35,000 cfs at Kansas City, Missouri. Flow support for the second half of the navigation season, as well as the navigation season length, will be based on the actual System storage on July 1. The current forecast indicates that minimum service flow support will be required throughout the navigation season and flow support may be shortened by slightly less than two weeks.

Monthly Water Management Conference Calls

Water management calls include an update from the National Weather Service’s Missouri Basin River Forecast Center, and an update on the Missouri River mainstem reservoir system operations. The next call will be held Thursday, June 9. Due to continuing drought conditions, a call will be held July 7. All calls are recorded in their entirety and are available to the public on our website at https://go.usa.gov/xARQv.

Reservoir Forecasts:

• Gavins Point Dam
  • Average releases past month – 20,400 cfs
  • Current release rate – 20,500 cfs
  • Forecast release rate – 21,000 cfs
  • End-of-May reservoir level – 1206.8 feet
  • Forecast end-of-June reservoir level – 1206.0 feet
  • Notes: The Gavins Point release will be adjusted to provide minimum-service navigation flow support on the lower Missouri River.
     
• Fort Randall Dam
  • Average releases past month – 17,100 cfs
  • End-of-May reservoir level – 1355.0 feet
  • Forecast end-of-June reservoir level – 1355.3 feet
  • Notes: Releases will be adjusted as necessary to maintain the desired reservoir elevation at Gavins Point and to back up Gavins Point releases.
     
• Big Bend Dam
  • Average releases past month – 15,100 cfs
  • Forecast average release rate – 17,200 cfs
  • Forecast reservoir level – 1420.5 feet
     
• Oahe Dam
  • Average releases past month – 14,500 cfs
  • Forecast average release rate – 16,900 cfs
  • End-of-May reservoir level – 1596.7 feet (up 1.6 feet from April 30)
  • Forecast end-of-June reservoir level – 1598.2 feet
     
• Garrison Dam
  • Average releases past month – 16,800 cfs
  • Current release rate – 19,000 cfs
  • Forecast release rate – 19,000 cfs
  • End-of-May reservoir level – 1829.5 feet (up 1.4 feet from April 30)
  • Forecast end-of-June reservoir level – 1831.8 feet
  • Notes – Releases will be maintained at 19,000 cfs through August.
     
• Fort Peck Dam
  • Average releases past month – 7,300 cfs
  • Current release rate – 8,500 cfs
  • Forecast average release rate – 8,500 cfs
  • End-of-May reservoir level – 2222.1 feet (down 0.5 feet from April 30)
  • Forecast end-of-June reservoir level – 2222.1 feet
  • Notes: Releases will be maintained at 8,500 cfs through August.

The forecast reservoir releases and elevations discussed above are not definitive. Additional precipitation, lack of precipitation or other circumstances could cause adjustments to the reservoir release rates.

Hydropower:

The six mainstem power plants generated 558 million kWh of electricity in May. Typical energy generation for May is 797 million kWh. The power plants are expected to generate 7.1 billion kWh this year, compared to the long-term average of 9.4 billion kWh.

To view the detailed three-week release forecast for the mainstem dams, go to https://go.usa.gov/xARQB.

The Missouri Basin Web App provides links to these reports and others that are updated more frequently. http://go.usa.gov/xE6fC