Environmental

Drought conditions affect 73% of Missouri River Basin, hampering hydropower

The six mainstem hydropower plants across the basin generated 912 million kWh of electricity in August, while typical energy generation for August is 1,007 million kWh, the Army Corps of Engineers said.

Drought conditions affect 73% of Missouri River Basin, hampering hydropower
Gavins Point Dam (Credit: U.S. Army Corps of Engineers)

“Abnormally dry” or drought conditions are present across 73% of the Missouri River Basin, with drought conditions likely to persist or worsen through November, according to the U.S. Army Corps of Engineers.

The six mainstem hydropower plants across the basin generated 912 million kWh of electricity in August, while typical energy generation for August is 1,007 million kWh, the Corps said. The power plants are projected to generate 8.1 billion kWh of electricity this year, compared to the long-term average of 9.4 billion kWh.

August runoff was 1.2 million acre-feet (MAF), 86% of average above Sioux City. The updated 2024 calendar year forecast for the upper basin is 23.8 MAF, 92% of average. Average annual runoff for the upper basin is 25.7 MAF.

“August rainfall was generally near normal across most of the Missouri River Basin, with isolated areas of above normal precipitation in every state except Nebraska. Nebraska was generally below average with most of northern Nebraska measuring 50% of normal precipitation,” said John Remus, chief of the Corps’ Missouri River Basin Water Management Division. “Runoff in the Fort Peck and Fort Peck to Garrison reaches were well-below average while runoff in the reaches between Garrison Dam and Sioux City were all above average.”

As of Sept. 1, the total volume of water stored in the system was 55.1 MAF, which is 1.0 MAF below the base of the system’s flood control zone. System storage is expected to continue to decline through the fall. The updated reservoir studies indicate that system storage is expected to be about 4.7 MAF below the base of flood control at the start of the 2025 runoff season.

Releases from Fort Peck and Garrison dams will be reduced to the fall release rates in mid-September. Fort Peck releases will be lowered from 9,000 cubic feet per second (cfs) to 4,000 cfs starting on Sept. 16. Garrison releases will be stepped down from 22,000 cfs to 14,000 cfs starting on Sept. 16.

Gavins Point Dam releases are being set to provide navigation flow support at a level 500 cfs below full service at all four target locations (Sioux City, Omaha, Nebraska City and Kansas City). Flow targets may be missed to conserve water if there is no commercial navigation in a given reach, the Corps said. Season support will end on Dec. 1 at the mouth of the Missouri River.

WATER RELEASES AND ENERGY GENERATION FOR AUGUST
 Average Release in 1,000 cfsReleases in 1,000 acre-feetGeneration in Million kWh
Fort Peck9.055686
Garrison22.11,359213
Oahe27.81,710261
Big Bend27.61,69691
Fort Randall27.91,716180
Gavins Point29.01,78481
  Total912
(Credit: U.S. Army Corps of Engineers)