Precipitation was once again below average in the Missouri River basin in September. Runoff above Sioux City, Iowa, measured 0.6 million acre-feet, 47% of the long-term average, according to the U.S. Army Corps of Engineers.
Soil conditions in the upper Missouri River Basin continue to be very dry. According to the National Drought Mitigation Center at the University of Nebraska, more than 90% of the basin is experiencing some form of abnormally dry conditions or drought, an almost 20% increase from the end of August.
The 2022 calendar year runoff forecast for the upper basin, updated on Oct. 1, is 19.5 MAF, 76% of average. That is also 0.7 MAF lower than September’s forecast. Average annual runoff for the upper basin is 25.7 MAF.
“Runoff in the upper Missouri River Basin was below average during the month of September and is expected to remain low throughout the rest of 2022,” said John Remus, chief of the Corps’ Missouri River Basin Water Management Division. He saids that releases from Gavins Point Dam would continue to be set to maintain a service level 500 cubic feet-per-second above the minimum service level.
Total system storage as of October 5 was 48.5 MAF. The system is expected to lose an additional 2.0 MAF before the 2023 runoff season begins in March.
The winter release rate is determined based on system storage as of September 1. As a result, winter releases from Gavins Point Dam will be at the minimum rate of 12,000 cfs. In anticipation of the low winter releases, a letter was sent in early July warning all water users below Gavins Point Dam of the planned releases and encouraging them to assess the risk to their facilities. The volume of water in the Missouri River downstream of the system is expected to be adequate for water supply needs.
The six mainstem hydroelectric power plants are (upstream to downstream) Fort Peck, Garrison, Oahe, Big Bend, Fort Randall and Gavins Point. Together, they generated 832 million kWh of electricity in September, compared with typical energy generation for the month of 902 million kWh. The power plants are projected to generate 7.4 billion kWh of electricity this year, compared to the long-term average of 9.4 billion kWh annually.
In mid-September, the USACE posted the draft 2022-2023 Annual Operating Plan, and the comment period will close November 23.
The Drought Mitigation Center said in early October that the country as a whole recently hit what it called a “sobering” record: more than two years with over 40% of the contiguous U.S. in moderate drought or worse, classified as D1 or above. The latest figures put the streak at 106 weeks.
The current widespread drought marks the longest such streak since the Drought Monitor began in 2000. The second longest streak, from June 2012 to October 2013, was 68 weeks. After that was a 65-week stretch from March 2002 to June 2003. Both of those earlier periods are recognized as some of the most severe droughts on record in the U.S.
Meteorologists with the U.S. Department of Agriculture calculate that, statistically, drought coverage should be closer to 20% this time of year. Instead, as of October 4, nearly 53% of the contiguous U.S. and over 44% of the entire country and its territories was in D1 or worse condition.
Te longevity and extent of the current drought is due in part to back-to-back-to-back La Niña events. That scenario has happened only two other times in the modern record, first in the mid-1970s and then the late 1990s.
The October HYDRO+ free virtual training program, brought to you by Hydro Review and HYDROVISION International, will cover the topic of drought conditions in the U.S. and how the hydropower industry is affected. David Raff with the U.S. Bureau of Reclamation is one of the speakers for this session. Click here to register for the Oct. 13 webcast.
