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DVIDS – News – End of May slightly above average; The Fort Peck flow test continues

Active rain patterns in the Midwest provided much-needed moisture to several parts of the Missouri River basin. Large parts of Montana, North Dakota, Wyoming, eastern South Dakota and eastern Nebraska received more than 200% of normal precipitation during the month of May. However, central South Dakota, western Nebraska and eastern Colorado received only 25% of normal precipitation.

“The month of May brought significant rainfall to the northern and eastern portions of the Missouri River basin, resulting in slightly above average runoff in May,” said John Remus, chief of the Missouri River Basin Water Management Division of the U.S. Army Corps of Engineers.

“The discharge was higher than predicted last month.”

May runoff for the Basin above Sioux City, Iowa, was 3.5 million acre-feet, 104% of average. The annual runoff forecast over Sioux City, Iowa is 21.0 MAF, 82% of average, and 1.8 MAF higher than last month’s forecast.

“While rainfall has brought relief to some parts of the basin, drought conditions remain a concern as we enter the summer months. Very little rain fell in the western part of the basin last month. As we enter the summer months, we will continue to serve all purposes authorized by Congress as we deal with the ongoing drought,” Remus said.

Currently, 31% of the catchment is experiencing abnormally dry or drought conditions, with the drought outlook showing continued drought through the end of August. Soil moisture is below normal in Montana, North Dakota, eastern Wyoming and Colorado and near normal in South Dakota and northern Nebraska.

System storage is currently 55.0 MAF, 1.1 MAF below the top of the multi-use transfer zone. In May, system storage increased by 1.0 MAF. The improved forecast and increased storage in the reservoir system indicate that navigation flow support for the second half of the sailing season will be higher than previous forecasts.

“The June 1 reservoir studies indicate that navigation flow support for the second half of the sailing season will be reduced to 1,000 cubic feet per second under full service,” Remus said.

“However, the official navigation power support level for the second half of the navigation season will be based on the July 1 system storage check.”
The condition of the basin and rivers is continuously monitored and system regulation will be adjusted based on the most current information.

Mountain snow package:
Mountain snowpack was below normal all season and peaked about a week earlier than normal. However, additional late-season storms have extended the expected snowmelt season and increased the total expected volume of snowmelt. As of June 1, 56% of the annual peak remains in the range above Fort Peck Dam, and 74% of the annual peak remains in the range from Fort Peck Dam to Garrison Dam. The mountain snow pack peaked in the range above Fort Peck on April 9 at 73% of average, while the mountain snow pack in the range from Fort Peck to Garrison peaked on April 10 at 82% of average. The snow cover in the mountains normally reaches its peak around April 17. The mountain snowpack images can be viewed at: http://go.usa.gov/xARQC.

Navigation:
Gavins Point Dam releases will continue to provide navigation flow support at a rate of 500 cubic feet per second under full service at all four target locations (Sioux City, Omaha, Nebraska City and Kansas City) through the first half of the navigation season, ending in July 1. The current forecast indicates that flow support of 1,000 cfs below full service time will be provided for the second half of the sailing season and that flow support may be provided for the entire sailing season ending December 1 at the mouth of the Missouri River .

Fort Peck flow test:
Test releases from Fort Peck to assess the potential benefits of alternative management scenarios for pallid sturgeon began April 26 and will be completed by September 1. The test includes two higher flow periods, late April and June, with target flows at Wolf Point, Montana. The first peak in emissions was completed in early May with peak flows of 18,000 cfs in Wolf Point, Montana. Emissions were reduced to 10,000 cfs by May 10. The second peak is expected to begin in mid-June with peak flows of 22,500 cfs. The test releases will not affect the river stages below Gavins Point Dam. The flow test has been extensively coordinated with local stakeholders and was discussed in depth at a public meeting in Poplar, Montana on March 28, 2024.

The US Army Corps of Engineers will host weekly virtual meetings during the flow test to keep the public informed of test progress and planned operations. Information about accessing the public meetings can be found at https://www.nwd.usace.army.mil/MRWM/Public-Meetings/Meetings. The June calls will be held on June 5, 12, 19 and 26 at 1:00 PM Central (12:00 PM Mountain).

A number of monitoring activities will be conducted during the flow test, including fish monitoring, lidar and aerial photography, physical surveys, cultural resource surveys and water quality sampling. Interested parties can also provide information through a web-based application found at https://hydroviz.ca/fort-peck-feedback.

Monthly conference calls on water management:
Water management calls include an update from the National Weather Service’s Missouri Basin River Forecast Center and an update on the operation of the Missouri River main reservoir system. The next call for 2023 will take place on Thursday 6 June. All calls are fully recorded and available to the public on our website at https://go.usa.gov/xARQv.

Reservoir forecasts:
Gavins Point Dam
o Average releases last month – 25,300 cfs
o Current release rate – 29,000 cfs
o Expected release rate – 29,000 cfs
o Reservoir level at end of May – 1206.0 feet
o Expected reservoir level at end of June – 1206.0 feet
o Comments: The Gavins Point release will be modified to provide navigation flow support on the lower Missouri River.

Fort Randall Dam
o Average releases last month – 21,100 cfs
o Reservoir level at end of May – 1355.4 feet
o Expected reservoir level at end of June – 1355.0 feet
o Comments: Emissions will be adjusted as necessary to maintain the desired reservoir height at Gavins Point and to support emissions from Gavins Point.

Big Bend Dam
o Average releases last month – 18,700 cfs
o Expected average release rate – 25,400 cfs
o Projected reservoir level – 1421.0 feet

Oahe Dam
o Average releases last month – 17,700 cfs
o Expected average release rate – 26,100 cfs
o Reservoir level at end of May – 1603.0 feet (increased 0.8 feet as of April 30)
o Expected reservoir level at end of June – 1603.0 feet

Garrison Dam
o Average releases last month – 19,600 cfs
o Current release rate – 21,000 cfs
o Expected release rate – 22,000 cfs
o Reservoir level at end of May – 1837.8 feet (an increase of 25 feet from April 30)
o Expected reservoir level at end of June – 1841.4 feet
o Comments – Releases will be maintained at 22,000 cfs through mid-September.

Fort Peck Dam
o Average releases last month – 11,400 cfs
o Current release rate – 10,000 cfs
o Expected average release rate – 15,200 cfs
o Reservoir level at end of May – 2231.6 feet (increased 0.3 feet as of April 30)
o Projected reservoir level at end of June – 2230.7 feet
o Comments: Releases will be adjusted in accordance with the Fort Peck flow test.

The predicted reservoir discharges and elevations discussed above are not final. Additional precipitation, lack of precipitation, or other conditions can cause adjustments in reservoir release rates.


Hydropower:
The six main power stations produced 715 million kWh of electricity in May. Typical energy generation for May is 790 million kWh. The plants are expected to generate 8.7 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, visit 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







Date of recording: 06.04.2024
Date posted: 06.04.2024 15:28
Story ID: 473032
Place: OMAHA, NEBRASKA, USA






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