Water Levels Climb At Fort Peck
The elevation of Fort Peck Reservoir’s water level has climbed 2.4 feet since last month thanks to spring runoff, the U.S. Army Corps of Engineers reports.
The runoff into Fort Peck has provided water to all but the highest boat ramps, located at Hell Creek State Park, Rock Creek Fishing Access Site and Crooked Creek.
It took about 443,000 acrefeet of water for the lake to climb. An acre-foot is the amount of water it takes to cover one acre in 1 foot of water. Fort Peck Reservoir is spread across roughly 245,000 acres along the Missouri River in eastern Montana.
April flooding from the Milk River, which enters the Missouri River downstream of Fort Peck Dam, helped boost the water elevation at neighboring Lake Sakakawea, just over the border in North Dakota, by 4.5 feet, the Corps reported. The Montana water that submerged large swaths of the Hi-Line helped add more than 1.2 million acre feet of water to the reservoir.
“The runoff forecast continues to improve thanks to late season plains and mountain snowfall in the upper basin,” said John Remus, chief of the U.S. Army Corps of Engineers’ Missouri River Basin Water Management Division, in a press release. “We hope to see the precipitation trend continue to provide the much needed moisture for the region.”
Late season plains snowpack accumulation and subsequent melting led to increased runoff throughout the upper Missouri River Basin during April. For the month, runoff was 4.7 million acre-feet, 159 percent of average, for the basin above Sioux City, Iowa.
The annual runoff forecast for the upper Missouri River Basin above Sioux City is 26.9 MAF, 105 percent of average, and 0.5 MAF higher than last month’s forecast. However, soil moisture remains slightly below normal in Eastern Montana and the western Dakotas, and well below normal in Nebraska. Even with the plains snowmelt, soils dried out in late April over a large portion of the upper basin.
The Montana drought monitor shows large swaths of eastern Montana and the northwestern corner of the state in moderate drought.
The one-month precipitation outlook for the state shows the drought continuing in northwestern Montana while the temperature in eastern Montana is predicted to be below normal.
Snowpack for this time of year shows the northwestern region at only 61 percent of normal. The Smith-Judith- Musselshell and Madison watersheds are reporting the highest snowpack at 111 percent and 117 percent, respectively, with warm weather quickly melting the mountain snow. The Fort Peck reach’s snowpack peaked at 117 percent of normal on April 24 and has 88 percent remaining.
Melting snow is evident at streamflow gauges. The Missouri River at Toston was running at 12,400 cfs, compared to the average for the date of 5,950 cfs.
Flows have also climbed along the Yellowstone River drainage, with the Billings gauge reporting a flow of 15,000 cfs compared to the average for the date of 6,250 cfs. Likewise, the Clark Fork and Blackfoot rivers are running higher than average for this early in the spring.
Releases from Fort Peck Dam will be reduced from 9,000 cubic feet per second to 6,000 cfs on May 22 to allow maintenance work. Releases will be increased back to 9,000 cfs on June 2. If the maintenance work is completed early, releases will return to 9,000 cfs as soon as possible.
Maintenance at the Fort Peck powerhouse, on the power tunnel, requires Units 1, 2 and 3 to be unavailable.
“The lowered releases will not have a significant impact on reservoir elevations at Fort Peck,” said John Remus, chief of the U.S. Army Corps of Engineers’ Missouri River Basin Water Management Division. “However, downstream users, such as irrigators and water supply intakes, will need to plan for the lower releases during this period.”
Releases will be gradually increased from 6,000 cfs beginning May 6 reaching 9,000 cfs May 12, prior to the scheduled power tunnel maintenance. Then, decreased May 22 during maintenance.