Corps cuts dam releases because of drought Continuing drought conditions on the plains and a disappointing mountain snowpack are setting the stage for lower reservoir levels and reduced Missouri River flows again this year. Runoff above Sioux City, IA, totaled 486,000 acre feet last month.
"January's runoff was only 66 percent of normal. As of Feb. 1, the mountain snowpack was 73 percent of normal in the reach above Fort Peck and 80 percent in the reach from Fort Peck to Garrison, essentially the Yellowstone River basin," said Larry Cieslik, chief of the Missouri River Basin Water Management Division in Omaha. Normally 60 percent of the peak snow in the mountains is accumulated by early February.
"With below normal mountain snow and normal precipitation the rest of the year, we are forecasting annual runoff to be 19.2 million acre feet (MAF)," said Cieslik. Normal is 25.2 MAF.
Support for the 2003 navigation season will begin April 1 at the mouth near St. Louis. River flows will be at minimum service levels. The Corps anticipates that the season will be shortened by five days in November. A final determination of the length of the shortening will be made after the water-in-storage check on July 1.
System storage ended January at 42.3 MAF, down 400,000 acre-feet during the month. Last January it was 48.7 MAF. "System storage is currently around 13 MAF below the average of 57.3 MAF," said Cieslik.
Releases from Gavins Point averaged 13,700 cubic feet per second (cfs) in January. They ranged from 13,000 cfs to 15,000 cfs based on weather and river ice conditions. "Because of the low reservoir levels and continued drought, we are setting releases as low as possible this winter to meet drinking water and powerplant needs while conserving water in the reservoirs. We will continue to monitor weather and river conditions to assure adequate water supply along the river," said Cieslik.
Lewis and Clark Lake, which is near elevation 1207 feet above mean sea level (msl), will gradually drop to 1206 feet msl by the end of February.
Fort Randall releases averaged 12,900 cfs in January. They will range from 10,000 to 13,000 cfs as needed to maintain the level of Lewis and Clark Lake. Lake Francis Case ended the month at elevation 1345.3 feet msl. It will continue to refill in February, ending the month near 1350 feet msl.
Lake Oahe rose 0.5 feet during December, ending the month at elevation 1585.3 feet msl. It will climb less than two feet during February, ending the month 17 feet below normal. The lake is 13 feet lower than last year at this time.
Garrison releases averaged 18,400 cfs during January. They were set at 18,000 cfs during cold weather events and then increased to 20,000 cfs near the end of the month. In February, releases will gradually be increased to 23,000 cfs as river conditions permit. Lake Sakakawea ended January at 1821.1 feet msl. It will drop two feet in February, ending the month 15 feet below normal. The lake is 7 feet lower than last year at this time.
Fort Peck releases averaged 9,800 cfs during January. They will remain at that rate during February. The lake ended the month at elevation 2212.6 feet msl. It will drop less than two feet during February, ending the month 20 feet below normal. Last year at this time it was 6 feet higher.
A planned test of modified flows from Fort Peck Dam, commonly referred to as the Fort Peck "mini-test," has been postponed due to the drought. It would have allowed evaluation of the impacts of higher-than-normal spring and summer releases from both the powerhouse and spillway. "The mini-test would include releases over the spillway to allow warmer water from the surface of the reservoir to combine with the relatively colder powerhouse releases. This will allow us to study the reaction of native river fish to the higher releases and warmer river water. Unfortunately, it is almost certain, given the pool level at Fort Peck and the anticipated runoff this spring, that the pool level will remain below the crest of the emergency spillway, making the test impossible," said Cieslik.
The six main stem powerplants generated 643 million kilowatt hours (kWh) of electricity in January, 72 percent of normal. The forecast for 2003 energy production is 7.5 billion kWh compared to a normal of 10 billion kWh.