Runoff shortages challenge Corps Despite an increase in the accumulation of snow in the mountains and near normal runoff in April, dry conditions persist across the entire Missouri River Basin. Lower reservoir levels and reduced flows are expected this year.
"Runoff above Sioux City in March was 3 million acre feet (MAF), 102 percent of normal. This is the first month of above normal inflow since Dec. 2001," said Larry Cieslik, chief of the Missouri River Basin Water Management Division in Omaha. "As of April 1, the mountain snowpack was 92 percent of normal in the reach above Fort Peck and 102 percent in the reach from Fort Peck to Garrison." Normally, the mountain snowpack peaks around mid-April.
With near normal mountain snow and normal precipitation the rest of the year, the forecasted annual runoff is 20
MAF. Normal is 25.2 MAF.
"The shortage of runoff will make it difficult to maintain steady to rising pools in the upper three revivors this spring," said Cieslik. "We have not received a recommendation from Montana, North Dakota and South Dakota on how we might best regulate the system during the forage fish spawn, so we intend to balance the pool levels in the three big reservoirs to the extent possible," he said.
Releases from Gavins Point varied from 12,000 cubic feet per second (cfs) to 23,500 cfs during March as support for the navigation season began. Because the reservoirs are low, river flows will be at minimum service levels. Under the most likely runoff scenario, the navigation season will be shortened six days to make up for the additional water released this winter for downstream water intakes. A final determination of the navigation season length will be made after the water-in-storage check on July 1.
The Corps and the U.S. Fish and Wildlife Service (USFWS) are completing consultation on the Gavins Point release schedule during the nesting season of the interior least tern and piping plover. The two birds are listed for protection under the Endangered Species Act. The Annual Operating Plan released in January presented a "steady release" schedule during the nesting season. The Corps prefers a "flow to target" operation, where releases would be gradually increased throughout the nesting season to meet minimum flow targets as the tributaries dry up. This provides more certainty to meet downstream needs while simultaneously conserving more water in the reservoirs. "A final announcement on water management during the nesting season will make around mid-April after completion of our consultation with the USFWS," said Ceislik.
System storage ended March at 43.9 MAF, up 1.5 MAF during the month. Last March it was 48.5 MAF. The amount of water currently stored in the reservoirs is more than 13 MAF below average.
Releases from Gavins Point averaged 17,500 cubic feet per second (cfs) in March, compared to the long-term of 21,000 cfs. Lewis and Clark Lake will remain near its current elevation of 1206 feet msl during April.
Fort Randall releases averaged 15,100 cfs in March. They will range from 21,000 to 23,000 cfs as needed to maintain the level of Lewis and Clark Lake. Lake Francis Case ended the month at elevation 1353.6 feet msl. It will end April near elevation 1355 feet msl.
Lake Oahe rose one foot during March, ending the month at elevation 1588.2 feet msl. It will drop slightly in April, ending the month 19 feet below normal. The lake is 10 feet lower than last year at this time.
Garrison releases were gradually reduced from 22,000 cfs in March, which resulted in an average of 17,300 cfs for the month. They were increased to 18,000 cfs last week and will be hiked to 19,000 cfs near mid-month to balance the level of the upper three reservoirs. Lake Sakakawea rose 2.7 feet in March, ending the month 14 feet below normal. The lake is 5 feet lower than last year at this time.
Fort Peck releases were gradually reduced from 9,000 cfs to 4,000 cfs during March, which resulted in an average of 5,100 cfs for the month. They were increased to 6,000 cfs last week. The lake ended the month at elevation 2212.8 feet msl, up 1.7 feet. It will drop slightly in April, ending the month 21 feet below normal. Last year at this time it was 6 feet higher.
The six main stem powerplants generated 564 million kilowatt hours (kWh) of electricity in March, 82 percent of normal. The forecast for 2003 energy production is 7.8 billion kWh compared to a normal of 10 billion kWh.