"Runoff throughout the basin has been extraordinarily low," said Larry Cieslik, chief of the Water Management office. "Reservoir storage fell by 1.2 million acre feet in July. Tributary inflow into the river between Kansas City and the mouth north of St. Louis was near the lowest levels in more than 100 years. This low runoff condition means more water is required from the reservoirs to maintain the target flows."
Because of low reservoir levels due to the drought, the main stem powerplants are expected to produce nearly 40 percent less hydropower this year. To make up for the lower generation in July, the Western Area Power Administration, which markets the power produced by the dams, had to purchase more than $2.7 million worth of electricity to meet its contract obligations to utilities throughout the upper Midwest.
With no relief in sight from the dry conditions, the Oahe reservoir was expected to reach an historic low level about Aug. 11, surpassing the record set in August 2004. It is forecast to drop nearly two feet below the record elevation of 1572 feet, ending the month at 1570.6 feet.
River flows to support navigation will remain at minimum service levels throughout the rest of the 2006 season. The season length will be shortened by 44 days. Gavins Point releases during October and November will be reduced to levels that will provide significant water conservation while continuing to support downstream water intakes.
Releases from Gavins Point Dam are expected to range from 28,000 to 32,000 cubic feet per second (cfs) in August to try to meet downstream targets while avoiding harm to chicks and nests of the protected least tern and piping plover. Regulation of the reservoirs will no longer be constrained by the birds once all chicks have reached flight stage later this month.
Gavins Point reservoir will rise two feet in August.
to elevation 1207 feet above main sea level (msl). Releases averaged 26,500 cfs in July, compared to the long-term average of 33,200 cfs.
Fort Randall releases averaged 26,00 cfs in July. They were adjusted as necessary to maintain Gavins Point reservoir near its desired elevation. The reservoir ended the month at 1354 feet. It will fall nearly a foot in August.
Big Bend reservoir will remain in its normal range of 1420 to 1421 feet. Releases will be adjusted to meet hydropower needs.
Oahe reservoir fell nearly 2.5 feet in July, ending the month at 1573.4 feet msl. It has been hit hard by drought conditions over much of the central part of South Dakota, with temperatures hovering near 115 degrees for several days. It will fall about 2.8 feet in August to 1570.6 feet, 1.4 feet below its previous low level and about 32.6 feet below normal. The reservoir is three feet lower than it was last year at this time.
Garrison releases averaged 20,600 cfs during July, compared to the long-term average of 24,900 cfs. Releases will remain at their current level in early August, but will be increased later in the month as the tern and plover chicks fledge to provide some relief to the record low level of Oahe reservoir. They are expected to average 22,500 cfs in August, compared to the 24,600 cfs average. Garrison reservoir fell nearly 2 feet in July, ending the month at 1815.5 feet msl. It will continue its normal annual decline in August, falling 3 feet to 1812.5 feet, ending the month 26.6 feet below normal. The reservoir is 1.7 feet lower than last year at this time.
Fort Peck releases averaged 8,200 cfs in July, compared to the long-term average of 10,300 cfs. They will average 8,000 cfs in August. The reservoir fell 1.3 feet in July, ending the month at elevation 2204.9 feet msl. It will continue its normal summer decline in August, falling 1.9 feet and ending the month at elevation 2203 feet, about 30.7 feet below normal. It is 1.7 feet higher than last year at this time.
The six main stream power plants generated 767 million kilowatt hours (kWh) of electricity in May, only 78 percent of normal because of lower pool levels and reduced releases from the dams. The forecast for energy production in 2006 is 6.3 billion kWh, compared to the average of 10 billion kWh.