beginning Oct. 5 to bring to the end the shortest navigation season since the reservoirs were filled in 1967.
Depending on downstream tributary contributions, Missouri River stages will drop 4 to 5 feet from Sioux City to the mouth near St. Louis.
Despite rain storms in the latter part of September, drought conditions persist over much of the upper basin with only 78 percent of normal runoff recorded so far this year. Runoff above Sioux City, Iowa, in September was 56 percent of normal.
"There has been enough rain downstream to allow us to maintain lower releases from the reservoirs, but the dry conditions upstream have kept Oahe and Fort Peck level while second lowest runoff into Garrison contributed to it falling a foot last month," said Larry Cieslik, Chief of the Water Management office in Omaha.
Releases from Gavins Point Dam will be gradually reduced in October from the current 24,000 cfs to 9,000 cfs with the closing of the commercial navigation season. The current runoff forecast for 2005 is 19.5 million acre feet (MAF), 77 percent of normal, compared to the normal of 25.2 MAF.
The 2005 commercial navigation season is being shortened 48 days due to the low reservoirs levels caused by the protected drought.
System storage ended September at 36.2 MAF, an increase from the 35.8 MAF recorded last year at this time. The amount of water currently stored in the reservoirs is nearly 21 MAF below average.
Gavins Point reservoir will remain near elevation 1207 feet above mean sea level (msl) during October. Releases averaged only 25,400 cfs in September compared to the normal 36,600 cfs. They are being gradually reduced from 24,000 cfs to 9,000 cfs by Oct. 19, where they will be held until late November or early December.
Fort Randall releases averaged 24,200 cfs in September. They will range from 19,000 cfs to 7,000 cfs in October as needed to maintain Gavins Point reservoir near its desired elevation. Fort Randall reservoir ended September at 1345 feet msl. The reservoir will end October near 1340 feet its way to the normal Fall elevation of 1337.5 feet msl.
Big Bend reservoir will remain in its normal elevation range of 1420 to 1421 feet. Releases will be adjusted to meet hydropower needs.
Oahe reservoir remained steady during September, ending the month at elevation 1572.9 feet msl. It will rise two feet in October, ending the month 26 feet below average. The reservoir is at the same elevation it was last year at this time.
Garrison releases averaged 14,100 cfs during September, compared to the normal 21,200 cfs. They will average 12,500 cfs through October. Garrison reservoir dropped 1.5 feet during September, ending the month at elevation 1814 feet msl. It will drop 1.5 feet in October, ending the month 25 feet below average. The reservoir is a foot higher than last year at this time.
Fort Peck releases averaged 5,600 cfs in September, compared to the normal 9,200 cfs. They will remain near the current 4,000 cfs through October. The reservoir remained essentially level in September, ending the month at elevation 2202 feet msl. It will remain level in October, ending the month 31 feet below average. It is currently 2 feet higher than last year at this time.
The six main stem power plants generated 523 million kilowatt hours (kWh) of electricity in September, 56 percent of normal because of reduced releases from the dams. The forecast for 2005 energy production is 5.5 billion kWh, compared to a normal of 10 billion kWh.