Despite rains, drought remains in Missouri basin Despite recent rains, drought continues to plague the upper Missouri River basin. May runoff above Sioux City, IA, was less than half of normal.
"Rain improved river stages in the lower portion of the river, but upstream runoff from rain and melting snow continues to be disappointing," said Brig. Gen. William Grisoli, Northwestern Division engineer. Last month's runoff of 1.6 million acre feet (MAF) was only 48 percent of normal, the sixth lowest on record.
"The continuing drought is having profound impacts throughout the basin. The Corps has taken a number of initiatives to ease these impacts," said Grisoli. Navigation targets at Sioux City and Omaha were not met in April. Efforts to maintain steady to rising reservoir levels to aid the spring fish spawn in the Lake Oahe and Lake Sakakawea in April and May were successful. Releases from Fort Peck were reduced in late May to hold that reservoir steady in June for the spawn and also supply irrigation water below the dam. Boat ramps have been extended and relocated at each of the reservoirs to maintain access to the water. Water intakes in North Dakota and South Dakota are being closely monitored.
"We are forecasting this year's runoff will be 15.7 MAF. Under the most likely runoff scenario, the navigation season could be shortened 53 days under the Revised Master Manual and its more stringent drought conservation measures," said Grisoli. A final determination of the navigation season length will be made after the water-in-storage check on July 1. Normal runoff is 25.2 MAF.
The Corps is approaching its goal of creating at least 1,200 acres of shallow water habitat for the endangered pallid sturgeon by July 1. More than 500 control dikes have been notched and dredging operations at 24 sites from Ponca State Park on the Nebraska-South Dakota border to the mouth of the Osage River in central Missouri are complete or well underway.
Releases from Gavins Point in May averaged 27,000 cubic feet per second (cfs), compared to a long-term average of 29,900 cfs. They are currently being held steady at 30,000 cfs to avoid harming the nests of the interior least terns and piping plovers and provide for all authorized purposes later in the summer when tributary flows decline.
The mountain snowpack crested near mid-March. It peaked in the reach above Fort Peck at 84 percent of normal, and in the reach from Fort Peck to Garrison at only 75 percent of normal.
Runoff from the remaining mountain snow will continue entering the reservoirs for a few more weeks, but is well below normal. Runoff into Garrison last month was only 38 percent of normal and into Fort Peck it was only 45 percent of normal.
System storage ended May at 38.7 MAF, down 600,000 acre feet during the month. Last year at this time is was 43.9 MAF. The amount of water in the reservoirs is more than 20 MAF below normal for this time of year.
Lewis and Clark Lake will gradually fall to elevation 1206 feet msl during June.
Fort Randall releases averaged 25,7000 cfs in May. They will range from 21,000 cfs to 29,000 cfs in June as needed to maintain Lewis and Clark Lake near its desired elevation. Lake Francis Case ended May at 1355.7 feet msl, where it will remain during the summer.
Lake Oahe dropped more than three feet during May, ending the month at elevation 1578.4 feet msl. It will fall less than two feet in June, ending the month 31 feet below average. The reservoir is 10 feet lower than last year at this time.
Garrison releases averaged 15,800 cfs during May, ranging from 14,000 to 19,000 cfs. Releases were cycled from 16,000 to 19,000 cfs the last half of May to encourage the interior least terns and piping plovers to nest higher while conserving water in Lake Sakakawea during its forage fish spawn. Releases were set to 18,000 cfs at the beginning of June. Lake Sakakawea rose nearly one foot in May, ending the month at elevation of 1815.3 feet msl. It will drop less than two feet in June, ending the month 27 feet below average. The reservoir is seven feet lower than last year at this time.
Fort Peck releases averaged 10,200 cfs in May as water was moved to help maintain the level of Lake Sakakawea. Releases were reduced to 7,000 cfs in late May to hold the lake steady during June. The reservoir fell more than one foot in May, ending the month at elevation of 2203.4 feet msl. It will remain near that elevation throughout the month. The reservoir will end June 33 feet below average. Last year at this time it was 10 feet higher. The six main stem powerplants generated 764 million kilowatt hours (kWh) of electricity in May, 92 percent of normal. The forecast for 2004 energy production is 6.7 billion kWh, compared to a normal of 10 billion kWh.