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Plenty Of Water On Missouri For Rest Of 2018

The Corps of Engineers’ Missouri River Basin Water Management Division plans to maintain higher-than-average releases from reservoirs in the upper Missouri basin through the summer and fall. That means that operators on the lower Missouri will have plenty of water for the rest of the navigation season, which is scheduled to end December 1.

The Corps increased flows from Gavins Point Dam—the lowest dam in the string of six large upstream reservoirs—by 25,000 cubic feet per second (cfs.) above normal full service in late June. The increase was in response to the higher-than-normal runoff being forecast in the basin and the already large amount of water in storage in the resevoirs.

As downstream tributary flows recede, Gavins Point releases will be approximately 60,000 cfs., and will remain at that level for the remainder of the navigation season, depending on basin conditions, said John Remus, chief of the division. When necessary, the Corps will reduce releases and utilize the available flood-control space in the reservoirs, in order to lessen potential flooding downstream.

The Corps updated its runoff forecast for this year to 39.8 million acre feet (maf.), which is 157 percent of average.

“The updated runoff forecast reflects the melting of the above-average mountain snowpack and moderate to heavy plains snowpack, as well as above-average rainfall that fell throughout the basin over the last four months,” said Remus. The June runoff was 10 maf., which is the third-highest monthly runoff in 120 years of record.

The reservoir system storage was 67.8 maf. as of July 1, occupying 11.7 maf. of the 16.3 maf. flood control zone.

“Approximately 25 percent of the system’s flood storage remains available to capture runoff from the remaining mountain snowmelt and summer rainfall events,” Remus said. “By comparison, on July 1, 2011 [the last time serious flooding was experienced on the lower Missouri], 16.0 of the 16.3 maf. flood control zone was occupied. The current amount of vacant flood control storage provides flexibility to lessen downstream flooding should suddenly-developing large rainfall events occur anywhere in the basin.”

System storage is expected to peak around mid-July.

The six mainstem power plants generated 1,153 million kwh. of electricity in June. Typical energy generation for June is 834 million kwh. The power plants are projected to generate 13.7 billion kwh. of electricity this year, compared to the long-term average of 9.3 billion kwh.

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