Operators of the Missouri River mainstem reservoir system say the region is in good shape for the coming spring runoff season. The Army Corps of Engineers announced Tuesday that the system has available more than its full capacity of flood control storage.
Criticism of storage policies and environmental projects ran rampant over the last year in the wake of record flooding in the Missouri River Basin.
The Corps says spring pulses from Gavins Point Dam in March and May are not planned this year due in part to last year’s extensive flooding.
The increased releases are intended to benefit the endangered pallid sturgeon. The 2003 Amended Biological Opinion of the U.S. Fish and Wildlife Service. The opinion identified the pulses as part of the Reasonable and Prudent Alternative to avoid jeopardizing the continued existence of the endangered pallid sturgeon as required by the Endangered Species Act.
But officials say they’re ready for the upcoming flooding season.
“It’s good news,” said Jody Farhat, Chief of the Water Management Division. “Our goal following the Flood of 2011 was to evacuate all of the flood waters and prepare the reservoir system for the 2012 runoff season. We’ve met that goal and have slightly more than the full capacity of the system available.”
During the fall and winter of each year, the Corps completes the evacuation of stored flood water as part of its flood risk reduction efforts. The mild winter allowed the Corps to make higher than normal releases throughout the winter. Gavins Point releases have been set on 22,000 cfs since mid-December. Normal winter release rates are near 17,000 cfs.
System storage fell as low as 56.1 million acre feet (MAF) in late January, 0.7 MAF below the base of the annual flood control pool. However, higher than normal reservoir inflows during the month of February filled up some of the additional storage prior to March 1, the typical start of the runoff season. Runoff above Sioux City totaled 1.6 MAF in February, 153 percent of normal. This was due in part to a combination of high base flows from three consecutive years of above normal runoff and also warm temperatures which melted much of the river ice, freeing up water that usually flows into the reservoirs in March.
On March 1, system storage was 56.5 MAF, 300,000 acre feet below the base of the annual flood control zone. The annual flood control zone is the desired operating zone for the system because it allows the Corps to serve all eight congressionally authorized purposes: flood control, navigation, water supply, irrigation, hydropower, recreation, water quality control, and fish and wildlife.
“Based on what we’re seeing today, runoff from the plains and mountain snowpack is expected to be near normal this year, however conditions can change dramatically as they did last spring” said Farhat. “The most important thing for people living along the river to be aware of is the potential for rainfall driven flood events.” Historically, localiz ed rainfall driven flood events occur somewhere along the river almost every year, Farhat said.