A four-member panel assembled by the Corps issued a 99-page report this week citing “climatic extremes” that appear to be getting “bigger and more frequent.” The group added the Corps was not negligent in its duty to manage the flood.
The panel of hydrologists from across the country called for updated flood probability models and procedures. It did not cite climate change as a factor, saying the issue was “beyond the scope of this report.”
According to the corps, record floods on the Missouri River last summer caused $630 million in damage to the levees, dams and channels built to control the river. The corps manages the 2,341-mile-long river, which flows from Montana through North Dakota, South Dakota, Nebraska, Kansas, Iowa and Missouri.
The flood was "the largest of the period of record in terms of runoff volume, and it stressed the mainstream reservoir system and its operators as never before. Many people were dismayed that such a damaging event could occur, in spite of the flood control reservoir system."
The panel blamed most of the problems on high levels of runoff due to above average snowfall and rainfall in May over much of Montana that exceeded 300 percent of normal. Neither the Corps, or other forecasting groups, predicted the runoff.
The agency is bound to strict protocols contained in its master manual to manage the river, which forced the release of water from full upstream reservoirs leading to downstream flooding.
The panel called for a review of storage allocations to include plans accommodating high levels of water like those experienced in 2011.
The corps is required to keep water in upstream reservoirs it manages for eight competing uses: flood control, irrigation, navigation, hydroelectric power generation, water supply, water quality, recreation, and fish and wildlife enhancement.
Flood control requires leaving reservoirs as empty as possible, while the other uses, like recreation, necessitates water be kept in the reservoirs.
Other panel recommendations included improved monitoring of pending snowmelt in plains states, mimicking that conducted in the northern Rocky Mountains that feed the river.
Any changes in the Corps’ master manual could require new federal legislation. The last time the master manual was thoroughly updated was in 2004 when it took 14 years and cost $33 million to complete.