Commentary on Corps flood operations

Heavy rain and melting mountain snow have caused flooding along the Missouri River and many of its tributaries in much of Missouri, Wyoming, South Dakota, Nebraska, Iowa, and Kansas.  The pain and financial loss to individual families and businesses is wrenching.

The federal levees along the river are performing well, with 6 feet or more of freeboard common throughout the system.  However, many non-federal levees with lower levels of protection are facing risk of overtopping; some have recently overtopped or breached.

In addition to dispatching teams of experts, several million sandbags and pumps throughout the basin to support local flood fighting efforts, the Army Corps of Engineers has adjusted releases from its reservoirs to store millions of acre feet of water, preventing it from adding to the high river.  Without the reservoirs, downstream flows in recent weeks would have been approximately 80,000 to 100,000 cfs higher and river stages 4 feet to 6 feet higher.  The system is operating as designed.  

In order to be prepared for the next flood event, flood water must be evacuated as soon as downstream conditions permit.  Currently, there is 6.5 million acre feet of flood water stored in the reservoir system, with Garrison, Oahe, Fort Randall and Gavins Point in their respective flood control zones.  

Last week, heavy upstream rain rapidly filled the flood zones of both Gavins Point and Fort Randall reservoirs. On June 14, the Gavins Point level was approaching the top of the emergency spillway gates, so releases were gradually increased to 33,000 cfs while those from Fort Randall were cut significantly. The higher releases halted the rise in Gavins Point reservoir just 4 inches from the top of the spillway gates.  This was the third highest pool on record and the highest in nearly 50 years.  

We are continually monitoring the situation on the Missouri River and its tributaries as well as weather forecasts to make timely adjustments to the flows within our ability to control them and in accordance with our statutory responsibilities. Precipitation forecasts continue to show significant rainfall, particularly in the lower basin.  Our real time operations will continue to take the best available information into account and make adjustments to system flows accordingly.

The Army Corps of Engineers takes its flood reduction responsibilities very seriously and will do everything within its ability to manage the flows from its reservoirs to reduce the risk from current and future high water events throughout the system.

General McMahon is the commander of the Northwestern Division of the Army Corps of Engineers.  He oversees the operation of dams and reservoirs throughout the Missouri River basin.

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