Dam Safety

Corps says Arkabutla Dam failure not imminent

Corps says Arkabutla Dam failure not imminent
(photo courtesy U.S. Army Corps of Engineers)

The U.S. Army Corps of Engineers (USACE) Vicksburg District teams are assessing conditions and exploring temporary solutions at Arkabutla Dam after a May 8 emergency declaration, but dam failure or breach are currently not imminent.

Constructed in 1943, Arkabutla Dam is 65 feet high and 10,000 feet long and reduces flood risk for 19,000 residents. The dam protects $510 million in homes and businesses. The district’s Emergency Operations Center (EOC) activated after crews discovered a depression near the toe of the dam, where the dam meets the earth, which could cause severe foundation loss and a breach if left untreated.

USACE defines an imminent breach as: “the emergency level when time has run out, and the dam has breached, is breaching, or is about to breach. It is not usually possible to determine what amount of time a complete breach will take to develop. Therefore, once a decision is made that there is no time to prevent a breach, the emergency warning must be issued.”

The district continues to release water from the dam to achieve an elevation of 210 feet by about June 20, which will significantly decrease the risk of a failure. The controlled release reduces flood risk for surrounding low-lying areas and homes.

Dam releases flow into the Coldwater River, which is expected to crest at Sarah and Marks, Miss., early this week. Sarah will crest at 12 feet and Marks at 34 feet. The district expects stages to remain at crest stages through at least the next few weeks. The district will monitor conditions based on future local rainfall and length of time releases are required from Arkabutla.

Current Interim Risk Reduction Measures (IRRM), or temporary solutions, include structural modifications, increased instrumentation and monitoring, and emergency action planning. The district continues to assess the repairs timeline and will provide updates as they become available.

The USACE Vicksburg District encompasses a 68,000-square-mile area across portions of Mississippi, Arkansas and Louisiana that holds nine major river basins and incorporates about 460 miles of mainline Mississippi River levees.