continue with no operational changes to the MKARNS. The study was completed in coordination with local, state, and federal agencies, including the U.S. Fish and Wildlife Service and the Arkansas Game and Fish Commission. The Three Rivers project consists of four construction components: a new containment structure at an elevation of 157 feet; a relief channel through the historic cutoff; removal of the existing Melinda structure; and opening the Owens Lake structure between Owens Lake and the White River. The risk of a cut-off or breach forming is caused by water elevation differences or “head differentials” that occur when one or both of the White or Arkansas rivers are above their bank during a high-water event. When one or both rivers are out of their bank, flood waters flow over land across the isthmus along several paths of least resistance. This is what causes significant erosion issues and leads to bank instability and head-cutting. If a cut-off or breach forms in the Three Rivers Study area, navigation would cease until repairs to the MKARNS could be made, causing a negative economic impact throughout a multi-state region. “The McClellan-Kerr Arkansas River Navigation System is an economic driver for the nation,” said Deidre Smith, director of the Arkansas Waterways Commission. “A recent regional impact study indicated that more than 56,000 jobs, $1.6 billion in transportation cost savings, $8.5 billion sales impact nationally, and $4 billion in Arkansas alone can be attributed to this asset on an annual basis. “On average, about 12 million tons are shipped annually. The MKARNS creates a competitive advantage for enticing industries to locate where this indispensable resource resides in Arkansas and Oklahoma, giving the states an incomparable economic development tool. The Three Rivers permanent fix is imperative to ensure
USACE PROVIDES TECHNICAL CONSULTATION TO OFFICIALS DURING MAY FLOOD BY BR ANNEN PARRISH, Tulsa District
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t approximately 275,000 cubic feet per second (cfs), the flood of May 2019 resulted in the highest releases from Keystone Dam into the Arkansas River since 1986. Though significantly smaller than the approximately 305,000 cfs release in 1986, potential impacts to downstream flood
LITTLE ROCK DISTRICT PHOTO
SOUTHWESTERN DIVISION
A long-term environmentally sustainable solution known as the Three Rivers Study, designed to ensure the continued safe use of the McClellanKerr Arkansas River Navigation System (MKARNS) and prevent long-term lost navigation recently moved closer to construction. If a cut-off or breach forms in the Three Rivers Study area, navigation would cease until repairs to the MKARNS could be made, causing a negative economic impact throughout a multi-state region. Currently the project is in preconstruction, engineering, and design. The new structures outlined in red will ensure the reliability of the navigation system and sustainability of the unique ecosystem that exists in the Three Rivers Study area.
a reliable navigation system that remains viable for generations to come.” Current structures are in place to ensure that the Arkansas and White rivers do not merge. However, USACE has spent about $23 million, since 1989, on repairs to the navigation system after each high-water event. This project will ensure the reliability of the navigation system and sustainability of the unique ecosystem that exists in the Three Rivers Study area. n
risk reduction structures caused enough concern that local officials requested the expertise of the Tulsa District of the U.S. Army Corps of Engineers (USACE). When flows on the Arkansas River below Keystone Dam reach approximately 150,000 cfs, the entire length of the Tulsa-West Tulsa Levee System is loaded. The system stretches approximately 20 miles from Sand Springs, Oklahoma, to Tulsa, and reduces flood risk for approximately 10,000 people who live or work behind the structure. As flows on the Arkansas River increased, Tulsa County Drainage District 12, which owns and is responsible for maintenance of the levee, requested assistance from the Corps of Engineers. USACE responded by providing consultation and technical advice on methods to protect the structure. “For this event, we were requested by the Levee District 12 through emergency management channels, but the Tulsa District, U.S. Army Corps of Engineers, provides continual support and technical assistance to the levee sponsors that are in the Tulsa District Levee Safety Program,” said David Sconyers, the district’s chief of Infrastructure. The district provided engineers, including geotechnical engineers, and other technical specialists who made assessments in the field during the flood. 81
