PARTNERSHIP ON THE MKARNS IDENTIFIES SOLUTION TO PREVENT LONG-TERM LOST NAVIGATION

BY LAURIE DRIVER, Little Rock District

The U.S. Army Corps of Engineers (USACE) Little Rock District is moving the Three Rivers Study closer to construction. Currently, the project is in preconstruction, engineering, and design.

“We are currently working on the design documentation report and the plans and specifications for this project,” said Project Manager Dana Coburn.

The study, which was cost-shared with the Arkansas Waterways Commission, identified a long-term environmentally sustainable solution to ensure the continued safe use of the McClellan-Kerr Arkansas River Navigation System (MKARNS) and prevent long-term lost navigation.

The study area is located at the confluence of the Arkansas, White, and Mississippi rivers in Arkansas and Desha counties, focusing on 208 square miles where the rivers all meet in southeast Arkansas.

Implementation of the Three Rivers project would not alter hydrology in surrounding bottomland hardwood forests, and navigation would 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.

A long-term environmentally sustainable solution known as the Three Rivers Study, designed to ensure the continued safe use of the McClellan- Kerr 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.

Little Rock District Photo

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 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.