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Levees and Vegetation

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Public safety is the number one priority of the U.S. Army Corps of Engineers’ Levee Safety Program. Policies and standards, consistently applied and enforced, are critical components of the Levee Safety Program. Levee vegetation management standards are contained in Engineering Technical Letter (ETL) No. 1110-2-583 Guidelines for Landscape Planting and Vegetation Management at Levees, Floodwalls, Embankment Dams, and Appurtenant Structures, dated April 30, 2014.

Levees must be properly operated and maintained to reduce flood risk to people living and working in communities behind these levees. The Corps Levee Safety Program requires inspections be conducted to determine whether levees are being properly operated and maintained. Vegetation and other encroachments can harm the structural integrity of levees, obscure visibility, impede access for maintenance and inspection and/or hinder emergency flood-fighting operations. The minimum acceptable Vegetation-Free Zone (VFZ) is defined as including the levee itself (including any appurtenant structures) plus a corridor fifteen feet in width on either side of the levee and its appurtenant structures. If an existing project easement (real estate interest) allows for less than 15 feet, the VFZ shall be the maximum attainable within the existing real estate interest. The Corps continues to work with local sponsors to determine the best path forward for areas containing noncompliant vegetation on levees whose removal may impact endangered species. The Corps’ Engineering Research and Development Center is conducting research to further investigate the affects of large woody vegetation on levees. Any change to current Corps vegetation management policy and standards will be based upon sound engineering and science, and will not adversely affect public safety. Public safety will remain the paramount consideration.

The U.S. Army Corps of Engineers considers its levee vegetation management standards critical to flood-risk reduction project performance and reliability -- and most importantly -- public safety. The Corps also recognizes that minimizing public risk through the operation and maintenance of structurally-sound levee systems requires addressing environmental and natural resource requirements, and the rights and interests of Tribal Nations through compliance with applicable laws, regulations and treaties. The U.S. Army Corps of Engineers System-wide Improvement Framework (SWIF) policy can provide continued coverage under the PL 94-99 Rehabilitation Program while a sponsor corrects project deficiencies to include vegetation. One of two end states can result: 1) all deficiencies remedied or 2) a variance is submitted for approval. Additional information on the SWIF policy is available on the U.S. Army Corps of Engineers National Flood Risk Management Program website. The U.S. Army Corps of Engineers also continues to develop the process and standards for a vegetation variance. The ETL 1110-2-571 is being updated to address alternative vegetation management standards for a levee or portion of a levee while assuring the structural integrity and functionality of the levee are retained. A new Policy Guidance Letter is currently in the draft-review process at Corps headquarters with significant input from the public and sponsors.

Levee sponsors needing additional information about the Corps’ Levee Safety Program in the Walla Walla District can contact the district Levee Safety Program manager at 509-527-7144 or e-mail LeveeSafetyNWW@usace.army.mil.