Lower White River Countyline Levee Setback

Herrera led analysis and design of this King County project that removed over 4,000 feet of an existing levee and built a setback levee over a mile long, reconnecting 120+ acres of historical floodplain area to the White River near the King/Pierce County line. The former levee prevented floodplain habitat connectivity for nearly a century and offered minimal flood protection to nearby developed areas. This project reduces flood risks for commercial, agricultural, and residential land uses while restoring habitat functions for endangered salmon and many other fish and wildlife species. Herrera completed analysis, alternatives development, design, permitting, and construction support services. The design was complicated by the fact that the White River deposits huge amounts of cobble and gravel in the project area. Herrera co-designed the project with County staff, with responsibility for large wood structures, which include a 5,000-foot biorevetment fronting the setback levee, construction access and in-water work area isolation, and revegetation of nearly 18 acres of the site. This is among the largest-scale riverine project sites Herrera has helped to design.