This project’s objective was the eradication of invasive Japanese, Giant, and Bohemian knotweed in order to preserve and restore the Hoh River’s riparian forests, and to thereby maintain the ecosystem services they provide to the river. Knotweed rapidly and completely disrupts natural succession in Washington’s native riparian forests, impairing or eliminating critical habitats that support native species such as the Hoh River’s wild salmon, steelhead, and bull trout. The Hoh River watershed is famous for recreational fishing and boating, and supports tribal and non-tribal subsistence and commercial fisheries. The project covered 26 miles of the Hoh River floodplain on the Olympic Peninsula in west Jefferson County, from the point of original infestation at a homestead, downstream to the river’s mouth at the Pacific Ocean. Both sides of the river were surveyed resulting in 52 miles of riparian habitat being assessed. By the end of the project 2,500 acres had been surveyed while only 1.13 acres required treatment for invasive weeds. After 9 years of surveys and treatment, the Hoh knotweed infestation has been successfully reduced to a sparse but widely dispersed population. The majority of 108 plant sites observed in 2010 were less than 3’ in height, and only 1 to 2 stems. New plants grow from stem and root fragments, deposited by floodwaters. Data from this project also informed scientists about this species’ ecology and effectiveness of evolving control strategies, and helped to educate policy-makers, resource professionals, landowners and the public about the ability of this plant to replace native plant communities, and impact aquatic and riparian habitats.