Riparian Enhancement & Knotweed Control 2023

The Hood Canal Summer Chum Riparian Enhancement and Knotweed Control Project is a restoration project focused on eight Hood Canal Summer Chum river basins, with the goal of restoring the structure and function of native riparian plant communities. The riparian zone is defined as the transitional area between terrestrial and aquatic ecosystems, including the active floodplain, riverine wetlands, terraces and adjacent upland that directly contribute organic matter to the active channel or floodplain. According to WDFWs Riparian Ecosystems, Volume 2: Management Recommendations (2020), riparian buffer widths for Type 1 or the equivalent Type S streams shoreline of the state, should be a minimum of 215-225 feet from the active channel based on one 200-year site-potential tree height (SPTH). This project will restore degraded riparian habitat, through replanting with an emphasis on conifers and fast growing shade producing deciduous trees and shrubs; and the survey and treatment of the invasive knotweed complex (polygonum spp.).

The goal of this two-year project is to restore the structure and function of native riparian plant communities to create resilient riparian ecosystems in a changing climate. The project does not seek to restore riparian environments identical to pre euro-American settlement (Prior to 1850s), rather the project seeks to restore the structure and functions of those original plant communities that will sustainably provide critical habitat for Hood Canal Summer Chum during their freshwater stream environment life stage. The desired future structural conditions include: riparian forests dominated by conifers; large live and dead standing trees; wide within-stand range of tree sizes and spacing; shade producing canopies; understory of tree seedlings, shrubs, and herbs; multilayered canopy; and numerous large logs on the forest floor and stream environment. The desired future riparian functions include: large durable woody debris recruitment, stream shading and stream temperature regulation, forest and understory tree regeneration, modulation of low and high flow events, interception and infiltration of surface water, bank stabilization, and nutrient inputs into the aquatic food web. This project will benefit Hood Canal Summer Chum, specifically during the spawning, egg incubation and emergence life stages; but will also benefit Puget Sound Steelhead, Puget Sound Chinook, and other salmon species such as coho and pink (odd year).