Riparian Enhancement and Knotweed Control 2021

The Hood Canal Riparian Enhancement and Knotweed Control Project (21-1034) was a two-year restoration project focused on eight Hood Canal Summer Chum streams, with the goal of restoring the structure and function of native riparian plant communities. The two measurable objectives this project completed are: 1) Planting 23.4 acres of new riparian habitat with a focus on native conifers and fast growing deciduous trees and shrubs; and 2) The survey and control of the invasive knotweed complex (Polygonum spp.) on over 40 stream miles each year, July through September; for a total of two treatments over the two year project period. The project addressed historic and current anthropogenic degradation to riparian habitat along the freshwater stream environment; specifically where there is low large woody debris recruitment, high stream temperatures, low or no canopy cover, immature deciduously dominated canopies, and the presence of invasive knotweeds within the riparian zone of various watersheds across the Hood Canal.

See Final Report 21-1034 attached in PRISM for more detailed reporting including as-built maps and knotweed comparison maps showing reduction in knotweed acreage.

The goal of this two-year project was to restore the structure and function of native riparian plant communities to create resilient riparian ecosystems. 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; multi-layered 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 benefited Hood Canal Summer Chum, specifically during the spawning, egg incubation and emergence life stages; but also benefited Puget Sound Steelhead, Puget Sound Chinook, and other salmon species such as coho and pink (odd year).