Stream enhancement and restoration improves habitat for refuge fish, amphibians and invertebrates. Enhancement or restoration efforts can include the addition of large woody debris and root wads to stream channels, removal of fish passage barriers (such as undersized culverts), planting streamside vegetation to increase shade, rehabilitating spawning beds, and in some cases re-establishing populations of native fish and freshwater mussels. Enhancement work benefits other stream-dependent wildlife species, including the western brook lamprey, rare amphibian species, and a large variety of aquatic insects.
Optimal stream habitat provides protective cover, improved forage, and structural diversity that create in-stream riffles and pools for anadromous fish, especially adult and juvenile salmon and cutthroat trout. Land use practices have altered many of the area’s streams and they no longer support these fish.
Stream and estuarine restoration is undertaken as a management action to restore historic ecological processes and functions to refuge streams and estuarine habitats to benefit anadromous fish populations and other stream-dependent wildlife. The Refuge restores stream habitat by re-establishing large woody debris in a fashion that mimics natural large woody debris presumed to have been historically present in the stream. Large woody debris is placed in the existing stream channels by high-line cabling or other heavy equipment where feasible, keeping impacts to streamside habitat to a minimum. Debris complexes that contain root wads are preferred as this is a more natural condition. Channel structure sometimes needs to be modified, fish barriers may need to be removed, and portions of the riparian zone may need to be restored by plantings. The Refuge has an environmental assessment for stream restoration that was signed in 2003.
The initial restoration project on the Refuge was at Headquarters Stream, with the goal of re-establishing chum and coho salmon and searun cutthroat trout, which were extirpated from this stream in the late 1940s. Restoration activities were initiated in 1997. Physical improvements consisted of removing fish passage barriers (which included a tidegate, flash board risers, culverts, and a check dam), incorporation of large woody debris and root wads within the stream, rehabilitating spawning beds, and re-establishing a chum salmon run as well as cutthroat trout. Coho salmon recolonized the stream when passage barriers were removed.
As a management tool, Willapa National Wildlife Refuge has had a reintroduction program for salmonids, including chum and coho salmon as well as sea-run cutthroat trout, since 1996. Wild sea-run cutthroat trout have been introduced to several refuge streams, starting in December 2000 and continuing on an annual basis as fish have been available. The fish are trapped incidental to salmon hatchery operations at the Naselle and Nemah River hatcheries, transported to the Refuge, and released in refuge streams. During the relocation process, fish are released in small groups along a length of the target stream, primarily in pools. Fish are placed in buckets and hand-carried to the stream site. On occasion, fresh or frozen salmon eggs are also placed in pools or broadcast as a food source for the cutthroat trout. Salmon carcasses are also received from local fish hatcheries and are placed along streams to enhance nutrient levels.
In addition, the Refuge maintains fish egg trays for egg reintroduction efforts for chum and coho salmon and conducts release of chum and coho fry. A chum restoration project was initiated in 1998 in cooperation with the Willapa Bay Regional Fisheries Enhancement Group and the Washington Department of Fish and Wildlife.