Habitat - Fish Passage Technical Assistance
Date Published: September 1998
Number of Pages: 117
Author(s): Eric Gower, Ethan Espie, Brian Benson and Paul Sekulich
The Department of Fish and Wildlife manages over 840,000 acres, to preserve, protect and perpetuate the state’s valuable fish and wildlife resources (RCW 75.08.012, RCW 77.04.055, RCW 77.12.010). In order to maximize accessibility to these lands and other areas for all citizens, several hundred Department of Fish and Wildlife Access Areas have been constructed. Due to the increasing interest of the agency and public in factors affecting fish resources, the Salmonid Screening, Habitat Enhancement and Restoration Division (SSHEAR) initiated an inventory of all fish passage structures (e.g culverts, dams, fishways, lake screens) and unscreened irrigation diversions on agency lands. Potential habitat gain was assessed for features identified as fish passage barriers.
A priority index for order of inventory was calculated for each wildlife area according to the ranking of four separate factors: the number of estimated fish passage problems, fish species status (potential ESA listings or at-risk SASSI stock status), species mobility (resident and/or anadromous fish species), and interest (high profile fish passage issues of public concern). Based on this prioritization the Snoqualmie Wildlife Area and Region 2 Access Areas were selected for the pilot study.
Fish passage barriers alone prevented access to 4,130 square meters and 4,092,185 square meters of spawning and summer rearing habitat, respectively. These barriers were prioritized based on proportion of potential passage improvement, annual adult equivalent production potential per square meter, habitat gain, species mobility, species condition, and a cost modifier. The unscreened water diversions were prioritized based on flow, species mobility, species condition and cost.
If the Snoqualmie Wildlife Area is an indication of the problems with fish passage structures and unscreened water diversions that exist on Department of Fish and Wildlife owned or managed land, there are many corrections that need to be made on the wildlife and access areas. For example, with the Snoqualmie Wildlife Area and Region 2 Access Areas combined, 33% of the culverts (15 of 45), 75% of the dams (3of 4), 100% of the fishways (2), 67% of the lake screen structures (2 of 3) and 100% of the water diversions (1) were partial or total barriers and/or unscreened. To compliment the state salmonid recovery effort, the problem features should be corrected as soon as possible.