Gales Creek Fish Passage Assessment and Prioritization

Washington County conducted a fish passage inventory of the culverts acting as stream crossings in the Gales Creek watershed during the fall of 2008 to identify barriers to migratory fish passage. In Oregon, a culvert is considered a barrier when it inhibits passage of migratory fish any time the stream discharge is between the 10% and 95% exceedance flow for the migration period. The inventory followed the format and methodology established during the 2006 Dairy-McKay culvert inventory (see “Dairy- McKay Fish Passage Assessment and Prioritization”, December 2006). 

Field inspections for the Gales Creek watershed were conducted on 95 culverts, 43 of which were surveyed and prioritized. Barrier determination was based on the swimming ability of juvenile cutthroat trout, using the BLM Coarse Screen Filter Version 2.2 (Appendix C) as a passage standard. Indeterminate barriers were further analyzed with FishXing 3 beta to confirm their ability to pass fish. The 52 non-surveyed culverts were identified as cross- tiles or crossings over non-fish bearing streams. Culverts identified as high priority barriers were organized in groupings based on geographic location, stream connectivity, and ease of construction.