Ninety streams throughout the SF Eel River Basin were rated as salmonid refugia areas. Refugia criteria included measures of watershed and stream ecosystem processes, the presence and status of fishery resources, timber harvest and other land uses, land ownership, diversion, potential risk from sediment delivery, water quality, and other factors that may affect refugia productivity. Refugia categories were defined as:
High Quality – relatively undisturbed habitat, with the range and variability of conditions necessary to support species diversity and natural salmonid production;
High Potential – diminished but good quality habitat with salmonids present, currently managed to protect natural resources with the possibility to become high quality refugia;
Medium Potential – degraded or fragmented instream and riparian habitat, with salmonids present but reduced densities and age class representation. Habitat may improve with modified management practices and restoration efforts;
Low Quality – highly impaired riparian and instream habitat with few salmonids (species, life stages, and year classes). Current management practices and conditions have significantly altered the natural ecosystem and major changes are required to improve habitat.
Conditions were generally better for salmonids in Western Subbasin streams, where 35 of the 51 streams rated were high potential refugia areas. In the Eastern and Northern Subbasins, the majority of streams were rated medium potential.
The Western Subbasin streams with the highest quality refugia areas were located in Sproul, Indian, and Hollow Tree Creek Basins, and in the headwater tributaries of the SF Eel River.
High quality and high potential refugia areas in the Northern Subbasin are found in the Bull Creek drainage, with low quality areas in Salmon, Fish, Cuneo, and Ohman Creeks.
Eastern Subbasin streams were generally medium potential and low quality due primarily to lack of canopy, warm temperatures, and unstable geology; Dean Creek, East Branch SF Eel River, Cummings Creek, and Cahto Creek were classified as low quality refugia.
Number of streams in each salmonid refugia category in SF Eel River Basin and subbasins.