Despite urbanization, a variety of wildlife species live in the Fanno Creek Watershed. Species most commonly observed are those that can tolerate a wide variety of habitat and the disturbance usually associated with residential and commercial development. At least 100 bird species are thought to use the watershed, including black-capped chickadees, American robins, and song sparrows. Typical mammals include racoons, opossums, and fox squirrels.
In 1999-2001, ODFW assessed the biological integrity of Fanno Creek and Ash Creek. Upper Fanno Creek is severely impaired much of the year. Ash Creek is severely impaired year round. Coho are assumed to inhabit the greater portion of mainstem Fanno Creek up to rivermile 11.5. Steelhead (winter-run) have been observed in upper Fanno Creek and Ash Creek. Cutthroat trout were observed in middle and upper Fanno Creek year round.
A 1993 Environmental Services study of benthic macroinvertebrates indicated a macroinvertebrate community low in diversity and number of organisms. Lack of suitable substrate, particularly cobble and gravel size particles, was the primary reason for the poor macroinvertebrate scores. The predominantly silt substrate in Fanno Creek limits periphyton growth, which in turn limits the food base for “scraper” organisms such as snails and caddisflies.
Fanno Creek Mainstem
Biological communities are generally limited in the Fanno Creek Mainstem subwatershed. Coho, steelhead, and cutthroat have all been observed in main stem Fanno Creek. However, data to determine abundance, productivity, and diversity is lacking. Sensitive macroinvertebrate populations are low, but present. The ODFW assessment indicates that upper Fanno Creek is only marginally impaired in the spring. Natural areas also provide habitat for many small and adaptive mammal species, many species of birds, and a number of amphibian and reptile species.
Biological communities are limited in Pendleton Creek by habitat degradation, including impassable culverts. Salmonid and trout have not been documented.
Biological communities are limited in Vermont Creek by habitat degradation stemming from urban development. In particular, road culverts severely limit fish access to much of the creek. No salmonids have been documented in the upper reaches of the creek. Macroinvertebrate production in the creek is low.
Biological communities are limited in Woods Creek by habitat degradation, including impassable culverts. Salmonids have not been documented. Only Sculpin were observed in 2001 ODFW habitat surveys.
North Ash Creek
Biological communities are limited in South Ash Creek by habitat degradation, including impassable culverts. Upper Ash Creek is severely impaired year-round. Sculpin were observed during 2001 ODFW habitat surveys, but trout have not been documented.
South Ash Creek
Biological communities are limited in South Ash Creek. Upper Ash Creek is severely impaired year-round. Unidentified trout (steelhead or cutthroat) were observed during 2001 ODFW habitat surveys, but no data on distribution or abundance are available. As mentioned above, populations are limited by habitat degradation, including impassable culverts.
Red Rock Creek
Biological communities are limited in Red Rock Creek by habitat degradation, including impassable culverts. Salmonid and trout have not been documented in the headwaters reach.