[8] In 1995 a review of coho south of San Francisco Bay found coho restricted to only one remnant population in Waddell Creek, one small naturalized (hatchery-influenced) population in Scott Creek and a small hatchery-maintained, non-native run in the San Lorenzo River, all in Santa Cruz County.

Historically, coho were found in approximately 50 coastal drainages in San Mateo and Santa Cruz counties, but by the 1960s spawning runs were limited to 11 stream systems.

The 1995 combined average annual spawning population of native and naturalized coho salmon in Waddell and Scott Creeks was estimated at only 50–60 adults, comprising only 1.5% of the estimated abundance of coho salmon south of San Francisco Bay in the early 1960s.

[8] The upper stream banks are in the coast redwood (Sequoia sempervirens) belt of the Santa Cruz Mountains while the lower stream banks are lined by red alder (Alnus rubra), big-leaf maple (Acer macrophyllum), California buckeye (Aesculus californica), Pacific madrone (Arbutus menziesii), California laurel (Umbellularia californica), and, in the lowermost portion, by willows (Salix spp.).

californicum), white alder (Alnus rhombifolia), black cottonwood (Populus trichocarpa), California nutmeg (Torreya californica), and coast Douglas fir (Pseudotsuga menziesii var.