California Sea Grant College Program

This study annually estimated the minimum number of spawning fall chinook along a section of the West Branch Mill Creek, a tributary of the Smith River near the California-Oregon border, from 1980 to 2002. The consistent use of one survey method along the same stretch of creek for 23 years has made it possible to link trends in salmon spawning and growth to habitat change due to changing oceanic conditions and creek flows, and to draw conclusions about the timing and number of salmon runs, the age composition of spawning salmon, and the ratio of males to females. Several groups have cited the study’s findings as objective metrics of the region’s ecological value. This information has helped to preserve old-growth redwoods around Mill Creek.