Walker Creek is a year-round perennial stream in Marin County that flows approximately 21 kilometers (13 miles) from the Soulajule Reservoir through rolling hills and steep terrain before reaching Tomales Bay and eventually the Pacific Ocean. This moderate to high-gradient creek drains approximately 76 square miles of primarily rural watershed, with over 90% of the land privately owned for ranching and agricultural uses. The riparian woodland along the mainstem provides critical habitat for federally protected salmonids. While the watershed once supported abundant runs of salmon and steelhead—with historical accounts describing fish so numerous they made crossing difficult during spawning season—the population has been greatly reduced due to the construction of Soulajule Dam and intensive land use practices. However, ongoing collaborative conservation efforts among landowners, resource agencies, and conservation groups have resulted in significant habitat restoration and notable increases in fish abundance in recent years.