The Lagunitas Creek Watershed (LCW), located in west Marin County, California currently supports California's largest wild population of Central Coast coho salmon and at least its second largest population of steelhead trout. It has been identified as one of the most important waterways left for wild California coho, federally listed as endangered. Local impacts on this population mirror the global impacts facing salmonids around the world. As their natal watershed vanishes, so do these coho, the steelhead trout, red-legged frogs, freshwater shrimp, and all the creatures that depend on a healthy watershed.

Estimates of the annual coho and steelhead population in the Lagunitas Creek Watershed were 6,000 about sixty years ago. Now the annual population of coho averages 500 spawning fish, less than 10% of their historic numbers. Lagunitas Creek Watershed coho, though greatly reduced in numbers, represent 10 to 20% of all wild California coho surviving today. This watershed is also the home of threatened steelhead trout.

Despite the endangered status of these fish and the importance of the Lagunitas watershed in recovering coho salmon statewide, human impacts still threaten the habitat - and the species here. Over 50% of the habitat has been lost since the 1940s, due to dam-building and other barriers to migration. Two major dams (Peters on Lagunitas Creek and Seeger's on Nicasio Creek, built to create reservoirs that provide the majority of drinking water for Marin County) have reduced available habitat to salmonids by almost 50 percent. Spawning and nursery habitat for salmonids has been greatly reduced in the LCW through the creation of barriers that block migration. Destruction of habitat due to development and land use practices continues.

Thus, the need to restore and make all other potential habitat available for LCW salmonids is critical. The loss of habitat is considered to be a major impediment to salmonid restoration in LCW. Even on the creeks unfettered by these major dams, road culverts impede upstream migration into tributaries. Some of the barriers hinder adult fish returning to spawn in tributaries, and others prevent juvenile fish from entering the calmer waters of the tributaries to find refuge from the rushing waters that come with winter storms.