The Big River is a coastal watershed located in Mendocino County, and drains 180 square miles before entering the Pacific Ocean 10 miles south of Fort Bragg at Mendocino Headlands State Park. The Big River watershed borders the watersheds of Russian Gulch and the Noyo River to the north, the Eel River and Russian River to the east, and the Little River, Albion River, and Navarro River to the south. A diverse range of forest stewardship occurs within its headwaters, spanning the virgin redwoods of Montgomery Woods State Reserve, as well as Jackson Demonstration State Forest, Conservation Fund and Mendocino Redwood Company. The lower reaches of the river pass through at Mendocino Headlands State Park’s Big River Unit. Over three-quarters of the watershed is privately owned and the dominant land use is timber harvest. The river provides wildlife habitat including cold freshwater habitat for fish migration and spawning.
Big River is included on the federal Clean Water Act list of impaired water bodies due to excessive sediment and high temperatures. Coho salmon in the Big River watershed are state and federally listed as endangered; Chinook salmon and steelhead are federally listed as threatened. Preventing the extinction of coho salmon means restoring many key habitat attributes within the Big River watershed that are in poor condition.