The Trinity River begins in the rugged Trinity Alps in northwestern California. On its journey, it tumbles through steep canyons and meanders through broad valleys until it joins with the Klamath River to flow into the Pacific Ocean. This powerful river once supported large populations of fall- and spring-run chinook salmon, as well as smaller runs of coho salmon and steelhead. Floods, as predictable as the salmon, refreshed spawning gravels, scoured deep holes and provided clear, cool water. Today, as for thousands of years, the Hoopa and Yurok tribes use the fish, plants and animals in and along the Trinity River for subsistence, cultural, ceremonial and commercial purposes.

In 1958, a plan was developed to increase water supplies and generate power for California’s Central Valley in part by transferring water from the Trinity River into the Sacramento River. Completed in 1964 for these socially and economically important purposes, the Trinity River Division of the Central Valley Project (TRD) began a decades-long era wherein up to 75-90% of the inflow to Trinity Lake was exported from the river each year.

The impacts of land use and dams combined to push the river past its regenerative capacity. By 1970, less than 10 years after the dams were completed, the extent of habitat alteration and decline in salmon and steelhead populations became obvious. Intent on reversing the decline, the U.S. Fish and Wildlife Service, Hoopa Valley Tribe and other agencies began studies that culminated in the Trinity River Flow Evaluation Study. Completed in June 1999, this study is the foundation of the Trinity River Restoration Program which is designed to restore naturally-spawning populations of salmon and steelhead to near pre-dam levels.