Historical Influences
"GOLD!” discovery in the late 1840s marked the start of drastic changes in the Trinity River and its watershed. Small-scale placer mining, like panning and sluicing, was mostly replaced by more efficient hydraulic and dredger mining by the early 1900s and continued through the 1950s. From the beginning, miners, homesteaders and others making their living in Trinity County logged the hillsides and valleys for lumber and firewood. In the 1950s, industrial logging began in earnest. In sensitive areas of the watershed, such as Grass Valley Creek, highly erodible granitic soils were left unprotected and large volumes of sand washed into the Trinity River. Even with all of these disturbances, the Trinity River had adequate flows and habitat, and salmon and steelhead continued to return in large numbers.
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| Pre-dam Trinity River upstream of Lewiston. | Hoopa fisherman, early 1900s |
Gold dredger near Lewiston, 1950 (TCHS photo)
The Trinity River Division (TRD) of the Central Valley Project was authorized in 1955 by Public Law 84-386. In this Act, Congress directed construction of Trinity and Lewiston dams, the Clear Creek Tunnel, Whiskeytown dam, and a series of powerplants. Completed in 1964, the TRD began a decades-long era wherein up to 75-90% of the inflow to Trinity Reservoir was exported from the river each year.
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| Cofferdam impoundment near Trinity Dam marking the beginning of flow regulation in 1958. Trinity and Lewiston dams were completed in 1964. | Dedication plaque at Trinity Dam |
The 1955 Act specifically directed the Secretary of the Interior to “…adopt appropriate measures to ensure the preservation and propagation of fish and wildlife…” In spite of this intention which was based on scientific knowledge available at the time, it soon became obvious that anadromous fish populations could not be sustained with the original level of diversions.