Sacramento River - Dams and Water Use

Dams and Water Use

In the late 19th century through the 20th, California experienced an economic boom that led to the rapid expansion of both agricultural and urban infrastructure. The Central Valley was becoming a heavily developed irrigation farming region, and cities along the state's Pacific coast and the Sacramento and San Joaquin rivers were growing rapidly, requiring ways to manage the river's water to prevent flooding (and resulting economic loss) on one hand, and to ensure a consistent supply of it on the other. The U.S. Army Corps of Engineers and the state of California completed reports as early as the 1870s and 1880s that detailed the geography and water supplies of the Sacramento, Feather, Yuba and Bear rivers.

Back in 1873, Colonel B.S. Alexander of the Army Corps of Engineers had written in his surveys of the Central Valley's hydrology and irrigation systems of a great network of pumps and canals that would take water from the water-rich Sacramento River basin into drought-prone South and Central California, especially the San Joaquin Valley. The Sacramento River is often said to receive "two-thirds to three-quarters of northern California's precipitation though it has only one-third to one-quarter of the land. The San Joaquin River watershed occupies two-thirds to three quarters of northern California's land, but only collects one-third to one-quarter of the precipitation."

During the Great Depression in the 1930s, the first plans for statewide water engineering projects emerged backed by first the Californian, then the United States government. The California State Water Project and Central Valley Project both began their rise to reality during this period. Both began as brainchilds of the state government, but because of lack of funds, the construction work and costs were shifted to the federal U.S. Army Corps of Engineers and U.S. Bureau of Reclamation. As the construction of dams, power plants and canals required immense labor, which was rare in the middle of the Depression, the government authorized Sacramento River dams and other structures as public works projects beginning in 1935.

Construction of Shasta Dam, the main dam on the Sacramento, started in 1938 and was completed in 1945. Capable of absorbing enormous flood flows and storing the water for use in prolonged drought as well as navigation and electricity generation, it gave inhabitants of the Sacramento Valley nearly complete control over the whims of the river. In the following decades, more dams–huge dams hundreds of feet high and capable of storing millions of acre-feet of water–were constructed on the Sacramento's main tributaries: the Pit, Feather and American. Folsom Dam, Oroville Dam and New Bullards Bar Dam, built in the 1950s and '60s for both the State Water Project and the Central Valley Project, are among the most important. With a firm water management system in place, the Sacramento River's flow was thus regulated and a highly controlled regime of irrigation and water diversions was able to begin.

Part of the purpose of constructing dams on the Sacramento was to regulate flows for irrigation agriculture purposes. After the river's flow was under control, two major canals serving the western side of the Sacramento Valley – the Tehama-Colusa and Corning Canals. Both starting at the Red Bluff Diversion Dam on the Sacramento, the two canals are 111 mi (179 km) and 21 mi (34 km) long respectively, and divert a total of over 3,000 cubic feet per second (85 m3/s) from the river to serve some 100,019 acres (404.76 km2) of land. A third major canal, the Sacramento River Deep Water Ship Channel, exists not for irrigation purposes but rather to facilitate navigation of large oceangoing ships from the Delta to the city of Sacramento. Built by the Army Corps of Engineers, the canal is 43 miles (69 km) long and is maintained to 30 feet (9.1 m) deep.

In 1959, construction began on the final link for the Sacramento-San Joaquin River water system, the California Aqueduct. A series of dams, dikes, channels and pump plants was constructed in the Delta to facilitate water flow from the Sacramento into this huge man-made river, which can carry up to 5,834 cubic feet per second (165.2 m3/s) of water. From its origin at the Delta the canal runs some 444 miles (715 km) southwards through the west side of the San Joaquin Valley, providing irrigation water to farmlands along its length. The remainder is then powered over the Tehachapi Mountains via a 3,000-foot (910 m) pump lift. The Aqueduct's waters, which functionally extend the Sacramento River southwards, then run on to serve the enormous populace of California's south, supplying the needs of some 22 million people.

Over the years, several other plans materialized to take water from other drainage basins into that of the Sacramento to bolster the river's petering discharge. A successful one was the Trinity River diversion, which sent over 90 percent of the flow of that river into the Sacramento through a tunnel under the Klamath Mountains. Because of resulting ecological destruction and fish kills, less water is diverted today than a few decades ago. Others failed to take root – one of the most notorious, the Klamath Diversion, proposed to send the entire flow of the Klamath River into the Sacramento Valley through a complex system of reservoirs, canals, flumes and tunnels. Similarly, the Dos Rios Dam project would have diverted almost the entire flow of the Eel River to the Sacramento. Both projects were defeated by locals' and environmentalists' opposition, as well as, for the former, staggering costs.