Peripheral Canals: Way Past, Past, and Present

Comparing Export Strategies
Courtesy of Public Policy Institute of California.

Since the inception of statehood in 1850, redistributing water from northern to southern California has intrigued social visionaries, planners, and engineers..

The image at right outlines the basic alternatives for obtaining water supplies from the Delta: sending water through the Delta; a single peripheral canal to move water around the Delta; and two canals to accomplish the same end. C-WIN supports none of these options. We maintain that regional self-sufficiency in water use, including conservation, recycling and stormwater capture are a far more effective, sustainable, resilient, and cheaper strategy than horrendously expensive and environmentally destructive conveyance systems. 

The "peripheral canal" concept has been around since the 1940s. Municipalities in the south state and irrigators in the San Joaquin Valley wanted access to water that didn’t have to pass through the Bay-Delta estuary prior to delivery. Their rationale was simple: water quality upstream of the Delta is far higher than water obtained directly from the Delta.

Virtually all Delta diversions are environmentally destructive. By removing water from the tidal estuary, diversions kill fish directly and harm the nurseries of a wide range of aquatic species. These negative impacts encompass the entire Delta and extend westward to Suisun Bay and its encompassing marshlands.

Canal alignment around the Delta, 1946.

Courtesy of US Bureau of Reclamation, Central Valley Basin: Our Rivers: Total Use for Greater Wealth, Senate Document 113, 1946. Click to enlarge.

The idea of a conveyance system around the Delta originated with the U.S. Bureau of Reclamation. It was promoted as a means for diverting high-quality water from Sacramento Valley rivers to south Delta pumps, incidentally irrigating San Joaquin Valley lands en route. As indicated on the map at left, a proposed Folsom-Newman Canal would divert water from the American River near Folsom Dam, and a "Hood-Clay Pump Canal" would divert Sacramento River water in the north Delta to the Folsom-Newman canal. The combined water would flow by gravity south to a point on the Delta Mendota Canal near San Luis Reservoir.

Further east, a "Folsom-Ione Canal" would take water from Folsom Lake to a conceptual "Ione Reservoir" on the Mokelumne River. An Ione-Mendota Canal, would then leave the Ione area, and pick up additional water from a proposed Cooperstown Reservoir on its way to the Mendota Pool (where the Delta-Mendota Canal ends). The Folsom-Newman canal would be joined to the Ione-Mendota canal by an Elliot-Wallace pump canal. All of this water would not enter the Delta until after it had irrigated eastern San Joaquin Valley lands and drained into the Mendota Pool and various San Joaquin River tributaries.

A Peripheral Canal alignment, 1978

Peripheral Canal alignment, 1978
Courtesy of California Department of Water Resources, Bulletin 76: Delta Water Facilities, 1978.

In the 1960s and 1970s, another canal was proposed, one  that would divert the Sacramento River at Hood around the "periphery" of the Delta region. This canal would have been about 43 miles long and would have delivered canal water directly to the state and federal pumps near Tracy. The 1982 design for the canal would have enabled it to carry 15,000 cubic feet of water per second.

The "release points" designated on the plan would enable the Department of Water Resources to provide water from the canal into existing channels of the Delta to address flow needs for salmon migration and water quality and water level concerns. This required the public to trust DWR and its contractors to protect fish and water quality – a situation analogous to trusting the fox to protect the henhouse. Instead, the issue went to the voters for final disposition.  Subsequently, a public referendum (Proposition 9) supporting the legislature's approval of bonds for  the  canal was defeated in June 1982 by a vote of 63 to 37 percent of the electorate.

At the time, some observers of California water politics believed the peripheral canal was dead. It was not.

CalFED's "isolated conveyance facility" alignment, 1998

CalFED Alternative 3 1998.jpg
Courtesy of the CalFED Bay-Delta Program.

By 1998, the CalFED Bay Delta Program developed three alternatives for moving water through or around the Delta, including a so-called"isolated conveyance facility." This plan called for a canal smaller in capacity than the original peripheral canal (around 5,000 cubic feet per second). The CalFED plan also included an ecosystem restoration plan, a multi-species habitat conservation plan, a levee repair strategy, reservoir planning studies, an ambitious science program to study Delta estuarine and river systems, a water transfer program, an "environmental water account" program to mitigate export pumping losses of fish and of water to contractors, and programs for water use efficiency and drinking water quality. This plan failed to receive sufficient funding, and (with the exception of the science program) essentially has been retired.

Next: Bay Delta Conservation Plan