The Peripheral Canal is a recurring proposal to divert water from California's Sacramento River, around the periphery of the San Joaquin-Sacramento River Delta. It is currently proposed in the form of two tunnels to be constructed as part of the $25 billion Bay Delta Conservation Plan.
Currently, freshwater entering the Delta has to flow from the Delta Cross Channel through a maze of river channels and sloughs before entering the Clifton Court Forebay north of Tracy, where water is pumped into the California Aqueduct and the Delta-Mendota Canal. Large numbers of Delta smelt and other endangered species are killed by the pumping plants, which provide water for the aqueducts. Freshwater flowing into the Delta displaces salt water entering from the San Francisco Bay. The freshwater to saltwater gradient has shifted inland because of 5 to 7 million acre feet (6.2 to 8.6 km3) increases in the amount of water being exported each year to the Central Valley and Southern California. The proposed peripheral canal would reduce the overall freshwater flow into the Delta and move the freshwater-saltwater interface further inland, causing damage to Delta agriculture and ecosystems.
Senator Dianne Feinstein, former California Governor Arnold Schwarzenegger and current Governor Jerry Brown have all declared their support for the Peripheral Canal. However, the Peripheral Canal proposal has been criticized because it would further reduce the amount of freshwater flowing through the Delta. Farmers in the Delta are among the most opposed to the project because it would decrease the amount of water available to them for irrigation. On August 28, 2014 the United States Environmental Protection Agency commented that the plan could violate the Clean Water Act and harm endangered fish species.
Before 2015, the Bay Delta Conservation Plan had two coequal goals of habitat restoration and water supply improvement. In April 2015, the habitat restoration plan and the water supply improvement plan were separated. In effect, the 50-year guarantee to restore the Delta's environment has been dropped.
Prior to the 1940s, water was drawn from the southern end of the Delta. Since then, various groups have lobbied for the construction of a Peripheral Canal to instead draw water from the Sacramento and San Joaquin rivers to the federal aqueducts. Because of drought and other low flow issues that cause salty ocean water to flow from pumping stations which are located at the southern edge of the Sacramento–San Joaquin River Delta into the aqueducts of both the state (California Aqueduct) and federal government (Delta-Mendota Canal), aquatic environments as well as water for drinking and irrigation are contaminated. Thus, both state and federal agencies proposed a plan in 1965 for the second phase of the California State Water Project, which created a canal that would transport fresh water from the Sacramento River bypassing the delta, instead of through it.
Voters defeated a ballot initiative to build a similar Canal in 1982.
- Paul Rogers (2013-12-09). "Is Jerry Brown's Delta tunnels plan repeating the errors of high-speed rail?". San Jose Mercury-News.
- Piazza, Tamara (2012). "The Peripheral Canal: What It Means for the Delta". Delta Winds. San Joaquin Delta College. Retrieved 2013-08-17.
- Kazakoff, Lois. "The return of the peripheral canal". The Opinion Shop. SFGate. Retrieved 2013-08-17.
- Carle, David (2004). Introduction to Water in California. Berkeley, CA: University of California Press. pp. 42–43. ISBN 0-520-24086-3.
- Newton, Jim (2012-06-25). "Newton: Water ethics and a peripheral canal – Southern California needs the water, and Northern California has it. But let's not sacrifice the delta.". Los Angeles Times. Retrieved 2013-08-21.
- Matt Weiser (2014-08-28). "EPA says California’s Delta water tunnel project could violate federal law". Sacramento Bee.
- "DWR Announces Modified Preferred Alternative". Bay Delta Conservation Plan. Retrieved 8 May 2015.
- Rogers, Paul (11 April 2015). "Delta tunnels: Major changes to environmental restoration could endanger Brown's water plan". San Jose Mercury News. Retrieved 8 May 2015.
- "Peripheral Canals: Way Past, Past, and Present". California Water Impact Network. Retrieved 2013-08-17.
- Garone, Philip (2011). The Fall and Rise of the Wetlands of California's Great Central Valley. University of California Press. p. 242. ISBN 9780520266636.
- "The California Peripheral Canal: who backed it, who fought it" (PDF). California Agriculture. 1983.
- Home page for the Bay Delta Conservation Plan, which includes Peripheral Canal-like tunnels.
- The Bay Delta Conservation Plan: An Overview and Local Perspectives in Western City.
- Bay-Delta Consevation from Save the Bay.