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How the CVP Works

Power Drain: How the CVP Works

May 30, 2007

The Central Valley Project stretches 400 miles, north to south, across California, from the Cascade Mountains near Redding to the Tehachapi Mountains near Bakersfield. It is anchored by six major dams on the Sacramento, Trinity, American, Stanislaus, and San Joaquin rivers. [5] These dams alone would be enough to radically reshape the hydrology of California, but they are only the first piece of a complex water storage and delivery system.

Overall, the CVP encompasses 20 dams and reservoirs, 9 major canals, dozens of pumping plants, and 11 hydropower plants, in addition to a vast network of smaller canals, conduits, tunnels and other facilities that divert the natural of flow of water in the state to a staggering degree. [5] The volume of water carried by the CVP each year is staggering, amounting to more than 2 trillion gallons, or 18 percent of the state's fresh water supply. [6,7] The CVP is comprised of such a dizzying array of interconnected features that trying to understand how the system operates is challenging. Yet it is key to understanding how energy – and energy subsidies – power the Project...

  • Historically, 90 percent of the Trinity River's water has been diverted through dams, reservoirs, and massive tunnels bored into the Trinity Mountains. Although a recent court decision has reduced these diversions, today still more than 50 percent of the river does not flow to the North Coast as it has for millennia – but instead is rerouted into the Sacramento River. [8] Some of the rerouted water is pumped into the Tehama-Colusa, Corning, and other smaller canals that serve Colusa, Glenn, Shasta, Tehama and Yolo counties. A series of pumping stations move this water into the canals, and send it trudging along a distribution area more than 150 miles long. The remaining diverted Trinity River water flows down the Sacramento River into the Sacramento-San Joaquin Delta where it is captured by another set of CVP pumps and canals. [9]
  • The Tracy Pumping Plant on the Sacramento-San Joaquin Delta sucks massive quantities of water out of the Delta, lifts it 197 feet, and pushes it into the 117-mile-long Delta-Mendota Canal that serves irrigation water to Western San Joaquin Valley. [10] With its six pumps, each powered by a 22,500-horsepower motor, the Tracy Plant alone accounts for 46 percent of the energy used by the CVP each year for moving and storing water. [11] In late spring, when the least amount of pumping is required, the Tracy Plant pumps about 600,000 gallons of water per minute out of the Delta. At the height of summer, when the pumps are working at their maximum, the pumping rate increases to about 2 million gallons per minute. [12]
  • In addition to the federal pumping facilities in the Delta, the State of California has its own set of eleven pumps that take water from the Delta near the Tracy Plant. (The operation of these two sets of pumps, as well as certain other CVP and SWP activities, are coordinated according to an official 1986 agreement between state and federal agencies.) The water is then sent south to the Central Valley and Southern California via State Water Project (SWP) canals. The CVP and SWP pumps are so powerful that together they actually reverse the Delta's natural flow of water during certain times of the year. [11] The damage to fish in the Delta is severe. The reverse flows confuse salmon as they attempt to migrate to their spawning grounds, and the pumps suck in and kill thousands of fish each year - including endangered Chinook Salmon and Delta Smelt. In April, California's Superior Court found that the Department of Water Resources was violating the state's Endangered Species Act (ESA) and ordered the Department to "cease and desist from further operation" of the SWP pumps if it could not comply with the Act within 60 days. [13] A similar case is pending in federal court over the operation of the CVP pumps.
  • Seventy miles downstream from the Tracy Pumping Plant, an intake channel leading off the Delta-Mendota Canal feeds into the O'Neill Pumping Plant. Here, six 6,000 horsepower pumps lift water 45 feet into a reservoir called the O'Neill Forebay, where it merges with water from the California Aquaduct. Eight massive pumps lift water out of the O'Neill Forebay 297 feet into the San Luis Reservoir, the largest off-stream storage reservoir in the country. The 138-foot-wide San Luis Canal, run jointly by the State of California and the federal government, extends 103 miles southeast from the O'Neill Forebay and serves irrigation water to the Western San Joaquin Valley. At two different points along the San Luis Canal, six powerful pumps lift the water again to a higher elevation, and another eight pumps push water into the Coalinga Canal. Westlands Water District is the major CVP user of the water in both the San Luis and Coalinga Canals. [14]
  • The Friant Dam on the San Joaquin River feeds water into the 152 mile-long Friant-Kern Canal and the 36 mile-long Madera Canal that provide irrigation water to the Southern Central Valley. While this unit has fewer pumping-related concerns than other parts of the CVP, its environmental impact has been no less severe. [15] Before the Friant Dam was completed in 1942, the San Joaquin was home to a vibrant salmon fishery. Unfortunately, the dam not only blocked the salmon's natural spawning route, but massive water diversions for agriculture drained a 63-mile stretch of the river for more than half a century and prevented the San Joaquin River from actually flowing into Sacramento-San Joaquin Delta for much of the year. In 2006, an 18-year lawsuit was finally settled requiring the Bureau of Reclamation to restore at least some amount of water to the San Joaquin River year round. [16]

The Bureau of Reclamation, the federal agency that manages the CVP, often boasts of the 5.6 billion kWh of electricity that the Project's hydroelectric dams produce each year. [5] But rarely does the agency mention the vast amount of energy it takes to run the CVP's water delivery operations. Yet EWG's analysis of Bureau data shows that pumping agricultural water around the CVP consumes almost 1 billion kilowatt-hours of electricity each year. [3,4]

For accounting purposes, the Bureau of Reclamation breaks down this energy usage into three different categories: water storage, water conveyance, and direct pumping. [3] It might seem counterintuitive to need electricity for water storage, as we typically think of dams and reservoirs being used to generate electricity rather than consuming it. But, as in the case of the San Luis Reservoir, if a reservoir is located off-stream and uphill from a canal, getting the water into the reservoir takes energy. The basic laws of physics dictate that not all of this energy can be recaptured when the water is later released and used to power turbines. Water storage accounts for about 21 percent of total CVP energy use each year. [3]

The terms conveyance and direct pumping are also confusing. Both refer to the energy required to move CVP water from its source - either the Sacramento-San Joaquin Delta or one of the CVP's many reservoirs - to its ultimate destination. The difference is that conveyance-related pumping, which accounts for 64 percent of CVP energy usage, moves water to a group of downstream users. Direct pumping, on the other hand, serves just a single water district or contractor. It accounts for 25 percent of power use in the CVP each year. [3]