Voters in the Contra Costa Water District will decide early next year whether to quadruple the capacity of five-year-old Los Vaqueros Reservoir in the hills east of Mount Diablo. The reservoir expansion would increase water reliability and improve water quality but would not provide more water for growth, water district officials insist. The environmental community — which is a factor in many East Bay elections — appears to be ambivalent so far. The project could benefit the San Francisco Bay Delta ecosystem. But some environmentalists fear the project could induce growth in the East Bay. Notably, one of the potential partners in the expansion project is Zone 7 of the Alameda County Flood Control and Water Conservation District, which provides water to Livermore and the Amador Valley — an area where the growth wars have raged for decades. In July, the water district board of directors set an advisory vote for March 2004. Directors say they will not go forward with the expansion without voter approval. Water district voters in 1988 approved construction of Los Vaqueros Reservoir, which cost the agency about $450 million. Construction was completed 10 years later and today the lake can hold up to 100,000 acre-feet of water. Expansion would increase the reservoir's capacity to as much as 500,000 acre-feet. Los Vaqueros appears to fit well in an age when damming rivers is infeasible for a variety of reasons (see Environment Watch). Los Vaqueros is located "off stream," meaning that water is pumped from elsewhere to an isolated surface storage location. The off-stream nature of the reservoir gives the operators a great deal of flexibility for filling and drawing down the lake. "An expansion project would provide improved water quality, drought reliability and a significant financial reimbursement to the customers of the CCWD [Contra Costa Water District]," states a project planning report released in May. "An expansion project would contribute to enhancing the Delta environment and contribute to Cal-Fed's goal for restoration of the Delta ecosystem." To improve water quality, operators would fill Los Vaqueros with freshwater from the Delta when flows are high and water quality is good. This water would then serve Bay Area water customers during the summer and fall, when flows into the Delta are low and the water quality is poor. Reliability would be aided by storing water at Los Vaqueros during wet years for use during drought periods, according to the planning report. The additional storage could also be used if other portions of the Bay Area's public water system were shut down because of earthquake, levee failure or a chemical spill. The potential environmental benefits are many. Reducing pumping from the Delta when flows are low would reduce the number of fish — some of which are endangered species — that get sucked into pumps. Letting more water flow during dry periods would also improve habitat conditions in the Delta and the San Joaquin River, which State Water Project pumps cause to flow uphill at times. The additional storage could also be part of an environmental water account, allowing Bay Area water agencies that rely on the South Bay Aqueduct to shut down Delta pumps for periods of time. The details of all of these benefits, however, remain uncertain because the agencies potentially involved in the project have not yet decided how to operate the reservoir. The studies completed to date provide "bookends" for how the reservoir would operate, with the different scenarios emphasizing different benefits, said Marguerite Naillon, project manager for CCWD. Operating plans will not be finalized until the water district knows who its partners will be for the project. At any rate, Naillon said, operations would be restricted by the Cal-Fed Record of Decision and CCWD board policy. Together, those ensure that the additional storage would not serve growth and — importantly for CCWD voters — would not be shipped to Southern California. "The existing reservoir is not growth inducing, and this one wouldn't be either. It's basically just timing of the diversion," Naillon said. "Nobody here in the Bay Area is concerned about water for growth. What people care about in the Bay Area is water quality and having enough water for drought." But some environmentalists are not convinced. The water district has no business asking voters to decide on an undefined project, said Mike Daley, conservation director for the San Francisco Bay Chapter of the Sierra Club. Daley said his group does not necessarily oppose expansion of Los Vaqueros. But the Sierra Club wants to see more details, including well-defined mitigation measures and a stronger assurance that the additional storage will not be additional water for new houses. "They are going to voters without a project. They haven't done an environmental impact report," said Daley. The water district might be headed to the ballot early because voters might be less likely to approve the expansion if they knew all of the potential impacts and mitigations, he charged. But CCWD officials, who have been talking with Daley and other environmentalists, dismiss his complaints. The state Department of Water Resources and the federal Bureau of Reclamation have funded about $7 million worth of studies and planning. Although there is no EIR, Naillon said much of the analysis is detailed and could easily be folded into an EIR or environmental impact statement (the federal equivalent of an EIR). As for the timing of the election, the district tried the find the point at which it had enough information but had not spent so much money on planning and studies that it was committing itself, Naillon said. A number of federal, state and local agencies will be closely watching the advisory election results. Zone 7 Assistant General Manager Vince Wong said an expanded Los Vaqueros could be "another tool in water management" for his agency. But Zone 7, which recently completed a groundwater banking agreement with the Semitropic Water Storage District in Kern County, has made no commitments to the Los Vaqueros project. "It seems to us that the cost of water supply reliability from the project might be high for us," Wong said. Still, the water quality benefits are appealing, he added. Cost is likely to become an issue at some point. The expansion is estimated to cost $1 billion to $1.5 billion. Contra Costa Water District directors say that their constituents will not pay for the expansion. In fact, the agency contends it could make money by operating a larger facility. But exactly who would pay the construction tab is unknown and depends largely on who the eventual partners are. State and federal agencies involved in the Cal-Fed effort might be interested, but money for Cal-Fed has dried up faster than the San Joaquin River below Friant Dam. The Los Vaqueros expansion is one of five surface water storage projects identified by Cal-Fed as worth pursuing. Although it is the only one of the five that hinges on voter approval, the Los Vaqueros project might be the first to actually get built. Two of the five options — enlarging Shasta Dam, and enlarging Friant Dam or building an equivalent — depend on the Bureau of Reclamation, which is short of money for water storage projects these days. And the final two options — new storage in the Delta and the long-proposed off-stream Sites Reservoir in Colusa County — would have to be built from scratch. Contacts: Marguerite Naillon, Contra Costa Water District, (925) 688-8018. Vince Wong, Alameda County Flood Control and Water Conservation District Zone 7, (925) 484-2600. Mike Daley, Sierra Club, San Francisco Bay Chapter, (510) 848-0800. Los Vaqueros website: