This summer, another huge ice shelf broke off the north polar ice cap and began drifting out to sea. The event made world news because it added to the mounting, tangible evidence of a phenomenon that the Bush administration ignores but that California’s government cannot afford to dismiss: Climate change.

The effects of climate change — including rising sea levels and associated coastal flooding, the need for new and better levee systems inland, and greater extremes in wet and dry years — could affect many parts of daily life. But perhaps the most immediate effect for California is on the state’s water supply — not necessarily to the quantity because overall precipitation will not necessarily decline, but to storage and management of that supply.

Water planners are grappling with the storage issue right now, according to Doug Osugi, water resource engineer with California’s Department of Water Resources. Osugi’s agency is in the middle of its mandatory, five-year update of the California Water Plan – a toothless but important informational tool that tells legislators of the status of this fundamental natural resource. For the first time since the plan was initiated during the 1950s, climate change has been elevated to chapter status in the plan, signaling the recognition among water experts that this emerging variable needs to have a part in the water supply calculus.

“The primary change that the data is showing is a gradual decrease over the last 100 years of April through July runoff” says Osugi. “Other data indicate a corresponding increase in winter runoff.”

In other words, more of the state’s precipitation is falling as rain, and less is coming down as snow. Ramifications of this shift in precipitation have big implications for the ways we store water.

“Historically, California has been able to rely on snowpack to serve as a kind of storage system, delaying that precipitation that falls as snow from reaching downstream reservoirs until summer months, when reservoir capacity is more available, ” explained Jeff Loux, director of Land Use and Natural Resources at University of California, Davis Extension, and an expert in water planning. “Statewide, we are currently short of storage,” said Loux, who pointed out that when reservoirs are full, water is sent out to sea because there is no place to store it.

The state of the art water management technique is conjunctive use of groundwater and surface storage supplies. “With conjunctive use, we can rely on surface water when it is available, and then switch to groundwater when reservoirs lower,” Loux said. But conjunctive use on a massive scale will require complicated new infrastructure and monitoring systems to carry out the difficult task of replenishing and withdrawing groundwater without long-term negative impacts. Detailed adjudication agreements amongst users will almost certainly be required, too.

Concerns about adequate holding supply have always driven new surface storage projects. New dams, however, are politically unpopular and difficult to get permitted. Nevertheless, there are a handful of new generation reservoirs that either have or are soon to come on line. These include a planned expansion to Los Vaqueros Reservoir in Contra Costa County (see CP&DR Public Development, August 2003), and the massive new Diamond Valley reservoir the Metropolitan Water District is filling in Riverside County. These newer reservoirs are called “off-stream” storage, and essentially function like huge bathtubs. Unlike traditional dams, which also generate hydroelectricity, off-stream reservoirs do not lie along main river branches. Instead, water is piped in from one or more sources to an isolated facility. In wet years, excess water can be stored in off-stream reservoirs to free up on-stream capacity.

Desalination is another potential supply solution (see CP&DR Trends, February, 2002). However, some areas with the fastest growing thirst, such as San Bernardino and Riverside counties, are a long way from the ocean.

Finally, there is the once taboo area of agriculture-urban water transfer. Agriculture remains the state’s biggest water user, consuming between 75% and 80% of supply, a figure that makes transfers appealing. But further reliance on water transfers has many planners wringing their hands because the practice may accelerate the demise of farming in California. Though agriculture is struggling with increased international competition, it remains the state’s top industry, and one with strong cultural and social qualities.

Is anyone working on the demand side?

“Not really,” said UCD’s Loux. “The assumption in the California Water Plan is that water agencies will endeavor to meet an expected continued growth in population. The good news is that the paradigm has shifted to the concept of water management versus developing new sources. But we get into this circular planning argument where conservation frees up more capacity to grow, which in turn creates more demand for water. It’s the classic vicious cycle.”

Stephen Svete, AICP, is president of Rincon Consultants, Inc., a Ventura-based consulting firm.