The Future of Water
The Future of Water
This article is excerpted from the SPUR report Future-Proof Water. Read the complete report at spur.org/futureproofwater >>
For more than a century, water supply and management has been one of the most enduring and complex policy issues in California. Monumental investments in water delivery and infrastructure — largely to move water from north to south and east to west — supported the state’s economic expansion and urban growth in the 20th century. Today, this water delivery system is aging and ever more at risk from new challenges like climate change, sea level rise, earthquakes and a public mandate to reduce impacts on ecosystems and endangered species. As key parts of the system are retrofitted  or even reconsidered altogether, demand for water is growing rapidly: California’s population is expected to grow by more than 50 percent by 2050, increasing the competition for available water supplies.
- Does the Bay Area have the water we need to support projected population growth?
- How should we supply our region’s future water needs?
Bay Area Water Supplies
- The Mokelumne River watershed supplies 90 percent of the water for the East Bay Municipal Utility District (EBMUD). EBMUD has water rights to divert up to 325 million gallons a day (mgd) from this river system and owns and operates two major reservoirs, comprising the Mokelumne Project, which is managed for water storage, flood control, recreation and fisheries.
- The Tuolumne River watershed in Yosemite National Park supplies 85 percent of the SFPUC’s water, which serves the City and County of San Francisco and 26 wholesale customers in three counties with about 218 mgd through the Hetch Hetchy system.
- The State Water Project, managed by the California Department of Water Resources (DWR), supplies water from the Feather River watershed that is conveyed through the Sacramento-San Joaquin River Delta (the Delta) to several Bay Area agencies, including the Alameda County Water District, the Alameda County Zone 7 Water Agency, Solano County Water Agency and the Santa Clara Valley Water District (SCVWD).
- The Central Valley Project, managed by the U.S. Bureau of Reclamation, supplies water from the Trinity, Sacramento, American and San Joaquin river watersheds that is also conveyed through the Delta and is a significant supplier to the SCVWD and Contra Costa Water District (CCWD); it also provides a supplemental water supply to EBMUD in dry years.
The Bay Area’s Future Water Demand
- The California Water Conservation Act of 2009 (SB X7-7) set a state goal to reduce urban per capita water use 20 percent by 2020. All urban retail water agencies must establish a baseline per capita water use level and develop reduction targets, which may be a straight 20 percent reduction or one of three other DWR-approved methods.
- As of 2009, California’s building code, Title 24 (or CALGreen), mandates that new construction demonstrate a 20 percent savings from baseline water use through installation of high-efficiency fixtures like toilets, faucets and showerheads. Title 24 also requires outdoor water use to conform to local water-efficient landscape ordinances (which cities are required to have) and for irrigated landscape design to reduce water use by 50 percent from initial plant establishment. 
- Most urban water agencies actively implement conservation and efficiency programs to reduce per capita consumption on top of plumbing code savings. Such “active” conservation includes dozens of best management practices in water conservation, including education programs, water audits and surveys. Water agencies usually factor or report savings from these programs into their future demand forecasts but may report demand numbers both with and without expected conservation.
- Climate change
- End year of conservation measures
- Housing type distribution
Supply and Demand
Tools for Meeting Water Needs
1. Develop water supply scenarios for mid-century and beyond that include assumptions about changes (especially decreases) in precipitation amounts and timing.
Although Urban Water Management Plans only require a 30-year outlook, water agencies should look further into the future in light of climate change and the uncertain pace of the region’s growth. As little as 20 percent of the Sierra snowpack, which provides most of California’s urban water, may be available by the end of this century. Modeling conducted by the SFPUC for its customers in three Bay Area counties suggests that by the end of the century, under drought conditions, much higher temperatures and less precipitation, runoff from Hetch Hetchy may be less than half of what it is today. Water agencies must consider potential impacts of climate change both in terms of reductions in supply —and more competition for new supplies — and increases in demand. Agencies should plan ahead at least 50 years and evaluate the vulnerability of their service territories and supply portfolios to a range of future climate scenarios.
In SPUR’s report on earthquakes and lifeline infrastructure, we recommended target levels of service for water supply following an earthquake. SPUR recommended that water service be 100 percent restored for critical earthquake response functions, such as firefighting, within four hours of an event. We recommended that 90 percent of a system’s customers have water service restored within three days, and 95 percent of customers have water service restored within 30 days. Water utilities should use these metrics, or adopt similar ones, to evaluate system vulnerabilities and to plan reinvestments in their critical lifeline infrastructure, if they haven’t already. Because two-thirds of the region’s water supply is imported from outside the region and major aqueducts to the region cross several earthquake faults, resilient pipelines and reliable water service are critical to the health and welfare of our growing population.
FIGURE 8: Projected Decreases in California’s Snowpack
- Water agencies should develop and advance retrofit-on-resale ordinances to improve the water efficiency of existing commercial and residential buildings.
- Water agencies should study pricing and rate structure reforms, including tiered pricing, to create incentives for conservation at higher volumes of use.
- Land use planning agencies and elected officials should require new development to be compact and land-efficient and should support multifamily housing and urban infill development to minimize future water demand.
The more the region invests in compact development and reducing outdoor water use, the more water-efficient it will be in the future. Green building programs can require new construction or major retrofits to achieve water efficiency standards above and beyond state building code requirements. For example, San Francisco’s Green Building Ordinance requires 30 percent water savings compared to baseline water use, whereas CALGreen, the state code, only requires 20 percent. Water-neutrality requires developers to fund demand offsets, or retrofits, within the service territory of a new development to meet that new development’s demand, resulting in a “zero water” footprint for the new project.
Rationing only produces water savings on a temporary basis and has significant negative economic impacts.