The Bay Area’s extensive water supply system includes a wide variety of hydrologic features, such as San Pablo Reservoir in the East Bay. Photo by Alec MacDonald.

Water. It flows out of the tap every time we want, cool, clear, and clean. We take it for granted even now, three years into one of California’s driest stretches on record. But we can’t go on like this for much longer — the Bay Area’s water could start to run short in just two decades.

“Population growth will increase demand, and climate change will reduce the supply and increase demand,” said Heather Cooley, director of the Water Program at the Pacific Institute, an Oakland-based nonprofit dedicated to sustainable resource research.

The Bay Area’s population is projected to rise about 25 percent in the next two decades, from 7 million people today to 9 million in 2035. And without preparation there won’t always be enough water for us all. Our expected water demand will exceed the supply by nearly 7 percent in a dry year, and by more than 11 percent in the worst case scenario of multiple dry years, according to the 2013 San Francisco Bay Area Integrated Regional Water Management Plan, which was developed by representatives from local water supply and treatment agencies, local and state government, and nonprofit organizations.

Our future is likely to be drier, partly due to warming from climate change. “Increased evaporation off watersheds could decrease water supplies by 5 to 10 percent,” said Jay Lund, director of the UC Davis Center for Watershed Sciences. In addition, when it’s hot out, water demand rises because people use more for their landscaping.

Moreover, climate patterns going back thousands of years raise the possibility that upcoming droughts could be worse than any we’ve experienced lately. “California has seen much bigger, longer droughts,” Lund said. “In medieval times, there were a couple of droughts in Southern California and the Eastern Sierras that lasted about 100 years.” This conclusion was reached by UC Berkeley paleoclimatologist Lynn Ingram, who used indicators like tree rings, which are wide during wet years and narrow during dry ones, forming a record of the past.

While the future may be daunting, it isn’t here yet and California cities are using almost as much water as usual despite the extreme drought. In January of this year, Governor Jerry Brown requested a 20 percent voluntary reduction in urban water use. But we were only using 5 percent less at the end of May, revealed a June 2014 survey by the State Water Resources Control Board, which divvies up state water.

That said, the Bay Area’s water use is already relatively low. About half of California’s urban water goes to landscaping, and the Bay Area uses less water outdoors because much of our land is urban with a cool climate. Daily use per person is less than 100 gallons in San Francisco compared to 200-300 gallons in the Central Valley, according to the 2013 report Future-Proof Water: Where the Bay Area Should Get Its Water in the 21st Century by SPUR, a San Francisco-based nonprofit that focuses on Bay Area planning and government.

In addition, while supplies are down in much of California — reservoirs were at 54 percent of the average volume statewide in July — water remains sufficient in much of the Bay Area. “It’s not dire there yet,” Lund said.

The San Francisco Bay Area hydrologic region, a major drainage basin that is smaller than the nine-county region, gets nearly 40 percent of its water from Sierra Nevada-fed reservoirs that are close to full. Much of the East Bay’s water is from the Pardee Reservoir in the Sierra foothills, which was at 87 percent capacity in mid-July. Likewise, much of San Francisco’s water is from the Hetch Hetchy Reservoir in Yosemite, which was at 97 percent capacity in mid-July. Hetch Hetchy also supplies considerable amounts of water to Alameda, Santa Clara, and San Mateo counties.

The rest of the Bay Area’s water comes from local sources and government water projects. Local surface waters and groundwater account for about 30 percent of our water, and another nearly 30 percent is delivered by the federal Central Valley Project (CVP) and the State Water Project (SWP). These projects, which funnel water through the Sacramento-San Joaquin Delta, have curtailed water deliveries sharply this year. The CVP is giving the Contra Costa Water District only half of its historic supply, and SWP allocations are down to just 5 percent of usual.

For now, water conservation is voluntary in most of the Bay Area, with water agencies asking us to use 10-20 percent less. The few exceptions where mandatory restrictions have passed are primarily in hotter, more suburban areas, according to the Association of California Water Agencies. These include Cloverdale, Healdsburg, the Santa Clara Valley, Fremont, Newark, Union City, Pleasanton, Dublin, and part of San Ramon, which have mandated 20-25 percent cuts, and Livermore, which has mandated cutting outdoor use in half.

“Our water problems are solvable,” said David Sedlak, co-director of the Berkeley Water Center at UC Berkeley. “The worst thing would be being caught unprepared — we don’t want to respond to a water shortage in panic mode.” Citing Australia’s recent decade-long drought, Sedlak explained that when Brisbane’s reservoir was down to just a year or so of water, major cities there built costly desalination plants that for the most part are little-used today.

We can save a lot of water with technologically simple fixes such as repairing the leaks that waste 11 gallons per person per day in California, switching to the front-loading washing machines that use a third as much water as top-loaders, and replacing lawns with drought-tolerant plants. Such efficiency measures could decrease the Bay Area’s water use by 40 percent, according to the 2014 report The Untapped Potential of California’s Water Supply by the Pacific Institute and the Natural Resources Defense Council.

We can also create new supplies by capturing the stormwater that now runs off into the sea, and by recycling graywater — from sinks, bathtubs, showers, and washing machines — for use in toilets and on landscaping. Together, these sources could provide more than 30 percent of the Bay Area’s water, the report stated. Recycling can also turn wastewater into drinking water. Orange County has replenished groundwater with ultrapurified wastewater since 2008.

Updates to our water supply will take time to finance, design, and put in place. “Cities are usually insulated from the worst of droughts but our water systems are not designed for megadroughts or climate change,” Sedlak said. “We need to start planning today — we’ll be lucky if our new systems are built in 20 years.”

Robin Meadows is the reporting fellow for the 2014-15 Water Education Initiative.

Created by the League of Women Voters of the Bay Area Education Fund to promote better understanding of regional water issues, the initiative is underwritten by the Association of Bay Area Governments, Bay Area Biosolids to Energy, the East Bay Municipal Utility District, the League of Women Voters of Marin County, Louise Anderson, the Marin Municipal Water District, Marion Taylor, the San Francisco Public Utilities Commission, the Santa Clara Valley Water District, and the Sonoma County Water Agency.[/vc_column_text][/vc_column][/vc_row]