A Coastal City's Journey to Quenching Its Thirst

to Quenching Its Thirst San Diego water-delivery infrastructure plays an especially complex — and critical — role in making sure one of America's driest cities has the water it needs.

By Mayor Jerry Sanders, city of San Diego Photography courtesy of the San Diego Mayor's Office

San Diego's boundaries stretch 40 miles from north to south, with 93 miles of shoreline along various bays, lagoons and the Pacific Ocean. The city's ideal climate, postcard beaches and world-famous cultural attractions make it one of the nation's top tourist destinations, with nearly 30 million visitors per year.

San Diegans are rightly proud of our beautiful city, with its diverse population and rich cultural attractions, but even San Diego's most ardent civic boosters will acknowledge the city's most persistent shortcoming — a limited water supply. For this reason, the city's water-delivery infrastructure plays an especially complex — and, of course, critical — role in making sure San Diegans have all the water they need.

Like many other cities in the arid climate of Southern California, San Diego imports most of its water. In San Diego's case, roughly 90 percent comes from either the mountains of Northern California — hundreds of miles to the north — or the Colorado River — roughly 150 miles to the east. Only 10 percent or less comes from San Diego-area reservoirs or other local sources.

What's more, as California's southernmost big city, the city's downtown district is 20 miles from the Mexico border. This means that San Diego sits at the very bottom of the snaking chain of aqueducts, levees, pipes and pump stations that comprise the state's water-delivery system. In recent years, several events have conspired to make the city's water supply even more unreliable than usual. As a result, we are exploring a variety of solutions, including the possibility of recycling local wastewater into drinking water so we are less reliant on imported sources. Such an undertaking would require expanding the city's water infrastructure even further.

Every year, San Diegans become more adept at saving water through methods ranging from cutting back on the length of their showers to using more efficient sprinkler systems for their lawns. The city and its residents use less water today than 20 years ago, even though the population has increased by 25 percent. Still, the basic reality is no matter how much water we save through conservation, we must continue to invest in our water infrastructure if we want to meet the region's future needs.

When San Diegans turn on the taps, there's a good chance the water coming out began its journey as snow on some mountain ranges hundreds of miles away. In California, the state delivers water to San Diego County through the State Water Project, a massive system of 34 lakes and reservoirs, 20 pump stations, five hydroelectric power plants and 700 miles of canals and pipelines, according to the California Department of Water Resources.

Once the water arrives in San Diego, it is treated at any one of the city's three water treatment plants. Then it enters a system comprised of 3,200 miles of water pipes ranging in size from 4 inches to 7 feet in diameter. An average of 207 million gallons of water a day passes through these pipes with the assistance of 49 pump stations spread throughout the city. The city owns a total of 10 raw-water reservoirs, five of which collect water imported from outside the San Diego region, and five hold water collected strictly from local sources.

Maintaining this complex system is expensive. First, the city must buy all of its imported water from various wholesalers outside the city — and these wholesalers have been raising their rates in recent years. This year, the city will spend roughly $180 million just on water purchases. Second, much of the system is approaching the end of its lifespan. San Diego saw a big building boom in the late 1950s and early 1960s. A typical water pipe needs replacing every 50 to 80 years. Today, roughly a quarter of the city's water pipes are more than 50 years old.

The city tries to replace roughly 35 miles of water pipes a year. The cost of replacing a mile of water pipe is roughly $1.5 million. Then there are all the miscellaneous expenses. In any given year, for instance, bad drivers will knock over roughly 150 of the city's 25,000 fire hydrants. In any given year, roughly 120 water mains will suffer a catastrophic break. In addition to the day-to-day operating and maintenance expenses, the city must also invest in long-term capital projects. Over the next decades, San Diego will need to improve its groundwater infrastructure and invest in miles of new water transmission pipelines, among other things.

The city's water wholesaler, the San Diego County Water Authority, has also embarked on an ambitious plan to diversify the region's water supplies. This plan includes securing additional water sources and embarking on a capital-improvement plan to help the region reduce its dependence on imported water. (The County Water Authority buys its water from a Los Angeles-based agency called the Metropolitan Water District, which sells water to 26 Southern California jurisdictions.)

Decreasing San Diego's dependence on imported water remains a vital goal for reasons beyond the soaring cost of this commodity. Political and environmental issues threaten the region's access to water from outside the county. In recent years, legal rulings and regulatory restrictions have curtailed the amount of water that can be pumped to Southern California through the Sacramento-San Joaquin River Delta in the central part of the state. The restrictions are designed to protect the fish that live in the Delta. The result is less water for San Diego and the rest of Southern California.

Also, as it stands, a major earthquake in Central or Northern California could destroy the system of aqueducts and levees that move the water to Southern California. All too aware of the risks of being cut off from its imported water supply, the San Diego County Water Authority embarked several years ago on $1.5 billion worth of projects to protect the region in the event its imported water supply is curtailed. These projects will increase local water storage capacity by 90,100 acre-feet, enough to supply the region with water for six months in an emergency. The biggest project broke ground last summer — raising the height of the San Vicente Reservoir by 117 feet. The project, scheduled to be finished in early 2013, is the tallest dam-raising project in the nation. When complete, the San Vicente Reservoir, which is owned by the city of San Diego, will expand the region's emergency water storage by 52,000 acre-feet. This project will also provide 100,000 acre-feet of additional storage to capture water during rainy periods for use during dry spells.

The city of San Diego is also taking steps to reduce our dependence on water from Northern California and the Colorado River. This spring, we will finish construction on a new test facility designed to convert raw sewage into water that is clean enough to be pumped back into a reservoir. Once construction is finished, the city will spend the next year running tests on the treated water to make sure the system works as designed.

The outcome of this pilot program will determine whether the city decides to add another layer of infrastructure to the city's water supply system. If the city is satisfied with the results of the pilot program, we could pursue the option of building a full-scale Advanced Water Treatment plant capable of treating roughly 40 million gallons per day of effluent water. Such a project would also require the city to build a 20-mile pipe that would connect the new plant to the San Vicente Reservoir.

As with every other infrastructure project in the history of San Diego, the city will have to decide whether the longterm benefits will outweigh the big price tag.

Mayor Jerry Sanders is currently serving his second term as the mayor of San Diego since taking office in2005. For more information, visit www.sandiego.gov.