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C. K. Chou

C. K. Chou
Associate Director of Energy and Environment, retired in June 2004

Technologies to Address California’s Water-Supply Challenge

THE growth of California’s economy in the 20th century depended on large investments in the state’s infrastructure, including major water-supply projects implemented by local, state, and federal agencies. In the 21st century, the state must continue to address important challenges to ensure that it has the water resources needed to sustain continued economic and population growth.
The 1987–1992 drought prompted aggressive moves by urban water agencies to improve water conservation efforts. After the drought, continued conservation provided much of the water for urban growth during the past decade. With California’s population increasing at about 500,000 people per year, the state will need new supplies and storage facilities to maintain the reliability of its water supply—particularly during drought conditions.
Where will California find this “new” water? Part of the supply will undoubtedly come from even better water conservation programs, and agricultural water districts may transfer supplies to urban agencies. Other options include building new dams and conveyance facilities or expanding old ones, reusing wastewater, and desalinating seawater. The state may also decide to increase its reliance on groundwater to meet dry-year demands. Any combination of these options will present environmental consequences that must be addressed.
No matter which choices are made, water agencies will have a more difficult time balancing the increasing demands for water with the available supplies because the state’s primary source of freshwater—snowmelt from the Sierra Nevada—may be at risk. Each summer, as the Sierra snowpack gradually melts, the water is stored for distribution throughout California. But hydrologic trend analyses and climate simulations now indicate that this runoff may occur earlier in the spring. Many of the state’s reservoirs cannot accumulate supplies from an early spring runoff because flood-control regulations limit the amount of water they can store at this time of year. The unfortunate result of this small change in timing is that the overall annual yields from reservoirs may decrease because excess water must be released to avoid flooding.
To make up for the reduced yield of surface reservoirs, California must increase its use of groundwater reservoirs. Although the state has major aquifer systems, many are contaminated with industrial and agricultural chemicals. For example, nitrate from domestic and agricultural sources has contaminated thousands of the state’s drinking water wells. Other contaminants also threaten groundwater supplies, including the gasoline additive methyl tertiary butyl ether, or MTBE, and perchlorate, an oxidizing agent.
Given these problems, California water agencies may need to consider nontraditional sources: urban wastewaters, impaired groundwater, and seawater. However, with current technologies, the cost to treat these sources will be about two times more than it is for existing water supplies, and competing demands for the required energy will substantially add to the overall cost. Clearly, California’s success in the 21st century depends on developing solutions to these emerging challenges. But unlike past water-supply projects, which relied primarily on engineering expertise for implementation, future solutions will depend on advanced science and technology.
Lawrence Livermore has a significant opportunity to contribute its expertise to this area, as described in the article Helping Water Managers Ensure Clean and Reliable Supplies. For example, the Laboratory’s advanced climate and hydrologic simulations can be used to predict future climate patterns and how changes to climate may affect water supplies. Until recently, water managers have had only the historic data to help them plan new infrastructure projects, which will operate far into this century. Applying Livermore’s ability to measure, characterize, and simulate the complex biogeochemical processes that control groundwater contamination will benefit managers who increasingly rely on groundwater sources. The development of energy-efficient selective separation technologies tailored to remove specific contaminants would constitute a major advance in water treatment. Collectively, these applications will give water agencies the tools they need to meet the increasingly difficult challenges that lie ahead.

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UCRL-52000-04-7/8 | July 12, 2004