Should Desalination be a part of Los Angeles’ Water Supply for the Future?
|The current drought has again raised interest on the part of the public and water agencies in developing seawater desalination as a resource. We know that desalination represents a significant source in the water supplies of the Middle East. The construction of seawater desalination facilities also played a major role in Australia’s response to a decade-long drought in the 1990s, albeit at a substantially increased cost for water. Currently there are at least a dozen projects in California that are under consideration. The largest seawater desalination project in the western hemisphere is scheduled to become operational by the end of the year in San Diego, and the Orange County Water District is actively pursuing a similar project. The city of Santa Barbara is also almost completely rebuilding its 25 year old facility (built during the last major drought, but never put into full operation). What role can and should desalination play in the water supply for Los Angeles?
In early 2000, Los Angeles Mayor James K. Hahn, after a trip to Israel, encouraged the L.A. Department of Water and Power (LADWP) to investigate the role that seawater desalination should play in Los Angeles’ water supply. In response, the LADWP developed a conceptual plan for a modest sized project to be co-located with its Scattergood Power Generating Station near the Los Angeles International Airport. This plan would have allowed the LADWP to gain firsthand knowledge and experience in the technology with a minor impact on rates. The Scattergood Generating Station had an existing seawater intake for plant cooling that was to be used as the desalination source and existing available space that would have allowed for new plant construction without purchasing any additional land. The proposed capacity of 10 MGD (million gallons per day) would have served the area in the vicinity of the plant with minimal requirements for pumping and distribution. The disposal of brine that results from the desalination process would have been handled by the existing city of Los Angeles Hyperion Wastewater Treatment Plant outlet; this method of brine disposal was considered at the time as environmentally beneficial as it would have raised the salinity level of Hyperion's discharge effluent closer to that of the ocean.
While this desalinated water would have been more expensive than purchases from the Metropolitan Water District at that time, the overall cost impact would have been negligible, as the quantity delivered would have been less than two percent of LA’s overall water supply. In actuality, projected costs would have been within the range of the some of the more expensive water recycling projects under consideration at the time. However, interest in the proposed desalination project eventually waned in favor of continued focus on water conservation, wastewater recycling and storm water capture.
In light of the current drought and ongoing long-term water supply issues, Los Angeles should carefully study and critically evaluate the desirability of adding some measure of desalinated water to the city’s water supply portfolio. This is not to suggest immediately beginning construction, since it is likely (although not certain) that the current crisis will be over long before a facility could be built. Much information should become available from the first few years of operation of the San Diego project, although information sharing may be severely limited due to the private ownership of the facility and the owner's desire to protect competitive advantage. The Santa Barbara facility will be another, likely more open, source of information. Los Angeles should do all it can to encourage information sharing through the regulatory and permitting processes for the benefit of the entire state.
It is unlikely that desalination of seawater will be a "magic bullet" to solve all of California’s water issues due to the limited number of feasible sites and the immense cost that would be involved in facility construction and moving the water from sea level elevation where it would originate to inland areas where water demand is highest. However, there is substantial water use in coastal Southern California and desalinated water could provide a significant benefit to local water supply reliability (as a drought-proof source) and to the economies of Los Angeles and the Southern California region.
Conservation, as the cheapest and most immediate source of water, has been mandated by Governor Brown to reduce California's urban water use in response to the current drought. However, conservation alone cannot be counted on to fully offset the effects of future droughts as well as increasing demands due to population growth and continuing water allocations for the environment. Therefore, serious consideration should be given to expanding Los Angeles' current water supply portfolio (traditional sources, recycled water, storm water capture) to include desalination, a proven source of water in the middle east and Australia, to reliably meet LA's water needs of the future.
Jerry Gewe is a retired Assistant General Manager, LADWP Water System and is currently on the Executive Board of the Water and Power Associates.
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