Tapping the World’s Largest Reservoir: Desalination
“Water, water, everywhere, nor any drop to drink.” – Samuel Taylor Coleridge
For time immemorial, the seas of the Earth have been seen as an enticing but unreachable source of fresh water. Separating the salt from ocean water was always a cost prohibitive process, primarily reserved to wealthy Middle Eastern nations and small-scale operations such as ocean-bound vessels and small islands. Otherwise, through the evolution of modern civilization, man has depended upon lakes, rivers and groundwater – a supply that comprises less than 3 percent of the planet’s total water.
What once seemed impractical is today gaining momentum in the United States, as entrepreneurial spirit has teamed with engineering know-how to propel desalination technology towards being a permanent addition to the water supply outlook. “Ten years ago, desalination was the crazy aunt in the attic,” said Barry Nelson, senior policy analyst with the Natural Resources Defense Council (NRDC). “That’s changed, and as a water supply strategy, it is now entering the mainstream and being taken seriously.”
The focus has been especially keen along the California coast, where seaside communities long dependent upon the whims of Mother Nature see the conversion of salt water to fresh water as an insurance policy against ever-apparent drought. A recent study by the Scripps Institute of Oceanography predicts that global warming could reduce the West’s water supply by as much as 30 percent by 2050.
“Snowpack depletion is a threat to California because, in addition to Colorado River water, the region depends heavily on snowpack to provide a natural reservoir for water storage, gradually releasing water from the mountains to the valleys in the spring and summer,” wrote water attorneys C. Michael Cowett and Reagan Brenneman, in a San Diego Union-Tribune opinion piece supporting desalination. “Ironically, as a result of global warming, sea level is likely to rise two feet along most of the U.S. coast. Therefore, southern California should be looking to the ocean to supply its water demand, rather than to the mountains and rivers.”
Interest in desalination is not confined to the California coast. In Tampa, Fla., officials are poised to unveil the largest desalination plant in the United States, a 25 million gallons per day (mgd) facility that is expected to meet 10 percent of the region’s water needs. Meanwhile, in New Mexico, federal scientists are exploring how to tap a vast reservoir of underground saline water in the southern part of the state. It is the allure of the ocean’s permanence that makes desalination a valued prospect, given that southern California endured its driest year in 2002. And it is not only the sea but also the vast amount of brackish groundwater that agencies hope to tap for the region’s long-term water needs.
“Most people in the industry and much of the public are aware of such solutions as conservation, various forms of storage and water recycling, but a ‘new’ source has emerged – a source you know as the Pacific Ocean that is now being called by some the ‘Pacific Aqueduct,’” states a fact sheet by the West Basin Municipal Water District in El Segundo. The district completed construction of a desalination demonstration project last May.
Remarkable technological advances are a substantial reason why desalination has emerged from the fringe as a viable supply alternative. Manufacturers of the membrane filtration systems that separate salts and other constituents from seawater have been able to produce filters that last longer at a much lower cost than just a decade ago. “The most significant driver has been the improvement in the technology of membranes,” said Anatole Falagan, assistant group manager for water resource management with the Metropolitan Water District (MWD) of Southern California.
Cognizant of the need to maximize all water supply alternatives, MWD has embarked on a course of actively promoting desalination because of its newfound viability. “Although the Pacific Ocean lies at our doorstep, desalting seawater for drinking has in the past been far too expensive compared to our other sources of water,” said Ron Gastelum, MWD’s chief executive officer. “Now, as Metropolitan expands its portfolio of resources to prepare southern California’s water supply for the next 20 years and beyond, we’re anxious to see if advances in filtering processes have brought desalination into an acceptable price range.”
Besides the improved technology, desalination has benefited from reduced operating costs in terms of electrical energy use. Because of improved filtration, desalination facilities require much less energy to operate than in the past, an important milestone given that energy consumption can account for as much as one-half the total cost of the process.
To some, however, the costs and environmental impacts outweigh the benefits of desalination. “Instead of pursuing such costly schemes as this to add to the supply side of the water equation, our local water agencies can reduce the demand side an equivalent volume merely by adopting a simple … and effective strategy … known as conservation,” wrote Robert Simmons in a San Diego Union-Tribune opinion piece. Simmons, a retired law professor, is a member of the San Diego Sierra Club’s executive committee.
Others say desalination should not be expected to be a comprehensive answer to tightening water supplies.
Desalination “is likely to be economically attractive only in spot situations – coastal communities that have no access to supplemental surface water,” said Henry J. Vaux, Jr., associate vice president of the University of California’s Division of Agriculture and Natural Resources. “So, of course, it may look attractive at a place like Morro Bay where there is no alternative. Where there are alternatives, seawater desalting is not usually attractive.”
Although the cost of desalination is an obstacle to its implementation on a wide scale, there are others. Perhaps foremost is the matter of siting. Many plants are coupled with energy generation facilities – an arrangement that maximizes both intake and discharge infrastructure. Siting desalination plants elsewhere along the coast would be a daunting task, given the shortage of suitable locations and the costs of permitting. Other issues include the effects of brine discharges on the marine environment, drawing in small marine organisms from nearshore and estuarine areas, siting new intakes and outfalls, and the possibility that the availability of desalinated water could induce greater growth in coastal areas.
“There’s a lot of concern, just as there was 10 years ago, over the possible impacts of desalination on the marine environment,” said Frank Palmer, head of the ocean standards unit at the California State Water Resources Control Board (State Board).
This issue of Western Water examines desalination and the role it could play in the future of water supply. In addition to an explanation of the basics of the technology, the article looks at costs, environmental impacts and groundwater application. Pilot desalination projects are featured, including a much-touted Carlsbad, Calif., facility that promises to substantially boost that region’s water supply. The article is not intended to be an all-encompassing, comprehensive review of desalination, but a snapshot of the issue as agencies move closer toward greater reliance on turning salt water into fresh, potable water.
NOTE: A complete copy of the 20-page magazine is available from the Foundation for $3. Visit our Products Page and add the January/February 2003 issue of Western Water to your shopping cart.
Our “In the News” article provides a brief summary of the efforts among the state’s Colorado River users to reach agreement on a transfer of California’s Colorado River water as part of an overall strategy to reduce the state’s dependence on this resource. As California faces a possible immediate cutback in Colorado River water, the question is raised about other sources of water to make up for that shortfall. Several newspaper reporters in northern California recently have asked me what this cutback will mean north of the Tehachapi Mountains. I’ve told them that more eyes would look north for water sources. Indeed the Metropolitan Water District of Southern California is purchasing options to buy water in the Sacramento Valley. A few years ago, this action would have raised eyebrows. However, today water transfers are seen as part of the solution to the water supply problem.
With the emphasis on searching for more water, we take a look at desalination in this issue of Western Water. From time to time people ask me about desalting the ocean as a way to solve all water problems on the West Coast. Because of the high energy cost to convert the salt water to fresh water, I’ve always told them it’s not practical. In this article, Writer Gary Pitzer looks at the emergence of today’s more cost-efficient desalting technology, which, coupled with this growing instability of surface water, has increased interest among some coastal cities in turning to the sea.
To learn more about Colorado River issues, be sure to sign up for our Lower Colorado River Tour, March 26-28. This tour follows the course of the lower Colorado River through Nevada, Arizona and California. The discussions on the tour will cover water needs in the three states, water conservation and transfer agreements, water banking, Salton Sea restoration, endangered species, tribal water rights and water quality issues. The tour begins in Las Vegas and ends at Ontario International Airport. This tour always fills up fast so contact us by phone or on-line where you can sign up immediately.
As we move into another year, I want to remind everyone how important it is to teach our children about water conservation. That’s why I’m enthusiastic about the Foundation being the California coordinator for Project WET. Project WET (Water Education for Teachers) is an international, interdisciplinary water science and education program for formal and non-formal educators of K-12 students. With some help from a grant from the U.S. Bureau of Reclamation Mid-Pacific Region, the Foundation organizes California’s network of formal and non-formal educators.
Over the last six years, the Foundation has given over 350 workshops to approximately 4,000 educators who estimate that they have contact with close to 3 million students. Project WET is a cost-effective way for water districts to access high quality water education and meet education outreach responsibilities in their BMP plans. The expense for the workshops is minimal, so if you aren’t using Project WET as part of your community water education outreach, contact our Education Director, Judy Maben, or me for more information and get going on a great water education program in 2003!
In the News
Rejection of Water Transfer Threatens California Coastal Cities
As this edition of Western Water went to press, California water agencies continued attempts to secure an agreement on an Imperial Valley-San Diego water transfer in order to avoid an immediate cutoff of Colorado River surplus water. Talks among the Imperial Irrigation District (IID), San Diego County Water Authority and others continued in the wake of the IID’s rejection of a transfer deal that was considered a key element in the overall reduction of Colorado River water by California.
One option, offered by IID, is a short-term transfer of 100,000 to 200,000 acre-feet of water a year for five years (an acre-foot of water meets the average yearly needs of one to two households). Under the terms of the short-term transfer, IID would agree to cap its use of Colorado River water at 3.1 million acre-feet. The water would be priced at $200 per acre-foot and $20 million up front to cover the cost of “socioeconomic mitigation,” according to IID.
Another hitch lies in a law that conditionally waives application of California’s fully protected species law to allow the water transfer and other components of the Colorado River Plan to proceed. The measure was to expire Dec. 31 if no deal was reached.
IID’s refusal to accept a 75-year sale of as much as 200,000 acre-feet of water to San Diego caused condemnation in some quarters while compelling water officials to reconvene with the hope of striking a deal that avoids the cutoff of as much as 800,000 acre-feet of Colorado River water. The transfer was seen as a major part of the Quantification Settlement Agreement designed to reduce California’s consumption to 4.4 million acre-feet a year.
IID uses more than 3 million acre-feet to irrigate 500,000 acres. Five years ago, a deal was proposed in which the district would conserve water on a large scale and sell most of the water to San Diego for about $50 million per year for 75 years. Things grew complicated when the transfer was integrated into the overall plan to reduce California’s draw from the Colorado by 2015.
Under tremendous pressure from local farmers, the IID board rejected the transfer by a 3-2 vote Dec. 9 and subsequently offered a scaled-back transfer proposal. Directors nixed the initial sale because of several factors, not the least of which was the stipulation that land be fallowed to help preserve the Salton Sea. Board members also expressed concern about IID’s possible liability for environmental restoration costs at the hyper-saline inland sea.
Federal and state officials lobbied hard for IID to accept the transfer plan, even granting IID some additional supply for farmers’ use at the end of 2002. In a Dec. 16 speech to the Colorado River Water Users Association, Interior Secretary Gale Norton urged the various California water interests to put aside their differences and accept some means to meet their agreed to allocation of Colorado River water.
“The issue is not whether but when California will live within its apportionment of 4.4 million acre-feet of water,” she said. “If California chooses a hard landing approach, California will lose access to surplus water beginning January 1, 2003. Cities in southern California will bear the immediate shortfall, potentially losing as much as half of the Colorado River water they currently receive.”
– by Gary Pitzer