Desalination Isn't the Solution to L.A.'s Water Supply | KCET
Desalination Isn't the Solution to L.A.'s Water Supply
California is already in year four of its multi-year drought and many locals are wondering, "There's so much water in the ocean, why can't we retrieve some of that?"
In a timely forum sponsored by Assemblymember Adrin Nazarian's office, water experts laid out their positions with an eye towards answering that question. More than a hundred attendees gathered to listen.
After two hours, the main takeaway could be summed up with Dennis Cushman's words: "Desalination projects are site specific." Cushman, assistant general manager of San Diego County Water Authority (SDCWA), explains that despite San Diego's plans to construct a $1 billion desalination project, which when completed would be the largest in the country, similar ambitious infrastructure projects in other places would have different circumstances and may not provide the best answer.
Cushman says that for San Diego, a desalination plant made sense. Local water supplies haven't been enough to provide for all of the region since 1946. Local groundwater supplies made up only 5 percent of the county's water sources in 1991 (during the last devastating drought, which saw the area's water supplies slashed by about a third); the rest of its water was purchased from the Metropolitan Water District of Southern California (MWD). In that memorable year, MWD delivered devastating news: it would cut water deliveries to the district in half, effectively crippling many households and businesses in San Diego. Surprise rains cut these planned decreases to 31 percent, but still, residents were already wary of the future.
San Diego's groundwater storage space is terribly scant: 19,000 acre-feet versus (an acre-feet is the amount of liquid that would fill one acre of an area to the depth of one foot) versus 450,000 acre-feet beneath Los Angeles County.
Given this scenario, Cushman says SDCWA saw that the only way to provide water to its residents is by establishing "long term water supply through diversification."
San Diego started purchasing water from Imperial Valley, which had senior water rights to Colorado River water. Should shortages happen, San Diego would be front of the water line. It will also construct concrete-lined canals alongside the existing earthen canals, which would entitle it to 77,700 acre-feet per year for 110 years.
It also began the Carlsbad Desalination project, which would deliver up to 50 million gallons per day of treated seawater to households, which would cover 7 percent of the region's water demands. This would also up the district's residential water bill by $5 to 7 a month.
Even though the drought rages in San Diego, Cushman says that with these strategies the agency will be able to meet 99 percent of the needs of the residents, despite a population increase of 700,000 residents in the last quarter of a century.
The same solution can't be applied to Los Angeles County, however, according to Martin Adams, senior assistant general manager of the water system for the Los Angeles Department of Water and Power (LADWP). Adams says Los Angeles went through an assessment process, initiated in 2002, which found a number of issues with embarking on a desalination project.
He says that for Los Angeles, it would be more prudent to encourage water recycling, stormwater capture, and water conservation. This strategy encompasses many projects, including improving dams and encouraging the use of rain barrels and cisterns, and incentivizing water conservation by offering rebates for water efficient household supplies.
It would be cheaper to concentrate on treating wastewater than to embark in desalination, Adams says. Every day the Hyperion Wastewater Treatment Plant in Playa del Rey discharges between 300-400 gallons of high quality treated wastewater to the Santa Monica Bay, costing the agency about $1000 per acre-feet to treat this water to this level. It would make more sense to re-use that already high-quality water and treat it to drinking water quality than to take seawater and treat it to the same drinking water level. If such plans materialize, these could yield 43 percent of the city's water needs by 2035.
In addition, desalination project would have an effect on marine life. As Heal the Bay's Rita Kampalath explains, desalination plants take in water in one of two ways: a direct intake, which literally sucks ocean water directly into the plant, taking in plankton and other marine life with it; or a more expensive subsurface intake, which goes under the surface of the ocean floor to take in water. "Sea water desalination should be the last option used to expand water supply," says Kampalath unequivocally. She points out that Los Angeles has other options, such as increasing conversation efforts, stormwater capture, and using recycled water.
Sam Kramer, a civil engineer with IDE Technologies, the Israeli company that built three of the Israel's plants along the Mediterranean, says technology and cost is improving every year. The technology has also become a godsend to Israel, which in 20 years went from having "no water to considering water as a potential commodity for export" because of desalination. Desalination's current reverse osmosis technology, which involves forcing seawater through a membrane with holes so tiny water molecules can pass through but larger salt molecules cannot, is already three times more efficient than previous thermal technology. "There will come a time when the technology will improve and costs will reduce."
Conner Everts, executive director of the Souther California Watershed Alliance, and the co-chair of the Desal Response Group, however, agrees with Kampalath. He adds, "Los Angeles needs to get over the yuck factor." He says that we could also re-use our toilet water and reprocess it to clean, drinking water, a project that could take twenty years to realize. Today, Los Angeles could concentrate on encouraging the public to replace its water guzzling lawns with native plants, or protecting our groundwater resources from industrial pollution. He also points out that Los Angeles still has a long way to go to reduce its personal consumption levels of water first. In Santa Cruz, per capita demand for water is at 40 gallons per person. In Los Angeles, that figure is closer to 100 gallons per person. "Rather than build a desalination plant, we need to create a priority matrix to outline what our options are. We need to prioritize," he says.
Everts also adds that ambitious projects like the Carlsbad plant takes decades of work and planning. By the time desalination plants get built, the city might not have any use for it, but still be saddled with debt for its construction. In Australia, for example, four desalinations plants out of six sit idle when a dry spell gave way. Yet Australians are still liable for billion dollars' worth of construction bills.
L.A. County's Integrated Water Management Plan is a good start to address the region's water issues. The initiatives within the project are designed to prioritize building of local water supplies.
LADWP is currently embarking on capturing more rainfall for treatment instead of it falling onto the pavement, which is carried through the Los Angeles River out to the oceans, by pushing solutions such as larger and improved spreading grounds to collect water, to rainwater capturing gardens and water-permeable pavement. Though five-inch rainfall means Los Angeles could capture about 3.6 billion gallons of rainwater countywide, that only represents 2 percent o the city's 179 billion gallon yearly demand. LADWP's strategy would add to this supply.
Even without rain, it's possible collect water from the Los Angeles River watershed. The California Conservation Solutions says that dry weather runoff could also supply 334,000 homes a year.
Everts quotes influential California environmental activist Dorothy Green, "We don't have a water crisis, we have a water management crisis." So, before Angelenos look toward costly projects that take decades to finish, it should build a strong foundation for water conservation. Solutions are already beginning to take shape, but Los Angeles needs to accelerate its progress.
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