Energy & Environment

The Salty Solution

by | May 31, 2007

It's tough to imagine that steamy Florida may be running out of water. Yet state and local water managers this spring barred homeowners from sprinkling their lush lawns more than twice a week in the thin urbanized strand - between sandy Atlantic beaches and the swampy Everglades - where 6 million people now live. As they're adjusting to the peninsula's worst drought since 1895, local governments are also accepting that even the 52 inches of rain that falls in a normal year won't supply South Florida with enough water.

North of Miami, with 2 million newcomers expected to move into the region, Broward County could be short 98 million gallons every day by 2025. Fort Lauderdale alone would need 30 million more gallons per day to supply its growing population. Those figures have prompted state and local governments to look for reservoir sites where rainwater could be stored before it rushes off to the sea. Eventually, however, the region will be forced to look to the ocean itself, or possibly deep underground, and start removing the salt from salty water to turn it into drinkable liquid.

Oceans hold 97 percent of the earth's water, and water-short communities on Florida's Gulf of Mexico coast have already begun tapping that potential. This April, after two years of expensive repairs, a troubled desalinization plant run by regional utility Tampa Bay Water resumed pumping 20 million gallons of processed seawater daily into the region's drinking water systems. The region has been severely overdrawing limited groundwater reserves, so local water agencies may have no choice but to count on the plant to stay up and running.

It's not as if desalinization were pie-in-the-sky technology. Saudi Arabia has used desalted seawater since 1938, and more than 2,000 small-scale facilities already operate in the United States. Nearly all the U.S. plants process brackish groundwater, saline river water or in some cases wastewater to create usable supplies for isolated desert regions. By far, Tampa Bay's plant is North America's most ambitious attempt to convert saltier seawater to serve a large population center. Fully operational, it's designed to provide 10 percent of the water that Tampa, St. Petersburg and three rapidly urbanizing counties pipe to nearly 2.4 million residents.

How Tampa's plant performs is being closely scrutinized by water utilities in other regions along the nation's shores where the needs of rapidly growing populations have begun surpassing nearby freshwater resources. California utilities are taking preliminary looks at more than 20 large-capacity plants to convert Pacific Ocean water. Four would serve the San Francisco region, but most are being designed to end Southern California's century-long search for "drought-proof" supplies of city water. If built, those projects could produce 6 percent of California's water.

As appealing as that goal sounds, it's not clear that desalinization will ever achieve it. Troublesome economic, environmental and technological issues must still be overcome, and some experimental plants have fallen short of expectations. After several dry years, Santa Barbara, California, in 1992 built a $34 million desalinization facility. But when the drought ended, the city found cheaper supplies and mothballed the plant as insurance against future supply emergencies.

Tampa Bay's $110 million plant ran into major glitches. Tampa Bay Water bought out the original private owner, shut the plant down for two years and spent $29 million on correcting problems that fouled membranes and rusted out pumps. The setbacks drove up the projected cost of Tampa's desalted water. In California, the uncertainties caused San Diego County's water authority to back off from building a 50 million gallon-per-day plant on the Pacific coast. A private firm stepped in to negotiate deals with the city of Carlsbad and other systems for a similar project at the same site.

Using seawater would be preferable to tapping underground supplies, especially if the only alternatives are drying up the Everglades or diverting water from the Great Lakes, the Columbia River or even Canada's Arctic streams to keep California and Arizona livable. But that isn't the only choice. To their credit, water-short states are also trying to curb wasteful uses and recycling wastewater.

That won't be enough, unfortunately, if communities keep growing haphazardly. In time, their golf courses, swimming pools and other water-consuming luxuries will create their own drought conditions. Tampa Bay still could prove that desalinization provides a practical option for stretching out supplies. Industry officials say improving technology has cut desalinization costs by more than half in the past decade. But it would be mistaken to bank solely on engineering the country's way out of long-term water shortages.

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