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Brockton, MA eyes desalting plant

By Beth Daley, Globe Staff, 4/10/2004

To relieve chronic water shortages, several Massachusetts communities are considering plans to draw their drinking water from a vast but long off-limits source: the Atlantic Ocean.

Construction of a $40 million plant to purify salt water and deliver it to the city of Brockton could start as early as September. Hull residents will be asked this month for $280,000 to determine whether a desalting plant would lower the town's soaring water rates, and Braintree has set aside $75,000 for a similar study this year. Seabrook, N.H., and several North Shore communities and groups also are interested in desalination plants.

"We are out of water; we are looking east," said Robert Marquis, water superintendent for the town of Swansea, which recently notified the state that it wants to build a $16 million plant to desalinate water from the tidal Palmer River. "When there is a drought, you still have the ocean."

Long impractical and prohibitively expensive, desalting seawater has become cheaper as technology has improved in the past decade. The only drinking-water desalination plant built in New England so far has been a tiny one on Maine's MacMahan Island, but as growing communities scramble for fresh water, desalination has begun to look more attractive.

"Supplies of water have dwindled down to precious few, and there are no other ones to be developed in Eastern Massachusetts," said John Murphy of Hanson, Murphy & Associates, an engineering firm that is helping build Brockton's plant and is interested in building other desalination plants in the state.

The sea's newest use, however, brings with it fresh worries. Many of the plants are proposed in tidal rivers, where environmentalists say aquatic life may be harmed by powerful intake pipes and briny discharge. Public policy specialists look at such plants, some of which are privately owned, and worry that public water supplies could one day be sold to the highest bidder. And in a region that gets almost 4 feet of precipitation a year, others say that more plants are simply a Band-Aid on a problem that should be treated by deeper changes.

"We don't need to be building any of these facilities," said Christopher Kilian, a senior attorney with the Conservation Law Foundation, who argues that many of the region's water woes could be solved by conservation.

Desalting water has a long history. Mariners once hung sheepskins over ships' bows at night, and squeezed out the evaporated seawater they trapped. At an industrial scale, much the same process was used in 20th-century desalination plants, which were so expensive that they were economically feasible only in the world's aridest places, such as Saudi Arabia and the Caribbean.

By the 1990s, however, new filtering technology began to lower the cost of obtaining fresh water from the sea. Today, seawater is pushed through membranes that remove salt and virtually everything else. The resulting water is so purified that it must have minerals added to make it palatable.

That technique has so reduced the price of desalinated ocean water that it is a little more than twice as expensive as water from a well or reservoir, according to specialists. If the water source is less salty, the water is cheaper yet, which is why some Massachusetts communities are looking to locate desalination plants on diluted tidal rivers.

Today, some specialists say, there are fewer than 100 plants used for drinking water in the United States, the vast majority of them facilities that serve small communities. But that is changing quickly. There are at least 10 large-scale desalting projects planned for California, and the country's biggest plant, in Tampa, went on line last year, although it has been plagued by technical problems. Meanwhile, federal legislation was filed in February to give electricity subsidies to the plants, so they can be more competitive with other water sources.

Few communities in Massachusetts have Brockton's excessive water woes, largely the result of a lack of storage dating to the late 1800s. Today, there is no city water for new car washes. There are $200 fines for people who disobey the ban on watering lawns during certain times of the day. Brockton has pursued desalination for more than 10 years, but permitting delays, opposition, and financial troubles stymied the project.

Its proposed plant, 16 miles away in Dighton, on the Taunton River, recently received a key state permit, and its owners say that if other permits are approved soon, they could be supplying water in two years.

Brockton water officials say part of the attraction of the plant was that all upfront costs would be paid by its developer, Aquaria, which would then sell the water to Brockton, Norton, and any other town willing to buy it. City officials dismiss worries about water privatization, saying that a 20-year contract ensures affordable water rates and that the desalinated water will only supplement more traditional supplies. The seawater will add about $50 to $75 to residents' annual water bills.

The cost to the environment may be higher. Conservationists say the plant may kill fragile marine life that can get pressed against filter screens sucking in millions of gallons of water or harm wildlife by reduced water levels or increased salinity.

"We don't know what will happen," said John Torgan of Save the Bay. His group watches over Narragansett Bay, into which Taunton River water eventually flows.

He is particularly concerned about the plant's ability to take advantage of different salinity levels in the river during different times of day. The plant will remove water from the river during low tide, when salinity is at its lowest. After filtering out fresh water, it will mix the remaining brine with other river water and pump it back into the river at high tide, when salinity is much higher. Its owners say the discharge will never be saltier than the river.

"They found a loophole," said Torgan, who points out that the plant will still be removing fresh water from the river and says that too much water withdrawal could fundamentally change the river and hurt wildlife habitat.

Despite their wariness, some environmental groups can't help but wonder if it's better than the alternative, tapping groundwater until rivers run dry.

"We're not against [desalination]," said Kerry Mackin, executive director of the Ispwich River Watershed Association. The river was recently named one of the country's most endangered by a respected conservation group. "It has some real potential to solve the water problems here."

State officials say there is no official Massachusetts policy on desalination, but want to be assured that every avenue, including water conservation, has been exhausted before permits are issued. Other communities have examined desalination and rejected it. Stoughton researched the issue, but ultimately decided it would spend less money buying water from the plentiful supply of the Massachusetts Water Resource Authority. Provincetown also decided against it. And in Swansea, some town officials say they believe it would be cheaper to buy water from Fall River than to build a plant.

Beth Daley can be reached at bdaley@globe.com.