Friday, February 24, 2006

Desalination and the Environment

Whenever we hear the term "desalination", it conjures an image of a water factory turning an inexhaustible supply of seawater to an unlimited amount of drinking water. This idealized vision is something like modern alchemy, although the technology does exist and is not terribly complex. Still, the practical application of desalination is much more complicated, expensive, and energy-intensive than most alternatives almost anywhere in the United States.

In Narragansett Bay's watershed, we receive an average of about 42 inches of rain per year. With this much rain pouring into our rivers, reservoirs, and groundwater, it would seem that natural sources of fresh water would always be cheaper and more easily available than desalinated seawater. However, rising demand for fresh water has led communities and municpalities in Rhode Island and Massachusetts to turn to desalination as a means of supplementing or replacing natural supplies.

Two desalination plants are presently proposed for the Bay: One on the
Taunton River, one on the Palmer. The first, Aquaria, is proposed for Dighton, MA, on the Taunton. Save The Bay, along with the Taunton River and Jones River Watershed Associations, fought the development of this plant for more than a decade. Proposed for a rare freshwater-tidal portion of the river, our groups were concerned that the facility would remove too much freshwater from the estuary and cause impacts to migratory fish and river habitat. We appealed state permits for the facility, and entered settlement negotiations with the applicants. Ultimately, we dropped our appeal in exchange for more stringent river protections, monitoring, and a stewardship funds. Our groups remain committed to watching over this project to ensure that the Taunton is adequately protected. It looks like this project will actually be constructed in the next two to three years.

The Swansea facility, proposed for the Palmer River, is presently under review by State and Federal environmental agencies. We are also reviewing the latest version, and comments are due for this on March 24th. See the MA Environmental Monitor for more details on that

Environmental impacts from desalination can include effects of brine discharge, entrainment of fish eggs and larvae, antifouling chemicals such as chlorine, corrosion by-products such as copper and other metals, and thermal pollution from warmer-than-natural discharges. Effects on salinity, dissolved oxygen, pH, and other paramters are possible.

When choosing locations for desalination plants, Save The Bay discourages siting plants on estuaries, critical fish habitats, or other designated marine sancturaries. They should be operated using the best available technology for minimizing impacts to fish and other river or marine life. Finally, they should be carefully monitored, and shut down if unexpected environmental impacts are discovered.

There is a bill in Congress now H 1071 that includes a $200 million subsidy for the development of desalination facilities, but the bill does not specify any of the environmental standards or safeguards described above. While desalination plants can be sited and operated to reduce environmental impacts and can be a safe and sustainable water supply, it is not automatically so just because a facilitiy uses desalination.

It's time for the States and the Federal Government to establish policies for desalination facilities to clarify the process and provide for environmental performance standards and other safeguards. As water resources become increasingly scarce, we need to make sure desalination really is an environmentally-sound and viable option. More to come on this... JT

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