Waterford - A much-anticipated decision due Nov. 4 from the Environmental Protection Agency is not expected to settle whether the Millstone Power Station ultimately must construct cooling towers, massive concrete structures that environmental groups say would reduce the destruction of fish and other harm to the Long Island Sound ecosystem, but that others warn pose their own drawbacks.

But "nobody will literally be able to do the status quo," said Kent Zammit, senior program manager for the Electric Power Research Institute, which has weighed in on EPA reviews and researched the impact of cooling towers and other technologies. Any change, he said, would require studies of the potential environmental effects.

The decision the EPA is preparing to release on Nov. 4 will issue new standards for how the "best available technology" requirement of the federal Clean Water Act will be applied to 740 of the nation's power plants and other facilities, including nuclear energy plants such as Millstone.

The ruling stems from a 1993 lawsuit in which Riverkeeper, Soundkeeper and 17 other groups successfully argued that the EPA was failing to enforce the Clean Water Act by not requiring retrofitting of power plants that are cooled by large amounts of water drawn from nearby sources. Cooling towers remove waste heat from the plants by emitting it into the air through evaporation rather than by using a nearby body of water as a heat sink.

Nuclear plants built in recent decades have been required to have cooling towers, noted Reed Super, attorney for Riverkeeper, one of the environmental groups pushing for the retroactive requirement for all plants. Several U.S. plants not located on waterways have been successfully using the technology, he said.

"A plant couldn't be built today without cooling towers," he said. "They protect fish and dozens of other marine creatures."

Plants that use large amounts of water for cooling later discharge warmed water back into the same river, lake or estuary, he noted.

"It changes the habitat," Super said. "There are enormous environmental impacts."

Saltwater intake, output

At Millstone, the two operating plants pull in about 1.3 million gallons of water per minute to remove heat generated in the production of electricity and discharge that warmed water back into the Sound. The intake pipes are fitted with 3/8-inch mesh screens that stop many fish and other marinelife from entering the plant. Fish caught in the screens are washed and returned to Niantic Bay.

"The screening process has been very successful at reducing impingement impacts," said Ken Holt, spokesman for Millstone owner Dominion.

Millstone also curtails water use by 40 percent during he winter flounder spawning season, and has installed new equipment on cooling water pumps to reduce the amount of water used, Holt said. He could not provide an estimate of the numbers of fish and fish larvae that perish in the intake structures.

Instead of a definitive ruling on cooling towers, the EPA is expected to leave the matter up to state regulators as part of permitting requirements for plants, said William Skaff, director of policy analysis for the Nuclear Energy Institute.

"We think the final rule will be workable, environmentally sound, and sound in terms of the cost-benefit," he said. "State regulators would have to consider a number of factors, including environmental, social and economic considerations, before they determine what constitutes the 'best available technology.'"

In Connecticut, the state Department of Energy and Environmental Protection is awaiting the EPA ruling to determine how it will proceed on Millstone's pending application for renewal of its water discharge permit, DEEP spokesman Dennis Schain said. The current permit expires in 2015.

As a condition of its last permit renewal, in 2010, Millstone was required to conduct a study of cooling technology and take steps to reduce water use and screen out more fish from its intake pipes. The requirements were the result of a settlement among DEEP, Soundkeeper and the Connecticut Fund for the Environment, which is continuing to advocate for cooling towers at Millstone, said Roger Reynolds, legal director of the Connecticut Fund for the Environment.

"Cooling towers should be required," he said, adding that water use would be reduced by 98 percent. "Millstone uses over 2 billion gallons of water a day. That's remarkably destructive to marine life."

The required study conducted by Millstone concluded that the equipment currently in use meets the "best available technology" standard, and that there is no upgrade that would be a substantial improvement. Reynolds said the Connecticut Fund for the Environment came to a different conclusion.

"They evaluated their options and determined what was feasible, and we disagree," Reynolds said. The plant is profitable, he said, and can afford the expense of installing cooling towers.

Flexible standards

EPA spokesman Dale Kemery, in an email last week, said the agency is considering instituting "flexible technology standards" that would require plants to reduce the numbers of aquatic organisms killed in intake structures, but not mandate one particular type of equipment to accomplish this. Possible methods include reducing water use or intake velocity, using advanced screens and fish return systems, and moving intake pipes, along with cooling towers.

The EPA would not impose a uniform standard for cooling towers, Kemery said, because of four factors: energy reliability, air emissions issues, land availability at power plant sites and age of plants. Cooling towers, according to David Lochbaum, director of the Nuclear Safety Project at the Union of Concerned Scientists, can reduce electricity output by 10 to 15 megawatts, would emit "vapors" over the surrounding area that are "like a cloud maker" in certain weather conditions, and are costly and complicated to retrofit onto existing plants, requiring a temporary shutdown.

"It's not as easy as it might seem," he said. "There are downsides."

Lochbaum said if Millstone were required to install cooling towers, "it might lead to a plant shutdown." But he said he believes the EPA "won't issue such a draconian edict."

Millstone estimates it would cost $2.6 billion to retrofit the plants with the three massive towers that would be needed. Each would rise about 500 feet - about as tall as a 50-story building. Reduced energy output caused by the towers would cost $16.9 million annually, Millstone said in its study, and annual operation and maintenance of the towers would cost $5.7 million. Holt said the plant would have to shut down for a year to install cooling towers, a retrofit "that has never been done onto an existing nuclear power plant."

"Dominion has not said it would shut down if forced to install cooling towers," Holt said. "However, like every business, Dominion constantly evaluates its various assets. The cost-benefit analysis will certainly be taken into consideration if we are mandated to install cooling towers at Millstone."

Waterford First Selectman Dan Steward opposes cooling towers at Millstone, the town's largest taxpayer.

"They would each be the size of a football field, and coming out of that is steam, which creates mist, which will fog the entire Niantic Bay and all the houses in that area will live in a fog," he said. "It's just ugly, and you don't need to do this."

The plant's current system of using seawater from the Sound to cool the plant, he said, has been working well.

Super, the attorney for Riverkeeper and Soundkeeper, and Reynolds, attorney for the Connecticut Fund for the Environment, both say opponents are exaggerating the cost estimates and effects of cooling towers on the surrounding landscape.

"It's overblown," Super said. He added that the costs for the retrofit at Millstone could be borne by ratepayers, increasing rates by about 50 cents to $1 per month.

Compared to cooling towers, he said, "any other technology is vastly inferior."

If the EPA acts as expected, and leaves the decision about how plants must meet the "best available technology" standard up to states to decide on a case-by-case basis, his group and others will renew their push for cooling towers, Super said.

"We'll be back in court as quick as you can say 'court,'" he said.

j.benson@theday.com

Staff Writer Johanna Somers contributed to this story.