Waterford - Southeastern Connecticut Council of Governments representatives and staff toured Millstone Power Station on Wednesday, learning about cooling water, storage of spent fuel and key issues facing the nuclear plant.

Officials of Dominion, the company that owns Millstone, told council attendees that now that the U.S. Environmental Protection Agency has issued its ruling governing water at power facilities, it's up to the state to decide how Millstone must handle its water in the future.

The EPA's ruling, issued in May, means Millstone will not be forced by federal regulators to retrofit the plant with the massive concrete structures that plant owner Dominion contends would cost $2.6 billion and reduce energy output.

Instead, the EPA said facilities that withdraw more than 2 million gallons a day from marine and fresh waterways can comply with Clean Water Act standards, which require that the best available technology be used to reduce fish mortality, by employing one of seven options.

The list of available options includes cooling towers, but also installing equipment to ensure intake water speeds are slow enough so that healthy fish can escape, or installing special types of screens to trap marine life before it enters the plant.

Company representatives Wednesday pointed to alternatives to cooling towers it is employing.

Dominion has invested in variable frequency drives, a technology in which the company can control how much water it takes in, similar to a dimmer on a light switch, said Kevin Hennessy, director of federal, state and local affairs for Dominion's New England operations.

"Those are the types of investments you can make to mitigate your environmental impact," he said.

The company reduced its water intake to coincide with spawning season of winter flounder and implemented screening technologies to return fish to Long Island Sound.

Millstone officials then led Preston First Selectman Bob Congdon, Montville Mayor Ronald McDaniel and Ledyard Mayor John Rodolico, as well as the council's staff and guests, on a tour of the facility.

Attendees asked questions ranging from the plant's intake of water - a million gallons per minute - to how the ruling to not allow nuclear waste storage at Yucca Mountain affects the plant.

Millstone currently holds some of its spent fuel in dry cask storage in protected areas on-site. Mike O'Connor, Millstone's assistant manager of outage and planning, said the plant will need to build more storage bunkers, as it continues to unload fuel in the future.

In addition to Millstone, the council has toured the Preston Riverwalk site, the Charles W. Morgan whaleship, and both casinos while under construction, among other sites, in an effort to better understand the region, said Executive Director James Butler.

k.drelich@theday.com