Arguing that fish and other sea life in the Gulf of Mexico are being damaged, two environmental groups are challenging the state's decision to renew a permit for Progress Energy Florida power plants in Citrus County.

The Sierra Club and the Florida Wildlife Federation, in a case filed last week in the state Division of Administrative Hearings, target two coal-fired plants at Progress Energy's Crystal River complex.

In part, the groups say Progress Energy's discharges of hot water into the Gulf are damaging a large ecosystem. Also, they take issue with water intake systems that can trap and kill sea life such as shellfish and small organisms.

"FWF and the Sierra Club dispute that this permit meets Florida water quality standards or satisfies obligations under the (federal) Clean Water Act,'' the groups said in a petition seeking an administrative hearing.

The Florida Department of Environmental Protection gave notice last month that it planned to renew the water-discharge permit, which the plants have had since the late 1970s. Progress spokesman Scott Sutton said the permit addresses the issues raised by the environmental groups.

"It went through the process, and DEP made the determination this is the permit that adequately protects the environment, and we're ready to go forth and comply with it,'' Sutton said.

Progress has five plants at Crystal River, though the permit only deals with two coal plants and a nuclear plant. David Guest, an attorney for the environmental groups, said the legal challenge does not address the nuclear plant because it does not pose the same water-related concerns as the coal plants.

Part of the dispute centers on water that is used to cool the plants and then discharged into the Gulf.

The Sierra Club and Wildlife Federation argue that the discharged water is so hot it damages sea life, including environmentally important sea grasses, and that Progress should install a type of cooling system known as a "cooling tower.'' Guest and the petition indicate the damage could spread as far as 3,000 acres.

The permit requires that the average discharged-water temperature cannot exceed 96.5 degrees, which also has been the requirement in the past. Sutton said Progress will be required to conduct analyses to determine whether the 96.5-degree standard is adequate and whether changes should be made in the future.

Another key part of the challenge involves water that is drawn from the Gulf as part of the plants' cooling process. Progress uses screens to try to prevent sea life from getting sucked into the plants, but the environmental groups say a massive amount of shrimp and other small organisms get trapped on the screens or pass through to their deaths.

The environmental groups raise several questions about the water-intake systems, including whether Progress should use finer mesh screens to reduce the threat to sea life.

The dispute comes as the U.S. Environmental Protection Agency works on regulations aimed at reducing threats to sea life from water-intake systems across the country. Those regulations are expected to be finalized in 2012.

Sutton said the permit will require Progress to comply with any new federal standards, though it could be years before those standards take full effect.

Progress on Tuesday filed a document requesting that an administrative law judge dismiss the permit challenge. The utility argued that the California-based Sierra Club can't legally pursue the case and that, as a permit renewal, almost all of the disputed issues have been resolved in the past.

But Guest, an attorney for the environmental-law group Earthjustice, disputed both arguments.

"The reason that you have permit renewals is to decide if something needs to be done differently,'' Guest said.