Environmental groups called on Congress to strengthen laws protecting rivers and other waterways on Thursday in response to a report showing that 80 percent of Maine’s major industries and municipalities violated their permits at least once in 2005.

Nationally, 57 percent of major industries and municipal wastewater treatment facilities exceeded their pollution discharge limits on at least one occasion in 2005, according to the report “Troubled Waters,” released Thursday by the U.S. Public Interest Research Group.

Maine topped the list with 81 percent of facilities reporting at least one violation. U.S. PIRG worked with its state organizations, including Environment Maine, to gather and analyze federal pollution discharge data.

The vast majority of Maine’s violators were municipal wastewater treatment facilities struggling to control such things as the amount of suspended solids being discharged. That’s an issue that has been on the front burner for state environmental officials for several years.

Kristin Elia, the federal field associate for the group Environment Maine, said many of the municipal violations are due to the fact that towns and cities do not have the money to complete costly treatment plant upgrades.

That is why the $18.3 million bond package for municipal water and sewer systems that voters approved in June was so important, Elia said.

But while the state of Maine is taking positive steps, the “Troubled Waters” report accused the Bush administration of taking steps to weaken protections under the Clean Water Act, which became law 35 years ago this month.

During a press conference on the Bangor waterfront Thursday morning, Elia urged Maine’s congressional delegation to support reauthorization of the Clean Water Act. The report’s authors also call on the federal government to revoke the permits of repeat violators and to tighten permit limits.

‘”Facilities across Maine and the country continue to dump more pollution into our waterways than is allowed by law,” Elia said.

Adam Goode of the Maine People’s Alliance said he was most concerned about discharges of mercury, lead and arsenic, all of which clearly have been shown to be detrimental to human health.

“These are serious health problems. They are not to be taken lightly,” Goode said.

Andy Fisk, director of the Maine Department of Environmental Protection’s Bureau of Land and Water Quality, pointed out that the DEP closely tracks pollution discharges and conducts more site visits and compliance checks than the national average.

But looking at simple permit violations does not tell the whole story about the discharge’s potential impact on a waterway. He said that 88 percent of municipal wastewater treatment facilities were in “substantial compliance” with their permits in 2006. The number was even higher for industrial facilities, 95 percent of which were in substantial compliance, which is a federal designation.

Maine also has much cleaner waters than the national average, Fisk said.

“If you look at Maine’s rivers and streams, about 2.5 percent of the 30,000-plus miles do not meet their [water quality] standards,” Fisk said. “Nationally, it’s about 40 percent.”