Republican U.S. Sen. Susan Collins has joined two colleagues in introducing legislation to create a nationwide mercury monitoring program to detect harmful levels of the heavy metal in the environment.

The bill would establish monitoring sites throughout the country to assess mercury contamination levels in the air, soils and waters as well as plant and wildlife populations. Collins’ bill, which is co-sponsored by Democratic Sen. Hillary Clinton of New York and independent Sen. Joseph Lieberman of Connecticut, also would authorize funding for the ambitious monitoring program through 2013.

The proposal comes about four months after reports identified five “biological hot spots” for mercury contamination in wildlife in New England, New York and eastern Canada. While mercury was present throughout the region, the five “hot spots” were contaminated above healthy levels.

One of the identified “hot spots” was the upper watersheds of the Androscoggin and Kennebec rivers, which include Moosehead and Flagstaff lakes. The lower Penobscot River, Down East Maine and the St. John River were listed as “areas of concern” in the report, meaning preliminary data indicated a possible problem.

Researchers said the findings mean people should be aware of the health risks of eating too much fish from “hot spots” and adjust their diets accordingly.

At the time, Collins said the study underscored the need for a comprehensive program to detect and track environmental levels of mercury, a neurotoxin particularly harmful to young children and pregnant women. Mercury is dangerous because it accumulates in tissue and becomes more concentrated as it moves up through the food chain.

On Wednesday, the senator also repeated her earlier criticisms of the U.S. Environmental Protection Agency’s “Clean Air Mercury Rule,” which regulates mercury emissions from coal-fired power plants. The “hot spots” report identified such power plants as a primary culprit in contamination.

Collins said she was “deeply troubled” by the computer modeling that the EPA used to create the rules on mercury.

“This data was neither peer-reviewed nor verified with scientific measurements, and yet EPA used [the data] as the basis for its mercury rule, which does not account for mercury hot spots and which places children and pregnant women at risk,” Collins said in a statement.

“Hopefully, the new measurements provided by this legislation will form the basis for a new mercury rule which adequately protects human health and environment.”

EPA officials have defended the mercury rule as helping to achieve a projected 80 percent reduction in mercury deposition in the northeastern U.S. Officials said at the time of the “hot spots” studies that the agency was working to establish a coordinated, nationwide network of monitoring sites for atmospheric mercury.

One of the researchers involved in the “hot spots” reports and discussion over a monitoring program was David Evers, executive director of the BioDiversity Research Institute in Gorham.

Evers was one of about 30 scientists from around the nation invited to a 2003 workshop sponsored by the EPA and industry to talk about mercury monitoring. Workshop participants developed a conceptual plan for 200 monitoring sites spread throughout the country.

In the years since, Evers and other researchers have delved into studying mercury’s impact on wildlife. For the “hot spots” studies, the researchers looked at mercury levels in perch, loons, bald eagles, brook trout, otters and other animal species.

But the nationwide monitoring program never materialized, at least not yet. Evers is nonetheless optimistic and strongly supports Collins’ bill. Evers said he acted as a scientific adviser to Collins’ office on the issue.

“Is it realistic? I think it is because all of the industries and agencies have been involved in putting together a plan,” said Evers, whose BioDiversity Research Institute is also behind the popular “eagle cam” in Hancock County.

The “hot spots” studies also found that mercury contamination levels near a coal-fired power plant in southern New Hampshire were five times the levels predicted by the EPA’s computer models.

The four other hot spots identified by the reports were in New York’s Adirondack Mountains, the upper Connecticut River in Vermont and New Hampshire, the Merrimack River in Massachusetts and southern New Hampshire, and in central Nova Scotia.