The rules would limit mercury output for the first time in Wisconsin, and it would mean higher energy costs for utility customers in the decades to come.

Coal-burning plants would be required to cut mercury emissions by 40 percent in 2010 and by 75 percent in 2015.

This is the second time that the rules will go to the seven- member policy board of the Department of Natural Resources. The board approved a mercury-emissions package a year ago. But the Republican-controlled Legislature held up the rules after leaders said the DNR should wait for federal rules instead.

After months of negotiations between DNR staff and lawmakers, along with business groups and environmental organizations, the revised rules will go to the board Wednesday at a meeting in Milwaukee.

The DNR said the new package is a compromise: Proposed new limits would be eased but still protect Wisconsin's lakes, rivers and streams.

Major changes in the package include: Companies would have to meet a 75 percent reduction -- not the 80 percent cut by 2015 as first proposed. Environmental groups have pushed for a 90 percent reduction, but business said limits of 80 percent and 90 percent may not be technologically feasible. Wisconsin's regulations would shift to a federal standard when the U.S. Environmental Protection Agency and Congress eventually write mercury reduction rules.

"That's the big one," said Rep. DuWayne Johnsrud (R-Eastman), chairman of the Assembly Natural Resources Committee.

The Bush administration had advanced a mercury rule package that was weaker than Wisconsin's. In April, the agency said it would delay final action until March 2005 after environmentalists said the rule would take too long to cut emissions.

Johnsrud said the DNR rules are fundamentally flawed unless the federal government steps in with its own limits. Mercury that goes up smokestacks can travel for hundreds of miles and eventually settles on land and water. That means mercury from other states falls on Wisconsin waterways.

In the water, bacteria convert mercury to a more toxic form, methylmercury, which accumulates in fish.

Last year, the DNR estimated that a 40 percent reduction in mercury emissions could cost the state's four largest utilities $28 million to $33 million a year, or $6 to $7 a year for the average residential customers. The second phase of cuts, then estimated at 80 percent, would cumulatively cost $87 million to $104 million, or $18 to $21 a year.

Rick James, a spokesman for We Energies in Milwaukee, said the utility was studying the rules. James said the company was voluntarily cutting emissions of several pollutants, including a 50 percent reduction in mercury over the next decade.

Eric Uram of the Sierra Club said he did not think the rules went far enough.

The goal was to ensure that Wisconsin will eventually be able to end fish consumption advisories, he said. "Wisconsin should be setting the bar higher."

A growing body of science has pointed to the dangers of eating too much mercury-laden fish. That prompted the DNR in 2001 to broaden its fish consumption advisory sharply, from 341 lakes to all of the more than 15,000 lakes in Wisconsin.