MINNEAPOLIS — Minnesota’s coal-fired power plants have cut their mercury emissions in half over the last 15 years, the Minnesota Pollution Control Agency said Monday.

MPCA Commissioner John Linc Stine praised the state’s utility companies for their cooperation, which has put Minnesota three years ahead of its plan to reduce mercury emissions by 90 percent. The Legislature set that goal with the Mercury Emissions Reduction Act of 2006.

Emissions are down statewide from about 1,850 pounds per year in the mid-1990s to 870 pounds today. The MPCA expects that to dip as low as 200 pounds per year by 2016. Mercury is a toxin released from utility plants, taconite production and consumer products. It accumulates in fish and is most harmful to children and pregnant women.

Stine and other state and industry officials highlighted the improvements at Xcel Energy Corp.’s Riverside Plant in Minneapolis, one of several that have drastically cut their mercury output.

“Minnesota’s willingness to take responsibility for its own mercury has paved the way to a safer environment, both here and around the country,” said Bill Grant, deputy commissioner of the Minnesota Department of Commerce.

Xcel and Minnesota Power — two of the state’s largest utilities — have each spent hundreds of millions of dollars to cut emissions of mercury and other pollutants, representatives from the companies said. They spray a special carbon compound into exhaust vents to help filter out mercury. Xcel also converted its Riverside plant and another in St. Paul to run on natural gas rather than burn coal.

MPCA air assessment manager Frank Kohlasch said the two companies have already cut their mercury emissions by about 90 percent.

“We value environmental stewardship, and mercury is a key component of our work in that arena,” said Margaret Hodnik, Minnesota Power’s vice president of regulatory and legislative affairs. The company will complete its mercury reduction plan in 2016 when it retrofits another power generator in Cohasset, Minn.

For the past decade, the state has tried to weed out mercury from consumer products like older thermostats, thermometers, automobiles and even dental fillings. Kohlasch said some of the state’s taconite mines will try out new mercury reduction technologies later this year.

Despite the progress, the Minnesota Department of Health hasn’t measured a significant decrease of mercury levels in fish.

“It’s going to take time to get it out of the food chain,” Stine said.

Much of the problem may be out of the state’s control. About 90 percent of the mercury in Minnesota comes from outside the state, from natural sources like volcanoes or coal-powered plants across the nation and world, MPCA said.