WASHINGTON – One of every three lakes in America, and nearly one-quarter of the nation’s rivers, contain enough pollution that people should limit or avoid eating fish caught there.

Every state but Alaska and Wyoming issued fish advisories covering some and occasionally all of their lakes or rivers in 2003, according to a national database maintained by the Environmental Protection Agency and updated every year.

Though the number of advisories rose to 3,094, up from 2,814 in 2002, according to figures released yesterday, EPA Administrator Mike Leavitt said the increase was due to more monitoring, not more pollution.

Nearly all the advisories involve contaminants such as mercury, dioxins, PCBs, pesticides, and heavy metals, including arsenic, copper, and lead. Currently they cover 35% of the nation’s lake acreage and 24% of river miles.

Mr. Leavitt said mercury pollution from industry is decreasing, though he cited figures only as recent as five years ago. Primary sources of mercury pollution include coal-burning power plants, the burning of hazardous and medical waste, and production of chlorine. It also occurs naturally in the environment.

The advisories cover fish caught during recreational and sport fishing, not deep-sea commercial fishing or fish farming operations.

“It’s about trout, not tuna. It’s about what you catch on the shore, not what you buy on the shelf,” Mr. Leavitt said. “This is about the health of pregnant mothers and small children, that’s the primary focus of our concern.”

But he also acknowledged that virtually every acre of lakes and mile of rivers could eventually be covered by advisories. Since pollution is found in fish nearly every time a state looks for it, the EPA assumes that whenever a state does that kind of monitoring it will wind up issuing a fish advisory, he said.

“I want to make clear that this agency views mercury as a toxin. Manmade emissions need to be reduced and regulated. There has been an appropriate, heightened public concern,” Mr. Leavitt said.

This year, 44 states had a fish advisory for mercury, a persistent substance that affects the nervous system. Two more states, Montana and Washington, added statewide advisories to warn of the potential for widespread contamination of fish.

Servings of fish caught by family or friends and not covered by an advisory should be limited to one six-ounce portion a week, according to the Food and Drug Administration.

The latest figures troubled frequent critics of the Bush administration, including environmentalist groups such as the Sierra Club, the National Wildlife Federation, and Natural Resources Defense Council. They want stricter limits imposed on mercury pollution from coal-fired power plants.

Earlier this month an environmental advocacy coalition released a report citing EPA figures to claim that 76% of fish samples collected from 260 bodies of water exceeded the agency’s mercury exposure limits for children under 3.

“Sadly, America’s women and children are paying for the administration’s procrastination,” said Carl Pope, executive director of the Sierra Club, which noted that state advisories now cover 13 million acres of lakes and three-quarter million miles of rivers.

“This listing clearly indicates that we are moving in the wrong direction on mercury pollution,” said Senator Jeffords, an Independent of Vermont and a senior member of the Senate Environment and Public Works Committee.

Mr. Jeffords and President Bush have each proposed ways of regulating mercury and other pollution from coal fired power plants.