With mounting evidence of damage to loons, eagles and other wildlife, environmental groups are asking the state to try again to outlaw or limit the use of lead in fishing gear, birdshot and rifle bullets.

Their petition, filed last month with the Minnesota Department of Natural Resources, would require hunters to use steel, copper or other nontoxic ammunition during all hunting seasons throughout the state. It also asks the DNR to ban lead jigs and fishing tackle from lakes that have nesting loons.

Lead jigs and sinkers can poison loons when the birds scoop them up on lake bottoms while they are searching for pebbles to help them digest their food. Eagles can be poisoned when they eat "gut piles" left by hunters who shoot deer with lead shot and then dress them in the wild.

"The science is indisputable," said Tom Casey, chairman of Friends of Minnesota Scientific and Natural Areas, which filed the petition along with the Isaak Walton League and Friends of the Mississippi River, among other groups. "We've banned the use of lead in paint, in toys and in pretty much every other consumer product."

Lead ammunition has been banned on federal wetlands since the early 1990s. Duck and geese hunters are prohibited from using toxic shot across the United States. But Minnesota has never regulated the use of lead for taking other birds, small game or deer. Nor has it regulated lead in fishing tackle.

In a long-running education campaign, the Minnesota Pollution Control Agency (MPCA) has encouraged hunters and anglers to switch to nontoxic gear. But there's little evidence that campaign has made much difference.

In 2015, the state released a study of more than 130 loons that had been found dead over the course of several years, said Carrol Henderson, the now-retired longtime leader of the DNR's nongame wildlife program. More than 11% of the loons had died of lead poisoning.

Around that same time, scientists published a paper in the peer-reviewed Journal of Wildlife Management, which found that lead tackle killed more than 40% of all loons that had been found dead in New Hampshire.

Loons are particularly vulnerable because they eat small pebbles, almost exactly the same size as a common jig, to grind up minnows and small fish in their gizzards, Henderson said.

"People don't make that connection — that when they lose a lead jig, it never rusts or decomposes," Henderson said. "It sits there for decades."

Public backlash

The DNR has proposed more limited lead bans in the past, but it either withdrew them after public backlash or saw them shot down by state lawmakers. In 2015 and 2016, the DNR proposed banning lead birdshot on state-owned hunting land in the southern half of Minnesota. After months of public input, and opposition from hunter groups and the National Rifle Association, the DNR dropped the plans. The next year, the Legislature passed a bill that temporarily prohibited the DNR from changing its rules on lead shot. That ban expired July 1.

DNR officials said they haven't considered changing the rules since the moratorium was lifted this summer. Spokesman Chris Niskanen said the agency is reviewing the environmentalists' petition and will make a decision by an early November deadline.

Under current law, hunters and anglers have a choice, said Pat Rivers, DNR deputy director of fish and wildlife. "And we encourage them to use nontoxic."

A growing number of states, including New Hampshire, New York, Vermont and Maine, have either banned lead in fishing gear or prohibited its use in smaller jigs and sinkers. This year, California became the first state to ban the use of lead ammunition entirely.

Even so, many hunters and anglers have resisted change. Lead ammunition and fishing tackle have historically been cheaper than nontoxic products and have long been much more readily available on store shelves. Steel shot, especially, earned a reputation for poor quality in the 1990s as manufacturers rushed to meet federal regulations. That's changing now that more companies are producing more lead alternatives to keep up with new regulations and rising demand.

Minnesota-based Pheasants Forever, one of the nation's most prominent hunter and habitat conservation groups, prefers that hunters have a choice about using lead ammunition, said spokesman Jared Wiklund.

"We have members on both sides of the aisle on this," he said. He added that a number of ammunition makers, including Minnesota's own Federal Ammunition, have made great strides toward new materials over the past decade, producing steel or nontoxic shot that is affordable and more than capable in the field.

National Rifle Association officials did not return phone calls seeking comment. The group's lobbying arm has posted a statement online applauding past efforts to derail Minnesota's proposed limits on lead shot. "Arguments in favor of these bans are based on faulty science," the group wrote, adding that there has been no evidence that lead ammunition has had a "population-level impact" on any Minnesota species.

While federal regulations have targeted lead in waterfowl hunting, much of the impact in the Upper Midwest has turned up during gun deer seasons.

Poisoned eagles

Studies have shown that lead rifle bullets shatter on impact, sending lead fragments up to 18 inches in any direction throughout the body of the deer.

In the mid-2000s, North Dakota started testing venison donated by hunters to food pantries and found lead in about 6% of the meat samples.

In addition, lead fragments often reach a deer's guts, which remain behind after a hunter field-dresses the animal and can be eaten by eagles, hawks and other scavengers, said Julia Ponder, a veterinarian and executive director of the Raptor Center at the University of Minnesota.

More than a quarter of all injured eagles rescued and brought to the Raptor Center are sick or dying from lead poisoning, Ponder said.

The center has cared for hundreds of injured eagles over the decades and tests every eagle it treats for lead. Since 1991, more than 70% of all eagles had measurable amounts of lead in their bodies, Ponder said.

"No amount of lead is normal in a biological system," she added.

The Raptor Center saw little difference in the number of poisoned eagles it treated before and after the federal ban on lead ammunition in wetlands. But every year there is an uptick during deer-hunting season, Ponder said.

"It's these soft lead bullets that just fragment," she said. "Once they make it into the gut pile, it becomes totally contaminated. That's just a toxic meal for whatever wildlife comes to feed on it."

Greg Stanley • 612-673-4882