ST. PAUL, Minn. -- In some Minnesota lakes, invasive species are limiting the growth of a popular fish, according to a new study of the effects on walleye.

University of Minnesota researchers say the culprits are zebra mussels and spiny waterflea. They found in lakes where these are present, they can reduce the growth size of walleye from 12% to 14%. The species take away zooplankton, a food source for the fish.

Jeff Forester, executive director of the group Minnesota Lakes and Rivers Advocates, said the findings should spur stronger action by the state to prevent the spread of these species.

"What we've been doing -- this kind of emphasis on education and personal responsibility -- that's not getting it done," he said. "I think it's slowed the spread, but it certainly hasn't stopped it."

Forester said he'd like to see the state adopt more stringent boat-inspection policies, such as making it a requirement for people getting an operator's license. The Department of Natural Resources said that, in coordination with local governments, it conducted more than 500,000 watercraft inspections last year, a record number.

Walleye is a favorite fish for anglers and many resorts rely on its popularity for business. Forester acknowledged that it's a difficult balance for the state because boats are helping to spread these species, but many lake communities are dependent on water recreation.

"How do we use the lakes in such a way that they're protected for the future," he said, "and we're protecting the resource, which is not the lake itself, but the quality of life and the economics."

One of the lakes in the study, Mille Lacs Lake, has seen many controversies surrounding walleye fishing in recent years. The DNR has enforced strong limits for anglers so the walleye population can rebound. Some of those restrictions have been slowly lifted as walleye makes a comeback in the popular lake.

The study is online at springer.com.

The U.S. Supreme Court has gutted federal protections for much of the country's wetlands.

The court found that the Waters of the United States rule, part of the Clean Water Act, only applies to wetlands with a surface connection to a navigable body of water. Conservation groups have said that puts up to 80% of U.S. wetlands at risk for pollution and development, with ephemeral streams and headwaters in western states at particular risk.

Alex Funk, director of water resources and senior counsel for the Theodore Roosevelt Conservation Partnership, predicted the ruling will have widespread negative consequences.

"This is going to put major setbacks on our ability to adapt to climate change, respond to extreme weather events," he said. "So, anyone that hunts, fishes, or recreates - there was a big hit to that from the court."

The case was brought by a family in Idaho that was prevented from building on their land. The court unanimously decided that the EPA rule did not apply to their property, but then went much further, narrowing the authority of the agency nationwide.

Supporters cheered the ruling, saying the Obama-era Waters of the U.S. rule went too far and had been a burden to property owners.

Funk said pristine wetlands are the superstars of the natural infrastructure.

"Everything from mitigating downstream flooding impacts by absorbing runoff and precipitation to encouraging groundwater recharge, to improving water quality and capturing sediment, and other pollutants that might end up in drinking-water supplies," he said, "and, of course, the fish and wildlife impacts."

California Gov. Gavin Newsom said in a statement that "California has adopted some of the strongest laws in this country to protect our waters and the environment, and we will continue enforcing our own laws vigorously."

Environmental advocates say the U.S. Supreme Court has dealt a major blow to the Clean Water Act and to Maine's ability to protect some of its most pristine wetlands.

A 5-4 decision in Sackett v. EPA held wetlands can only be regulated under the Clean Water Act if they have a "continuous surface connection" to larger, regulated bodies of water.

Alex Funk, director of water resources and senior counsel for the Theodore Roosevelt Conservation Partnership, said the ruling eliminates federal protections for nearly all wetlands in the country.

"Anyone that hunts, fishes, recreates or uses water, there was a big hit to that today from the court," Funk asserted.

The high court ruled in favor of an Idaho couple who had been prevented from building a home near a lake federal officials identified as also containing wetland property and required a special permit. About one-fourth of Maine's land area is wetlands, which is four times the wetland area of the other five New England states combined.

Maine's coastal waters, rivers and lakes all depend on wetlands to filter out pollutants. Wetlands also serve as vital habitat for wildlife and flood protection for communities.

John Rumpler, clean water program director for Environment Maine, called today's ruling a devastating blow to protecting the state's waterways, and a misguided interpretation of the Clean Water Act.

"If a vast number of acres of remaining wetlands in Maine are no longer protected by our federal Clean Water Act, then there's a risk that polluters and developers will run amok and put our water at risk," Rumpler contended.

Rumpler stressed it is now up to state agencies and lawmakers in Augusta to ensure all of Maine's waterways, especially its wetlands, are protected by state law. He argued Congress will eventually need to create greater federal protections for the nation's vital water resources.

From protecting and studying waterways to addressing chronic wasting disease, conservation voices say there are a lot of important items in Minnesota's environmental and energy spending bill. Supporters say it brings sharper focus to many long-standing requests.

With Democrats holding majorities, the Legislature approved a nearly $2 billion omnibus bill to cover environmental, climate and energy priorities.

Jeff Forester, executive director of Minnesota Lakes and Rivers Advocates, said investments like improving boat ramps will help stop the spread of aquatic invasive species.

"Where does it get into the lakes? It gets into the lakes at the boat ramps as equipment and watercraft are moved from one lake to another," Forester explained. "So making those investments in the boat ramps in signage and places to pull over, it really is an integrated package."

He also applauded provisions to rein in harmful PFAS chemicals and their connection to waterways and fish. Another item bans new deer farms in hopes of limiting the spread of chronic wasting disease.

Some fee hikes will be used to help cover the new spending, including higher boat registration fees. Republican lawmakers voiced opposition to those aspects of the plan.

Forester credits lawmakers for addressing many long-standing issues, while also looking ahead so agencies and conservation groups are not blindsided by other climate threats down the road. He added part of the forward thinking is a 50-year water study included in the bill.

"Given current conditions, what can we expect the quality and the quantity of water to be in Minnesota in 50 years? What's it going to look like?" Forester asked. "That's such a simple question, but it hasn't been studied yet."

The bill also wove in the issue of environmental justice, by adding regulations taking into account the cumulative effect of a development project might pose health risks to historically marginalized communities. However, the provision was watered down from the original proposal introduced earlier this session.


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