A Supreme Court ruling that removed EPA's authority to protect some wetlands from pollution will have impacts from Indiana Dunes National Park (photo) to Everglades National Park, according to the National Parks Conservation Association

A ruling Thursday by the U.S. Supreme Court that greatly limits the federal government's Clean Water Act oversight of water pollution impacting wetlands is damaging to national parks from Everglades National Park and Great Smoky Mountains National Park to Indiana Dunes National Park and other units of the National Park System, according to the National Parks Conservation Association.

Under the ruling, the Environmental Protection Agency's authority over wetlands applies only to those wetlands that have “a continuous surface connection to bodies that are ‘waters of the United States’ in their own right, so that there is no clear demarcation between ‘waters’ and wetlands.”

According to NPCA, nearly 90 percent of the wetlands within Indiana Dunes will lose Clean Water Act protections. "Nearly 70 percent of the park’s waters are already impaired due to industrial pollution outside of its boundaries and it will only get worse with this decision," the group said. "It is one of the most biodiverse in the country and is home to the Great Marsh and more than 1,500 plant and animal species."

At Everglades in Florida, NPCA said roughly 81 percent of the park's wetlands would lose protections under the ruling. "This will lead to more harmful pollution flowing into the park, impairing the park’s water and harming the many endangered and threatened species, including the Florida panther," NPCA said in a release.

In North Carolina and Tennessee, many of the wetlands around Great Smoky Mountains National Park are losing protections. "These out-of-park wetlands are critical for improving the health of park waterways, better protecting its prized native book trout and the area’s recreational fishing industry," said the group.

How many units of the National Park System would be affected by the ruling wasn't immediately known, though NPCA staff said "[P]retty much all of them that have waters flowing in and around them — which is more than 300 of the 420+."

Chad Lord, NPCA's senior director of environmental policy and climate change, said the court's ruling stands to damage the country's waters for drinking and recreating and that Congress must act to restore protections for wetlands.

"Today’s decision deals another blow to decades of collaborative work to clean up our nation’s waterways. It prioritizes polluters over clean drinking water for millions of people and jeopardizes the waters that flow through our communities and our national parks," said Lord. "The Environmental Protection Agency was created more than 50 years ago to protect human health and our environment from known pollution and today their hands are tied by the Court ignoring America’s overwhelming support for more protections — not less.

“With communities in America today still living with unsafe drinking water and more than two-thirds of our national park waters impaired we cannot stand for this," he added. "Many national park waters originate outside their borders and depend on strong Clean Water Act protections for the health of the park, wildlife and visitors who swim and fish park waters. The Court has failed the most vulnerable communities — namely those on the frontlines, facing the intensifying climate crisis and pollution in already underserved areas and tribal communities."

Tom Kiernan, who once headed NPCA and now is the president and CEO of American Rivers, said the ruling is "a serious blow to wetlands, which are essential to clean, affordable drinking water, public health, and flood protection. Today’s ruling puts rivers and people at greater risk from pollution and harm."

“Without strong, science-based protections, the rivers and wetlands that are the lifeblood of our nation will suffer irreparable harm," added Kiernan. "We risk going backwards to a time of fish beach closures and rivers choked with pollution. This ruling will exacerbate environmental injustices as the worst impacts harm communities of color."

NPCA's Lord, pointing to impacts from climate change to algal blooms and drought, said "cleaner water works in tandem with restoration investments already underway in and around our parks. When we prioritize clean water for people and parks, we promote businesses, tourism and recreational opportunities that draw record visitors to these places, and billions in economic support to the gateway communities that surround them."

Michael Regan, the EPA's administrator, said the agency was studying the court's ruling and debating next steps.