Wetlands are vital to Arizona ecosystems. A Supreme Court ruling could weaken their protections.

Spread over 700 acres, the Tres Rios Wetlands form a bustling tapestry of nature, home to more than 150 species birds and animals, including bobcats, beavers and coyotes. The captivating colors showcase an impressive plant community of marshes, cattail stands, bulrush beds and mesquite bosques that each year lure thousands of migratory birds.

The wetlands, roughly 15 miles west of Phoenix, were established as part of a rehabilitation project in and around the Salt River to restore the natural habitat of an area that had been severely degraded. But a recent U.S. Supreme Court decision threatens the future of the area, along with millions of other acres of wetlands across the country.

In a 5-4 decision last month, the court curtailed the Environmental Protection Agency’s authority to regulate the nation's wetlands and waterways under the Clean Water Act.

The challenge to the regulations was brought by Michael and Chantell Sackett, an Idaho couple who bought property on what an appeals court called a “soggy residential lot” next to Priest Lake, a 19-mile stretch of water fed by mountain streams and bordered by state and national parkland. After the couple started preparing the property for construction in 2007, adding sand gravel and fill, the EPA halted construction and ordered the Sacketts to return the property to its original state because they had failed to get a permit for disturbing wetlands.

In its ruling, the high court sided with the Sacketts and rolled back longstanding rules adopted to carry out the 51-year-old Clean Water Act. It was the court's second decision in the last year limiting the ability of the agency to enact anti-pollution regulations and combat climate change.

Writing for the court majority, Justice Samuel Alito said that the “navigable waters” of the United States, as defined under the Clean Water Act and regulated by the EPA do not include many previously regulated wetlands. Rather, he said, the Clean Water Act extends to only streams, oceans, rivers and lakes, and those wetlands with a "continuous surface connection to those bodies."

That means wetlands that are not directly connected to a flowing body of water will no longer be monitored for pollution or be protected from development.

This decision will affect millions of acres of wetlands across the country that play a vital role in maintaining water quality, biodiversity, providing habitat for endangered species and flood control. In Arizona, the question of what water bodies will be affected is still up in the air, as many of the state’s rivers do not flow year-round.

Tres Rios Wetlands sits next to the Salt River, but are not connected through surface water, thwarting federal protections for the 700 acres of land.

“A vast number of wetlands that were regulated and required permits under the clean water act no longer do because they are no longer defined within the jurisdiction of the act,” said Stephanie Stern, a professor of law at the University of Arizona who focuses on climate adaption policy and water law. “This is very much a shifting of power from federal to state government.”

Justice Brett Kavanaugh joined the three liberal justices in a concurring opinion and said the decision would harm the federal government’s ability to address pollution and flooding.

“By narrowing the act's coverage of wetlands to only adjoining wetlands the court's new test will leave some long-regulated adjacent wetlands no longer covered by the Clean Water Act, with significant repercussions for water quality and flood control throughout the United States,” he wrote.

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How wetlands play an important role in a watershed

In the early 1970s, the newly created EPA commissioned hundreds of freelance photographers to document the state of the nation’s land and water, emphasizing pollution and waste. Photos emerged of the devastation humans had caused on the environment: trash and old tires piled along the shores of Baltimore Harbor, a sludge-filled lake in New Orleans, and a smoggy sunset in Philadelphia documented the degraded state of air and waterways throughout the nation.

It was one of the first times for many Americans to see the widespread damage caused by humans, and the photographs were fundamental in the creation of the Clean Water Act. The act established a basic structure of regulating discharges of pollutants into the waters of the United States and regulating quality standards for surface waters.

The law would, for the next 51 years, safeguard water quality, ensure public health, preserve biodiversity and ecology and maintain the value of watersheds across the country.

Wetlands play an integral role in the ecology of the watershed. The combination of shallow water, high levels of nutrients and primary productivity create ideal conditions for organisms that form the base of the food web and feed many species of fish, amphibians, shellfish and insects. Many species of birds and mammals rely on wetlands for food, water and shelter, especially during migration and breeding.

“Wetlands aren’t the most charismatic of the water bodies and I think it’s been harder to get protection for them,” Stern said. “They play an incredibly important role, but that isn’t always evident.”

Wetlands can even be used as atmospheric maintenance, as they store carbon within their plant communities and soil instead of releasing it to the atmosphere as carbon dioxide, helping to moderate global climate conditions.

Water regulations are imposed, revoked, reinstated

The new ruling will limit protections for millions of acres of wetlands, and the species they house, its implications for Arizona and the West may not be so clear, due to the relatively high number of intermittent and ephemeral rivers and streams throughout the region. These are temporary or seasonal rivers that do not have a consistent flow of surface water throughout the year.

While most rivers in the U.S. are perennial, across the arid West, ephemeral and intermittent rivers are more common because of drought and their reliance on snowmelt mountain runoff.

Under the Clean Water Act, the term “navigable waters” meant all waters of the United States, including oceans, would be protected, and made it a criminal offense for industries to pollute or degrade waterways unless they had permission through a permit.

But two Supreme Court cases in 2001 and 2006, brought through challenges by a municipal waste agency and real state developers, began adding exceptions to what water bodies could be protected, such as some wetlands and ponds.

The rulings prompted the Obama administration in 2015 to release a 400-page report titled, “Connectivity of Streams and Wetlands to Downstream Waters.” The review, based on scientific evidence, laid out a hydrological understanding of how water sources interact with each other in watersheds.

The report would be used by the administration to reestablish protections for wetlands removed by those court rulings. The protections would later be undone by the Trump administration and then reinstated again by President Joe Biden.

The report laid out how bodies of water in a watershed interact with each other. A perennial water source may be a primary waterway, but ephemeral and intermittent streams and rivers will feed into it. And adjacent wetlands are either connected through the surface, by flooding, or under the surface through groundwater.

A watershed acts as a sponge, expanding and contracting with the volume of water present. All water bodies in this sponge will share organisms, nutrients and pollutants, as water is transported above or below the surface. Thus, scientists say, all bodies of water in a watershed become intrinsically connected, including the sort of isolated wetlands that have now lost protection.

With no regulations for these adjacent wetlands, the likelihood of pollutants entering perennial and ephemeral streams and rivers is greatly increased, critics of the ruling say, either by surface water through a flood event, or through groundwater transport.

“Since the Clean Water Act was enacted, there has been a tremendous advancement in our knowledge of hydrology and how interconnected water is both above ground and underground,” Stern said. “This, in my opinion, moves us backwards to a very segmented view rather than a science-based view of the hydrological connectivity.”