The Trump Administration is removing environmental protections from a large portion of the nation's wetlands, rivers and streams, marking one of the most significant rollbacks to date.

The move is a giveaway to big industry, including property developers, oil and gas producers, and the agricultural industry, which have long criticized water permit requirements and restrictions on development. The action will open up vast stretches of the United States to uncontrolled pollution discharges and the decimation of wetlands.

It is the latest in an unprecedented assault on environmental regulations by Trump. Over the past three years, Administration officials have finalized approximately 60 environmental rollbacks to lift restrictions on fossil fuel and mineral extraction, weaken limits on air pollution and undermine other environmental safeguards.

The Environmental Protection Agency (EPA) and Army Corps of Engineers announced last week the water pollution rollback, finalizing new definitions of which water bodies are covered by federal rules. The rule scales back the applicability of virtually all sections the Clean Air Act, the legal foundation for much of the nation's water pollution controls.

In December the agencies rescinded the Obama Administration's definitions in the 2015 Waters of the United States rule, without offering a replacement until now. The new rule, however, goes well beyond a return to pre-2015 conditions. Some waterways covered for decades will now fall outside of the Clean Air Act's jurisdiction.

Small headwaters, streams that flow intermittently, and wetlands without surface connections to larger bodies of water are now excluded from the federal regulations. In some areas of the West, the vast majority of tributaries feeding into major rivers are intermittent, running dry at some point during the year. In all, more than half of the wetlands and nearly 20 percent of the rivers and streams around the country will be exempted from pollution controls.

“This will be the biggest loss of clean water protection the country has ever seen,” Blan Holman, a lawyer at the Southern Environmental Law Center told the New York Times. “This puts drinking water for millions of Americans at risk of contamination from unregulated pollution.”

The EPA's scientific advisory board, packed with Trump Administration appointees, took the unusual step of criticizing the proposed rule change on the verge of its release. The panel concluded in late December that the main components of the rule were “in conflict with established science... and the objectives of the Clean Water Act.” The scientists insisted that the limiting applicability to wetlands adjacent to major bodies of water while ignoring the connectivity of ground water is at odds with a basic scientific understanding of watershed systems and processes.

They also warned of substantial new risks to human and environmental health by removing controls on sources that are serious threats to public health. E. coli contamination of vegetables, for instance, is often traceable to polluted runoff in irrigation canals adjacent to animal feed lots.

Trump promoted the rollback at the annual convention of the American Farm Bureau Federation on January 19, referring to the Obama-era rules as “one of the most ridiculous regulations of all.” He added, “That was a rule that basically took your property away from you.” Obama's 2015 Waters of the United States rule has been a key target of the agricultural industry, despite maintaining exemptions for many polluting farming practices, because it was broad enough to interpret sources like irrigation canals in the definition of US waters.

EPA chief Andrew Wheeler spoke before another key beneficiary of the rollback, the National Association of Home Builders, at their annual conference in Las Vegas last Thursday. He criticized the vagueness of Obama's clean water rule, which court rulings put on hold in 28 states, touting instead the “clarity and certainty” the new rule will afford real estate developers.

While industries favored by the Trump Administration stand to profit from the rollback, the consequences of removing vital environmental safeguards are potentially far-reaching. Wetlands not only serve as vital habitats for a wide range of species, they are also critical natural defenses to mitigate the impact of climate change. Wetlands reduce the impact of droughts and can provide flood and shoreline protection from extreme storms.

The additional pollution load from the use of previously restricted chemicals, pesticides and fertilizers reaching the country's rivers, lakes, and drinking water sources threatens to further undermine human and environmental health. According to EPA data, already more than half of all streams, 80 percent of estuaries and 90 percent of coastal waters in the US are categorized as impaired. Nearly one quarter of the US population lives in areas that failed to meet safe drinking water standards.