What’s protected by the Clean Water Act?

Jan 31, 2024

Researchers at the University of California, Berkeley, used a machine learning model to predict which surface waters and wetlands were federally regulated in order to help answer a long-standing question: What does the Clean Water Act actually protect?

The original 1972 Clean Water Act forbids dredging, filling, or discharging pollutants into a wetland or stream without first receiving a permit, but the law only applies to those waters and wetlands that are considered “waters of the U.S.,” a nebulous term that has been subject to extensive controversy and debate over the years.

The first-of-its-kind analysis of over 150,000 water permitting decisions showed that a Trump-era update to the Clean Water Act may have stripped federal protections for more wetlands and streams than previously thought. According to their findings, the Trump administration’s 2020 rule only covered about a quarter of U.S. wetlands and stripped federal protections for roughly 30 percent of waterways that feed into drinking water sources. In addition, only about half of wetlands and streams were federally regulated prior to 2020 to begin with. The findings also raise questions about the Clean Water Act’s current reach, given the Supreme Court’s ruling on Sackett vs. EPA last year that led to as many as half of the 118 million acres of wetlands in the U.S. no longer being protected by the Clean Water Act.

Joseph Shapiro, an associate professor of agricultural and resource economics at UC Berkeley and a senior author on the paper, said, “There’s been these huge debates about whether the Clean Water Act should regulate [various waters]. What I came to struggle with is we don’t actually know if we have been regulating them, because there’s been no systematic assessment of what we have been doing.”

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Quote of the day

The 1872 Mining Law is an outdated law that has failed to protect communities like mine. It’s hard to believe that Congress is considering legislation today that would make this law worse.”

—Jeffrey Stiffarm, president of the Fort Belknap Indian Community in central Montana, E&E News

Picture This

 A mountain lion stands on the bank of a winding river that is covered in snow. Around the river, there are reddish-brown shrubs that are barren from the winter.


Known by a variety of names – cougars, pumas, panthers – mountain lions are graceful and powerful. Weighing up to 200 pounds, they can leap as high as 18 feet vertically and can cover 40 feet horizontally in one bound.

They are shy and solitary creatures that move with the migration of elk and deer herds. They can sprint to chase down prey over short distances, but they are even better built for the ambush. Mountain lions stalk prey quietly until they reach a striking distance, then leap onto their target.

Photo on LaBarge Creek in Wyoming by Mark Thonhoff / @mypubliclands

#mountainlion #wildlife #publiclands #wyoming

Featured image: Cosumnes River Preserve, California. Photo by Bob Wick, BLM