A 2006 Supreme Court ruling created widespread confusion about which wetlands and other waters are federally protected. The Trump administration's latest action isn't likely to clear things up.
A grade of 92 is an A at most schools, but for tap water it means that millions of Americans drink water that fails to met federal standards.
Air quality in the US has improved greatly since 1990, but a new report finds progress stalling in some cities. Meanwhile, the Trump administration is rolling back air pollution controls.
Are health risks from air pollution less serious than we think? Mainstream scientists call this a fringe view, but it's getting high-level attention at the Environmental Protection Agency.
An air pollution expert with years of experience advising federal regulators describes how the Trump administration is speeding up reviews and reducing scientific input.