On April 21, the Trump administration implemented its new definition of waters that fall within the scope of those regulated under the Clean Water Act (CWA).

The new waters of the United States (WOTUS) definition narrows federal jurisdiction over intrastate waters as well as groundwater, roadside ditches, converted cropland, stormwater controls, and waste treatment systems. The new WOTUS definition is effective as of June 22, 2020.

According to the summary of the updated definition posted in the Federal Register, the new rule aims “to restore and maintain the integrity of the nation’s waters by maintaining federal authority over those waters that Congress determined should be regulated by the Federal government under its Commerce Clause powers, while adhering to Congress’ policy directive to preserve States’ primary authority over land and water resources.”

The U.S. Department of Defense (DOD) and the U.S. Environmental Protection Agency (EPA) had originally proposed a revision of the definition of WOTUS in December 2018 to replace the Obama Administration’s expansion of federal powers under the Clean Water Act. They had done so after President Trump signed an executive order on February 28, 2017, directing the EPA to review and either rescind or revise the 2015 Obama administration definition.

Opponents of the revision argue that the new WOTUS definition is too narrow and might allow pollutants to enter Americans’ drinking water. Supporters of the revision believe it is necessary because, in their view, the Obama-era definition infringed on property rights and on state authority to regulate inland waters.

Learn more about the Clean Water Act and the EPA.