Conservationists in Virginia and Maryland say a Trump administration proposal could undermine efforts to clean up the Chesapeake Bay.
The measure would roll back federal protections for certain waterways and wetlands.
It would specifically impact “ephemeral” streams, which flow after a rainstorm or snowmelt.
Also under threat are isolated wetlands that experts say help to filter pesticides and fertilizer from nation’s largest estuary.
An Obama-era rule protects those particular streams and wetlands and restricts some farming on land that sits near them. Critics say the rule forces farmers to hire expensive consultants to figure out which land they can use.
But Geoff Gisler, senior attorney for the Southern Environmental Law Center, called the Trump plan “a sledgehammer to the Clean Water Act.”