WASHINGTON (AP) — Maryland is joining three other jurisdictions in supporting the Obama administration’s plan to clean up the Chesapeake Bay watershed, seeking to counter an election-year legal challenge by farmers and 21 attorneys general that could shape future U.S. environmental policy.

The case before the 3rd U.S. Circuit Court of Appeals in Philadelphia asks whether the Environmental Protection Agency went too far in negotiating a 2010 agreement that sets pollution limits in the nation’s largest estuary.