The Conservation Law Foundation has sued the U.S. Environmental Protection Agency, accusing the EPA of failing to take steps to protect the Charles River from polluted runoff. The legal action comes after both sides tried to reach a negotiated settlement.

The dispute is about fertilizers, pesticides, and everything else we put on the ground that washes off into rivers and streams. Experts say that runoff feeds the growth of harmful algae that smothers other life, creating so-called dead zones.

The CLF says the EPA is failing to hold big landowners—like universities, strip malls, and office parks—accountable for their runoff. Last year the CLF and Charles River Watershed Association sued the EPA to take action.

CLF spokesman Josh Block says they voluntarily withdrew that suit in August to negotiate with the EPA. 

“We were unable to find common ground," Block said. "And so now we voluntarily refiled the suit in hopes of reaching a resolution.”

In a statement, the EPA says it doesn’t comment on litigation, but the agency says it’s proud of its efforts over the last few decades to clean up the Charles River. Some of those efforts were spurred by other CLF lawsuits.