Water-quality advocacy groups say they have filed a lawsuit alleging that the Environmental Protection Agency violated federal law when it acted to remove dozens of Maryland waterways from its impaired-waters list.

In a lawsuit filed Tuesday in federal court in Washington, the organizations say the EPA violated the Clean Water Act when officials excused 53 river segments from “total maximum daily load” requirements in 2012.

The groups say the Maryland Department of the Environment, the state agency responsible for implementing the federal Clean Water Act, failed to provide timely notice of its decision to remove 53 waterways from the impaired-waters list, and thus denied the public an opportunity to comment.

Because of this, they say, the EPA's approval of the state list was “arbitrary, capricious, an abuse of discretion, or otherwise not in accordance with law.”

Plaintiffs include Blue Water Baltimore, the Chester River Association, the Gunpowder Riverkeeper in Monkton, the Midshore Riverkeeper Conservancy in Easton, the Potomac Riverkeeper Network in Washington and Waterkeepers Chesapeake in Takoma Park.

They say the removal of the waterways from the impaired-waters list leaves them without total maximum daily load limits for nitrogen, phosphorus and sediment, and deprives the public of “an essential tool for independently verifying that their local waters are meeting the water quality standards mandated by the Clean Water Act.”

“Pollution doesn't just originate in the middle of the Chesapeake Bay,” Elizabeth Nicholas, executive director of Waterkeepers Chesapeake, said in a statement. “We have to look at all the smaller creeks and streams that are suffering impaired water quality throughout the watershed.”

The groups are asking the court to declare the EPA's approval of the state's list “unlawful and arbitrary” and set it aside.

A spokesman for the EPA said the agency would review the complaint but would not comment on pending litigation.

A spokesman for the Maryland Department of the Environment said tracking the water quality of small waterways remains crucial.

“Addressing the pollution limits for certain Chesapeake Bay tributaries within the context of the broader bay pollution diet makes sense,” spokesman Jay Apperson said.