A federally protected endangered species located in Rock Creek Park in Washington could tie up plans for the proposed light-rail Purple Line in Maryland.
The Hay's Spring amphipod, a tiny crustacean, has been spotted inside the park downstream of where Purple Line trains would cross.
The Washington Post reported environmentalists are concerned about the transit project's impact on the rare species and are contemplating a lawsuit.
The Maryland Transit Administration is proposing a Purple Line with a 16-mile route between Montgomery and Prince George's counties.
Maryland transit officials said state and federal environmental officials have not mentioned the presence of any endangered species along the proposed route. A state Department of Natural Resources biologist said the agency didn't find Hay's Spring amphipods during a search in the late-1990s.