The Hay’s Spring Amphipod. Image via Michelle Brown/Smithsonian Institution, National Museum of Natural History, Department of Invertebrate Zoology.

One of the biggest delays for the proposed Purple Line—a light rail line that would connect D.C. to the Maryland suburbs through Rock Creek Park—is two rare, endangered shrimp-like crustaceans called the Hay’s Spring Amphipod and Kenk’s amphipod.

As the Post reported last November, a study of the proposed light rail line’s environmental impact “erred in omitting the colorless crustacean as an endangered species that must be avoided or protected,” a group of concerned environmentalists said.

That group—Friends of the Capital Crescent Trail—said they were contemplating filing a lawsuit to take a closer look at the environmental impact the Purple Line would have. WCP reports that the group filed a suit in federal court yesterday to block the Purple Line from moving forward:

Friends of the Capital Crescent Trail and two Maryland residents filed suit in federal court Tuesday to block the Purple Line, claiming the $2.4 billion line would harm two endangered shrimp-like species: The Hay’s Spring amphipod and Kenk’s amphipod. The suit, filed in U.S. District Court for the District of Columbia, was lodged against the Fish and Wildlife Service, the Department of Transportation, the Department of Interior, and the Federal Transit Administration. The plaintiffs want the government to reroute part of the line because construction of the Purple Line, the suit alleges, could hurt the Rock Creek watershed where the two species live.

Despite a federal environmental review conducted in March that found the proposed light rail line won’t impact the endangered species, the plaintiffs argue that the review was rushed and not sufficient enough.

But the U.S. Fish and Wildlife Service says that the Purple Line won’t have any effect on the two endangered amphipod species. In a letter to the Federal Transit Association in April, the USFWS says that the Purple Line construction will be far away enough from the habitats of both amphipods that it won’t have any impact on them. “The Purple Line FEIS indicates that most of the project-related development will occur in areas already zoned commercial and already mostly developed and covered with buildings and impervious pavement.

Additionally, the Purple Line project has gained approval from other environmental groups, including the Chesapeake Bay Foundation, the Natural Resources Defense Council, Clean Water Action, and more. In a statement, Purple Line NOW President Ralph Bennett said that “despite the assertions of those who filed the lawsuit, the fact remains that there is no evidence that the species exists within the planned route of the Purple Line.” According to the research on the amphipods, they’re only known to “exist in a few springs in the District of Columbia,” which aren’t located near where the Purple Line would be built.

Construction on the Purple Line is slated to begin in 2015, with a proposed completion sometime in 2020, but if the lawsuit moves forward, it could delay those plans.

Last December, DCist “interviewed” one of the Hay’s Spring Amphipods living in Rock Creek Park about the Purple Line. DCist reached to our source in the Hay’s Spring Amphipod community in Rock Creek Park, who merely returned our request for comment with this: ¯(ツ)/¯