WASHINGTON (AP) — A trail group in Bethesda, Maryland, is suing the U.S. Transportation Department, alleging a planned light-rail route through some Washington suburbs would harm two rare, shrimplike creatures.

The Friends of the Capital Crescent Trail and two residents of Chevy Chase, Maryland, filed the lawsuit Tuesday in U.S. District Court in Washington.

It alleges the Purple Line should be rerouted to protect the Rock Creek watershed in Montgomery County. The filing says the area includes habitat for the Hay’s spring amphipod, listed as endangered since 1982, and the Kenk’s amphipod, which is a candidate for federal listing.

Federal officials have said the 16-mile project would have no impact on either animal.

The nearly $2.4 billion project would run through parts of Montgomery and Prince George’s counties.

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