(Courtesy of U.S. Fish and Wildlife Service)

The Hay’s Spring amphipod may soon have to make way for another rare shrimp-like crustacean on the endangered species list: the Kenk’s amphiopod.

If you have any idea of what an amphipod is, either you’re a scientist or have been paying attention to the Purple Line saga. A group of environmentalists people in Chevy Chase who really don’t want a light rail line nearby sued because an environmental study didn’t consider the impact on the two species, which are tiny, eyeless, and colorless. The Hay’s Spring amphiopod has been on the endangered species list since 1982, and is only known to be found in a few springs along Rock Creek.

But the U.S. Fish and Wildlife Service determined that the Purple Line wouldn’t have any effect on the Hay’s Spring or Kenk’s amphipods because the construction is far from the habitats of both. The group later amended the ongoing suit to focus on how the problems plaguing Metro might affect the (unaffiliated) rail line.

Now the U.S. Fish and Wildlife Service is formally proposing endangered status for Kenk’s amphipods, writing that they are “threatened by poor water quality, degraded natural spring habitat, and small populations.” The species is known to be in four sites in Caroline County, Virginia and six in D.C. and Maryland. But scientists couldn’t haven’t been able to find any amphipods at five of those six sites in recent surveys. That’s bad news for the species, but also humans concerned about water quality.

“Found almost entirely on park or federal lands, the amphipod’s sensitivity to water quality makes its presence an indication of cleaner water. While many of the northern springs are in protected areas, activities occurring outside park boundaries could be affecting the groundwater,” USFWS writes.

If successful, the listing wouldn’t affect the earlier analysis of the Purple Line, since it concluded that the project wouldn’t affect the amphipod.