On June 7, 2011, the U.S. Fish and Wildlife Service (Service) issued a final rule under section 4 of the federal Endangered Species Act revising the critical habitat designated for the Pecos assiminea (Assiminea pecos), and designating critical habitat for the Roswell springsnail (Pyrgulopsis roswellensis), Koster’s springsnail (Juturnia kosteri), and Noel’s amphipod (Gammarus desperatus).  The designated critical habitat for the four endangered species, which occur primarily in sinkholes, springs, and associated spring runs and wetland habitats, is located in Chaves County, New Mexico, and Pecos and Reeves Counties, Texas.  

Although the shrimp (Noel’s amphipod) and three snails were added to the endangered species list in 2005, the Service initially designated only 396.5 acres of critical habitat for the Pecos assiminea; the Service did not designate any critical habitat for the other three species.  In 2009, however, in response to a complaint filed by Forest Guardians (now WildEarth Guardians), the Service agreed to revisit its critical habitat designation.  As a result, the Service designated in its final rule approximately 70.2 acres as critical habitat for the Roswell springsnail and Koster’s springsnail, approximately 75.9 acres as critical habitat for the Noel’s amphipod, and approximately 494.7 acres as critical habitat for the Pecos assiminea. 

The Service notes in the final rule that, as previously stated in 2005, the primary "threats to the four invertebrates include reducing or eliminating water in suitable or occupied habitat through drought or pumping; introducing pollutants to levels unsuitable for the species from urban areas, agriculture, release of chemicals, and oil and gas operations; fires that reduce or eliminate available habitat; and introducing nonnative species into the invertebrates’ inhabited spring systems such that suitable habitat is reduced or eliminated."