An environmental advocacy group has filed a lawsuit against the U.S. Fish and Wildlife Service, claiming federal officials are failing to protect threatened species of salamanders in Central Texas.

The Arizona-based Center for Biological Diversity argues the federal agency has not taken steps to protect the habitats of the Georgetown and Salado salamanders since they were first listed as threatened five years ago.

"This lawsuit is all about making sure that there will be clean water and habitat for these salamanders moving into the future," said Elise Bennett, an attorney with the group.

The salamanders’ habitat includes springs, wet caves, and groundwater around the northern part of the Edwards Aquifer.

"One thing that’s really unique about them and I find particularly endearing is that their heads are crowned by these beautiful fluffy gills," Bennett said. "They use these gills to live their entire lives underwater, and that’s why it’s so important to protect springs for these salamanders.”

Earlier this year, the Center for Biological Diversity and the Save Our Springs Alliance announced plans to sue the Texas Department of Transportation over highway construction in Austin that they said threatened endangered salamanders living in cave systems under the project. An attorney with the Center for Biological Diversity told KUT at the time the intent was not to stop the project but to make sure the salamanders were protected going forward.