A large aquatic salamander found only in the Black Warrior River basin in Alabama has been granted federal protections under the Endangered Species Act.

The U.S. Fish and Wildlife Service announced Tuesday that the Black Warrior waterdog -- also called the Alabama mudpuppy -- has been listed as an endangered species under the Act.

Conservation groups call the waterdog one of the most endangered amphibians in the country, and its populations have been heavily impacted by habitat degradation and segmentation, as well as pollution and sedimentation of the Black Warrior tributaries in which it lives.

As part of the listing, the Fish and Wildlife Service designated 420 river miles within the river basin as critical habitat for the waterdog. That designation requires all entities that receive federal funding to ensure that their actions don't imperil the species. It does not impact what private landowners can do on their own lands, so long as those actions don't require a federal permit on their own.

The FWS said in its announcement said the critical habitat designation "should have minimal or no impact on the forestry and coal mining community."

"Since there are already critical habitat designations for other species in this area, very little additional regulatory action will be necessary for the waterdog," the Service said. "The designation will also have no impact on private landowners taking actions on their land that do not require federal funding or permits."

The critical habitat includes portions of: Sipsey Fork (Lawrence and Winston Counties); Locust Fork (Blount, Etowah, Jefferson, and Marshall Counties); Blackwater Creek (Walker and Winston Counties); and Yellow Creek (Tuscaloosa County).

Get to know the Black Warrior waterdog

The Black Warrior waterdog reaches a maximum length of about 10 inches, and is a striking creature, with feathery red external gills jutting out from the salamander's body. But even regular visitors to the Black Warrior streams where they live are unlikely to ever see one in person.

Matt Laschet is the FWS's lead biologist working on the waterdog, and he's only seen a few of them, which he trapped for his research.

The salamanders are mostly active during the winter and at night, Laschet said, spending most of its time hiding under submerged ledges, rocks, or logs. During the day, and during the hot summer months, the salamander rarely leaves its underwater burrows.

The waterdog is fully aquatic, never venturing onto land, and maintaining its feathery external gills and tail for life, whereas some salamanders lose them as they mature.

Declining water quality and sedimentation are believed to be the biggest factors in the waterdog's population declines in recent decades.

Laschet said that of the 13 locations where the waterdog was known to reside, two are now in impoundments. Of the remaining 11, the population levels are only high enough to have a good chance at catching one in a single location inside the Bankhead National Forest.

"There's pretty much only one stable population known where researchers could find it on a regular basis," Laschet said. "Most of the other locations, the populations are so low that for a long time there were no captures in any of those locations."

Black Warrior waterdog (Necturus alabamnesis)

Although the waterdog is rarely seen in those 11 other spots, they do leave traces behind. Laschet said the researchers have used a technique called e-DNA, which can detect traces of the waterdog's DNA in stream water samples, proving the animal still exists there.

"Some of this critical habitat is where we've gotten positive e-DNA hits indicating that they're still there and we have not captured one," Laschet said. "That would be like along the Locust Fork where we have not captured one in the last few years, but yet we're still getting positive e-DNA hits in that area."

Among the biggest threats to the species is the amount of sediment and other pollutants entering the rivers.

"They like to live in the rock crevices and if sand comes into the area and starts filling in those crevices, it can drive them out, it can bury their eggs or the sand also is an abrasive on their gills," Laschet said.

Waterdog listing was years in the making

The species was evaluated as part of a legal settlement between the Fish and Wildlife Service and environmental groups led by the Center for Biological Diversity, which sued FWS after the agency delayed listing decisions for years.

The Black Warrior waterdog was first put on the candidate waiting list in 1982 and the Center for Biological Diversity petitioned FWS to list the waterdog as endangered in 2004 and again in 2010.

"I am elated that the Black Warrior waterdog has received the Endangered Species Act's invaluable protections," said Elise Bennett, an attorney at the Center for Biological Diversity dedicated to protecting rare reptiles and amphibians. "These protections will not only preserve a future for this unique aquatic salamander but also protect hundreds of miles of rivers for the benefit of the species and Alabamians alike."

Though the endangered status for the salamander is seen as a win for conservation activists, it was not a complete victory. The original proposal -- published in 2016 -- suggested designating 669 river miles as critical habitat for the waterdog. The final version included just 420 miles.

Eva Dillard, staff attorney for Black Warrior Riverkeeper, said her group was pleased that the waterdog's protections were finalized but that the original proposal was more appropriate to protect the species.

"We think the Service articulated a sound scientific basis for the protection of 669 river miles as critical habitat and it is somewhat disappointing to see them walk that back in their announcement today," Dillard said via email. "However, given that prior to today's decision the Black Warrior basin had only 165 miles of critical habitat for all listed species, we are pleased with the designation of more critical habitat to protect the species that make Alabama and the Black Warrior special."

The Black Warrior waterdog is now the 16th aquatic species in the Black Warrior River basin to be protected as either endangered or threatened under the Endangered Species Act.