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The Sonoyta mud turtle’s only known home in the U.S. is a fragile, spring-fed pond in remote southwestern Pima County, just steps away from the international border.

Meanwhile, what’s left of its habitat in Mexico is being cut off or bled dry by drought, climate change, unregulated groundwater pumping and other, darker human activities.

Biologists haven’t checked on one isolated population of turtles in northwestern Sonora for years because of cartel violence in the area.

But with some international cooperation — and about $1.5 million in funding over the next 30 years or so — the species can be saved, according to a draft recovery plan just released by the U.S. Fish and Wildlife Service.

“The complexity is enormous, but I’m optimistic about the future of the turtles,� said , who heads up the all-volunteer Sonoyta Mud Turtle Recovery Team that helped write the draft plan. “I’m optimistic because the turtle itself is pretty tough and easy to keep alive. We just need a little bit of resources to do some genetic studies, do some surveys and to start to establish some additional populations.�

The Sonoyta mud turtle is a dark-colored freshwater reptile with webbed feet, mottled skin and an olive brown shell. It gets its name from the Rio Sonoyta, its native watershed along the U.S.-Mexico border.

Bogan said the turtles and other aquatic animals likely found their way into the desert river system more than a million years ago, back when the watershed reached all the way to the Colorado River. by Pleistocene lava flows from the volcanoes of El Pinacate, which blocked the Sonoyta and sent it south to the Gulf of California.

“Since that time period, all the aquatic species in the Rio Sonoyta have been evolving on their own little trajectory in isolation,� Bogan said.

The mud turtle was , after 20 years as a candidate species. Its lone patch of federally designated critical habitat in the U.S. is the roughly 12 acres surrounding Quitobaquito Springs, a small pond and wetland already protected as part of Organ Pipe Cactus National Monument.

Going to waste

Bogan described the species as “incredibly long-lived but slow to mature,� with females taking as much as seven years to reach reproductive age. One turtle at Quitobaquito has been captured multiple times by National Park Service staff members over the past 35 years, “and it’s still doing well,� he said.

The biggest individuals only reach about 7 inches long and weigh a little over a pound, not counting the layer of algae that often coats their shells. “They’re not big turtles, but like I said, they’re tough.They can survive poor water quality. They can survive short periods of drying,� Bogan said.

For decades, the largest known population could be found in the municipal sewage pond for the town of Sonoyta, where 300 to 400 turtles thrived in a stinky swamp of untreated wastewater.

Then a bureaucratic breakdown resulted in tragedy.

Bogan said the sewage pond was supposed to be preserved as turtle habitat under an agreement the struck with municipal officials in Sonoyta about 20 years ago, but the deal got lost or forgotten as a result of turnover within the local government.

When the town built new sewage facilities, the old pond was abandoned and allowed to dry out, eventually leading to a wildfire in the cattails that once surrounded it.

Bogan said he and one of his graduate students managed to catch and relocate 11 unhappy turtles from what was left of the old pond, but hundreds of others likely perished in the fire or from a lack of water before that.

Sonoyta’s municipal government also agreed to make at least one of its new sewage ponds friendly to mud turtles, but that didn’t happen either. Bogan said the handful of turtles he and his student saved during their “last-minute salvage� had to be released instead into the outflow stream, where wastewater from the new ponds is released into the channel of the Rio Sonoyta.

Still in danger

Historically, the endangered mud turtles have also been found in Quitovac, a tiny O’odham village in Sonora that’s technically outside of the Rio Sonoyta watershed but has its own small spring-fed lake.

According to the recovery plan, though, the status of that turtle population is unknown because biologists haven’t visited the site for almost 20 years.

“It just hasn’t been safe,� Bogan said. “It’s really been a safety concern for the last four-plus years now, and as of 18 to 24 months ago, the tribal community there had kind of been pushed out by the narcos.�

The security situation has since improved in the surrounding parts of northern Sonora, but not in Quitovac, he said. “We can’t safely go down there and check on the turtles yet.�

Once they are able to return to finally assess the population, members of the recovery team hope to collect samples that could help solve the mystery of how the turtles got there in the first place. “The general thought is that at some point in time they were brought there, so they didn’t naturally occur there,� Bogan said, “but we’d really have to get genetic information to verify that.�

The recovery plan identifies just four locations in Mexico where the species can still be found in the wild, and two of those populations are in decline.

That leaves Quitobaquito Springs as the only site where the turtles appear to be holding their own. Bogan said the population there remains stable at around 150, and habitat conditions have improved, thanks to .

In 2023, a team of park personnel and contractors reshaped the pond and installed a new liner to retain more water amid an ongoing decline in the spring flows that sustain the oasis 170 miles southwest of Tucson.

“They actually put some floating islands in the redesigned pond, and the last time I was out there, there were a bunch of turtles hanging out on the islands,� said Bogan, who was recently announced as the Cecil and Carol Schwalbe Endowed Chair in Cold-Blooded Research, Teaching, and Conservation for U of A’s School of Natural Resources and the Environment.

But concerns remain about the long-term viability of Quitobaquito and the rare wildlife it sustains.

“Over the last 35 years, the amount coming out of the spring has been going down and down and down,� Bogan said. “Part of that is probably long-term climate patterns (and) part of that is regional groundwater pumping, both of which are really, really hard to do anything about. So we kind of just hold our breath and hope for the best.�

Seeking release

The recovery plan is rooted in more than just hope, of course.

It calls for the identification of new places where mud turtles can be introduced or reestablished along the Rio Sonoyta watershed, which drains a sizeable part of the Tohono O’odham Nation near the Baboquivari Mountains on its way south and then west along the Mexican side of the border.

“It’s a species that really has a tri-national distribution, so it requires tri-national coordination in order to recover (it),� Bogan said. “That’s the beauty of the recovery team: We have Mexican team members, we have American team members, and we have tribal team members.�

Wastewater is expected to play a key role in the creation of new turtle habitat. It has to, Bogan said, “because there’s just not a lot of natural water left on the landscape.�

will provide any extra turtles needed to fulfill the recovery plan.

The world-famous institution west of Tucson has been harboring members of the species since 2007 and was the first facility to successfully breed the animals in captivity. The so-called “assurance population� now stands at more than 50, including the original turtles first brought there 18 years ago.

“That’s the thing with managing turtles: They’re long-term,� said Tom Weaver, curator of herpetology, ichthyology and invertebrate zoology at the Desert Museum.

For now, the turtles at the museum are being kept out of the public eye in behind-the-scenes enclosures meant to mimic their natural habitat, but Weaver said some sort of exhibit is being planned for the future.

They aren’t actively trying to make more turtles at the moment, he said, because they don’t really have anywhere to put them. “We’re full, I’d say.�

Release is the ultimate goal. Though the Desert Museum is serving as an ark of sorts for the Sonoyta mud turtle — one of 10 different endangered reptiles, fish and amphibians the institution is helping to keep alive — the animals’ stay is not meant to be permanent.

As Weaver put it, you can’t save a species by warehousing it in captivity while it vanishes from the wild forever. “This isn’t like stamp collecting (with) extinct species,� he said. “We have to give these animals a chance.�

Bogan said the publication of the draft recovery plan is an important step in that process. He considers the objectives outlined in the plan to be clear and achievable.

“I have so much more hope for the Sonoyta mud turtle than I do for so many other of our endangered aquatic species,� he said. “Some of these aquatic species, they’re realistically not going to come back, and that’s heartbreaking. But this is a species where we actually have a really good chance of bringing them back to their full glory.�