The last corridor: How conservationists are protecting wildlife in Arizona’s San Rafael Valley amid border wall construction
Javelinas pace back and forth along the U.S.-Mexico border in the San Bernardino National Wildlife Refuge. For decades, conservationists have expressed concern about the impact a border wall would have on wildlife. Now, as the second Trump administration prepares to close some of the last gaps in the wall, conservationists say the effect will be devastating. (Photo by Marissa Lindemann/News21)
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SAN RAFAEL VALLEY, Ariz. — Over the past few decades, the Arizona-Mexico border has undergone significant transformation. Vehicle barriers once marked the line. Then, shipping containers were double-stacked along the boundary. Now, the Trump administration has approved 27 miles of new wall construction intended to stop illegal crossings into the United States.
The 30-foot-high steel bollard wall will cut across the San Rafael Valley, a high-grassland region in southeastern Arizona. That has prompted conservationists to scramble for solutions to protect this critical wildlife corridor, one of the last unobstructed such corridors in Arizona – and one used by some of the state’s most endangered species.
The San Rafael Valley is one of Arizona’s last unwalled sections of the border and a critical wildlife corridor for endangered species. In June, Homeland Security Secretary Kristi Noem waived multiple environmental laws to expedite construction of 24.7 miles of border wall here, to replace the current vehicle barriers. (Photo by Marissa Lindemann/News21)
In June, the Department of Homeland Security awarded a $300 million contract to North Dakota-based Fisher Sand & Gravel Co. to begin construction. The project includes 24.7 miles of wall between Naco and Nogales – a segment of the border that includes the San Rafael Valley.
The construction will also wall off both sections of the Santa Cruz River that intersect the border, leaving the Tohono O’odham Nation as one of the only areas in Arizona without a border wall.
To expedite the process, Homeland Security Secretary Kristi Noem waived multiple environmental laws, including the National Environmental Policy Act. The Tucson-based Center for Biological Diversity pushed back in July, filing a lawsuit arguing DHS lacks the legal authority to issue such waivers.
Eamon Harrity, a wildlife program manager for Sky Island Alliance, replaces the batteries for a camera trap in the San Rafael Valley. The cameras are part of a study to document how wildlife is affected by border barriers across a 100-mile area in Arizona, including the San Rafael Valley and San Bernardino National Wildlife Refuge. (Photo by Marissa Lindemann/News21)
Sky Island Alliance maintains 60 motion-activated cameras in the region that have documented species such as mountain lions, black bears and pronghorns crossing the U.S.-Mexico border. (Photo by Marissa Lindemann/News21)
For five years now, organizations such as Sky Island Alliance, a Tucson-based nonprofit dedicated to protecting ecological diversity, have been documenting how wildlife is affected by border barriers, including in the San Rafael Valley.
The group’s border wildlife study estimates that replacing existing vehicle barriers with a wall will reduce wildlife crossings by 86%. Conservationists said the wall will close a corridor that wildlife have migrated through for millennia, blocking their access to water, food and mates.
According to the National Integrated Drought Information System, 95% of Arizona is experiencing drought. That makes wall construction in the region even more perilous for wildlife, conservationists said.
The San Rafael Valley is a biodiversity hotspot, meaning it has some of the greatest diversity of mammal species in North America. Animals like pronghorns, jaguars and black bears have migrated through this wildlife corridor for millennia to find water and food and to look for mates. (Photo by Marissa Lindemann/News21)
“It’s really hard for them to find watering holes and resources, so they need to travel large amounts of territory,” said Erick Meza, border program coordinator for the Sierra Club. “We might lose species in these areas forever.”
Eamon Harrity, Sky Island Alliance’s wildlife program manager, is on the front lines of the effort to document the effects by setting up and monitoring wildlife cameras across the valley.
“What we ultimately want is awareness of the impacts of the border,” Harrity said. Sky Island Alliance shares its findings with the DHS and U.S. Customs and Border Protection; it also proposes design changes, such as wildlife openings, to accommodate affected species.
Myles Traphagen, borderlands program coordinator with Wildlands Network, flies a drone to document the San Rafael Valley before wall construction begins. “What happens is people, they grow into their environments, and then the next generation that comes around has no idea of what things were like – that it used to be better, that it used to be more intact,” he said. (Photo by Marissa Lindemann/News21)
Traphagen, like many conservationists, knows that border wall construction is inevitable, but he continues to collect data. (Photo by Marissa Lindemann/News21)
Traphagen measures the distance between vehicle barriers and a ring of wooden stakes that mark the Roosevelt Reservation, a strip of federal land along the U.S.-Mexico border. In his 25 years working along the border, Traphagen has seen border markers evolve from obelisks and vehicle barriers to these pink ribbons, which show where wall construction will occur. (Photo by Marissa Lindemann/News21)
Wildlife openings were installed in the border wall at San Bernardino National Wildlife Refuge, about 100 miles east of the San Rafael Valley, as part of a 2023 settlement agreement between the Sierra Club and the Biden administration.
According to Harrity, the openings proved somewhat successful: Animals such as javelinas, coyotes and even female mountain lions have been able to squeeze through the ground-level, 8.5-by-11-inch gaps. However, he says, larger and more frequent openings are needed to accommodate more wildlife movement.
A study by Sky Island Alliance found that places with steel bollard walls, like the San Bernardino National Wildlife Refuge, reduced animal border crossings by 86% compared with places with vehicle barriers, like the San Rafael Valley. (Photo by Marissa Lindemann/News21)
A camera trap to record animals is situated at the front of a small wildlife opening in the San Bernardino National Wildlife Refuge. Conservationists say these openings, which widen the 4-inch gaps between posts to 8.5 inches, can increase wildlife movement for species like bobcats, coyotes, javelinas and female mountain lions. (Photo by Marissa Lindemann/News21)
Harrity looks at photos from camera traps at the Sky Island Alliance office in Tucson. Conservation nonprofits have been working to convince the Department of Homeland Security to install more wildlife passages along the border wall. (Photo by Marissa Lindemann/News21)
For conservationist Myles Traphagen, borderlands program coordinator at Wildlands Network, the threat of construction in the area feels personal.
“When mountains are being blown up, and watercourses are being dammed off, and steel structures are being erected that stop all wildlife movement and also cultural and social exchange along the border, it really is a personal matter,” he said. “It cuts real deep.”
In fiscal year 2025, CBP’s Tucson sector, which includes the San Rafael Valley, reported one of the country’s highest totals of illegal entries along the southern border.
A deer pokes its head through the border wall into Mexico after searching for a spot to cross in the San Bernardino National Wildlife Refuge. While small wildlife passages have helped some animals, larger species are unable to cross. (Photo by Marissa Lindemann/News21)
However, across Sky Island Alliance’s 60 motion-sensored wildlife cameras, Harrity said, “Less than 1% of all things on our cameras were humans, and more than half of those humans are hunters.”
The ghost town of Lochiel, about 65 miles southeast of Tucson, is one example of this notably quiet environment. The town became a protest site in late May, when environmental advocates from both sides of the border gathered to oppose wall construction.
“Blocking wildlife migration, plus the water movement on the rivers and the washes that exist on those areas, is going to be really bad for both communities,” said the Sierra Club’s Meza, who helped organize the protest.
Barbed wire spans the Santa Cruz River at its headwaters in the San Rafael Valley. The Santa Cruz is a binational river that crosses the U.S.-Mexico border twice. Both ends are important ecological corridors, because the river is one of the last remaining places where wildlife can easily cross for hundreds of miles. (Photo by Marissa Lindemann/News21)
A bridge frames open floodgates in the San Bernardino National Wildlife Refuge. These floodgates are a model for what wall construction over the Santa Cruz River could look like, but conservationists worry the perennial flow of the river, combined with monsoon rains, could cause debris to build up behind the floodgates. That could potentially rip the gates off and cause damage downstream, they say. (Photo by Marissa Lindemann/News21)
Conservationists have also raised the alarm about wall construction over the Santa Cruz River. The river has nourished the region, including the Tohono O’odham and Pascua Yaqui tribes, for more than 12,000 years. It’s currently fourth on a list of America’s most endangered rivers, and wall construction is the newest obstacle in the river’s path.
Michael Bogan, an ecologist at the University of Arizona who researches the Santa Cruz, said wall construction feels immune to legal challenges. In his opinion, construction is a “foregone conclusion” when considering the hundreds of miles of border infrastructure built during the first Trump administration.
He uses his research to advocate for turning parts of the Santa Cruz River into a national wildlife refuge.
“On a weekly basis, we’re having to mobilize and deal with triage – the ecological (and) environmental disasters that are being thrown our way by the administration,” Bogan said. “So, honestly, the wall is a little bit lower in that.”
Michael Bogan, an ecologist with the University of Arizona, is part of a local effort to have portions of the Santa Cruz River added to the U.S. Fish and Wildlife Service’s National Wildlife Refuge System.
Scully Young, a lab technician with Bogan’s Aquatic Ecology Lab, takes a photo of a damselfly during a dragonfly survey in the Santa Cruz River. The goal of Bogan’s lab is to document the biodiversity value of putting water back into the Santa Cruz River and to get the local community invested in protecting the river. (Photo by Marissa Lindemann/News21)
An American rubyspot damselfly is silhouetted against the Santa Cruz river. (Photo by Marissa Lindemann/News21)
Young, left, and Bogan, right, work together to record their findings from a damselfly and dragonfly survey in the Santa Cruz River. Bogan said that while he doesn’t want to see border wall construction upstream, he has to prioritize what he can conserve. (Photo by Marissa Lindemann/News21)
He added that the effects of wall construction will be seen primarily downstream, closer to the border. That construction, he said, produces fine sediment that can smother aquatic wildlife and change the shape of the river. Debris builds up behind the border wall – particularly in the wake of seasonal monsoons – and could prevent aquatic species, such as the endangered Gila topminnow, from replenishing populations in the United States.
In an email to News21, CBP spokesman Dennis Smith said all border wall projects “are designed to take into consideration transboundary water flows including rivers, creeks, or ephemeral washes” and that construction can include “culverts or other drainage systems with flood gates or grates.”
He added that CBP plans to open the floodgates to allow for higher seasonal flows of water and that the agency will remove any debris and sediment.
Harrity walks his bike away from the Sky Island Alliance office. Even though the future of the San Rafael Valley is uncertain, Harrity says that even after the border wall is finished, cameras will remain to document the impacts on wildlife. (Photo by Marissa Lindemann/News21)
Nature-based tourism and conservation contributed nearly $36 million to Santa Cruz County’s economy in 2019, according to a study by the UA Cooperative Extension and Department of Agricultural & Resource Economics.
While advocates and researchers continue their work to slow wall construction and push for changes that would benefit wildlife, Traphagen said the San Rafael Valley is only the beginning of what is to come.
“We are trying to slow the wheels down,” he said, “but it seems like it will be inevitable.”
A family of javelina, also called a squadron, uses a small wildlife passage to cross from Mexico into San Bernardino National Wildlife Refuge, where they drink from a pool of water. (Photo by Marissa Lindemann/News21)
Marissa Lindemann is an undergraduate student at the University of Nebraska-Lincoln, majoring in broadcasting with a minor in fisheries and wildlife. Marissa’s passion for telling visual stories about the natural world has taken her from the Namib desert to the Mekong Delta. Currently, she’s an intern for the Platte Basin Timelapse project, a multimedia conservation storytelling group.
Lorenzo Gomez is a master’s student at Arizona State University’s Walter Cronkite School of Journalism and Mass Communication. He holds bachelor’s degrees in political science and psychology and has experience working as a policy analyst in the nonprofit sector. His work includes helping to establish Flagstaff, Arizona’s first Indigenous cultural center. His work as a writer and photographer focuses on Indigenous communities, borderlands and culture. In 2025, he traveled to Panamá to report on global migration through the Cronkite Borderlands Project.