This story is co-published with Arizona Luminaria, a nonprofit newsroom dedicated to community-centered reporting.

CASCABEL, Ariz.—On an overcast spring morning the land between the Galiuro and Rincon mountains of southern Arizona is lusher and greener than one unaccustomed to the desert might expect. 

Iconic saguaro cacti, some older than the state of Arizona itself, stand tall with arms that twist and twirl around themselves. Whole fields of cholla cactus appear like a room full of teddy bears. One of the last free-flowing rivers of the desert Southwest, the San Pedro, runs its course through the valley from Sonora, Mexico, to the Gila River, 140 miles north. As the perennial river cuts through the valley, massive cottonwood trees with luminous green canopies congregate. 

The San Pedro Valley is one of the last ecologically intact landscapes left in the country. Among unfragmented landscapes in Arizona, it’s second only to the Grand Canyon—the world-famous national park. There are no towering skyscrapers and no sprawling suburbs in the valley. Most of the roads are unpaved. The only sounds hikers hear through the valley’s hills are the whistling of the wind and the occasional song of a bird. Sparsely scattered shards of ancient pottery and carefully placed rocks give an idea of how Indigenous people who called this place home for thousands of years lived. 

The ability to not just live next to wild land, but to be part of it, is what brought people like Barbara Clark here. She arrived in 1970 in the small but tightly connected community of Cascabel. Here, ranchers and environmentalists alike shared a common appreciation for the land and could even work together, with some tied to the electrical grid while others live off of it. Across the country, landscapes have been destroyed, Clark said. Not here. The valley was a place to preserve nature, she said, not only for the next generation but also “to recognize that they have equal status in this world to us.”

In recent months, a new sight has appeared across the valley that to Clark is like watching “so many of my neighbors be slaughtered”—hilltops graded and new dirt roads cut for the route of the largest renewable energy project in U.S. history, a project largely opposed by those who live, study, recreate and celebrate their heritage here.

The SunZia transmission line is planned to stretch across more than 500 miles, connecting 3,000 megawatts of clean energy generated from wind farms in New Mexico to the power grid, which will carry most of it to utilities in California. As the U.S. looks to pivot away from generating electricity with fossil fuels, the nearly 50 miles of SunZia lines that would cut through the middle of the San Pedro Valley have sparked one of the nation’s most consequential fights over developing green spaces for green energy. 

Transmission lines are the backbone of the energy grid and a vital component of the transition away from fossil fuels. The lines send energy, often generated in remote places, over long distances, typically to major urban centers. But building them across swaths of federal, state, municipal, tribal and private lands can be a long and tedious process, involving regulators from various levels of government and the consultation and feedback of local and tribal communities, environmental groups and others. 

SunZia has been mired in controversy and delays, giving industry leaders and government officials examples of how the permitting process is delaying renewable energy projects and the need for reforms. To locals of the San Pedro Valley, tribes with ancestral ties to the area, archeologists and environmentalists who have been involved in its permitting process, SunZia is an example of how community stakeholders can be left behind as developments move forward, how environmentally and historically intact landscapes are at risk of being degraded in the nation’s energy transition and how the nation’s cultural heritage laws are not suited to address large-scale developments or climate change. 

Some places, opponents say, should not be developed. 

“When we first started fighting this thing 15 years ago, we didn’t fight the project, we fought the location,” Clark said. “This has become national news because of how horribly it was planned. We were in that planning session, and they ignored us and they ignored us and they ignored us and they ignored us.”

The fight is now playing out in federal and state courts. The biggest lawsuit centers on what tribal consultation should look like for a proposed development on the ancestral lands of Indigenous people and what qualifies as a historic property—a site easily identified by the physical features that form its borders, or a whole valley consisting of the traditional homes of multiple tribes that remain connected to the area. 

Earlier this year, the Tohono O’odham Nation and the San Carlos Apache Tribe, along with Archaeology Southwest, a nonprofit focused on exploring and protecting heritage in the region, and the Center for Biological Diversity, sued the BLM over its approval of the project, alleging the federal agency failed to properly review how the project would impact cultural heritage resources in the area as required by the National Historic Preservation Act.

“This has become national news because of how horribly it was planned. We were in that planning session, and they ignored us and they ignored us and they ignored us and they ignored us.”

BLM and Pattern Energy, the developer behind SunZia, say they properly permitted the project and it is too late to stop it, arguing the statute of limitations has passed, and the section plaintiffs want to be rerouted is situated on state and private land. Perhaps worse, they argue, a reroute could derail the entire project and signal to other developers that a project can be stopped even after it receives federal approval. 

“A reroute at this stage, I mean, that would really jeopardize the ability of our country to advance this clean energy transition,” said Natalie McCue, vice president of environmental affairs at Pattern Energy. 

Opponents to the route say their issue is not with the energy transition, but with how this specific project opted to go through an intact ecological and cultural landscape rather than along existing degraded places. Most of the line runs along multiple interstates in New Mexico and Arizona, but it veers off into the San Pedro Valley.

SunZia opponents argue the routing decision was done only to save money and say they will continue to fight. 

For Pearl Mast, a resident of Cascabel, the construction is the equivalent of saying “we’re going to rape your mother, but we’ll do it carefully and we’ll compensate for that.” For Leif Abrell, a local professor and steward for a section of the Arizona Trail where construction is visible, it represents the “false choice” that green spaces must be sacrificed for green energy. For Verlon Jose, the chairman of the Tohono O’odham Nation, it’s the latest example of the federal government and developers failing to properly consult with tribes and sacrificing landscapes vital to tribal history and beliefs “in the name of the almighty dollar.”

Routing through the San Pedro Valley may be the cheaper option for the developer, Jose said, but it will never be cheaper for the tribes in opposition to the project. 

“You don’t have enough money to bring back what’s going to be destroyed,” he said. 

The disputes threaten to derail the $11 billion project, with implications that could be far-reaching: How can large renewable energy projects be built in the U.S. without sacrificing culturally important places and the intact biodiverse landscapes needed for preserving other species and storing carbon, and what places should be off limits from development, no matter the cause?

It’s a question with no easy answer, but locals, tribes, archeologists, environmentalists and energy experts have ideas. Federal public land management plans similar to what’s been done with solar could identify areas best suited for the development of transmission lines and the areas that should be preserved. More extensive consultation with tribal nations whose ancestral lands could be impacted and the communities living in an area would improve buy-in for projects. A federal authority could coordinate transmission planning between a project’s various stakeholders. Updated cultural heritage laws would better define the areas that should be protected and ensure a project’s impact on historical and cultural resources are evaluated fully during the permitting process. 

Power Lines in the West Run Into Legal Challenges

The nation, but especially the Western U.S., needs new transmission lines to serve a rapidly growing population and to connect renewable energy sources to the grid; a study from the Lawrence Berkeley National Laboratory found that more than 10,000 clean energy projects representing 1,350 gigawatts of generation and 680 GW of storage were awaiting approval to connect to a transmission line in 2022. 

Out West, the energy grid was largely built in the mid-20th century, designed with the needs of the times, said Vijay Satyal, deputy director of regional markets at Western Resource Advocates. In the decades since, the region has seen a huge increase in population, a surge in the demand for energy and the development of new sources of electricity generation, he said, leading to the need for more transmission lines.

But the range of jurisdictions and legal processes involved and the requirements for consultations with various communities and groups make the process expensive and time-consuming, Satyal said. The average environmental impact statement, for example, takes four and a half years to complete. 

SunZia is a case in point.

The project, largely built on public land managed by the U.S. government, began the federal permitting process in the fall of 2008 and was fast-tracked by the Obama administration in 2011. 

The final record of decision over the route of the transmission lines was in 2015, with the path through the San Pedro found to be the least impactful of the routes submitted by the developer for evaluation by the BLM. 

But it would take another eight years for construction to begin, with struggles to raise the financing needed for the project and the need to reroute portions of the line delaying the project. Then, in 2022, the SunZia project was sold by the Southwestern Power Group to Pattern Energy. 

Construction will require up to 2,000 workers and create 150 permanent jobs, according to the developer, leading to billions of dollars of investment in local economies.

“This is the biggest renewable energy project ever built, certainly in this hemisphere … I hope that it really can set the bar that we can do big things, and we can build big projects in this country that have a meaningful impact,” said Cary Kottler, Pattern Energy’s head of transmission.

Last year, construction finally began after the BLM approved its final right-of-way grant but was quickly halted after the Tohono O’odham Tribal Chairman Verlon Jose wrote a letter to Interior Secretary Deb Haaland on Oct. 31 asking for a halt of “the unlawful and deeply harmful destruction of the San Pedro Valley” from building the project. But construction resumed not long after the halt.

In the January suit from the Tohono O’odham Nation, the San Carlos Apache Tribe, Archaeology Southwest and the Center for Biological Diversity, the plaintiffs argue that the BLM and developers failed to properly consult with tribes and evaluate their claim that the San Pedro Valley was a cultural landscape protected under the National Historic Preservation Act for being “associated with a historical event, activity, or person or exhibiting other cultural or aesthetic values.” They are seeking to have construction paused until the BLM properly conducts a cultural landscape study. 

They’ve also filed a complaint with the Arizona Corporation Commission, which regulates the state’s utilities and issued the project a Certificate of Environmental Compatibility, arguing developers failed to submit a cultural landscape study and a historic properties treatment plan as required as a condition of the project’s approval. 

Another lawsuit from a resident of the valley is also aimed at the Arizona Corporation Commission, arguing the project now being constructed is fundamentally different from what was narrowly approved in 2016 and must be reevaluated. 

A Dispute Over Cultural Heritage Laws

The lawsuit specifically is based on Section 106 of the National Historic Preservation Act of 1966, which requires federal agencies to consider the impacts any project involving the federal government will have on historic properties. 

But when these projects are evaluated, their impact on cultural heritage resources is often an afterthought, said Marcy Rockman, an associate research professor at the University of Maryland who studies how climate change is impacting cultural resource management. 

“It’s no one’s priority,” said Rockman, who previously was the inaugural climate change adaptation coordinator for cultural resources at the National Park Service, the agency tasked with preserving such heritage resources. “So developers and agencies, they get used to treating that as the thing that can be dismissed or that can be overwritten.”

By the time cultural resources are evaluated, she said, projects have often been in the works for years and spent large amounts of money, as is the case with SunZia. “That model runs into a whole lot of tension,” Rockman said.

According to the tribe’s lawsuit against SunZia, throughout the project’s permitting process, Archaeology Southwest and tribal officials repeatedly raised their concern that the San Pedro Valley was a traditional cultural property, an area that can be listed under the National Register of Historic Places because of its significance to a community’s history and cultural practices, and required an in-depth cultural landscape study. 

Those groups were informed by the BLM in 2011 that the agency would only begin the Section 106 review process after the draft environmental impact study was completed, resulting in the development of the agency’s preferred route for the transmission line before its impacts on cultural resources were considered. 

During oral arguments in March, the defendants argued they properly consulted with the tribes and identified cultural sites in the valley so that construction would avoid them. For years, defendants said they engaged in good faith efforts to consult with tribes and, with input from the groups now suing, conducted a cultural resources inventory in the area. The tribes, the defendants’ lawyers argue, never alerted the agency that they viewed the entire area as a traditional cultural property until 2023, and submitted insufficient documentation of additional cultural sites. 

The plaintiffs have a different story. The tribes had been informed by officials with the BLM that the cultural landscape study would be done separately from the cultural resources inventory, which only identified specific archeological sites that could be impacted, and did not evaluate the broader issue of impacts to the entire area. Archeology Southwest and the tribes repeatedly told the BLM that a cultural landscape study was needed. And because of their long history with the federal government and concerns about the confidentiality of these sites—areas with historically significant artifacts that have often been looted—the tribes were reluctant to share information on additional culturally important sites in the valley and federal policy dictates that agencies must respect a tribe’s decision not to disclose their locations. 

The burden of proof over whether the area is a traditional cultural property or not, the plaintiffs argue, is not on the tribes, but on the federal government. 

Rockman said the idea of a traditional cultural property stems from an interpretation of heritage codified in the 1990s that is both more modern and more Indigenous, a definition that isn’t easily defined under current federal regulations. Typically, cultural sites are defined by their borders, which can specify a place with historical importance as a monument, for example. “Nowhere in that is the idea that ‘We live here and we value it,’” she said.

That lack of a specific definition for cultural heritage at the federal level is increasingly a problem, Rockman said, as climate change continues to impact culturally important landscapes via extreme weather events, changing ecosystems and even developments meant to address those challenges. 

A Final Effort to Reroute

Ancestors of the Tohono O’odham, Hopi, Zuni and Western Apache tribes all once lived in the San Pedro Valley, a history remembered in its widespread cultural, ceremonial and burial sites. 

“In the Tohono O’odham way of life, we were placed here on this Earth to care and to live in harmony with one another and Mother Earth,” said Jose, the chairman of the Tohono O’odham Nation. “So a lot of our areas, we have not abandoned. We have not left. There still remains a strong connection with our people, including the San Pedro River area.”

That history is still visible. Behind the Cascabel Community Center, where the doors are open 24/7 and locals meet, pottery shards and chunks of red Jasper once used for arrowheads can be spotted on the ground. Other similar sites, many far more significant, are found across the valley. 

The reason history like that remains, along with one of the most intact ecosystems left in the country, is simple: The land has always had a small population, leading to little development, which has left a landscape unlike any other in southern Arizona, said Alex Binford-Walsh, the San Pedro community steward for Archaeology Southwest. 

The SunZia Transmission Line has already started changing that, as crews construct towers up to 195-foot-tall throughout the valley. Some areas of the line are so remote that helicopters transport the crews and materials needed to build the line. 

“They’re cutting the San Pedro Valley in half,” Binford-Walsh said. “The most rugged country you can imagine, completely untouched desert ecosystem, and they decided this is the best route.”

While some residents of the valley have roots that go back centuries, others were drawn more recently by the tight-knit community of Cascabel and wide-open desert. Had the transmission line existed decades ago, some might not have moved here.

Community members are being criticized for NIMBYism, said Edith Robinson, referring to the acronym for “not in my backyard.” But many of those who moved here did so to live smaller, Robinson said, to do their part to consume less.

They worry about what comes next. When the project’s route was given approval by the BLM in 2015, it wasn’t just for one transmission line, but two. The other hasn’t yet found the financing to begin construction. That could change, leading to a utility corridor across the San Pedro Valley, prompting a push to develop more energy sources and infrastructure throughout the area and undercutting local conservation efforts. They plan to continue fighting the power line projects and any other developments that could be proposed in the valley.

“To see it degraded is heartbreaking,” said David Omick, a Cascabel resident. “Particularly when those of us who live here, who love the place and who have worked for decades to promote conservation interests, get nothing out of this project. Nothing. That’s really hard.”