A request has been made to a federal judge to halt the construction of a $10 billion transmission line in a remote valley in southeastern Arizona. The purpose of the line is to transport wind-generated electricity to customers in California.

A lawsuit of 32 pages was submitted on January 17 in the U.S. District Court in Tucson, Arizona. It claims that the U.S. Interior Department and Bureau of Land Management have been ignoring “compelling evidence of the cultural importance” of the isolated San Pedro Valley to Native American tribes such as the Tohono O’odham, Hopi, Zuni, and San Carlos Apache Tribe for almost 15 years.

The lawsuit was filed soon after Pattern Energy was granted permission to transmit power from its SunZia wind farm in central New Mexico through the San Pedro Valley, located east of Tucson and north of Interstate 10.

The legal case refers to the region as “a highly preserved, ancient, and significant… area in southern Arizona” and requests that the court issue restraining orders or permanent injunctions to stop the building process.

According to the statement, the San Pedro Valley will suffer irreversible damage if construction continues.

Government representatives declined to comment Tuesday on the pending litigation. They are expected to respond in court. The project has been touted as the biggest U.S. electricity infrastructure undertaking since the Hoover Dam.

Pattern Energy representatives stated on Tuesday that it is no longer feasible to reassess the approved route, which was determined in 2015 through a comprehensive evaluation.

Pattern Energy representative Matt Dallas expressed disappointment that, despite a long period of discussion, some parties chose not to participate, and this decision was made at a late point in time.

The parties bringing the legal action are the Tohono O’odham Nation, the San Carlos Apache Tribe, and the nonprofit groups Center for Biological Diversity and Archaeology Southwest.

Archaeology Southwest has made a statement emphasizing the importance of preserving this landscape. They refer to the San Pedro river as Arizona’s only remaining unobstructed river and the valley as a representation of a remarkable and timely narrative of cultural and environmental sustainability spanning over 12,000 years.

The valley is a section of a 885-kilometer (550-mile) pipeline that will transport electricity from new wind farms in central New Mexico to existing transmission lines in Arizona, reaching populated areas as far as California. This project is a crucial component of President Joe Biden’s plan for a carbon-free power industry by 2035.

In September, work began in New Mexico following lengthy negotiations that took place over several years and resulted in approval from the Bureau of Land Management. This federal agency has jurisdiction over large areas of the western United States.

The path in New Mexico was changed following concerns raised by the U.S. Department of Defense regarding the impact of high-voltage lines on radar systems and military training exercises.

In November, work temporarily stopped due to requests from tribes to reevaluate the environmental approvals for the San Pedro Valley. It resumed a few weeks later, which was described by Tohono O’odham Chairman Verlon M. Jose as “a sudden and upsetting setback.”

The SunZia project anticipates that the transmission line will commence commercial operations in 2026, delivering over 3,500 megawatts of wind power to a population of 3 million. According to project representatives, surveys were conducted and collaboration with tribes took place over several years to identify cultural resources within the vicinity.

The court document includes a picture depicting the construction of access roads and tower sites in the western area of the San Pedro River near Redrock Canyon, taken from an aerial view in November. Officials from the tribal community and environmental activists claim that this particular region has remained largely undisturbed.

The Arizona Court of Appeals is currently evaluating the transmission line’s legitimacy. They are tasked with determining if the project’s potential advantages and drawbacks were adequately taken into account by state regulatory authorities.