SunZia Dawning

Preservation Archaeology Blog
John R. Welch, Vice President, Preservation & Collaboration

(November 3, 2025)—I am not big on fall. In my ledger, arborescent polychromes don’t balance out the shortening days or the calls to abandon shorts and sandals for pants and shoes. I favor Fourth of July and Jerry Garcia birthday (First of August) blasts over Thanksgiving and Solstice/Christmas reflections.

Because autumn compresses time so dramatically, I stick with getting busy early. So, a couple of Mondays ago, I headed onto Redington Pass before first light to look at the transmission corridor that the plaintiffs in our federal and state lawsuits allege has been opened for the SunZia and RioSol power  lines without due compliance with relevant laws. A three-judge panel ruled unanimously for the two Tribes (Tohono O’odham Nation and San Carlos Apache Tribe) and two nonprofits (Center for Biological Diversity and Archaeology Southwest) back in May. Read more about those legal wranglings here.

The SunZia power line along the west side of the San Pedro, with the Galiuro and Winchester mountains in the distance. The power corridor runs for about 550 miles, from wind- and solar-generating facilities in central New Mexico to Arizona Public Service and Salt River Project substations near Eloy, Arizona.
The SunZia power line along the west side of the San Pedro, with the Galiuro and Winchester mountains in the distance. The power corridor runs for about 550 miles, from wind- and solar-generating facilities in central New Mexico to Arizona Public Service and Salt River Project substations near Eloy, Arizona.

With U.S. District Court Judge Jennifer Zipps preparing to rule on the remanded case, I wanted personal, present-tense understanding of what’s been done to the San Pedro Valley by Pattern Energy (the SunZia developer) with permission from the U.S. Bureau of Land Management and the Arizona Corporation Commission. The great majority of the right-or-way in the San Pedro Valley is being leased to the SunZia and RioSol developers by Arizona’s State Lands Department.

SunZia towers, tower pads, roads, and tensioning sites run north from Redington Pass through a 33-mile tract of previously undisturbed lands in the most ecologically and culturally sensitive portion of the lower San Pedro River Watershed.
SunZia towers, tower pads, roads, and tensioning sites run north from Redington Pass through a 33-mile tract of previously undisturbed lands in the most ecologically and culturally sensitive portion of the lower San Pedro River Watershed.

The routing of the SunZia direct current (DC) line through the San Pedro is a stubborn holdover from the original developer’s plan (circa 2006) for an alternating current (AC) transmission line coupled with a fossil-fueled generation plant in Bowie, Arizona. Developers and regulators rejected all counter-proposals for routing alternatives, including a shorter route through central Arizona 100% co-located with pre-existing disturbance corridors and road systems. RioSol, SunZia’s AC twin, is said to be in the final stages of planning and would effectively double the number of towers, pads, and wires, wires, wires in the San Pedro. . . .

The massive SunZia towers vary somewhat in height and anchoring configurations. The developer apparently elected to strip more than an acre of land for each tower. In lieu of minimal impact construction protocols, and despite many reasoned objections, Pattern Energy and government regulators built more than 400 miles of new roads to enable SunZia, with an estimated 50 miles of new roads in the San Pedro Valley.
The massive SunZia towers vary somewhat in height and anchoring configurations. The developer apparently elected to strip more than an acre of land for each tower. In lieu of minimal impact construction protocols, and despite many reasoned objections, Pattern Energy and government regulators built more than 400 miles of new roads to enable SunZia, with an estimated 50 miles of new roads in the San Pedro Valley.

Developers bowed to government requirements in 2022 to double-circuit the DC and AC lines on the same towers to minimize ground impacts through the Sevilleta National Wildlife Refuge in New Mexico, but regulators rejected requests for similar consideration for the most ecologically and culturally sensitive portions of the Arizona route.

This double-wide road is one of countless examples of overuse of heavy equipment to clear swaths of desert far in excess of baseline construction requirements.
This double-wide road is one of countless examples of overuse of heavy equipment to clear swaths of desert far in excess of baseline construction requirements.

There is little evidence to support the claim on the Pattern Energy website that “SunZia Transmission is setting a precedent with a gold standard in environmental mitigation projects developed hand-in-hand with the environmental community.” Instead, Pattern Energy continues to ignore the concerns voiced by community members and Archaeology Southwest, especially regarding erosion and needless and still-unfolding losses of irreplaceable desert topsoils.

The prior image and this one show one of SunZia’s greatest and most enduring environmental harms: the preponderance of in-sloped roads and cleared areas. Out-sloping, in which roads and other cleared areas are built to allow precipitation to shed naturally and continuously, would have been easier and more sustainable. Instead of adopting well-established, environmentally friendly road-engineering protocols, Pattern Energy opted to in-slope most roads and many cleared areas. This technique, a relic of 1900s profit-maximizing quick-and-dirty extractive mindsets, leaves big berms on the downslope side of cleared areas instead of taking the care to gently contour the roads and clearings to match natural topography. The berms capture and concentrate rainfall and turbidity until the cascades gouge outlets through the berms. The results, as shown below, are gullies, further losses of native vegetation and habitat, none of which has been accounted for in SunZia’s “gold standard in environmental mitigation.”
The prior image and this one show one of SunZia’s greatest and most enduring environmental harms: the preponderance of in-sloped roads and cleared areas. Out-sloping, in which roads and other cleared areas are built to allow precipitation to shed naturally and continuously, would have been easier and more sustainable. Instead of adopting well-established, environmentally friendly road-engineering protocols, Pattern Energy opted to in-slope most roads and many cleared areas. This technique, a relic of 1900s profit-maximizing quick-and-dirty extractive mindsets, leaves big berms on the downslope side of cleared areas instead of taking the care to gently contour the roads and clearings to match natural topography. The berms capture and concentrate rainfall and turbidity until the cascades gouge outlets through the berms. The results, as shown below, are gullies, further losses of native vegetation and habitat, none of which has been accounted for in SunZia’s “gold standard in environmental mitigation.”
Rills converging on an oversized, in-sloped road.
Rills converging on an oversized, in-sloped road.

The in-sloped roads, coupled with insufficient water bars, rolling dips, and other erosion control measures will continue to cause erosion and stream siltation that could have been easily avoided. Indeed, more than a year ago, on August 13, 2024, Archaeology Southwest joined the Cascabel Conservation Association and other concerned groups in directing regulators’ and developers’ attention to the early signs of unmitigated environmental impacts from sloppy road building. The only response came from the BLM on September 9, 2024, in a short letter which claimed without evidence that “Pattern Energy has promptly addressed the erosion issues by implementing appropriate measures.”

Modest installations of straw wattles (blue tubes in the images above and below) are insufficient when roads and other cleared areas are installed using out-of-date principles that ignore widely adopted “best practices” for road construction and soil and plant conservation.
Modest installations of straw wattles (blue tubes in the images above and below) are insufficient when roads and other cleared areas are installed using out-of-date principles that ignore widely adopted “best practices” for road construction and soil and plant conservation.

Pattern Energy may want to make good on its “deep commitment to environmental stewardship.” All with access to a high-clearance vehicle may make the beautiful drive over Redington Pass and into the San Pedro Valley to judge whether the ends—that is, Pattern Energy’s version of “fuel-free, affordable energy”—justify the means, a power corridor hastily bulldozed through a former de facto wilderness. That judgment might include consideration of not only the local environmental harms, but also three broader questions:

First, and especially if you—like National Audubon, Western Resource Advocates, the National Resources Defense Council, and other Big Green organizations—believe that SunZia is required to address climate change, consider whether additional industrial intrusions should also be welcomed. Either way, SunZia’s alternating current companion, RioSol, is poised to bring another pulse of construction-related impacts and disruptions, multiplying SunZia’s ecological and visual consequences. Chances seem pretty good that transmission industry executives and their stockholders won’t stop there, and that these impacts may be used to justify additional infrastructure installations.

Second, if you judge the Climate Crisis as a paramount threat and agree with SunZia and RioSol developers that delivering wind- and solar-generated power from one sunny-windy place (NM) to another (CA), please consider that the developers’ websites are replacing most claims about the long-term benefits of renewables with promises like “economic development opportunities to attract hyperscalers and datacenters.” Big powerlines must remain energized, 24/7, and contracts to deliver electricity to prime markets in California must be honored. Central New Mexico is one of the sunny-windiest places in the country, with annual average “capacity factors” of about 39% for wind and 28% for solar (percentage of time generation can occur) (https://www.eia.gov/state/seds/data.php?incfile=/state/seds/sep_fuel/html/fuel_cf.html&sid=WI). The rest of the time, when the turbines are quiet or PV cells aren’t firing, SunZia and RioSol will transmit or depend upon new sources of “dispatchable” fossil fuel-generated electricity. Serious questions persist about whether and how SunZia and RioSol can produce a net decrease in greenhouse gas emissions from current levels. Answers to such questions should no longer be allowed to exclude the greenhouse gas emissions required to create, install, and maintain wind generating and transmission infrastructures. How many years must SunZia and RioSol operate at full capacity, including roughly 50% reliance on fossil fuels, before becoming part of any solution to the Climate Crisis?

Third, if you can embrace, even briefly, Life Magazine’s declaration of the San Pedro Valley as one of “America’s Last Great Places” (the only such in Arizona), ponder what this industrial corridor through their backyards means for the people of the San Pedro (https://www.hcn.org/issues/issue-37/the-southwests-last-real-river-will-it-flow-on/). Conversations with valley residents reveal this autumn as a time of reckoning. The collapse of their senses of place at the hands of this unprecedented intrusion into an otherwise interconnected landscape is driving many to despair. I’ve spent a fair amount of time learning from Indigenous historians about the variably institutionalized harms that reverberate when outside forces impose unwelcome changes and sever ties among peoples and places, the phenomena often referenced as intergenerational or historical trauma. It’s dawning on me that many San Pedro Valley residents are in the throes of intra-generational trauma, affording both glimpses into the roots and dynamics of this malady and incentives to do more and better to protect this beautiful and unique watershed.

 

P.S., Those interested in historical trauma may consult the extensive, peer-reviewed topical literature. Here are two good articles to get started:

Bombay, Amy et al. “The intergenerational effects of Indian Residential Schools: implications for the concept of historical trauma.” Transcultural Psychiatry vol. 51,3 (2014): 320–38. https://pmc.ncbi.nlm.nih.gov/articles/PMC4232330/

Cole, Ashley B. et al. “Intergenerational Impacts of Historical Trauma on Contemporary Depression Symptoms Among Indigenous Communities.” Journal of the American Academy of Child & Adolescent Psychiatry, 2025. https://www.sciencedirect.com/science/article/abs/pii/S089085672500019X

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