Death and New Life at the Santa Cruz River
An artist and a group of scientists on grieving and restoring Arizona-Sonora’s shared waterway. "It’s enormously inspiring.”
We are so happy to publish the inaugural piece by accomplished author and journalist Caroline Tracey. If you want to learn more about Caroline and why we are so enthused to have her on board, please check out “The Border Chronicle Forecast for 2025,” written by Melissa last week. There, Melissa provides an introduction to and more detailed biography of Caroline, as well as a rundown of what to expect on the border, and our coverage of it, this year. Todd
Death and New Life at the Santa Cruz River
An artist and a group of scientists on grieving and restoring Arizona-Sonora’s shared waterway. "It’s enormously inspiring.”

The installation Graves for the Rain, on view at the Museum of Contemporary Art in Tucson, Arizona, is an ellipse of brown and gray gravel and sand that stretches across the polished-concrete floor of the East Wing Gallery. From four speakers, the sound of stones crunching fills the space.
At intervals throughout her monthslong tenure at the MOCA, artist Karima Walker has brought the installation to life through a performance. For two hours—during which time visitors are free to enter and exit the space—she carries bags of sand collected from the bed of the Santa Cruz River, one of Arizona and Sonora’s shared waterways, and walks in a circle around the ellipse, releasing the material at her feet, one handful at a time, simultaneously building a berm and filling in the footsteps she has just created.
The installation and the performance conjure a feeling of coziness in the space. It’s an odd sensation, since Walker carries herself seriously, giving a sense that the event is a somber ritual. Nevertheless, the repetitive, ambient sound, the low ceilings of the gallery, the closed circle of the sand berm—all this creates a sense of being welcomed by the river’s channel. Though paradoxical, it is also appropriate: the Santa Cruz has been both cherished and devastated, and its uncertain future carries a balance of grief and hope.

The Santa Cruz River starts a few miles north of the U.S.-Mexico border in the San Rafael Valley, southeast of Patagonia, Arizona. From there, its channel crosses into Mexico but soon makes a U-turn to flow north back into the United States, where Nogales, Tubac, and Tucson all sit along its banks. Finally, after slightly under 200 miles, it joins the Gila River south of Phoenix.
While the river’s channel follows this course, however, water no longer flows through much of it. Starting around 1910, groundwater pumping for urban and agricultural use caused the river to go almost completely dry by 1940. After that, it remained a site of gravel and sand extraction throughout the 20th century, and a site of dumping: after Tucson’s trash incinerator closed in 1950, write the authors of Requiem for the Santa Cruz: An Environmental History of an Arizona River, “several million tons of garbage were dumped either in the [river’s] channel or on the adjacent floodplain.”
When residents of Tucson see the river, it’s often in this state: when you cross the river on major thoroughfares or bike along it on the Loop, the river appears as a dry, sandy bed. In 2024 the nonprofit environmental organization American Rivers named the Santa Cruz one of the United States’ 10 most endangered rivers.
Walker’s installation captures the Santa Cruz in this state. She began “getting to know the river,” in her words, during the 2020 COVID-19 shelter-in-place order. Later, she read that some scientists consider the river dead, given its collapse in the early 20th century. (The “dead” label can apply either when water ceases to flow through a river’s channel or when it is so polluted that life cannot survive in it.)
“I thought that was profoundly sad,” Walker said. At the time, she was also grieving the passing of her mother. “All these pieces came together—this private, personal experience of grief paired with ecological practice and research.”

In recent years, however, scientists and environmental managers have come to see the Santa Cruz River as a success story. They consider the river to have begun a recovery in 2008, after upgrades to the Nogales International Wastewater Treatment Plant in Rio Rico, Arizona. The treatment plant had long been releasing treated water into the riverbed, but the water’s poor quality was causing negative environmental impacts along with a noticeable smell. “It turned out that the water was high in nitrogen, so they made huge, federally funded upgrades,” said Luke Cole, Santa Cruz River program director at the Sonoran Institute.
After the improvements, from an ecological perspective, “it was like starting over,” said Michael Bogan, an aquatic ecologist and professor at the University of Arizona. Within several years, insects, birds, and wetland plants had established themselves along the river.
The successes in the river’s Tubac stretch helped spur similar improvements downstream in Tucson, where the city replaced its own notoriously foul-smelling wastewater treatment plant in 2013.
Now, at Agua Nueva Park, just south of the plant’s massive storage tanks, an outfall spouts clean treated water into a pond where visitors can see woodpeckers, herons, egrets, and many species of ducks. Another outlet into the adjacent riverbed provides the Santa Cruz with five miles of uninterrupted flow. The river has been resurrected, at least partially.
In 2019, the city of Tucson and Pima County decided to introduce some of the treated wastewater just south of Starr Pass Boulevard at the base of Sentinel Peak. The area is considered the city’s birthplace.
When they turned on the tap to what they had dubbed the “Heritage” Reach, Bogan, the aquatic ecologist, and a team of students were there to monitor how life returned. “At 3 p.m. on the same day,” said Bogan, “there were already seven species of dragonflies that had not only found the water but were mating and laying eggs—it was literally a matter of hours before we were seeing that ecosystem come back. We thought they’d be quick, but never thought they’d be that quick.”
By now, according to Cole, there are over 40 miles of the river “flowing with good, high-quality water.” A coalition of nonprofits, including the Sonoran Institute and the Wilderness Society, is working with the U.S. Fish and Wildlife Service to create an Urban National Wildlife Refuge. Pima County has offered over 500 acres for the refuge, and a private landowner has offered around 8,000, including 13 linear miles along river. “This refuge is the gold standard when it comes to land protection offered by the federal government,” said Cole.
Though these successes are a cause for optimism, they are not without complications. In the Tucson area, for instance, plans for “toilet-to-tap” water treatment means that there could be a new pressure on the water that feeds the Santa Cruz: human use.
In the Tubac stretch, meanwhile, the river’s recovery is based in part on problems with stormwater management in Nogales, Sonora. The Nogales International plant treats water from both Nogales, Arizona, and Nogales, Mexico. But during rainstorms, stormwater on the Sonora side mixes with sewage, meaning that far more wastewater ends up at the plant than its contract allows for.
That excess water ends up being a boon for the Santa Cruz River. Since, according to the treaties that govern cross-border waters, that water belongs to Mexico, “no one in the U.S. can use it,” said Adriana Zuniga-Teran, a professor at the University of Arizona’s School of Geography, Development, and Environment. “It’s just left in the river.”

Walker said she doesn’t know how to feel about the river’s recovery. “‘Restore’ and ‘conserve’ are complicated terms,” she said. “There’s a critical voice in my head that’s like, ‘Whose future?’ But at the same time you see species returning to a place, and it’s deeply moving.”
Bogan feels the ambivalence too. In the past, he said, the river’s many frogs could be heard throughout downtown. “There’s certainly a reason to grieve that—in Tucson, there’s no going back to that,” he said. “But we’ve learned that even putting a trickle of water can support a large number of species and be a great place for people to go and visit. So even though it’s got concrete banks and seems kind of depressing, as soon as you’re down in that restored ecosystem, it’s enormously inspiring.”
The Santa Cruz River’s partial recovery carries a history and reality of deep loss—that of a system that was once very different. Now, caught between optimistic conservation efforts and increasing demands on limited water resources, the river teeters between offering the sense of warmth that viewers can glimpse in Walker’s performances, and the static aridity of sinking into a grave. Graves for the Rain holds the tension of a river that is wholly dependent on the same society that laid waste to it just decades ago.
Look who it is! Great read.
Reminds me of how blessed I am to live in a water rich part of our country. Also one that doesn’t burn. I simply don’t understand why everyone left us. Well maybe 14 below wind chill this coming Monday has something to do with it.