Arizona has various water supplies that support habitat, communities, industry, agriculture, and our way of life. Groundwater makes up 41 percent of the state’s supply, followed by Colorado River water at roughly 36 percent, in-state rivers (like the Salt and Verde Rivers) at 18 percent, and reclaimed water (purified wastewater) at five percent.
In many communities, surface (river) water is not available, so groundwater is often the only source of water. As Colorado River water supplies shrink, the state will become increasingly reliant on other sources, like groundwater. This is why we must protect and maximize all our water resources—and the infrastructure that provides, captures, moves, and purifies that water.
To improve our understanding of what municipalities and organizations are doing to make water supplies more resilient, Audubon and partners went to southern Arizona to view water projects on the ground.
Removing contaminants from groundwater in Tucson
An aquifer is a layer of sand, gravel, or permeable rock where water collects underground. When rainfall, streamflow, or melting snow sinks into the ground, the groundwater recharges naturally into the aquifer. To protect groundwater resources in southern Arizona, it is vital to protect the aquifer.
Which took us to the first stop of our tour, Tucson Water’s Tucson Airport Remediation Project. This facility was originally constructed in 1994, to clean up a portion of Tucson’s groundwater, which had been designated a superfund site due to contamination by trichloroethylene (TCE) and 1,4 dioxane chemicals from military activity in the 1940s to the 1970s near what is now the Tucson International Airport. The facility also helps protect the aquifer and prevent the movement of TCE into Tucson’s central wellfield (where Tucson Water pumps clean groundwater to serve it to customers).
In 2022, the Arizona Department of Environmental Quality (ADEQ) awarded Tucson Water $25 million with funding from the American Rescue Plan Act to improve treatment of another contaminant in the groundwater: per- and polyfluoroalkyl substances (PFAS). Construction for this portion of the Tucson Airport Remediation Project was completed in September 2026. These facility upgrades will help reduce operation and maintenance costs, remove PFAS, allow the Advanced Oxidation Process to fulfill its originally intended purpose of treating for TCE and 1,4-dioxane, and increase the overall treatment capacity of the plant. Treated water from the project is added to the reclaimed water system and used for irrigating parks and golf courses. A small portion of the treated water is also discharged into the Santa Cruz River, where it supports riparian habitat along Tucson’s “The Loop” bike path.
Techniques to restore landscapes and invest in natural infrastructure
Watersheds are land areas that capture rain and snowmelt and drain into rivers, lakes, and streams. In Southern Arizona, healthy grassland landscapes and watersheds allow rain to soak into the soil, recharge the aquifer, and support native habitat. When these landscapes degrade and the plant cover is lost, the bare soil has less capacity to soak up the water, forcing it to run off, eroding dirt and sediment. This can create incisions, or downcutting on the landscape. These incisions (also called head cuts) can slowly expand and move upstream, disconnecting the land from the underground water table or floodplain, which can negatively impact habitat and water supplies.
Land managers utilize low-tech process-based restoration techniques to rehabilitate degraded landscapes and watersheds. Low-tech process-based restoration involves constructing simple, non-mechanical structures to reestablish natural hydrological functions and ultimately reconnect the floodplain—the surface water with the groundwater.
We heard from the Watershed Management Group about natural infrastructure projects they are tackling along the Lower Babocomari River (which flows into the San Pedro River) with funding from the U.S. Fish and Wildlife Service, Arizona Department of Environmental Quality, The Nature Conservancy, and other non-governmental organizations.
Along the Lower Babocomari River, Watershed Management Group and volunteers installed post-assisted log structures, a low-tech process-based restoration technique. These structures slow the flow of water, allowing the landscape to absorb the water and soak into the ground. It also reduces erosion because sediment can spread out instead of rushing downstream. This helps restore a healthier, more resilient river system where native plants can be reestablished as well.
Our last stop of the day took us to The Nature Conservancy’s Canelo Hills Cienega Preserve, a 260-acre nature sanctuary southeast of Sonoita, neighboring Audubon’s Appleton-Whittell Research Ranch. The Nature Conservancy manages the preserve to protect and restore the spring-fed wetland, also known as a cienega. While cienegas make up a small percentage of the southern Arizona landscape, this unique ecosystem provides essential habitat for various types of wildlife, including threatened and endangered species. This particular cienega is home to the rare and endangered Canelo Hills ladies’-tresses orchid (Spiranthes delitescens).).
To enhance the habitat for this rare flower, fire is critical. Fire has an essential function in grassland ecosystems because it controls the encroachment of woody plant species and minimizes the buildup of thatch—the dry vegetation that densely accumulates covering the soil preventing growth of new plants. Historically, the preserve’s habitat burned every five to ten years. But after 20 years without fire disturbance, the amount of fuel had reached an unhealthy level.
With funding and coordination from the U.S. Fish and Wildlife Service, U.S. Forest Service, Bureau of Land Management, National Park Service, The Nature Conservancy, Desert Botanical Garden, and private landowners, a beneficial prescribed burn was carefully executed in January 2025 to clear dead grass and encroaching trees. The prescribed burn ultimately opened up habitat, spread nutrients, protected the cienega’s spring water, and reduced the fuel load that could lead to catastrophic wildfire.
The Nature Conservancy and Desert Botanical garden will continue to monitor the impact of the burn on the land, water, and the Canelo Hills ladies’-tresses orchid. Recently, a flowering orchid was found on site (for the first time in 15 years).
In another section of the preserve, tour participants heard from Ryan Golb, Restoration Specialist with Borderlands Restoration Network, about a natural infrastructure project that reduces erosion and retains water and moisture on the landscape.
Borderlands Restoration Network utilized local materials (riprap rocks, larger stones, and logs) to create erosion control structures to improve the function of a usually-dry wash—so that when water does flow from storm events, the structures help divert water away from the nearby roadway, keeping the water in the wash along trees and shrubs. This prevents flooding on the road while rehydrating soil and plants and reducing the force of water during storms. Ryan explained there is evidence these structures are working: “You can see where the water is flowing based on where it deposits debris as it slows down. This is a key indication that our structures are working the way we want.”
To improve the resilience of our landscapes and water supplies, we must continue to invest in various types of infrastructure projects. As evidenced by this tour, many different techniques help protect and stretch our water supplies and rehabilitate landscapes, habitat, and aquifers. With the significant rainfall that hit the southwest in the fall of 2026, it is all the more important to invest in our landscapes and infrastructure, to replenish our reservoirs, recharge aquifers, and rehabilitate habitat. In Southern Arizona, funding from local, state, federal, philanthropic, and corporate partners, as well as cross-sector collaboration, proves essential to bring projects to fruition and make an impact for communities on the ground.