Witness the miracle: a dead Arizona river, resurrected after 70 years

Tucson’s 2019 Revival of the Century-Dry Santa Cruz

The Santa Cruz River fed life at Sentinel Peak for 4,000 years until 1910, when twenty wells dried it up in just five years. For seven decades, the riverbed sat empty.

Then in 2016, Tucson Water’s Tim Thomure had a bold plan: put treated wastewater back in. On June 24, 2019, they did just that, pumping 2.8 million gallons daily as 300 people and a mariachi band watched. Nature took note too.

Dragonflies found the water within hours, and by 2020, even endangered Gila topminnows swam there again after a century away. Today at Sweetwater Wetlands Park, you can see this desert miracle firsthand.

Ancient Farmers Tapped Into The Santa Cruz River 4,000 Years Ago

Folks first settled near Sentinel Peak over 4,000 years ago, digging irrigation canals in the Santa Cruz River floodplain.

Dig sites show some of North America’s oldest farming took root here during the Early Agriculture Period. Families grew corn, squash, and beans while building clever canal systems to pull river water to their fields.

The river made possible 12,000 years of people living and over 4,000 years of farming in what later became Tucson.

Spanish Missionaries Built Their Lives Around Flowing Water

Father Eusebio Kino found the O’odham village of “Stjuckshon” in the 1690s and called it “San Cosme del Tucson.”

Spanish missionaries started Mission San José de Tumacácori in 1691, growing orchards and gardens watered by the river.

They built Mission San Agustín de Tucson in 1771 as a strong two-story mud-brick building with big farm fields.

In the mid-1800s, Julius Froebel wrote about seeing the river valley full of poplars, willows, ash trees, and oaks.

The River Once Teemed With Wildlife Now Lost

The Santa Cruz once flowed all year long in many spots, feeding thick groves of cottonwood, mesquite, and willow trees.

Fish like Longfin Dace, Santa Cruz Pupfish, Gila Chub, and Gila Topminnow lived alongside hundreds of types of migrating birds. Early gold-seekers wrote about catching turkeys and hunting pronghorn near the riverbanks.

The green river area also housed fish, birds, beavers and even grizzly bears.

Businessmen’s Wells Killed A 4,000-Year-Old River

Pumping groundwater for Tucson’s growing population dried up water that flowed through downtown in the 1940s. Wells, diversions, and erosion in the late 1880s made the river stop flowing year-round by 1913.

Tucson dug about 17 wells across the valley after big floods in 1914 and 1915, but they completely failed. By 1910, streams that ran all year shrank, and by 1940, even seasonal flows stopped completely.

Mighty Cottonwoods Died As Water Tables Dropped

As underground water levels kept falling, large cottonwood and willow trees along the riverfront slowly died. Losing the flowing water directly killed off the Santa Cruz Pupfish and nearly wiped out the Gila Topminnow.

Only tough native mesquites, palo verdes, and non-native tamarisk trees survived where lush growth once drew farmers for over 4,000 years.

The river turned into a forgotten ditch and dump, with the Tucson Citizen writing in 1970 that it became “a garbage dump.

Water Director Dreamed Up A River Resurrection

In 2016, Tucson Water director Tim Thomure suggested expanding the Santa Cruz recharge project with another pipe to release cleaned wastewater in downtown Tucson.

After Pima County built the Agua Nueva Water Reclamation Facility in 2013, water got clean enough for native fish to return.

Thomure said the project would put treated water uphill in the city where Tucson officials could better control it for future pumping. The idea came to life three years later as the Santa Cruz River Heritage Project.

Hundreds Celebrated As Water Returned To Dry Riverbed

On June 24, 2019, Tucson Water released 2. 8 million gallons of cleaned wastewater daily with a party at 4:30 p.m. Planners expected a small event with one tent and a crate of water bottles, but over 300 people and a mariachi band showed up to celebrate.

They picked El Día de San Juan Fiesta for the release, celebrating the feast day of St. John the Baptist, patron saint of water.

University of Arizona student Axel Golden said a banner should say “Better late than never” as water rushed from the pipe.

Insects Found The New Water Within Hours

Stream expert Dr. Michael Bogan watched in surprise as dragonflies from all over Tucson found the water within hours after it started flowing.

The water went farther than engineers thought it would, reaching a few hundred yards north of Speedway just five days later. A coyote cooled off north of St. Mary’s Road, using wet mud from the recycled water.

After only 2 years of steady flow, the river came alive with dozens of mammal, amphibian, and insect species.

Life Exploded Along The Reborn Riverbanks

Within two years, the Heritage Reach supported 135 bird species, 149 plant species, and many mammals and amphibians.

In November 2017, the endangered Gila topminnow appeared in the Santa Cruz near Tucson after being gone for 75 years.

In March 2022, workers collected 600 longfin dace from Cienega Creek and released them to help restore the native fish population.

The Heritage Reach became a drought-proof habitat fed by treated wastewater, no longer needing floods to survive.

Endangered Fish Swam Downtown After 100-Year Absence

On October 26, 2020, Arizona Game and Fish Department collected over 700 endangered Gila topminnows in about an hour from upstream areas.

Tucson Mayor Regina Romero helped release more than 500 fish into downtown waters, marking the first time in 100 years the species returned to this section.

Less than a week before release, University of Arizona professor Michael Bogan found invasive mosquitofish downstream and spent evenings removing them.

Despite cold, gusty winds on release day, cheers filled the air as the Gila topminnows returned to their river home.

Treated Wastewater Created An Ecological Miracle

The USGS tracked recharge dispersal with repeat microgravity data, showing the project successfully recharged treated effluent to the regional aquifer.

Arizona’s 2019 Drought Contingency Plan increased long-term storage credit rates for effluent from 50% to 95%, making 95% of recharged water available for future use.

Efforts continue to establish the Santa Cruz as an Urban National Wildlife Refuge, with coalition support from about 50 partners.

The rapid recovery shows how engineered water solutions can bring back entire desert ecosystems while recharging aquifers for human use.

Visiting Sweetwater Wetlands Park, Tucson

Sweetwater Wetlands Park at 2511 W Sweetwater Drive shows you where the Santa Cruz River came back to life in 2019 after being dry for over 70 years.

Engineers released treated wastewater into the riverbed, bringing back dragonflies and endangered Gila topminnows. Admission is free and it’s open 6am to 7pm daily (Mondays 9am to 7pm).

Join Tucson Audubon Society’s Wednesday field trips or use the QR code tours at the main kiosk.

This article was created with AI assistance and human editing.

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