Reclaimed water is back in Santa Cruz River in downtown Tucson, attracting wildlife

Arizona News

Water is back in the Santa Cruz in downtown Tucson, drawing cattails, dragonflies and egrets, after the city kept the river dry since spring for sediment removal and other projects.

A steady stream, 10 or more feet wide in some places, runs downriver from 29th Street north to within a few hundred yards of Speedway.

Almost a year after Tucson Water first put reclaimed water back into the long-dead river, the Santa Cruz is carrying roughly the same amount as then, about 1,900 gallons a minute.

Two major hurdles that slashed, then stopped the water releases this year have been cleared, utility officials say.

First, Pima County flood control officials finished a monthlong project removing 83,000 cubic yards of sediment from the riverbed from West 29th Street north to West Cushing Street.

The work that ended May 31 pulled out an average of 4 to 5 feet of riverbed, and as much as 10 feet in some spots. The project also removed about half the trees and other vegetation from the river stretch.

The other hurdle was that utility officials wanted to halt “ponding” of the river water at about 22nd Street.

Officials said the ponding appeared to be a prime cause of a sharp spike in water levels in the underlying aquifer, rising fast enough to potentially undercut the old Rio Nuevo landfill lying west of the river between West 22nd and West Cushing streets. Officials need to ensure water in the aquifer doesn’t leach contaminants from the trash, buried no lower than 25 to 30 feet below ground.

The county obliged, installing small notches at a concrete grade control structure there and at three similar structures in the downtown area, allowing water to proceed more smoothly.

The notches “appear to be working, but we will continue to monitor their performance,” said Tucson Water spokesman Fernando Molina.

However, Eric Holler, a retired U.S. Bureau of Reclamation engineer and a frequent critic of the utility, said he’s not convinced the notches have fixed problems with recharge of the aquifer. The rise in water levels — exceeding 40 feet — was so high that “the geology has to be weird” in that area, Holler said.

“This is going to be a work in progress as we manage this project,” Tucson Water Deputy Director John Kmiec has said. “We are still studying how the river will react.”

Reclaimed water was first put into the downtown stretch on June 24, 2019, to a crowd of several hundred wildlife lovers, politicians, agency officials and longtime residents who were thrilled to see full-time water in the river for the first time since World War II.

The purpose was to restore some of the river’s historic habitat and allow for recharge of the effluent in an area within Tucson Water’s service area, making it easier to someday pump it back out if it’s ever needed for drinking or other domestic uses.

Vegetation and wildlife are returning after the river’s dry spell this year.

The birds and toads are back

A large wetland area that formed near 29th Street after the releases first started appears to be coming back. Green shoots of cattails are sprouting all over that area, next to yellowed marsh plants that died after the water releases were cut.

The birds, toads, roadrunners and other wildlife that had flocked to the area last year also have returned, said Michael Bogan, an assistant University of Arizona professor of natural resources who has been monitoring the riverfront for the past year.

“There’s an accidental wetland here,” said Bogan, as he stood just above where four small channels of water were rippling through bright green trees and shrubs. “When the water was first released, the channel it created went toward some large tamarisk trees. The trees held the riverbank there in place, and kept it from eroding. That allowed the marsh to form. It was great, not part of anybody’s plan.”

After the county started removing sediment and the trees from the riverbed, Bogan was concerned that might let water speed away and cause the wetland to drain.

So with help from some of his students and Tucson Water volunteers, he spent five days in late May digging four separate channels to diffuse the water’s power and allow it to flow gently.

“Now, it turns into kind of a delta,” he said. “The water spreads evenly.”

As for the wetland plants, Tucson Water planted one. The rest grew on their own, he said. This year, within 24 hours after the releases restarted, the plants had sprung back to life, he said. He’s counted six other plant varieties besides cattails, including sedges, manley flowers, pondweeds and speed wells.

Wildlife appears to be returning in the same pattern as last year, he said. So far, 20 species of dragonflies have appeared along the river. Sonoran toads were “breeding on Day 5,” and were followed by “thousands” of tadpoles on Day 7, he said. Great Plains toads showed up a few weeks later, and red-spotted toads appeared Friday.

The birds include killdeer, snowy egrets that eat toad tadpoles, and red-tailed hawks that one morning came in five strong to sip water.

The next variable will be the summer storm season, noted Molina, the Tucson Water spokesman.

“We expect the first substantial monsoon flows will move sediment around and create different flow paths” for the water.

Contact reporter Tony Davis at tdavis@tucson.com or 806-7746. On Twitter@tonydavis987

/* div { flex-grow: 1; padding-right: 1.5em; width: 50%; }
.newsletterpop_dialog_wrap .newsletterpop_dialog_body_wrap > div:last-child { padding-right: 0; }
.newsletterpop_dialog_wrap .newsletterpop_dialog_body_wrap_no_image { padding: 1.5em; box-sizing: border-box; }
.newsletterpop_dialog_wrap .newsletterpop_dialog_body_title { font-size: 1.4em; font-weight: bold; }
.newsletterpop_dialog_wrap .newsletterpop_dialog_body_desc { margin-top: 0.5em; margin-bottom: 2em; font-size: 0.9em; }
.newsletterpop_dialog_wrap .newsletterpop_dialog_error { margin-top: 1em; font-size: 1.1em; color: #DE5A41; display: none; }
.newsletterpop_dialog_wrap .newsletterpop_dialog_success { margin-top: 1em; font-size: 1.1em; color: #6BDD42; display: none; }
.newsletterpop_dialog_wrap .newsletterpop_dialog_field { margin-top: 1em; }
.newsletterpop_dialog_wrap .newsletterpop_dialog_body_wrap_no_image .newsletterpop_dialog_field { max-width: 300px; margin-left: auto; margin-right: auto; }
.newsletterpop_dialog_wrap .newsletterpop_dialog_field input { display: block; width: 100%; padding: 0.5em; font-size: 1em; }
.newsletterpop_dialog_wrap .newsletterpop_dialog_field .newsletterpop_dialog_button { text-align: center; padding: 0.7em; cursor: pointer; } @media (max-width: 520px) { .newsletterpop_dialog_wrap { font-size: 0.9em; } .newsletterpop_dialog_wrap .newsletterpop_dialog_body_wrap > div { width: auto; } .newsletterpop_dialog_wrap .newsletterpop_dialog_body_left { display: none; } .newsletterpop_dialog_wrap .newsletterpop_dialog_body_desc { font-size: 1em; }
}
/*]]>*/

Leave a Reply