More than 1,000 discarded passenger tires have been used to construct the dam, which is believed to be the first of its kind in the United States. It was built on one of the numerous dry arroyos that feed into the wash on the 50,000-acre King’s Anvil Ranch, located about an hour’s drive from Tucson. Nearly nine miles of the Brawley cross the property.

The wash began as a wagon trail in the 1840s and '50s, carved by prospectors traveling south into Mexico to seek their fortune in gold and silver. Time, Arizona’s annual summer rains and erosion combined to make the wash 200 feet wide and 25 feet deep in most sections. The Brawley stretches north from the Mexican border and feeds into the Santa Cruz river near Marana, Ariz., northwest of Tucson. 

The 45-foot-long, 35-foot-wide, 6-foot-high tire dam is the brainchild of Joshua Minyard, who holds a bachelor of science degree in geological engineering from the University of Arizona, and Dr. Stuart Hoenig, professor emeritus, electrical and computer engineering, University of Arizona. The tires are bound together with industrial-grade plastic strapping, filled with gravel and anchored in the arroyo. 

Minyard began thinking about tire dams after discussing soil erosion problems with John King, the owner of the ranch. Success of the project, which was approved by Pima County and the Arizona Department of Environmental Quality, will open the door for additional dams on the Brawley itself using large off-road tires such as those from mining sites.

Hoenig and Minyard seized upon the idea of using tires because it was less costly than building a concrete dam — and they felt the tires would aid in entrapping sediment carried north by rushing water, while allowing water to pass through. Hoenig notes that a lush fertile landscape is visible where concrete barriers were built on a similar wash in southeastern Arizona.

In sudden Arizona summer downpours, water run-off can become violent — sweeping away anything in its path. "Typical streams here can drop 50 to 80 feet per mile, so when they are running they can really move," Hoenig said. The men hope to see some visible signs of soil retention toward the end of the rainy season. 

The Anvil Ranch has been in John King’s family since 1908. He credits his family’s ranching longevity to fortune and struggle. His grandfather, Manuel Joseph King, began ranching in the vicinity in 1898. King said that in 1919 his grandfather was able to jump across the Brawley, the main portion of which is about a mile from the family’s adobe home. The state has had two very dry summers that were somewhat alleviated by a wet winter season. Arizona needs to receive about 8 inches of rainfall in July and August, according to King. Those two months of rain will fill tanks and help him grow cattle feed until the next year. 

"The arroyos run deep and wild. You need to slow the water down and allow it to spread out. We’ve tried all sorts of barriers and nothing we could construct would hold," King said. "A soil retention structure would slow erosion, giving the plants a chance to regenerate and heal the land." 

Minyard and Hoenig began building the dam in June. Work was done on weekends with a crew of 15 or more Pima County residents working on community projects as part of their probation. "They have really been an asset to this project. We would not have been able to make the progress that we have without them," Minyard said.

Hoenig said several neighboring ranch owners have made inquiries about building tire dams on their property. He and Minyard believe tire dams could be utilized to stop soil erosion across the entire state of Arizona.