Arizona’s Remaining Rivers Should Not Be Dammed

Colorado pikeminnows
Colorado pikeminnows (AGFD)
Arizona Rivers Photo Album

In July of 1862 Sergeant George Hand and his squad from Company G of the 1st California Volunteer Infantry regiment were ordered to start marching up the Gila River from Fort Yuma. His unit was part of a small Union army, called the California Column, which had driven the Confederates from Arizona and southern New Mexico.

The soldiers stuck to the trail along the river until they reached the point where it makes a loop to the north, called the Gila Bend, and then took the long-used short cut through Pima Pass in the Maricopa Mountains to reach the Pima and Maricopa Indian villages on the middle Gila River. From there they crossed the open desert through Picacho Pass to Tucson, like Interstate 10 does today.

Sergeant Hand kept a diary of the march, which was eventually published in the book The Civil War in Apacheland. It’s clear from his diary that his march along the river was much more pleasant than the stretch across the open desert. He wrote, “The Gila is a splendid river to bathe in, clear and very good to drink, little alkali.” He reported that the soldiers regularly caught and ate fish from the river and that, “Game is very plenty – mourning doves, quail, cottontail and other rabbits very thick.” At one point along the river he said, “The quail astonished me. Millions. They rose in flocks. The air was black with them and their whirr was like a rolling thunder.”

The trail along the Gila River was the most popular route for travelers crossing Arizona in those days, because it provided the water and shade trees they needed to survive. But in the late 1800s water was diverted upstream from the Akimel Oʼodham (Pima) villages along the middle Gila by white settlers. They dried up much of the river and the Akimel Oʼodham were no longer able to feed themselves by by farming. In order to survive, they were forced to cut and sell the mesquite trees that grew in the river bottom. A large mesquite forest (bosque) that ran along the river for more than 60 miles was destroyed. When Coolidge Dam was dedicated in eastern Arizona in 1930, it was the final nail in the coffin for the lower Gila River. If you’ve ever driven across the dry Gila River on the bridge on Interstate 10, you probably find it difficult to believe that it used to flow yearlong and was lined with trees.

Mesquite bosque, Patagonia-Sonoita Creek Preserve, The Nature Conservancy of Arizona (Jeff Burgess)

When Sergeant Hand and his fellow troopers reached Tucson in 1862 they found the Santa Cruz River flowing past the town. Most of the Santa Cruz is dry today due to groundwater pumping, but it used to flow perennially for most of its length from the Mexican border at Nogales downstream to Tucson. Dense forests of mesquite trees, now gone, lined its banks too.

And if you live in the Phoenix area you might be surprised to learn that the Salt River, the Gila’s largest tributary, used to flow yearlong through town. That’s because upstream dams were built at the beginning of the 20th century that diverted the river’s flow into irrigation canals. Like the Gila River, the lower Salt used to support wildlife and trees. Fishing was good in the Salt too, and both rivers used to have enormous annual runs of big, edible fish called Colorado pikeminnows. But today, 20 of Arizona’s original 36 native fish species are federally listed as endangered or threatened, and one has already gone extinct.

Many terrestrial wildlife species relied on these rivers too. Sergeant Hand wrote of seeing large herds of pronghorn antelope during his march. But today, the Sonoran pronghorn is an endangered species, reduced to about 250 animals. Even if there were still some water in the lower Gila River, the few remaining antelope couldn’t get to it because their access routes were severed by the construction of Interstate 8.

No More Dams Should be Built

I’m not suggesting that we should dismantle the dams that killed these rivers. There are millions of people that rely on the water they store. I’ve described their history because the ongoing severe drought in the Southwest has renewed discussion about Arizona’s water supply. The consensus of local water managers is that we have enough for the near future, but we will need to pursue new sources of water as the state’s population grows and the climate gets hotter. Furthermore, there are already problems from groundwater overdrafts in some locations, including along the San Pedro River Riparian National Conservation Area.

The cheapest and easiest way to increase our water supply is through conservation. There’s a lot of low hanging fruit there. And agriculture still uses about 70% of the state’s water supply, with more than half of that being used to grow livestock forage. Urban dwellers are more efficient and productive users of water than irrigated agriculture, so some of that agricultural water could be converted to municipal use. These are our two easiest and cheapest options. The other options are much more expensive.

I think the most expensive option of all is to build new dams. And I’m not just talking about the construction costs. Rivers are the arteries of our planet and Arizona’s rivers have already suffered enough. Tempe Town Lake is a good measure of how much we’ve lost. The city was willing to spend millions to fill a short stretch of the dry Salt River bed with water and it has become one of the state’s most popular destinations. Building new dams that would kill Arizona’s remaining rivers should be the last thing we consider.


In 2018 a short stretch of the Santa Cruz River on the Tohono O’odham Nation’s San Xavier Reservation, south of Tucson, began to flow again. A reduction in amount of local groundwater pumping was cited as the main reason.

In July 2019 researchers at the University of Arizona confirmed that unregulated groundwater pumping is helping to dry up Arizona’s remaining rivers.

On September 23, 2019, the Arizona Republic reported that a developer of a proposed massive new housing development along the San Pedro River Riparian National Conservation Area near Benson, AZ, claimed the Trump administration’s plan to repeal a portion of the Clean Water Act will give a green light for the project to proceed. The concern of many people is that the development will pump large amounts of ground water that could dry up nearby portions of the river.

On September 23, 2019, an application by a Phoenix, AZ, company to build two hydroelectric dams on the Little Colorado River, near the Grand Canyon, was published in the Federal Register.

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