Water Conservation in the Desert
Once upon a time cottonwood trees and riparian plants lined the river banks. Fish swam in the waters, and wildlife thrived.
Over 12,000 years ago early nomadic people found our desert to be rich and welcoming as they paused here in their hunter/gatherer lifestyle. Around 4,000 years ago people began to settle permanently and plant their crops at the base of Sentinel Peak (A Mountain), along the Santa Cruz River. The agrarian community grew. And the rivers flowed.
The mid-1500s marked the beginning of the Spanish influence, from explorers and gold seekers to missionaries and their accompanying military presidios. By the 1700s several missions had been established to convert the Indians to Catholicism. Still a Mexican village of a few hundred, the population of Tucson continued to grow. And the rivers still flowed.
The mid 1850s saw the influx of Anglos from the east. The U.S. government bought southern Arizona from Mexico and encouraged Americans to move westward. Tucson continued to grow. Residents dug shallow wells to access water. And still the rivers flowed.
By 1900 Tucson’s population was about 7,500. A municipal water system pumped and delivered clean water. Indoor plumbing did away with outhouses. Homes had the luxury of running water. Ten years later, the population was 13,000. Due to pumping and diversion for irrigation, the water table dropped enough that the flow of the Santa Cruz River could no longer be sustained. Water flowed above ground only after a heavy rain.
In 1922, recognizing the need for water in the arid west, the seven western states that bordered on or fed water into the Colorado River drew up The Colorado River Compact, allocating a specific amount of the river’s water to each state. Oddly, they based their figures on several unusually wet years which meant that, in effect, they over-allocated the contents of the river during normal flows. Further, when Mexico later pointed out that the river had its mouth in that country, more acre-feet were allocated out of thin air. Ah, well. For the most part that didn’t pose any real problem since there was more water than was needed at that time. When drier times followed the issue was ignored.
Tucson’s population grew during and after World War II. Modern technology made it possible to pump ever deeper for water. However, by 1960 it was clear that continued pumping was unsustainable and would lead to serious subsidence of the land. Eventually the building of the Central Arizona Project (CAP), a 336-mile canal to bring Colorado River water inland for the cities and farmers, seemed imperative.
By 1980 the population surpassed 500,000, and deep pumping continued. Finally, after 20 years of construction, the CAP finally reached completion in 1992. But joy over this “endless” source of water was short-lived when the new water’s chemistry/ph effectively scoured out years and years of deposits and rust from the city’s old pipes and delivered brown, smelly water to people’s homes. With massive water main breaks and leaks, that expensive disaster set back the use of the canal for another decade.
At the turn of the 21st century, the plan we use today had been implemented. Water from the canal is diverted into a series of shallow “recharge” basins from which it filters through the desert floor into the aquifer (basically an underground “valley” filled with gravel and sand) below where it can be stored and pumped out by Tucson Water for delivery to the city. You can easily see some of these basins from the Desert Museum. At this time, depending on where you are in Tucson, around 80% of the water that comes out of your faucets has the Colorado River as its origin.
And that brings us to the dilemma we face today. With ongoing drought and the impacts of climate change, the level of the Colorado River is dropping with no end in sight. Lakes Mead and Powell, the nation’s two largest reservoirs, are well below half and likely to continue to fall. If that continues, the mighty Hoover Dam will no longer be able to generate electricity or even release water downstream.
Yikes! What can we do to forestall disaster? For starters we can recognize that we live in a desert where water is precious. We must be mindful of the amount of water we use. Let us look back and learn from Tucson’s earlier residents. Since they had to haul it from the river (or the well), you can bet they didn’t waste it! The Reid Park Zoo offers some great examples and suggestions. As you walk around, read the signs to learn all that the Zoo is doing to conserve and what you can do at home. And rest assured that water conservation is already a priority in the plans for the Reid Park Zoo expansion.
Grow shade on your property to help it stay cooler and hold moisture in the land. Sculpt your yard into basins and swales to capture and slow the flow of any rain that falls. Plant native trees and bushes next to or in your basins. Give water a second use. Direct water from your washing machine, shower, and bathroom sink outside to feed a thirsty plant.
In front of the Zoo’s Conservation Learning Center (CLC) there is a huge rain cistern to collect rainwater from the roof to use as needed during dry times. You may be amazed by how much water can be collected from one monsoon storm. For example, from a 1,000 square foot rooftop (25' x 40'), if a single inch of rain falls, 600 gallons of water will flow into the tank. Since many people live in houses that are 2,000 square feet, that would mean 1,200 gallons of water! When you consider the rooftop space of the CLC, you’ll realize why that cistern is so gigantic.
If you’re a Tucson Water customer, check out the amazing rebates available to help you pay for installing rainwater and gray water harvesting systems.
In a normal year, Tucson receives 10–12 inches of rain. When you convert those inches into gallons, the surprising but calculated fact is that the amount of water used by the city of Tucson is LESS than the amount of rainfall! If we can harvest enough rain, we wouldn’t even need the CAP water. We don’t need expensive, complex equipment and technology. We simply need the will to take up the challenge. When we do, we may find that in fact it doesn’t feel like pain and sacrifice; it feels like satisfaction and success.
And our rivers can flow again.
Originally published at http://reidparkzooexpansion.org on June 5, 2021.