Phoenix is built in the middle of a huge Arizona desert. Average rainfall in Phoenix is around 6 or 7 inches per year. The state wide average, including the high country, is around 12 inches.

People often ask where we get all the water needed for home, business, and irrigation.

We get it from the Colorado River as well as other rivers and streams flowing through Arizona. We also have groundwater and treated wastewater.

No, we don’t drink treated wastewater and neither will you if you visit Arizona. It’s used for golf courses, industrial cooling, agriculture, parks, and management of wildlife areas.

In my opinion, the reason we have enough is more important than where we get it.

Good management

Salt River Project (SRP) is a large public power utility company which provides power and water to most of the valley. They, with others, have established a great management system to provide for our needs throughout drought years.

In my opinion, the system is amazing.

Arizona receives an allotment of 2.8 million acre-feet from the Colorado River each year through a “law of the river” agreement with other states using the Colorado River.


This water comes into the valley and other counties by way of a large canal across the desert. This canal is linked with many other canals as well as rivers and streams.

There are also pumping wells to obtain groundwater. In addition, treatment centers add water for the above mentioned uses.

Like plumbing in a building

The amazing part is how all this is tied together like plumbing in a large building. Engineering involved in such a design rivals that of a self-driving car or complex transportation system.

The linkage of all the canals and waterways through dams, pumping stations, and diversion dams allows SRP to control the distribution throughout the state at any given time.

Diversion dams

The diversion dams also allow excess water during high flow times to be pumped into artificial underground aquifers. It is saved there for later use when the supplies from streams are slow.

It’s like a savings account. These aquifers are used as storage tanks until needed and help replenish normal groundwater supply.

Branches of tree roots

In general, all the water from the various sources is routed into the canal system and then branches off into smaller canals much like tree roots. This can be seen easily from the air. Maybe you could even see them from the Arizona balloon to space.

Some of these irrigation canals serve large farming areas, some go for irrigating landscaping in the city areas.

So basically, the entire state works together to put all available water into one big system. They take their allotment from the Colorado, but save what they can in the artificial aquifers.

Then the reclaimed, river, and groundwater is more than enough to meet the yearly demand of 7 to 8 million acre-feet of water used in Arizona.

Other parts of the Arizona irrigation system will be discussed in more detail in upcoming articles. Watch for it.