Water in the middle of the desert

To go in the kitchen and to have a glass of tap water is almost a luxury. Access to water is a precious good. We could be multimillionaires if the scale of value was not based upon market value. Indeed more than 900 million people on Earth do not have any access to drinking water and more than 2,6 billion no access to sanitation system (leading to diseases and higher mortality).

In desert region such as Arizona can be, everyone tends to know the value of water. But it hasn't always been the case. Rivers are dry nowadays and aquifers are low. The main reason? Overuse of water for agriculture and farming, in comparison to what nature can refill them. Even earlier than that, First Nations were moving from places to places depending on drought and access to water. They were even moving on trails along the rivers.

In the 1920's, the seven States covering the Colorado basin (Wyoming, Utah, Colorado, New Mexico, Arizona, Nevada, and California) negotiated share of Colorado River water. Then two dams were built: Powell for the Upper division and Hoover for the Lower division of the Colorado basin. But Arizona understood it will be difficult to provide the South of the State with Colorado water coming from Lake Mead (North Arizona, where the Hoover Dam is). It decided to build a canal to irrigate the South, in particular Phoenix and Tucson regions. The open-sky canal crosses the desert to end 336 miles (540 km) away from its source. Some 15 pumping plants help lift water more than 2,900 vertical feet (1,000 meters).

Arizona uses its water quota from Colorado River and distributes it more equally over the State. The canal, a.k.a. Central Arizona Project / CAP (which I visited thanks to Mitch), helps decrease pumping in aquifers: groundwater pumping is still allowed, even for those with CAP water – but any pumping needs to be managed to meet state laws. Approximately 1/3 of CAP water goes for population in towns and 1/3 for agriculture. The remaining 1/3 is used by Indian reservations and the left-over is stored in aquifers to renew them.

Obviously man can ask about expansion of cities. But no one dare give any figures. When will cities like Phoenix or Tucson have to say “stop! we can't have more people living in town because of water shortage”? The question (and the answer!) are highly political. So instead, the focus is put on education, rain water harvesting, less waste, recycling. For instance, Phoenix grey water directly goes to cool down Palo Verde nuclear power plant, located 50 mi / 80 km away in the desert. Tucson has more room for improvement: only 35% of its grey water is recycled nowadays.

And what about the future? The question remain to know until when cities are going to grow at the same pace. Then agriculture might have to be rethink. Hay and cotton (Arizona grows enough cotton each year to make more than one pair of jeans for every person in the United States) are highly water-dependent. Dry farming and low water needing culture are also alternating solutions.