Giving Compass' Take:

• Chris Malloy explains the causes of Phoenix's water sustainability challenges and highlights efforts to address these challenges. 

• How can funders work to safeguard communities from drought as climate change intensifies? 

• Read about America's water inequality crisis. 

Walking parts of Phoenix today, you might spot the ruins of an ancient canal, but probably not. Phoenix expanded so fast in the 20th century that developers razed structures built by the Hohokam, prehistoric North American Indians who lived in present-day central and southern Arizona as early as the 3rd century, until laws were enacted to protect what remained. In 1920, before the building boom began, Phoenix was home to 29,000 people—fewer than the area supported 800 years before. By 1950, Phoenix had grown to 107,000 people; by 1960, to 439,000. And today, Phoenix is home to 1,660,000 people, making it the fifth-largest city in the country. The suburban towns around the city—which, together with Phoenix, are collectively known as Metro Phoenix—house some 4.5 million human souls. And today, just like in the past, the good people of this Sonoran basin face immense resource challenges.

These challenges threaten the desert metropolis’s sustainability, in both the near and distant future. By 2100, city summer temperatures are projected to have risen by 9.2 degrees. (July days already average 104 degrees.) Many of Phoenix’s sustainability obstacles are tied to food systems: farming, transportation, recycling. But the most elemental and harrowing issue that city leaders will have to face reaches back not only to the Hohokam, but to the very meaning of “desert.”

Water. The main issue is water. In Metro Phoenix, everyday dihydrogen monoxide will soon be liquid gold.

Together, the Salt River and Verde River—through a network of canals, wells, dams, and lakes known as The Salt River Project—provide Metro Phoenix with one of its primary water sources. The city and its outlying towns use groundwater—water naturally settled into subterranean aquifers—as a second vital source. The third and final primary water source comes through the pumps and aqueducts of the Central Arizona Project, some 190 miles from the body of water that gives Arizona its squiggled western border: the Colorado River.

The problem is that the Colorado River’s water supply is changing. Seven states (and parts of Mexico) rely on Colorado River water. Just east of Las Vegas, Nevada and nestled into the high, western horn of Arizona’s border, Lake Mead—the reservoir above the Hoover Dam that collects the Colorado and routes to the lower basin states (Arizona, California, and Nevada)—has dipped to historic lows.

The Colorado River Drought Contingency Plan (DCP) provides safeguards that, in response to past overallocation, protect the Colorado River from being overdrawn. The goal is a continued water supply. If Lake Mead were ever projected to fall below certain levels, the DCP would trigger rationing, ensuring that the 40 million basin state people who benefit from the Colorado River’s water could continue to do so—and that agriculture, powerplants, and other vital cogs in the clockwork of Southwestern civilization would keep running.

If triggered, rationing would diminish greater Phoenix’s water supply. This is because, as a result of the U.S. Supreme Court case Arizona v. California, decided in 1963, Arizona’s rights are junior to other basin states, like neighboring California. As such, under the DCP, Arizona would face earlier cuts. With higher tiers of rationing and less Colorado River water, the metro area would have to draw more heavily on groundwater and the Salt River Project, including from the Verde River. And like many rivers of the West, the Verde has become fragile.

Read the full article about water sustainability challenges by Chris Malloy at The Counter.