Climate Change Series: Maricopa County

maricopa county


By David A. Schaller
By David A. Schaller

Maricopa County is the largest, most prosperous county in Arizona and home to the state capital of Phoenix. The county’s population now tops four million, making it home as well to more than half of all Arizonans. While Maricopa County includes its share of smaller rural towns and census-designated places, it is the Phoenix-Mesa-Glendale Metropolitan Statistical Area that comes to mind when most people think of the county.

Maricopa County is highlighted in red.

Maricopa County’s rapid growth has been fueled by a diversified economy led by professional, scientific, financial, real estate, education and health services. Its cities host civic centers and arenas, a growing 26-mile light rail network, an international airport, and a thriving tourism industry. The county is also home to Arizona State University (ASU), the state’s largest university.

Despite these assets, the Maricopa County is as vulnerable to climate disruption as other areas of the state. Research shows that over the past five years every county in Arizona, including Maricopa, has been hit by at least one federally declared weather-related disaster. Seventeen years of drought and increasingly hotter daily temperatures are the two principal climate threats facing Maricopa County.

As the leading weather-related cause of death in the United States, extreme heat is being taken seriously in Maricopa County. A recent study in an American Meteorological Society journal evaluated the county’s cooling centers to understand better their capacity to provide relief for vulnerable populations during extreme heat events. County and state health agencies have also stepped up with informative sources on extreme heat, while the Maricopa Association of Governments has created a heat-relief network that allows the public to sign-on as a heat refuge site or a hydration station during heat emergencies.

When it comesMaricopa County Seal to water, the massive Central Arizona Project (CAP) canal system is Arizona’s and Maricopa County’s water lifeline. Its normal flow is now threatened by a declining water level in Lake Mead, with a formal shortage declaration looming. Former Reclamation Commissioner Estevan Lopez told a conference of regional water providers last year that the unfolding issues with Colorado River water resources put users in “a very precarious position.”

CAP customers, many of whom are Maricopa County and Gila River Indian Community agricultural users, are already voluntarily receiving less water than they are legally allocated from the Colorado River due to fears of a shrinking Lake Mead. These users are currently leaving 200,000 acre-feet of water in Mead, an amount that would double under other plans now being negotiated. In effect, there has already been a Colorado River shortage “declaration” for Maricopa County and neighbors to the south. That it has so far been voluntary makes it no less a shortage.

In an example of forward-thinking preparation for continued drought, Phoenix and Tucson have agreed to a water swapping arrangement offering win-industrial-development climate changewin solutions for both. In the Tucson deal, Phoenix has agreed to send some of its share of CAP water to Tucson for aquifer recharge. When future needs arise, Phoenix will take an equivalent amount of water from Tucson’s CAP supply flowing through Maricopa County on its way south.

Creative solutions like this will be increasingly necessary as climate change unfolds. Maricopa County is home to a rich array of skills and resources needed to serve the county as climate change unfolds. The Arizona State Climate Office is a unit of the Julie Ann Wrigley Global Institute of Sustainability at ASU, and there may be no better or more convenient platform in the county from which to tackle the complexity of economic, social, and public health aspects of climate change. From the sustainability talent center at ASU, to the advances in light rail and energy-efficient building designs across metropolitan Phoenix, to its creative water storage plans, the county is not waiting for a crisis to take the smart actions needed to prepare for a drier, hotter future.


David A. Schaller is a retired environmental scientist living in Tucson where he writes on climate, water and energy security.

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