The Water Recycling Revolution by William M. Alley;Rosemarie Alley; & Rosemarie Alley

Author:William M. Alley;Rosemarie Alley; & Rosemarie Alley
Language: eng
Format: epub
Publisher: Rowman & Littlefield Publishing
Published: 2022-03-04T00:00:00+00:00

SCOTTSDALE, ARIZONA

Scottsdale, Arizona, an affluent community and golfing mecca in the Greater Phoenix area, is home to Arizona’s first advanced wastewater-treatment plant. This treatment facility relies on an unusual environmental barrier for indirect potable reuse—vadose zone wells (also known as dry wells). The story of this relatively unique approach to an environmental buffer, as well as Scottsdale’s leadership in water reuse, begins with groundwater overdraft accompanying rapid population growth after World War II.

By the 1970s, groundwater depletion in south-central Arizona from Phoenix to Tucson was impossible to ignore. In many areas, ground-water levels had declined hundreds of feet, often accompanied by land subsidence and earth fissures. The need to aggressively manage the state’s finite groundwater resources was obvious but controversial, particularly among the agricultural community. After years of debate, Arizona passed the landmark Groundwater Management Act in 1980.

The act created five Active Management Areas (AMAs) that cover much of the state’s population and groundwater use, including a large area around Phoenix. The act required each AMA to develop plans to wean itself from overreliance on groundwater pumping. The Phoenix AMA’s goal is for annual groundwater withdrawals not to exceed the annual rate of aquifer replenishment by 2025—a condition referred to as “safe yield.”20 In addition, new housing developments in AMAs must demonstrate an assured water supply lasting at least one hundred years, highlighting the need for renewable water supplies such as Colorado River water and treated wastewater.

Passage of the Groundwater Management Act was effectively a quid pro quo for receiving federal funding for the Central Arizona Project (CAP) to bring Colorado River water to Phoenix, Tucson, and other parts of south-central Arizona. The bottom line was that the federal government wasn’t going to fund construction of the CAP without hard evidence that Arizona would get its groundwater pumping under control.21

The Groundwater Management Act and CAP provided strong incentives for water recycling and for storing water underground, actions in which Arizona had already begun to establish itself as a leader. Beginning in the mid-1960s, Herman Bouwer with the U.S. Department of Agriculture in Phoenix and Sol Resnick at the Arizona Water Resources Research Center in Tucson carried out pioneering work on soil-aquifer treatment.22 In 1972, the state issued some of the first rules governing reclaimed water in the nation. Today, more than 80 percent of all treated wastewater generated within the Phoenix AMA is beneficially used for various purposes or recharged.23 Among the more notable uses, the Palo Verde Nuclear Generating Station, the country’s largest nuclear power plant, uses 100 percent reclaimed water for cooling.

With water available from the CAP, the state began an ambitious program to store its unused Colorado River allocation underground and went about developing a comprehensive regulatory framework for groundwater storage and recovery.24 Overdraft of the state’s aquifers had provided plenty of space for underground storage.

Water conservation also became a high priority in the AMAs. Phoenix uses the same amount of water as it did twenty years ago, despite adding four hundred thousand more residents. “In 2000,

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