10 Things You Should Know About Arizona’s Groundwater Management Act

Why protecting groundwater is so important for people and birds.

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In the midst of the ongoing drought and increasing temperatures throughout the West, Lake Mead and the Colorado River get a lot of attention. However, with all the dialogue around surface water, we cannot forget about groundwater—the water found underground in the cracks and spaces in soil, sand, and rock.

Due to rapid groundwater level declines in the 1960s and 1970s, plus the threat that Arizona would not get its federal authorization to build the Central Arizona Project, Arizona passed a forward-thinking measure, the Groundwater Management Act, in 1980. Since then, the state has regulated the use of groundwater in specific geographies called Active Management Areas. There are five in total—Prescott, Phoenix, Pinal, Tucson, and Santa Cruz—and within these boundaries there are specific rules on how cities, agriculture, industry, and individuals can use this underground water.

So here are 10 important things to know about groundwater and Arizona’s existing protections of it—and what they do and do not do:

  1. 41 percent of Arizona’s water use comes from groundwater. 38 percent of Arizona’s water use from the Colorado River, 18 percent from in-state rivers (such as the Salt and Verde), and 3 percent from high-quality treated wastewater (often called reclaimed water or effluent).

  2. More than 75 percent of Arizonans live within an Active Management Area, which have groundwater use protections.

  3. The Groundwater Management Act, when it passed in 1980, mandated conservation from all sectors (agricultural, industrial, and municipal) leading to a trend that continues today: declining per person water use.

  4. Outside of Active Management Areas (AMAs), there are few restrictions on groundwater use, consumer protections are weak, and significant problems are emerging. There are limited legal tools for local communities to prevent new large groundwater pumpers from coming in and negatively affecting existing wells. Where groundwater is declining, those communities are at risk of running out of water.  

  5. However, counties and municipalities outside of AMAs can voluntarily sign up for more rigorous groundwater protections. To protect homebuyers and business owners, Cochise and Yuma Counties, as well as the Towns of Clarkdale and Patagonia now require that new development prove it has enough water for the next 100 years.

  6. Overpumping of groundwater can result in the drying up of wells, less water in streams and rivers, decreasing water quality, and land subsidence (the land sinks).

  7. Iconic rivers critical to birds, such as the San Pedro and the Verde, rely on groundwater contributions to sustain their flows. Yet Arizona water law does not adequately recognize the hydrologic connection between groundwater and surface water (except in specific situations defined, but not yet enforced, by Arizona courts).

  8. The Groundwater Management Act is in need of protecting. In recent legislative sessions, there have been attempts to weaken it. We need to expand groundwater protections, not repeal those that already exist.

  9. For cities within an AMA, any water that is pumped out must be put back (or recharged) into the ground. Sometimes, more Colorado River supplies are available to a city than customers demand. In that case, many cities store that “extra” water underground and earn what are called long-term storage credits. Arizona established an accounting system to store and track these credits (think of credits as recharged groundwater). They act as a savings account where cities can put Colorado River water into the ground when it is available, and use them if surface water supplies (like the Colorado River) are reduced.

  10. Unfortunately, reclaimed water put into river channels (and eventually recharged back into the ground), does not earn the same amount of long-term storage credits as Colorado River water put into river channels. We should update the existing regulations to reflect the value that reclaimed water put back into dry riverbeds has for birds, fish, wildlife, and communities, and to incentivize cities to reinvest in their rivers.

Over the last century, the overuse of groundwater has contributed to the decline of healthy habitats (especially native trees) along western rivers with harmful consequences for birds. Studies have shown that losses of native habitat in central Arizona, including along the Santa Cruz, Gila, and Salt Rivers, are primarily due to groundwater drawdown. Many breeding birds that were once more common within the Colorado River Basin like the Southwestern Willow Flycatcher and Summer Tanager have experienced declines because of this loss of habitat.

There is an urgent need to improve groundwater protections. The future of many of Arizona’s rural and small communities is at risk without further planning and thoughtful action to empower local communities to protect their precious groundwater resources.