Our Water: What the Science Tells Us About the Future



Is safe yield attainable?


Achieving the long-term balance between groundwater withdrawal and replenishment, or safe yield, by 2025 has been a central talking point in Quad City water management since 1980 when the Arizona Groundwater Management Act first established that goal for the Prescott Management Area (PrAMA). But with no regulatory penalties for not meeting safe yield, action to do so has been minimal, and aquifer overdraft has increased. Dr. Peter Kroopnick, retired hydrologist and head of the Science Committee for the Citizens Water Advocacy Group (CWAG), will talk about the water outlook for the Quad Cities in the decades to come and will explain the science behind the groundwater flow models used to measure overdraft at a Zoom webinar on Saturday, May 14 from 10am-noon. A question and answer period will follow the presentation. The Zoom link is posted in the “Next Meeting” section at www.cwagaz.org .

Dr. Peter Kroopnick
Dr. Peter Kroopnick

It has long been recognized by groundwater professionals that pumping within the PrAMA has exceeded recharge, and that meeting safe yield, which is defined as a goal and is not a requirement, is unlikely to occur by 2025 or anytime soon. Dr. Kroopnick will explain how the Arizona Department of Water Resources (ADWR) collects data to estimate the annual overdraft and how it constructs its groundwater flow models to evaluate groundwater changes over several decades. He will also detail the specific components of that collected data.


While ADWR uses measured pumping and recharge rates to create its models, Dr. Kroopnick will discuss why some parts of the data used must be estimated. These include mountain-front recharge, flood recharge, underflow at groundwater basin boundaries, evapotranspiration, and canal and stream seepage.


Dr. Peter Kroopnick retired to Prescott in 2009 and promptly joined CWAG. He is currently serving as a member of the Board of Directors as well as head of the Science Committee. Before his retirement, he was a practicing hydrogeologist for a major engineering company and an instructor in Hydrogeology at Arizona State University. He specializes in groundwater modeling and environmental chemistry. For pleasure he works as a volunteer Park Ranger for the City of Prescott.

CWAG is a local citizens group advocating for a secure water future for Prescott and central Yavapai County and for the protection of the upper Verde River. For more information, visit www.cwagaz.org, or email info@cwagaz.org .

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