Category Archives: Hydro Notes

Arizona’s Groundwater Management Act: A model that incorporates policy, science, economics, and flexibility

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Thirty-five years ago, Arizona adopted its groundbreaking Groundwater Management Act (GMA). Although still a work in progress, the GMA’s success can largely be attributed to four key characteristics: Public policy that considers local circumstances A scientific basis Consideration of the dynamic economics of complex urban and urbanizing environments Flexibility afforded by a long, phased implementation […]

What is the source of the Upper Verde Springs?

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— Ed McGavock The Upper Verde Springs (UVS) were once a topic of lively debate, with claims that their source could not be the Big Chino basin. Initial proponents of this view referred to an infamous “clay plug” that supposedly blocked Big Chino groundwater from reaching the UVS. Then, in 1997, Dr. Paul Knauth wrote that Big […]

Is it time to rethink municipal water rates?

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A California court recently ruled that some municipal water rates — those featuring aggressive increasing block rates, or IBRs — violate the state’s constitution. The ruling triggered an outcry from water managers and elected officials who claim that IBRs are necessary to punish water waste, reward conservation, and cope with drought-induced shortfalls in supply. While […]

How economic brines form within closed basins

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In certain closed basins in the Andes and other parts of the world, groundwater can become so concentrated in total dissolved solids (TDS) that it exceeds the salinity of seawater and forms brine. Groundwater is generally considered saline if its TDS exceeds 1,000 mg/L but is classified as brackish when TDS concentrations are in the […]