During the years 1950 to 1980, various chlorofluorocarbons (CFCs) — including CFC-11, CFC-12, and CFC-113 — were used in refrigeration and other systems and released into the atmosphere. These substances then passed from the atmosphere to surface water and groundwater via precipitation as part of the hydrologic cycle. The concentrations of CFCs in groundwater in […]

As withdrawals from aquifers increase rapidly in the U.S. and around the world, new technologies must be applied to help manage and sustain groundwater resources. Research clearly shows that many of our critical aquifers are not replenished quickly. Fortunately, considerable progress is being made on one technology for aiding in their replenishment — Managed Aquifer […]

This is part 2 of our series on brine mineral resources. Part 1, “How economic brines form in closed basins” was the subject of our June 2015 HydroNote. — Daniel S. Weber, P.G. M&A routinely characterizes hydrogeologic conditions in closed hydrologic basins — known as “salars” in South America — that feature porous and/or fractured-rock […]

Environmental models are used to make predictions that form the technical basis for water-management decisions. For example, groundwater flow models can be used to predict the impacts of pumping on nearby surface water bodies, to inform mine dewatering activities, and to guide the design and operation of remediation facilities. Environmental model results are often presented […]

This is part 2 of our series on the Upper Verde River. Part 1, “What is the source of the Upper Verde Springs?” was the subject of our August 2015 Hydro Note. —Ed McGavock The debate continues over the potential effects of groundwater pumping in the Big Chino basin on base flows in the Upper […]

If you’re a typical Arizonan, you’ve probably heard about land subsidence or perhaps even witnessed its effects firsthand driving along the I-10 corridor between Tucson and Phoenix. What is land subsidence and where does it occur? Land subsidence results from the compaction, consolidation, or collapse of aquifer sediments and occurs throughout southern Arizona, in rural […]

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 […]

— 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 […]

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 […]

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 […]