As a result of this analysis, M&A obtained regulatory approval to use low-flow sampling methods for long-term monitoring, reducing sampling costs by 75 percent. M&A recently had the opportunity to challenge a long-established practice that hydrologists have applied when collecting groundwater samples. This practice, which has been largely driven by environmental regulators, involves “purging” three […]

This is Part 1 of two articles on grouted-in pressure transducers. Part 2 will present some case studies to show some innovative applications of this technology. Grouted-in transducers allow the monitoring of pressure heads in multiple aquifer zones — without the costs or regulatory requirements of wells. First introduced in the 1960s, fully grouted pressure […]

Matthew Weber, Ph.D., is a hydrologist and water resources economist who recently joined M&A. During his previous employment at the USEPA, he served as a principal investigator for a study that examines how the public values ecosystem services associated with the Santa Cruz River. This Hydro Note recaps some highlights of this study, which is […]

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 […]

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 […]