WATER SCIENCE Files

2014-09-06 How an Aquifer Works

A Cautionary Tale of Two Streamgages

An analysis of streamflow gage records shows that groundwater pumping in the Big Chino Valley and the Verde Valley will cause the Verde River to go dry for many summer days in the future. View Document.

Big Chino Valley is the source of the Verde River

An early report by an SRP hydrology consultant describing the Big Chino Valley as the groundwater source for the upper Verde.  View Document.

Biological impacts of emerging contaminants in wastewater effluent – Full Report

To develop a better understanding of the issues and best practices related to the use of treated effluent to help maintain river flows and habitat, the Conservancy commissioned a study to summarize the state of the science. The use of treated wastewater effluent is becoming a more prominent factor in Arizona's overall water management strategy. Treated effluent contains a wide array of chemical and pharmaceutical compounds referred to as emerging contaminants. Because many of the individual compounds in wastewater persist through the treatment process and can cause damage to biological systems, careful consid- eration must be given to the design of treatment systems and use of treated wastewater effluent. As the state strives to achieve sustainable use of water, treated effluent is one option to supplement human and environmental needs.
Understanding tradeoffs between water quantity, quality and the cost of alternative treatment strategies will require access to the best available information for those working to maintain the conservation, economic and cultural values of our rivers. The Conservancy recognizes that treated wastewater effluent is a valuable resource, but also has associated risks.
The literature was summarized in a report by Dr. Catherine Propper and Dr. David Quanrud that examines the biological impacts of exposure to municipal wastewater effluent and ways to reduce exposure through conventional, natural and advanced treatment processes, including a comparison of costs. This summary provides an overview of the report's major findings, including the best practices identified in the scientific literature for treating effluent. View Document.

Biological impacts of emerging contaminants in wastewater effluent – Summary Report

To develop a better understanding of the issues and best practices related to the use of treated effluent to help maintain river flows and habitat, the Conservancy commissioned a study to summarize the state of the science. The use of treated wastewater effluent is becoming a more prominent factor in Arizona's overall water management strategy. Treated effluent contains a wide array of chemical and pharmaceutical compounds referred to as emerging contaminants. Because many of the individual compounds in wastewater persist through the treatment process and can cause damage to biological systems, careful consideration must be given to the design of treatment systems and use of treated wastewater effluent. As the state strives to achieve sustainable use of water, treated effluent is one option to supplement human and environmental needs.
Understanding tradeoffs between water quantity, quality and the cost of alternative treatment strategies will require access to the best available information for those working to maintain the conservation, economic and cultural values of our rivers. The Conservancy recognizes that treated wastewater effluent is a valuable resource, but also has associated risks.
The literature was summarized in a report by Dr. Catherine Propper and Dr. David Quanrud that examines the biological impacts of exposure to municipal wastewater effluent and ways to reduce exposure through conventional, natural and advanced treatment processes, including a comparison of costs. This summary provides an overview of the report's major findings, including the best practices identified in the scientific literature for treating effluent. View Document.

Ecohydrological Implications of Woody Plant Encroachment

Increases in the abundance or density of woody plants in historically semiarid and arid grassland ecosystems have important ecological, hydrological, and socioeconomic implications. Using a simplified water-balance model, we propose a framework for conceptualizing how woody plant encroachment is likely to affect components of the water cycle within these ecosystems. We focus in particular on streamflow and the partitioning of evapotranspiration into evaporation and transpiration. On the basis of this framework, we suggest that streamflow and evaporation processes are affected by woody plant encroachment in different ways, depending on the degree and seasonality of aridity and the availability of subsurface water. Differences in landscape physiography, climate, and runoff mechanisms mediate the influence of woody plants on hydrological processes. View Document.

Ecological and Hydrological Significance of Ephemeral and Intermittent Streams in the Arid and Semi-arid America Southwest

This report represents a state-of-the-art synthesis of current knowledge of the ecology and hydrology of ephemeral (dry washes) and intermittent streams in the American Southwest, and may have important bearing on establishing nexus to traditional navigable waters (TNW) and defining connectivity relative to the Clean Water Act. Ephemeral and intermittent streams make up approximately 59% of all streams in the United States (excluding Alaska), and over 81% in the arid and semi-arid Southwest (Arizona, New Mexico, Nevada, Utah, Colorado and California) according to the U.S. Geological Survey National Hydrography Dataset. They are often the headwaters or major tributaries of perennial streams in the Southwest. This comprehensive review of the present scientific understanding of the ecology and hydrology of ephemeral and intermittent streams will help place them in a watershed context, thereby highlighting their importance in maintaining water quality, overall watershed function or health, and provisioning of the essential human and biological requirements of clean water. Published by US EPA. View Document.

Emerging Chemical Contaminants

There is growing concern worldwide about aquifer pollution by large numbers of emerging, anthropogenic chemicals (ECs) that escape standard wastewater treatment. Inasmuch as the rapidly-growing, arid Southwest uses such effluent to recharge depleting aquifers, there is an acute need for a better understanding of and a more complete treatment process to protect human and environmental health. Important among these contaminants is a broad suite of endocrine-disrupting chemicals (EDCs) that include natural or synthetic hormones as well as compounds that mimic hormones and may interfere with the operation of endocrine systems even at concentrations of parts per trillion. Indeed, evidence now indicates that some aquatic organisms are adversely affected at these levels where treated wastewater is discharged into streams. The paper will elaborate on these points building a case that this issue deserves attention. By Frank Butterworth, Ken Janecek, and Ed Wolfe. View Document.

Environmental Flows and Water Demands

This bulletin explains the water demands of the environment in the Central Arizona Region, an area that includes the Verde River, Agua Fria and Upper Hassayampa groundwater basins, as well as the Prescott Phoenix, and Pinal Active Management Areas (AMAs). Written by U of A WRRC. View Document. 

Evaluation of the NARGFM model

Evaluation of the groundwater model developed by the USGS (NARGFM), determining that the NARGFM model is an excellent tool for examining long- term changes in groundwater levels and related stream flow in the Paulden, Chino Valley, Prescott and Prescott Valley areas. By Dr. Peter Kroopnick, CWAG Science Committee Chair. View Document.

FAQ on the Northern Arizona Regional Groundwater Flow Model (NARGFM)

After securing project funding in 1999, the Arizona Department of Water Resources (ADWR) asked the USGS to develop a regional groundwater flow model for the north-central part of the State. In making this request, "the Department was fully aware of the capability of the USGS to develop an unbiased model that would improve understanding of the groundwater system and ultimately management of the region's water resources," according to Thomas G. Whitmer, ADWR's Manager of Statewide Water Planning. View Document.

Geologic Framework of Aquifer Units and Ground-Water Flowpaths, Verde River Headwaters, North-Central Arizona

Abstract: This study combines the results of geophysical, geologic, and geochemical investigations to provide a hydrogeologic framework of major aquifer units, identify ground-water flowpaths, and determine source(s) of base flow to the upper Verde River. This introductory chapter provides an overview of previous studies, predevelopment conditions, present surface-water and ground-water conditions, and a conceptual water budget of the hydrologic system. In subsequent chapters, this conceptual model will be evaluated and refined with respect to the results of each successive investigation. First, a compilation of mapping and field verification of the surficial geology, reinterpretation of driller’s logs, and contour mapping of alluvial thicknesses and buried volcanic rocks provide new three-dimensional geologic information. Second, a suite of geophysical techniques—including aeromagnetic and gravity surveys and inverse modeling approaches—was used to interpret the deeper subsurface geology. Third, geologic, geo- physical, and hydrological data were integrated to define basin boundaries, describe aquifer units in the basin-fill aquifers of Big and Little Chino valleys and the regional carbonate aquifer north of the upper Verde River, and develop a hydrogeologic framework. Water-level gradients were used to infer outlet flowpaths from the basin-fill aquifers through the carbonate aquifer toward the upper Verde River. Fourth, geochemical investigations employing analyses of dissolved major and trace elements and isotopes of δD, δ18O, 3H, 13C, and 14C were used to characterize major aquifers, identify recharge areas, and determine evolution of water chemistry along ground-water flowpaths. Fifth, results of a tracer-dilution study and synoptic sampling identify locations of major spring inflows discharging to the upper Verde River, measure base-flow contributions, which were used to calculate the relative contributions from each aquifer to upper Verde River springs using inverse geo- chemical modeling. In the final chapter, synthesis of multiple lines of evidence improve understanding of the relationships between the three aquifers, regional ground-water flowpaths, and the proportion of flow from each aquifer to the upper Verde River. Collectively, data from many varied and indepen-dent sources improves confidence in the conceptual model of the hydrogeologic system.

This file consists of 7 chapters and 246 pages totaling 135 mb. It can be downloaded here. 

Geologic Map of Prescott National Forest and the Headwaters of the Verde River

This file is a 95 mb detailed geologic map. It can be downloaded here.

Groundwater Flow Modeling - PrAMA

Presentation by Daniel Timmons to the Safe Yield Workgroup of the Coalition, August 13 2008, concerning the groundwater model for the Prescott AMA. Considers the liklihood of achieving safe yield with varying growth, conservation, and augmentation scenarios. View Document.

How Pumping the Big Chino Affects the Flow in the Verde River

Ground water pumping in the Big Chino Valley reduces the base flow of the Verde River by intercepting and consuming ground water that would otherwise discharge from springs in the Verde River Canyon. Historical and current data support this idea. Several ADWR, USGS, USBR and private consultants' investigations have all pointed to the hydrologic connection between the ground water flowing through the Big Chino Valley Aquifer and the base flow of the Verde River. Increased pumping in the Big Chino Valley will further deplete the flow of the Verde River, will potentially harm critical habitat for endangered species, and will injure downstream water rights. Document prepared by SRP. View Document.

Hydrogeology of the Upper and Middle Verde River Watersheds, Central Arizona

The upper and middle Verde River watersheds in central Arizona are primarily in Yavapai County, which in 1999 was determined to be the fastest growing rural county in the United States; by 2050 the population is projected to more than double its current size (132,000 in 2000). This study combines climatic, surface water, groundwater, water chemistry, and geologic data to describe the hydrogeologic systems within the upper and middle Verde River watersheds and to provide a conceptual understanding of the ground-water flow system. The study area includes the Big Chino and Little Chino subbasins in the upper Verde River watershed and the Verde Valley subbasin in the middle Verde River watershed. USGS report by Kyle Blasch. View Document.

Hydrograph of Verde River flow at the Paulden Gage 1964-2007

Hydrograph of Verde River flow at the Paulden Gage 1964-2007. View Document.

Investigation of the Geology and Hydrology of the Upper and Middle Verde River Watershed of Central Arizona: Summary Report

In 1999, the U.S. Geological Survey (USGS), in cooperation with the Arizona Department of Water Resources (ADWR), initiated a regional investigation of the hydrogeology of the upper and middle Verde River watershed. The project is part of the Rural Watershed Initiative (RWI), a program established by the State of Arizona and managed by the ADWR that addresses water supply issues in rural areas while encouraging participation from stakeholder groups in affected communities. The USGS is performing similar RWI investigations on the Colorado Plateau to the north and in the Mogollon Highlands to the east of the Verde River study area (Parker and Flynn, 2000). The objectives of the RWI investigations are to develop: (1) a single database containing all hydrogeologic data available for the combined areas, (2) an understanding of the geologic units and structures in each area with a focus on how geology influences the storage and movement of ground water, (3) a conceptual model that describes where and how much water enters, flows through, and exits the hydrogeologic system, and (4) a numerical ground-water flow model that can be used to improve understanding of the hydrogeologic system and to test
test the effects of various scenarios of water-resources development. In 2001, Yavapai County became an additional cooperator in the upper and middle Verde River RWI investigation. View Document.

Land Subsidence, Earth Fissures Change Arizona's Landscape

Mostly underground and out of sight, the effects of groundwater over-pumping and declining water tables are difficult for many people to envision, much less conceptualize. The most apparent and tangible manifestation of excessive groundwater pumping seems to be the political and public policy debates the issue provokes. In other words, the most obvious effect of groundwater overdraft in Arizona is the Groundwater Management Act.
With the increasing occurrence of land subsidence and resultant earth fissures in certain areas of the state, the consequences of dropping water tables become distinct, physical and sometimes dramatically visible. Land subsidence and fissuring provide tangible evidence that the over withdrawal of groundwater has geological as well as public policy consequences. Prepared by Joe Gelt, U of A WRRC. View Document.

Middle Verde Resource Analysis

Presentation slides describing VRBP project with USGS to better define water resources in the Verde Valley. View Document.

Possible Effects of Groundwater Pumping on Surface Water in the Verde Valley, Arizona

The U.S. Geological Survey (USGS), in cooperation with The Nature Conservancy, has applied a groundwater model to simulate effects of groundwater pumping and artificial recharge on surface water in the Verde Valley sub-basin of Arizona. This is the summary of the full report. Results are in two sets of maps that show effects of locations of pumping or recharge on streamflow. These maps will help managers make decisions that will meet water needs and minimize environmental impacts. View Document.

Potential Future Declines in Base Flow to the Upper Verde River Due to Groundwater Extraction

This report builds on earlier work by the USGS in cooperation with the Arizona Department of Water Resources and Yavapai County to develop a regional flow model for northern Arizona. The USGS, in conjunction with the Verde River Basin Partnership (VRBP) and the Town of Clarkdale, subsequently applied the model in a series of simulations to gain a greater understanding of the past and potential future human impacts on the Middle Verde River's streamflow.

The work discussed in this paper was carried out to: (A) test the accuracy and predictive capability of the model within the Big Chino and Little Chino sub-basins; (B) illustrate the historical change in base flow at the USGS Paulden and Clarkdale streamgages; and (C) perform forward-looking simulations for the period 2005-2110 that evaluate potential effects on base flow in the upper Verde River resulting from; (1) unchanged water demand from 2005 through 2110, (2) continuing drought, (3) increased water demand, (4) extraction of the ADWR allocated 12,000 acre-feet per year (ac-ft/yr) of groundwater from the central part of the Big Chino sub- basin beginning in 2020, and (5) the cumulative effect of cases (1) through (4).

My testing of NARGFM showed that excellent agreement was found between historically observed and simulated groundwater elevations within the area of concern. In addition, simulated trends in both groundwater elevation and discharge to the Verde River are accurate to within industry-standard ranges.

My forward-looking simulations using the NARGFM show that the cumulative effect of continuing drought, increased water demand, and extraction of 12,000 ac-ft/yr (16.6 cfs) of groundwater from the Big Chino, will decrease the base flow to the Verde River by 12.8 cfs at the Paulden streamgage by the year 2110. Since the base flow at the Paulden streamgage in 2005 was approximately 19 cfs, this would leave only 6.2 cfs in the river. View Document.

Author: Peter Kroopnick, PhD. Revised April, 2015

 

Predevelopment interconnection of surface and ground water along Big Chino Wash

The planform pattern of Big Chino Wash provides information on past streamflow characteristics that created the floor of Big Chino Valley. The valley floor, and thus the bed and bank of the wash channel, is composed of sediment transported by the wash. The shape of the alluvial channel is uniquely produced by the type of streamflow. For example, a pattern of meandering stream channels, when viewed from above, is uniquely produced by perennial or intermittent flow that is interconnection with underlying groundwater. In Arizona, the resulting saturated floodplain Holocene alluvium is defined as the subflow zone. Appropriable water includes surface water and subsurface water of the subflow zone. Thus, the present geomorphology of Big Chino Wash contains information of past streamflow and groundwater conditions that is useful to water managers, river engineers and hydrologists.
Analysis by Win Hjalmarson, PE, USGS Ret. View Document.

Prescott AMA Groundwater Model Update: 2006

Technical document by Daniel Timmons updating the PrAMA groundwater model, 2006. View Document.

Prescott AMA Groundwater Model Update: 2006

Technical document by Daniel Timmons updating the PrAMA groundwater model, 2006. View Document.

Prescott AMA Groundwater Model, 2002

Technical document by Keith Nelson updating the PrAMA groundwater model, 2002. View Document.

Reconnaissance Watershed Analysis on the Upper and Middle Verde Watershed

The quantity, quality, and timing of water generated in the watershed is the result of land uses and condition at smaller scales. Grazing, fire suppression, timber harvesting, roads, mining, urbanization, and other human uses have resulted in significantly changed hydrologic condition. Prepared by Lloyd Barnett and Richard Hawkins, U of A. View Document.

Regional Groundwater-Flow Model of the Redwall-Muav, Coconino, and Alluvial Basin Aquifer Systems of Northern and Central Arizona (NARGFM)

Results of a major effort by USGS: a numerical flow model of the groundwater flow system in the primary aquifers in northern Arizona was developed to simulate interactions between the aquifers, perennial streams, and springs for predevelopment and transient conditions during 1910 through 2005. Simulated aquifers include the Redwall-Muav, Coconino, and basin-fill aquifers. Perennial stream reaches and springs that derive base flow from the aquifers were simulated, including the Colorado River, Little Colorado River, Salt River, Verde River, and perennial reaches of tributary streams. Simulated major springs include Blue Spring, Del Rio Springs, Havasu Springs, Verde River headwater springs, several springs that discharge adjacent to major Verde River tributaries, and many springs that discharge to the Colorado River. View Document.

Simulated Effects of Groundwater Pumping and Artificial Recharge on Surface-Water Resources and Riparian Vegetation in the Verde Valley Sub-Basin, Central Arizona

A USGS publication. In the Verde Valley sub-basin, groundwater use has increased in recent decades. Residents and stakeholders in the area have established several groups to help in planning for sustainability of water and other resources of the area. One of the issues of concern is the effect of groundwater pumping in the sub-basin on surface water and on groundwater- dependent riparian vegetation. The Northern Arizona Regional Groundwater-Flow Model by Pool and others is the most comprehensive and up-to-date tool available to under- stand the effects of groundwater pumping in the sub-basin. Using a procedure by Leake and others (2008), this model was modified and used to calculate effects of groundwater pumping on surface-water flow and evapotranspiration for areas in the sub-basin. This report presents results for the upper two model layers for pumping durations of 10 and 50 years. Results are in the form of maps that indicate the fraction of the well pumping rate that can be accounted for as the combined effect of reduced surface-water flow and evapotranspiration. In general, the highest and most rapid responses to pumping were computed to occur near surface-water features simulated in the modified model, but results are not uniform along these features. The results are intended to indicate general patterns of model-computed response over large areas. For site-specific projects, improved results may require detailed studies of the local hydrologic conditions and a refinement of the modified model in the area of interest. View Document.