Strong Science

Understanding the workings and limitations of our water resources is critical—along with economic, social, and legal considerations—for successful public water-management policy. Credible, high-quality scientific information is the essential guide to that understanding.

The need for water-resource science we can trust is especially critical in the southwest, where changing conditions of population and climate threaten the long-term ability of our water resources to sustain human needs, as well as natural habitat and wildlife, into the distant future. Indeed, Arizona is replete with streams that once flowed year-round and that now, owing primarily to groundwater pumping and diversion for irrigation, they only flow intermittently, following storms or snowmelt. So far, the Verde River still flows year-round!

  1. What is science we can trust?

    At best, it is scientific investigation and peer-reviewed reporting produced by scientists who are as completely objective as humanly possible. In other words, the investigators “have no dog in the fight”. Their concern is for the quality of their scientific work, not for the implications of the results.

    After scientific investigation concludes with an initial report, this scientific work then undergoes a process of peer review. Review by scientific peers is the best tool we have to promote objectivity and scientific quality. However, neither authors nor peer reviewers are completely infallible. Thus peer review does not in itself guarantee that scientific reports are infallible or immutable.

    Science is an ever-evolving enterprise in which new data or new discoveries typically enable refinement of previous scientific results. In addition, the effectiveness of peer review is dependent upon (1) the objectivity, qualifications, and skills of the reviewers and (2) objective consideration and response by the authors of the peer-reviewed reports.

    Fortunately, there is a growing body of peer-reviewed, credible water-resource science pertaining to the Verde River Basin – much of it published by the United States Geological Survey (USGS) or the Arizona Department of Water Resources (ADWR). Objective, peer-reviewed reports and a never-ending goal to be apolitical and to maintain integrity and credibility are hallmarks of the scientific products originating from such agencies.

    The Partnership also prepares publications. We serve to help citizens, including elected and appointed officials, understand the importance and workings of our connected surface water and groundwater resources, as well as, the long-term risks to the Verde River and its perennial tributaries. The Partnership’s publications are based largely on recent scientific reports. Click here to view our publications.

Recent Scientific Reports Related to Water Resources of The Verde River Basin

U.S. Geological Survey Scientific Investigations Report 2013-5029 by Garner, B.D., Pool, D.R., Tillman, F.D., and Forbes, B.D., 2013.

This U.S. Geological Survey (USGS) report applies the Northern Arizona Regional Groundwater-Flow Model (NARGFM; see Pool and others, 2011) to evaluate the response of (1) the upper and middle Verde River groundwater system to the effects of pumpage across the entire NARGFM model area on base flow from 1910 through 2005 at the USGS Paulden, Clarkdale, and Camp Verde streamgages; and (2) to assess, through 2005 and 2109, the responses of groundwater underflow, riparian evapotranspiration, groundwater storage, and the altitude of the water table within the Verde Valley groundwater system (between the Clarkdale and Camp Verde streamgages) to pumpage across the entire NARGFM model area

Why is this study important?

This study applies USGS Northern Arizona Regional Groundwater-Flow Model to directly examine the effect of groundwater pumping across the model area on the timing and magnitude of changes of base flow at the Paulden, Clarkdale, and Camp Verde streamgages.

Similarly, it examines other hydrologic-system effects through time such as net underflow, storage change, and depth to groundwater within the Verde Valley (defined for this report as the drainage basin between the Clarkdale and Camp Verde streamgages.

Read a summary of this report by clicking here.

by U.S. Geological Survey Arizona Water Science Center in cooperation with the Verde River Basin Partnership, June 2009

This document is a draft of a plan to assist in a collaborative and science-based water-resource planning and management partnership for the Verde River Basin. It will serve as a guide for future water-resource studies.

Why is this study important?

It is the product of the authorization by the United States Congress for the United States Geological Survey (USGS) to assist in a collaborative and science-based water-resource planning and management partnership for the Verde River Basin.

It describes the investigations needed in support of that authorization that will fulfill water-resource planning and management needs and identify long-term water-supply management options within the Verde River Basin.

Read a summary of this report by clicking here.

by Pool, D.R., Blasch, K.W., Callegary, J.B., Leake, S.A., and Graser, L.F. USGS, 2010

The Northern Arizona Regional Groundwater-Flow Model was developed as a tool for assessing the adequacy of the regional groundwater supply and the potential effects of increased groundwater use on water levels, streamflow, and riparian vegetation—especially in the areas of the Little Chino, Big Chino, and Verde Valleys. It can be used by resource managers to examine the hydrologic consequences of various groundwater development and climate change scenarios.

Why is this study important?

This study documents a powerful new tool—the Northern Arizona regional groundwater-flow model—that enables elected officials and water-resource managers to evaluate the future consequences of local or regional water-management policies for groundwater levels and streamflow in the Verde River Basin.

Read a summary of this report by clicking here.

by Leake, S.A., and Pool, D.R., 2010, U.S. Geological Survey Scientific Investigations Report 2010-5147, 18 p.

This report represents the first published application of the northern Arizona regional groundwater-flow model to calculate the effects within the Verde Valley sub-basin on surface-water flow and riparian evapotranspiration of either groundwater pumping or artificial recharge. The report explains the process and graphically illustrates via colored maps the effects of either pumping or artificial recharge with increasing time.

Why is this study important?

This is the first published application of the Northern Arizona regional groundwater-flow model.
It predicts the effect of either pumping from wells or of artificial recharge on streamflow in the Verde Valley Basin.

Read a summary of this report by clicking here.

 

by Leake, S.A., and Haney, Jeanmarie, 2010, U.S. Geological Survey Fact Sheet 2010-3108, 4 p.

This USGS Fact Sheet is a 4-page summary and explanation of the more comprehensive report: Leake, S.A., and Pool, D.R., 2010, Simulated effects of groundwater pumping and artificial recharge on surface-water resources and riparian vegetation in the Verde Valley sub-basin, Central Arizona: U.S. Geological Survey Scientific Investigations Report 2010-5147, 18 p. Written by Stan Leake of the U.S. Geological Survey and Jeanmarie Haney of The Nature Conservancy, this fact sheet gives an overview intended for citizens and public officials.

Why is this study important?

This is a brief summary and explanation of the more comprehensive report by Leake and Pool (2010).

It is written in a style with the general public in mind, rather than an audience of scientists.

Read a summary of this report by clicking here.

 

by Blasch, K.W., Hoffmann, J.P., Graser, L.F., Bryson, J.R., and Flint, A.L., 2006, U.S. Geological Survey Scientific Investigations Report 2005-5198, 101 p., 3 plates.

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 groundwater 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.

Why is this study important?

This report represents several years of fieldwork and analysis by the U.S. Geological Survey and the Arizona Department of Water Resources.

It provides well-documented, fundamental geologic and hydrologic information essential to the more recent development of the northern Arizona regional groundwater-flow model.

Read a summary of this report by clicking here.

 

by Wirt, Laurie, DeWitt, Ed, and Langenheim, V.E., editors, 2005, U.S. Geological Survey, Open-File Report 2004-1411.

Seven chapters, each authored by one or more of three editors, combine the results of geologic, geophysical, 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.

Why is this study important?

The report applies multiple lines of evidence to examine contributions to the baseflow of the upper Verde River.

It concludes that the Little Chino aquifer provides approximately 14 percent and the Big Chino aquifer system provides between 80 and 86 percent of the Verde River baseflow measured at the Paulden stream gauge.

Read a summary of this report by clicking here.

 

by Langenheim, V.E., DeWitt, Ed, and Wirt, Laurie, 2005, U.S. Geological Survey Scientific Investigations Report 2005-5278, 25 p., 1 plate.

Aeromagnetic and gravity data, calibrated by borehole data provide an important basis for interpreting geologic structure and the thickness and distribution of the basin-fill aquifers in the Big Chino, Little Chino, and Verde Valley sub-basins.

Why is this study important?

This report combines data collected from boring deep narrow holes into the ground with new aeromagnetic and gravity measurements.

This combination of data provides the most comprehensive analysis to date of the thickness, shape, and boundaries of basin-fill aquifers of the Big Chino, Little Chino, and Verde Valley sub-basins.

Read a summary of this report by clicking here.

 

by Timmons, Daniel, and Springer, Abe, 2006, Arizona Department of Water Resources, 77 p.

To take advantage of additional, more recent data, this report updates a previously published groundwater-flow model for the Prescott Active management Area.

Why is this study important?

It represents the most recent published groundwater-flow model analysis specifically for the Little Chino Sub-basin.

Read a summary of this report by clicking here.

 

by DeWitt, Ed, Langenheim, Victoria, Force, Eric, Vance, R.K., Lindberg, P.A., and Driscoll, R.L., 2008, U.S. Geological Survey Scientific Investigations Map 2996, scale 1:100,000, 100 p., pamphlet.

This 100,000-scale map portrays the geology of the Prescott National Forest, the major alluvial basins of the upper and middle Verde River watersheds, and the uplands that bound them, such as all or parts of the Juniper Mountains, Santa Maria Mountains, Bradshaw Mountains, Black Hills, Big Black Mesa, and the Mogollon Rim country. It compiles the geologic mapping, both published and new, of numerous geologists, providing critically important documentation of the geologic framework in which the groundwater occurs.

Why is this study important?

This modern geologic map synthesizes the work of dozens of geologists over decades into a unified, comprehensive map of the upper and middle Verde River watersheds.

Read a summary of this report by clicking here.

 

by Haney, J.A., Turner, D.S., Springer, A.E., Stromberg, J.C., Stevens, L.E., Pearthree, P.A., and Supplee, V., 2008, A report by the Arizona Water Institute, The Nature Conservancy, and the Verde River Basin Partnership, 122 p.

The report presents a literature review and results of a May 2007 workshop where 35 subject experts from 16 agencies and institutions synthesized the state of knowledge for central Arizona’s Verde River. The report describes the river’s ecosystem, including its hydrology, geomorphology, riparian and aquatic habitats, and fish and wildlife species—and how components would respond to changes in surface-water and groundwater flows.

Why is this study important?

It represents a critical first step in characterizing the streamflow requirements of habitat and wildlife along the Verde River.

Read a summary of this report by clicking here.
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