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 Overview
The groundwater monitoring program seeks to characterize groundwater quality in each of
the 51 groundwater basins that have been designated in Arizona by state agencies.
Comprehensive groundwater sampling is conducted in a basin following the approval of a
sample plan. Various methodologies are used include systematic, grid-based random
sampling, stratified random sampling, and random sampling to determine regional
groundwater quality. Higher density sampling sometimes occurs around targeted land uses
to determine their affect on groundwater quality. All wells and springs selected for
sampling are located using a Global Positioning System (GPS).
Samples for Safe Drinking Water Act (SDWA) inorganic analysis as well as oxygen and
hydrogen isotopes are collected at each groundwater sampling site. Samples for
radiochemistry and radon analysis are also frequently collected while Volatile Organic
Compounds (VOCs), currently-registered pesticides, banned pesticides, perchlorate, and
other types of samples are sometimes collected where these parameters are likely to be
encountered.
Groundwater samples collected for regional studies are statistically analyzed to
determine significant differences in parameter levels between indices such as sub-basins,
physiographic areas, and aquifers. Similar analyses are conducted on data collected from
index wells or from historical groundwater studies to determine if any significant
changes have occurred over time in the concentrations of groundwater quality parameters.
The most important relationships identified through statistical analyses are displayed
visually in maps and graphs.
Data collected by this program are incorporated into ADEQ's Groundwater Database as
well as provided to the well owner from which the groundwater sample was collected. A
comprehensive Open File Report and a condensed four-page Fact Sheet are published for
each basin. Index wells are selected in these basins which will be resampled in the
future to determine groundwater quality change over time.
These ADEQ basin studies are an important resource, especially with many people moving
to locations in Arizona not served by public water systems. Residents utilizing
groundwater supplied by public water supply systems have the assurance that this resource
is regularly tested and meets water quality standards set by the SDWA. However, no such
regulations exist for residents served by private wells. While collecting and analyzing
groundwater samples from all private wells would be prohibitively expensive, ambient
groundwater quality studies that use scientific and statistical principles to estimate
groundwater quality conditions provide an affordable alternative. As such, this program
provides important groundwater quality information to the public, including the expected
groundwater quality within a basin, areas where specific groundwater quality problems can
be expected to occur, and whether there has been any change over time in the groundwater
quality of the basin.
Studies
 The ADEQ
Ambient Monitoring Program has completed studies and has reports available covering 15
groundwater basins in Arizona, shown in the bordering map in brown. These reports are
available in both a comprehensive Open File Report (OFR) as well as a compact four-page
fact sheet (FS). The OFR is designed for audiences desiring a more comprehensive
hydrologic picture of the study including the groundwater quality data. In contrast, the
FS is designed for a more general audience seeking a brief overview of the groundwater
quality of the basin. Any questions about these studies should be directed to Douglas Towne at (602) 771-4412.
The 12 basins shown in the map as green have had the groundwater quality samples
collected and analyzed; however, no report is currently available on these basins. The
basins shown in white are not currently the focus of groundwater studies.
The data for all samples collected for these studies, besides being available in the
individual OFRs are also available through the ADEQ Groundwater Database whose contact is
Marianne Gilbert at (602) 771-4563. This database
includes all samples collected by the ADEQ Ambient Groundwater Monitoring Program as well
as other monitoring programs within the agency.
Four-page factsheets on the following groundwater basins
Open File Groundwater Reports
Monitoring Index · Ambient Groundwater Monitoring · Ambient Lake Monitoring · Ambient River and Stream Monitoring
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| Web Site Services | Last Revision Jul. 08, 2008