Scientific Investigations Report 2006–5290
U.S. GEOLOGICAL SURVEY
Scientific Investigations Report 2006–5290
Microbial Quality of the Nation’s Ground-Water Resources, 1993–2004
National Water-Quality Assessment Program—Principal Aquifers
S.S. Embrey and D.L. Runkle
Table of Contents
Foreword
Conversion Factors and Abbreviations,
Acronyms, and Symbols
Abstract
Introduction
Study Methods
Microbial Quality of Water in Principal
Aquifers
Discussion
Summary
Acknowledgments
References Cited
Figures
Figure 1. Study units of the National
Water-Quality Assessment program in which microbiological samples were collected
from wells, 1993–2004.
Figure 2. Numbers of test results for
fecal-indicator microorganisms by each analytical method for environmental and
quality-control samples collected from wells in 22 study units of the National
Water-Quality Assessment program, 1993–2004.
Figure 3. Locations of wells in principal
aquifers that tested positive for fecal-indicator bacteria (A) and wells where
fecal-indicator bacteria were not detected in samples collected for the National
Water-Quality Assessment program (B), 1993–2004.
Figure 4. Number of wells sampled and
number of wells with detections of coliform bacteria in samples collected in
22 study units of the National Water-Quality Assessment program, 1993–2004.
Figure 5. Percentage of wells testing
positive for total coliform bacteria and Escherichia coli (A), and concentrations
of coliform bacteria (B) by study network in samples collected in 22 study units
of the National Water-Quality Assessment program, 1993–2004.
Figure 6. Percentage of wells testing
positive for coliform bacteria (A), and significantly different (p-value <0.0006)
detection frequencies of total coliform bacteria (B) by principal aquifer from
data collected in 22 study units of the National Water-Quality Assessment program,
1993–2004.
Figure 7. Percentage of detections
of coliform bacteria and coliphage virus in wells sampled as part of the major
aquifer studies (A) and source-water quality assessments (B) for the National
Water-Quality Assessment program, 1993–2004.
Figure 8. Concentrations of total coliform
and Escherichia coli by principal aquifer in samples collected in 22 study units
of the National Water-Quality Assessment program, 1993–2004.
Figure 9. Percentage of wells testing
positive for coliform bacteria (A), and significantly different detection frequencies
(p-value <0.002) of total coliform bacteria with respect to aquifer lithology
(B).
Figure 10. Concentrations of total
coliform and Escherichia coli by principal aquifer lithology in samples collected
in 22 study units of the National Water-Quality Assessment program, 1993–2004.
Figure 11. Percentage of major aquifer
study (MAS) and source-water quality assessment (SWQA) wells sampled by class
of water use in 22 study units of the National Water-Quality Assessment program,
1993-2004.
Figure 12. Percentage of wells testing
positive for coliform bacteria (A), and concentrations of coliform bacteria
by class of water use (B) in samples collected in major aquifer study (MAS)
and source-water quality assessment (SWQA) wells in 22 study units of the National
Water-Quality Assessment program, 1993–2004.
Figure 13. Relation of the presence
or absence of coliphage virus to concentrations of total coliforms for wells
in the major aquifer study (MAS) networks and source-water quality assessment
(SWQA) networks, and for principal aquifers with coliphage-positive wells.
Figure 14. Distributions of well depths
for the major aquifer study (MAS), land use study (LUS), and source-water quality
assessment (SWQA) networks, and distribution of well depths for the classes
of water use, from data collected in 22 study units of the National Water-Quality
Assessment program, 1993–2004.
Figure 15. Distribution of well depths
in the 16 principal aquifers studied by the National Water-Quality Assessment
program, 1993–2004.
Figure 16. Total-coliform concentrations
and depths of wells for all 16 principal aquifers combined on the basis of the
median depths of sampled wells, from data collected in 22 study units of the
National Water-Quality Assessment program, 1993–2004.
Figure 17. Detections of total-coliform
bacteria with concentrations of dissolved oxygen, nitrite-plus-nitrate nitrogen,
and orthophosphate in samples collected from wells in 22 study units of the
National Water-Quality Assessment program, 1993–2004.
Tables
Table 1. Total estimated withdrawals
of water from selected principal aquifers and withdrawals used for public supplies,
irrigation, and self-supplied industrial in the United States, 2000.
Table 2. Principal aquifers, primary
lithology of the aquifers, well-sampling networks within each study unit, and
the total number of wells sampled during water years 1993–2004.
Table 3. Consolidations and adjustments
to the raw microbiological and associated ground-water data by study unit and
network, water use, principal aquifer, and lithology.
Table 4. Summary of microbiological
data collected from wells in major aquifer study, land-use study, and source-water
quality assessment networks in 22 study units of the National Water-Quality
Assessment Program, 1993–2004.
Table 5. Summary of microbiological
data collected from wells in each principal aquifer in 22 study units of the
National Water-Quality Assessment Program, 1993–2004.
Table 6. Summary of microbiological
data, by type of principal-aquifer lithology, collected from wells in 22 study
units of the National Water-Quality Assessment program, 1993–2004.
Table 7. Summary of microbiological
data collected from major aquifer study and source-water-quality assessment
wells used for domestic, public supply, and other purposes, and from unused
wells by the National Water-Quality Assessment Program, 1993–2004.
Table 8. Summary of coliphage data collected
from major aquifer study and source-water quality assessment wells in each principal
aquifer studied by the National Water-Quality Assessment program, 1993–2004.
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Send questions or comments about this report to the author, S.S. Embrey, (253) 552-1644.
For more information about USGS activities in Washington, visit the USGS
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