United States
Environmental Protection
Agency
The Analysis of Occurrence Data
from the First Unregulated
Contaminant Monitoring Regulation
(UCMR 1) in Support of Regulatory
Determinations for the Second
Drinking Water Contaminant
Candidate List (CCL 2)
Office of Water (4607M) EPA 815-R-08-013 June 2008 www.epa.gov/safewater
-------
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
Disclaimer
This document is designed to provide technical background information for the
regulatory determinations being made on the second drinking water Contaminant Candidate List
(CCL 2).
This document is not a regulation itself, and it does not substitute for the Safe Drinking
Water Act (SDWA) or the Environmental Protection Agency's (EPA's) regulations. Mention of
trade names or commercial products does not constitute endorsement or recommendation for use.
in
-------
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
Acknowledgments
The preparation and analysis of the contaminant occurrence data presented in this report
were undertaken by EPA's Office of Ground Water and Drinking Water (OGWDW) in support
of the regulatory determinations for specific contaminants listed on CCL 2. This effort was
directed by Mr. Clifton Townsend and Ms. Yvette Selby-Mohamadu of OGWDW's Standards
and Risk Management Division (SRMD) Targeting and Analysis Branch (TAB). Yvette Selby-
Mohamadu served as the Team Lead for the CCL 2 final regulatory determinations under the
guidance of Wynne Miller (TAB Associate Branch Chief), Eric Burneson (TAB Branch Chief),
Phil Oshida (SRMD Deputy Division Director), Pamela Barr (SRMD Division Director), and
Cynthia Dougherty (OGWDW Office Director).
Gregory Carroll, Dan Hautman, Chris Frebis, Michella Karapondo, Kent Sorrell, Pat Fair,
Bonnie Newport, Phyllis Branson, Michael Cummins, Cory Wagner, and Brenda Parris at EPA's
Technical Support Center compiled, managed, and conducted quality assessment and quality
control reviews of all the data for the First Unregulated Contaminant Monitoring Regulation
(UCMR 1) program. Lee Kyle of the Infrastructure Branch managed the UCMR 1 data on
EPA's National Contaminant Occurrence Database (NCOD) and provided support in
establishing system inventory information. Roger Howard of the Infrastructure Branch managed
the Safe Drinking Water Accession and Review System (SDWARS), which is the information
system that supports the collection of data for the UCMR 1.
We would especially like to thank the many public water systems, States, and EPA
Regional Offices that have participated in the UCMR 1 program. The data collected and
reported by the participating systems enable the occurrence analyses presented in this report.
We are also grateful to the three peer reviewers, Mike Focazio, Dr. Mary Skopec, and Dr.
Craig Stow, who read and provided candid and critical comments on the draft version of this
report. Their comments assisted the development of this report though none of the peer
reviewers have read or are responsible for content in this final version of the report.
The Cadmus Group, Inc., served as the prime contractor for this project, supporting the
data management, occurrence analyses, and report development under Contract # 68-C-02-026.
Major contributions were made by Morgan Tingley, Alison Cullity, Erin Mateo, Brent Ranalli,
Dr. George Hallberg, Amit Kumar, and Dr. Song Qian. The Cadmus Project Manager was Dr.
Jonathan Koplos.
-------
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
Executive Summary
Contaminant occurrence data collected under the First Unregulated Contaminant
Monitoring Regulation (UCMR 1) are nationally representative public water system monitoring
results. This UCMR 1 monitoring was conducted for select unregulated contaminants in
drinking water under the authority of Safe Drinking Water Act. The UCMR 1 program specified
that a statistically representative group of small public water systems (serving between 25 and
10,000 persons) and all large public water systems (serving more than 10,000 persons) were
required to conduct monitoring and submit drinking water sample results for a list of specified
unregulated contaminants from the second Contaminant Candidate List (CCL 2).
This report presents the United States Environmental Protection Agency (EPA) analysis
of the national occurrence of unregulated contaminants on the CCL 2 that were monitored in
public water systems (PWSs) under the UCMR I.1 Detailed occurrence analyses are presented
for ten contaminants evaluated during EPA's CCL 2 regulatory determinations: the mono- and
di-acid degradates of dimethyl tetrachloroterephthalate (DCPA, also known as dacthal), 1,3-
dichloropropene,2 l,l-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE), 2,4-dinitrotoluene, 2,6-
dinitrotoluene, s-ethyl dipropylthiocarbamate (EPTC), fonofos, methyl tertiary butyl ether
(MTBE), and terbacil. Less detailed occurrence summaries are presented for several other
UCMR 1 contaminants as well. This report also describes the sources, quality, management, and
characteristics of the UCMR 1 data.
The UCMR 1 sampling was conducted from May 1, 2000 to October 25, 2005, with
almost 95% of monitoring conducted during the formal UCMR 1 sampling period of January
2001 to December 2003. A very high portion of eligible PWSs participated in the UCMR 1
monitoring, and collectively the systems submitted monitoring data of high quality. The data
have been collected from PWSs in all fifty States and six additional primacy entities. UCMR 1
monitoring data were collected and submitted by 797 (99.6%) of the 800 small systems selected
for the small system representative sample and by 3,090 (99.7%) of the 3,100 large systems
defined as eligible for the UCMR 1 large system census. Approximately 99% of submitted
monitoring data met the data quality acceptance criteria established for the UCMR 1 program.
These data quality measures exceeded the UCMR 1 Data Quality Objectives (DQOs) that
required a small systems participation rate of at least 83.275%, and required that at least 90% of
all submitted data meet the established data acceptance criteria.
Each small and large PWS participating in UCMR 1 monitoring conducted one year of
monitoring, with surface water systems sampling four times per year and ground water systems
sampling two times per year. The monitoring periods for the small and large PWSs were
staggered over the three primary years (2001-2003) of UCMR 1 monitoring. Approximately
one-third of all UCMR 1 small systems throughout the country conducted monitoring in each of
the three years of UCMR 1 monitoring. The monitoring schedules for these systems were
staggered to include monitoring in every month and every season around the country. Large
1 The sample occurrence data discussed and used in this report reflect UCMR 1 analytical samples submitted and
quality-checked as of March 2006 and posted on EPA's NCOD in October 2007.
21,3-Dichloropropene was not officially monitored under UCMR 1, but was as added as an extra contaminant for
monitoring by small systems conducting List 1 monitoring.
vii
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
systems could conduct their one year of monitoring anytime during the UCMR 1 period of 2001
to 2003. Like small systems, their monitoring schedules were spread throughout the year and
were to include one sample during what was designated as the season most vulnerable to
contaminant occurrence. In this way, the UCMR results reflect multiple seasons and multiple
years of climatic conditions throughout the country and are not directly affected (or biased) by
weather conditions of a single season, year, or geographic region.
Occurrence analyses of the UCMR 1 data are conducted using a two-stage analytical
approach. In Stage 1, the data are first reviewed, quality-checked, and characterized. They are
then analyzed to generate simple, clear non-parametric estimates of contaminant occurrence.
The Stage 1 analysis, based on maximum sample values, is inherently conservative; it is
designed not to underestimate occurrence in the protection of public health. Simple counts are
made of the number of systems, and populations served by those systems, with at least one result
above a specified concentration threshold. Any contaminant found to have significant
occurrence at or near health reference level concentrations based on the Stage 1 analysis and that
have health effects of a chronic nature (i.e., acute exposure is not a concern) can additionally be
analyzed using the Stage 2 analysis. In Stage 2, statistical modeling is used to generate national
probability estimates of contaminant occurrence based on estimated annual (or longer-term)
mean concentrations of contaminants along with statistical measures of uncertainty and error.
Stage 2 provides occurrence analyses that are less conservative than the Stage 1 analysis and as
noted earlier, may be more appropriate for assessing contaminants with chronic health endpoints.
Because none of the UCMR 1 contaminants discussed in this document (with concerns about
chronic exposure as opposed to acute) had significant levels of contaminant occurrence at or near
the health reference levels of concern based on the Stage 1 analyses, Stage 2 analyses were not
warranted for any of the UCMR contaminants. However, to illustrate the complete two-stage
analytical approach, a Stage 2 analysis is conducted for the DCPA degradates.
Stage 1 assessments of occurrence are presented in several ways for each contaminant to
characterize different aspects of occurrence. For each contaminant, occurrence statistics
presented include the number and percentage of samples with detections, which are values above
the minimum reporting level (MRL). Detections are summarized in aggregate by calculating and
presenting the minimum, median, and 99th percentile values of detections for each contaminant.
At the system level, the number and percent of systems with at least one detection at or above the
MRL and the number and percent of systems with at least two detections at or above the MRL
are presented. For contaminants with health reference levels (HRLs), similar types of occurrence
assessments are presented relative to the concentration values of the HRLs.
Occurrence statistics are presented for different categories of systems so that occurrence
can be assessed based on system characteristics such as source water type (ground water or
surface water) or system size (population served). Although the statistical sample of 800 small
systems is too small to support a statistically-rigorous State-level occurrence analysis, summary
tables of all UCMR 1 contaminant monitoring results are presented for each State, Territory, and
Tribe to provide a complete record of data collected and monitoring results for each State.
UCMR 1 occurrence data from the large systems (representing a census of large systems) do
support State occurrence analyses that are representative (statistically valid) at the State level.
Vlll
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
The UCMR 1 monitoring found no detections for five contaminants considered during
CCL 2 regulatory determinations: 1,3-dichloropropene, 2,6-dinitrotoluene, EPTC, fonofos, and
terbacil. Detections were found and reported for five other UCMR 1 contaminants considered
during CCL 2 regulatory determinations: the DCPA mono- and di-acid degradates (monitored
and reported in aggregate), DDE, 2,4-dinitrotoluene, and MTBE. The occurrence of these five
contaminants with detections is summarized as follows:
For the DCPA degradates (monitored in aggregate), a total of 33,910 samples were
collected by small and large PWSs; 776 detections were found, resulting in an overall
sample detection rate of 2.29%. The DCPA degradates were detected at or above the
MRL of 1 ng/L in 17 small systems (2.1%) and 160 large systems (5.2%). The
maximum concentration from all (small and large) PWSs sampling was 190 |ig/L. The
average value among detections was 3.48 |ig/L, and the median value was 2.00 |ig/L.
These DCPA degradate detections were found in PWSs in 24 States and the Territory of
Guam. PWSs with detections were found in four general regions: California and the
western Rocky Mountain States, the Southeast, the Northeast, and the upper Midwest.
The proportion of ground water systems with DCPA degradate detections was more than
two times greater than that for surface water systems, regardless of system size.
Extrapolating the small system findings (17 PWSs with detections) nationally,
approximately 689 small systems, serving approximately 1.1 million people, are
estimated to have at least one sample detection (i.e., greater than the MRL) of the DCPA
degradates. The 160 large PWSs with detections serve 11.3 million people. Combining
the national extrapolation of the small system results with the large system results,
approximately 849 small and large public water systems, serving 12.4 million people
nationally, are estimated to have at least one sample detection of DCPA degradates.
Although occurrence is relatively widespread, the DCPA degradate concentrations found
are consistently low. Only a single small PWS had any detection greater than the DCPA
degradate HRL of 70 |ig/L, and no other small PWS detected concentrations greater than
l/2 HRL. Extrapolating the small system findings, an estimated 373 small systems,
serving approximately 113,000 people, are estimated to have detectable levels of the
DCPA degradates above the HRL of 70 |ig/L. The census of large systems conducting
UCMR 1 found no detections of DCPA degradates greater than 70 |ig/L. One large PWS
had a detection of the DCPA degradates greater than 1A the HRL.
For DDE, a total of 33,797 samples were collected. DDE was detected at or above the
MRL of 0.8 |ig/L in only one large ground water system at a level of 3 |ig/L. No DDE
detections were found at any of the small systems conducting UCMR 1 sampling. The
single detection was greater than the DDE HRL of 0.2 |ig/L. (The MRL for DDE was
greater than its HRL. However, the MRL is within the 10"4 to the 10"6 cancer risk range,
which EPA considers an acceptable range for occurrence analysis of carcinogens.)
• For 2,4-dinitrotoluene, a total of 33,764 samples were collected. 2,4-Dinitrotoluene was
detected above the MRL of 2 jig/L in only one large system, a surface water system, at a
level of 333 |ig/L. No detections were found at any of the small systems conducting
UCMR 1 sampling. The single detection was greater than the 2,4-dinitrotoluene HRL of
0.05 |ig/L. (The MRL for 2,4-dinitrotoluene was greater than its HRL. However, the
IX
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
MRL is within the 10"4 to the 10"6 cancer risk range, which EPA considers an acceptable
range for occurrence analysis of carcinogens.)
For MTBE, a total of 33,768 samples were collected by small and large PWSs; 26
detections were found, resulting in an overall sample detection rate of 0.08%. MTBE
was detected at or above the MRL of 5 |ig/L in 3 small systems (0.4%) and 16 large
systems (0.5%). The maximum concentration of MTBE for all (small and large) systems
was 49 ng/L. The average value among detections was 15.2 |ig/L, and the median value
was 9.2 |ig/L. No HRL has yet been established for MTBE. Detections were found in
public water systems in 14 States. No distinct geographic trend in occurrence is apparent.
MTBE was detected in large ground water and surface water systems, but was more
prevalent in the ground water systems. All small system detections occurred in ground
water systems.
Extrapolating the small system findings (3 PWSs with detections), an estimated 149
small systems, serving approximately 147,000 people, are estimated to have at least one
sample detection of MTBE. The 16 large PWSs with MTBE analytical detections serve
749,000 people. Combining the national extrapolation of the small system findings with
the large system findings, approximately 165 small and large systems, serving 896,000
people nationally, are estimated to have at least one detection of MTBE.
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
Contents
Disclaimer iii
Acknowledgments v
Executive Summary vii
Exhibits xiii
Appendices xv
Acronyms xvii
1. Introduction 2
1.1 Regulatory Background 2
1.2 Two-Stage Analytical Approach for Small and Large Systems 3
1.3 Analytical Tools 5
2. UCMR 1 Program Overview 6
2.1 UCMR 1 Design and Implementation 6
2.2 Large Systems (Serving > 10,000 People) 10
2.3 Small Systems (Serving < 10,000 People) 10
2.3.1 Stratified, Random, Statistically-Weighted Sample 10
2.3.2 Sample Allocation of Systems to Strata and States/Territories 10
3. UCMR 1 Data Description 12
3.1 Data Overview 12
3.2 Data Management 13
3.2.1 Quality Assessments for Submitted Data 14
3.2.2 Spatial Data 17
3.3 Assessments of Data Completeness and Representativeness 17
3.3.1 Data Completeness 17
3.3.2 Data Representativeness 20
3.3.3 Other Characteristics of the UCMR 1 Monitoring Data (Focus Only on
Contaminants Considered for Regulatory Determinations) 23
3.4 Additional Data Management Considerations 32
3.4.1 Population Adjustments 32
3.4.2 Temporal Information 34
3.4.3 Threshold Evaluations 36
4. Description of Stage 1 Analytical Methodology 40
4.1 Stage 1 Analysis 40
4.2 Additional Considerations for Stage 1 Analysis 40
4.2.1 Ground Water and Surface Water Comparisons 40
4.2.2 Large System and Small System Totals 40
4.2.3 Extrapolation of the Small System Survey Results 41
4.2.4 Stage 1 Analyses and the Statistically-Weighted Sample of Small Systems 42
4.3 Sample-Point-Level Analyses 43
5. Description of Stage 2 Analytical Methodology 46
XI
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
6. Stage 1 Occurrence Estimates 48
6.1 DCPAMono- andDi-AcidDegradates 51
6.2 DDE 58
6.4 2,4-Dinitrotoluene 61
6.5 2,6-Dinitrotoluene 63
6.6 EPIC 65
6.7 Fonofbs 67
6.8 MTBE 68
6.9 Terbacil 73
7. Stage 2 Occurrence Estimates — An Example 76
7.1 DCPAMono- and Di-Acid Degradates 76
8. Spatial and Graphical Assessments of Contaminants 80
8.1 DCPA Mono-and Di-Acid Degradates 80
8.2 MTBE 83
9. Summary of Findings 86
10. References 88
Xll
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
Exhibits
Exhibit 2.1: Contaminants Considered During CCL 2 Regulatory Determinations That Were
Monitored Under the UCMR 1 9
Exhibit 3.2.1: UCMR 1 Data Elements Related to Analytical Samples 13
Exhibit 3.2.2: UCMR 1 Data Elements Related to Systems (Inventory Information) 14
Exhibit 3.3.1: UCMR 1 Large Systems by Source Water Type 19
Exhibit 3.3.2.a: UCMR 1 Small Systems by Source Water Type 20
Exhibit 3.3.2.b: Designed and Actual Small System Allocation for Assessment Monitoring 21
Exhibit 3.3.3.a: Number of UCMR 1 Analytical Samples and Systems in the 9-Contaminant
Data Set, by Source Water Type 24
Exhibit 3.3.3.b: Number of UCMR 1 Analytical Samples and Systems in the 9-Contaminant
Data Set, by System Type 25
Exhibit 3.3.3.c: All Public Water Systems with UCMR 1 Monitoring Results 26
Exhibit 3.3.3.d: All Public Water Systems with Fonofos (List 2) Monitoring Results 26
Exhibit 3.3.3.e: Distribution of PWSs in UCMR 1 by State & Size Category 27
Exhibit 3.3.3.f: Distribution of PWSs in UCMR 1 by State and Source Water Type 29
Exhibit 3.3.3.g: Distribution of PWSs in UCMR 1 by State and System Type 31
Exhibit 3.4.2.a: Number of PWSs collecting UCMR 1 Samples Each Year, 2000-2005 35
Exhibit 3.4.2.b: Number of PWSs collecting UCMR 1 Samples Each Month, 2000-2005 36
Exhibit 3.4.3: Contaminants Analyzed Using Stage 1 Methodology, Along with Relevant
Threshold Values 38
Exhibit 4.2.3: Calculating National Estimates (Extrapolations) Using DCPA Degradates Stage
1 Occurrence Findings 42
Exhibit 6.a: Stage 1 Summary of UCMR 1 Occurrence of Ten CCL 2 Contaminants Monitored
Under UCMR 1 (by System Size) 49
Exhibit 6.b: Stage 1 Summary of UCMR 1 Occurrence of Ten CCL 2 Contaminants Monitored
Under UCMR 1 (by Source Water Type) 50
Exhibit 6.1.a: Summary of Stage 1 Occurrence Measures of DCPA Mono-and Di-Acid
Degradates 52
Exhibit 6.1.b: National Extrapolation of Stage 1 Occurrence Measures of DCPA Mono- and
Di-Acid Degradates in Small PWSs 53
Exhibit 6.1.c: Stage 1 National Occurrence Measures of DCPA Mono- and Di-Acid Degradates
Based on UCMR 1 Small System Extrapolated Data and Large System Census Data 54
Exhibit 6.1.d: Summary of Sample-Point-Level Occurrence Measures of DCPA Mono- and Di-
Acid Degradates Based on UCMR 1 Small System Extrapolated Data and Large
System Census Data 56
Xlll
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
Exhibit 6.1.e: Percentage of SPs with Detections of DCPA Mono- and Di-Acid Degradates
(Among Systems with At Least One Detection) 57
Exhibit 6.2. a: Summary of Stage 1 Occurrence Measures of DDE 59
Exhibit 6.3: Summary of Stage 1 Occurrence Measures of 1,3-Dichloropropene 60
Exhibit 6.4: Summary of Stage 1 Occurrence Measures of 2,4-Dinitrotoluene 62
Exhibit 6.5: Summary of Stage 1 Occurrence Measures of 2,6-Dinitrotoluene 64
Exhibit 6.6: Summary of Stage 1 Occurrence Measures of EPTC 66
Exhibit 6.7: Summary of Stage 1 Occurrence Measures ofFonofos 67
Exhibit 6.8.a: Summary of Stage 1 Occurrence Measures of MTBE 69
Exhibit 6.8.b: National Extrapolation of Stage 1 Occurrence Measures of MTBE in Small
PWSs 69
Exhibit 6.8.c: Stage 1 National Occurrence Measures of MTBE Based on UCMR 1 Large
System and Extrapolated Small System Data 70
Exhibit 6.8.d: Summary of Sample-Point-Level Occurrence Measures of MTBE Based on
UCMR 1 Small System Extrapolated Data and Large System Census Data 71
Exhibit 6.8.e: Percentage of SPs with Detections of MTBE (Among Systems with At Least
One Detection) 72
Exhibit 6.9: Summary of Stage 1 Occurrence Measures of Terbacil 74
Exhibit 7.1.a: DCPA Degradates Stage 2 Occurrence Results for Small Systems 77
Exhibit 7.1.b: DCPA Degradates Stage 2 Occurrence Results for Large Systems 78
Exhibit 7.1.c: Comparison of DCPA Degradates Stage 1 and Stage 2 Occurrence Results for
Small Systems 79
Exhibit 7.1.d: Comparison of DCPA Degradates Stage 1 and Stage 2 Occurrence Results for
Large Systems 79
Exhibit 8.1.a: Geographic Distribution of the DCPA Degradates - States with At Least One
Detection Equal to or Above the MRL (> 1 |ig/L) 81
Exhibit S.l.b: Geographic Distribution of the DCPA Degradates - State Percentage of PWSs
with At Least One Detection Equal to or Above the MRL (> 1 |ig/L) 81
Exhibit S.l.c: System-Level Geographic Distribution of the DCPA Degradates - Maximum
Concentration of Detections per System 82
Exhibit 8.2.a: Geographic Distribution of MTBE - States with At Least One Detection Equal
to or Above the MRL (> 5 |ig/L) 84
Exhibit 8.2.b: Geographic Distribution of MTBE - State Percentage of PWSs with At Least
One Detection Equal to or Above the MRL (> 5 |ig/L) 84
Exhibit 8.2.c: System-Level Geographic Distribution of MTBE -Maximum Concentration of
Detections per System 85
XIV
-------
EPA - OGWDW
Analysis of Occurrence Data from the UCMR 1 for CCL 2
June 2008
APPENDIX A.
APPENDIX B.
APPENDIX C.
APPENDIX D.
APPENDIX E.
APPENDIX F.
APPENDIX G.
Appendices
Stage 1 Occurrence Measures for All Other UCMR Contaminants
Detailed Description of the Stage 2 (Bayesian-Based Hierarchical) Model
Example Stage 2 Analysis Details for DCPA Degradates
Detailed Description of UCMR Large System Population-Served Adjustments
Development of Health Reference Levels
Detailed Description of the Sensitivity Analysis Comparing Adjusted/
Unadjusted Findings
Stage 1 Occurrence Measures for CCL 2 Contaminants Monitored Under
UCMR1
APPENDIX H. Sample-Point-Level Occurrence Measures
XV
-------
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
Acronyms
CAS Chemical Abstract Services
CDX Central Data Exchange
CWS Community Water System
CCL Contaminant Candidate List
CCL 2 EPA's Second Contaminant Candidate List
DCPA Dimethyl Tetrachloroterephthalate (Dacthal)
DDE 1, l-Dichloro-2,2-bis(p-chlorophenyl)ethylene
DDT 1,1,1 -trichloro-2,2-bis(p-chlorophenyl)ethane
DQO Data Quality Objective
EPTDS (or EP) Entry Point(s) to the Distribution System
EPA Environmental Protection Agency
EPTC s-Ethyl Dipropylthiocarbamate
ESA Ethane Sulfonic Acid
GIS Geographic Information System
GW Ground Water
GWUDI or GU Ground Water Under Direct Influence (of Surface Water)
HRL Health Reference Level
LD Distribution System Location with Lowest Disinfectant Residual
MD Midpoint Location in Distribution System
MR Distribution System Location with Maximum Residence Time
MRL Minimum Reporting Level
MTBE Methyl Tertiary Butyl Ether
NCOD National Contaminant Occurrence Database
xvii
-------
EPA - OGWDW
Analysis of Occurrence Data from the UCMR 1 for CCL 2
June 2008
MRS National Inorganics and Radionuclides Survey
NPDWR National Primary Drinking Water Regulation
NTNCWS Non-Transient Non-Community Water System
OGWDW Office of Ground Water and Drinking Water
PWS Public Water System
PWSID Public Water System Identification Number
QA Quality Assurance
QAPP Quality Assurance Project Plan
QC Quality Control
RDX Royal Demolition Explosive
RFG Federal Reformulated Gasoline
SDWA Safe Drinking Water Act
SDWARS Safe Drinking Water Accession and Review System
SDWIS Safe Drinking Water Information System
SDWIS/Fed Safe Drinking Water Information System / Federal Version
SP Sampling Point
SR Source Water Sample Location
SRMD Standards and Risk Management Division
SW Surface Water
SWP Purchased Surface Water
TAB Targeting and Analysis Branch
TNCWS Transient Non-Community Water System
TSC Technical Support Center (EPA)
UCM Unregulated Contaminant Monitoring
XVlll
-------
EPA - OGWDW
Analysis of Occurrence Data from the UCMR 1 for CCL 2
June 2008
UCMR1
USGS
1D2SP
2D1SP
2,4-DNT
2,6-DNT
First Unregulated Contaminant Monitoring Regulation
United States Geological Survey
One Detections at Two Sample Points
Two Detections at One Sample Point
2,4-Dinitrotoluene
2,6-Dinitrotoluene
XIX
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
1. Introduction
The First Unregulated Contaminant Monitoring Regulation (UCMR 1), a revision of the
previous Unregulated Contaminant Monitoring program, was designed to create a nationwide
record of unregulated contaminant occurrence in public drinking water systems. Contaminant
monitoring under the UCMR 1 formally began in January 2001 and was essentially completed by
October 2005. This report presents detailed occurrence findings for ten of the contaminants
monitored under UCMR 1: six synthetic organic contaminants (l,l-dichloro-2,2-bis(p-
chlorophenyl)ethylene, also known as DDE; the mono- and di-acid degradates of dimethyl
tetrachloroterephthalate, also known as DCPA or dacthal; s-ethyl dipropylthiocarbamate, also
known as EPTC; fonofos; and terbacil), two volatile organic contaminants (1,3-dichloropropene
and methyl tertiary butyl ether, also known as MTBE), and two semi-volatile organic
contaminants (2,4-dinitrotoluene and 2,6-dinitrotoluene). These ten contaminants are on the
second Contaminant Candidate List (CCL 2), for which the United States Environmental
Protection Agency (EPA) is currently considering regulatory determinations.
EPA's regulatory determinations for the CCL 2 contaminants named above are supported
by the detailed occurrence findings presented here. Brief summaries of the occurrence of 16
other UCMR 1 contaminants are included in Appendix A of this report. Another contaminant on
the CCL 2 and also monitored under the UCMR 1 is perchlorate. Perchlorate occurrence
analyses based on the UCMR 1 data will be presented in a separate UCMR 1 perchlorate
occurrence report.
Three additional CCL 2 contaminants being considered for regulatory determinations,
boron, metolachlor, and 1,1,2,2-tetrachloroethane, were not monitored under the UCMR 1. EPA
presents the occurrence findings for these three contaminants, plus additional data on 1,3-
dichloropropene, in a separate report entitled The Analysis of Occurrence Data from the
Unregulated Contaminant Monitoring (UCM) Program and National Inorganics and
Radionuclides Survey (MRS) in Support of Regulatory Determinations for the Second Drinking
Water Contaminant Candidate List (USEPA, 2008a).
For those contaminants considered as part of the CCL 2 regulatory determinations, a
Regulatory Support Document (USEPA, 2008b) provides contaminant-specific information
regarding chemical and physical properties, use and release, and supplemental occurrence data
and analyses. Based on contaminant occurrence, exposure, and other risk considerations, EPA
must determine if regulating these contaminants will present a meaningful opportunity to reduce
public health risk.
1.1 Regulatory Background
Under §1445(a)(2)(A) of the Safe Drinking Water Act (SOWA), as amended in 1996,
EPA was required to establish criteria for a program to monitor for unregulated contaminants and
to publish a list of unregulated contaminants to be monitored. To fulfill the requirements of
SDWA, EPA published the Revisions to the Unregulated Contaminant Monitoring Regulation
for Public Water Systems (PWSs) on September 17, 1999 (USEPA, 1999). Additionally,
§1412(b)(l) required EPA to publish a list of currently unregulated contaminants (the CCL) to
assist in priority-setting efforts. The contaminants included on a CCL are not subject to any
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
current or proposed National Primary Drinking Water Regulation (NPDWR). CCL contaminants
may pose risks for drinking water, and therefore may require regulation under SDWA.
The First CCL (CCL 1) contained 60 contaminants, including 50 chemicals or chemical
groups and 10 microbiological contaminants or microbial groups. In 2003, EPA released final
regulatory decisions on nine of these contaminants (68 FR 42898). The second and current CCL
(CCL 2; 70 FR 9071) contains 51 contaminants, consisting of all the contaminants from CCL 1
that did not progress to regulatory determination. The 1996 SDWA Amendments require EPA to
make determinations on whether or not to regulate at least five contaminants on a five-year
cycle, or three and a half years after each CCL. This report presents contaminant occurrence
findings that serve to support the second round of regulatory determinations.
SDWA, as amended in 1986, required public water systems to monitor for specified
unregulated contaminants on a five-year cycle, and to report the monitoring results to the States.
This monitoring was historically conducted under the UCM program. Unregulated contaminants
are contaminants that do not have an established or proposed NPDWR, but they may be formally
listed and scheduled for monitoring under Federal regulations. The intent of the monitoring was
to gather scientific information on the occurrence of these contaminants to help enable EPA to
decide whether regulations were needed. All community water systems (CWSs) and non-
transient non-community water systems (NTNCWSs) that had more than 150 service
connections were required to participate in this unregulated contaminant monitoring. Smaller
systems were not universally required to participate in the monitoring, but they were required to
be available for monitoring if the State decided such monitoring was necessary. The 1993
Amendments to SDWA expanded the list of unregulated contaminants that required monitoring
under this program.
The 1996 SDWA Amendments directed EPA to develop a revised program for
unregulated-contaminant monitoring. The details of the new program, known as the Unregulated
Contaminant Monitoring Regulation, or UCMR (now called UCMR 1 to distinguish it from
subsequent UCMR monitoring), were formally published in the Federal Register on September
17, 1999 (64 FR 50556). The UCMR 1 and related rules replaced the older (UCM)
requirements, putting forth a new list of contaminants, a new set of rules about which systems
must monitor, a new structure to the monitoring program, and a new framework to ensure that all
the monitoring results are reported to EPA. Monitoring under UCMR 1 began in 2001. UCMR
1 was developed in coordination with the CCL and the National Drinking Water Contaminant
Occurrence Database (NCOD). The data collected through the UCMR 1 are first reviewed and
checked for quality, and then stored in the NCOD to facilitate analysis and public access. The
data are intended to inform the regulatory determination process and support the development of
subsequent CCLs. For more details regarding how the UCMR program supports the CCL and
SDWA, please refer to http://www.epa.gov/safewater/ucmr/index.html.
1.2 Two-Stage Analytical Approach for Small and Large Systems
A two-stage analytical approach is used to evaluate the UCMR 1 national contaminant
occurrence data. The first stage of analysis provides a straightforward evaluation of occurrence
of all contaminants under consideration. This "Stage 1 analysis" of occurrence assesses the data
sources, quality, and characteristics, and then uses the data to conduct simple, non-parametric,
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
and conservative assessments for a broad evaluation of contaminant occurrence.3 Occurrence
analyses for each contaminant are assessed at the level of samples, systems, population served by
systems, and sample point locations. A typical Stage 1 analysis is a simple count of the number
(or percentage) of systems with at least one analytical detection- of a specific contaminant, or at
least one analytical detection with a concentration greater than a health reference level (HRL).
Based on the Stage 1 analysis, any contaminant found to have significant occurrence at or
near HRL concentrations can be studied further with a "Stage 2 analysis." The Stage 2 analysis
uses statistical modeling to generate national probability estimates of contaminant occurrence by
generating estimated annual (or longer-term) mean concentrations of contaminants at PWSs.
This provides occurrence analyses that are less conservative than the Stage 1 analysis (since the
Stage 2 analysis is based on estimated mean concentrations rather than on maximum
concentrations), and also provides occurrence analyses that may be more reflective of potential
chronic exposure.
In other words, the Stage 1 analysis reflects a rough approximation of peak occurrence
while the Stage 2 analysis is based on estimated average occurrence. This fundamental
difference in the two analytical approaches has a very direct implication: regardless of the
occurrence values estimated by the Stage 1 analyses, the Stage 2 occurrence estimates will
always be lower. The decision of whether a contaminant should undergo a Stage 2 analysis is
based on occurrence analytical criteria, and whether health impacts are likely to occur after
chronic (as opposed to acute) exposure. If the estimated occurrence of a contaminant is
insignificant using the more conservative Stage 1 analysis, there is no need to analyze that
contaminant's occurrence using the Stage 2 analysis.
Because none of the UCMR 1 contaminants discussed in this document were found with
significant levels of contaminant occurrence at or near the HRLs of concern based on the Stage 1
analyses, Stage 2 analyses were not warranted for any of the UCMR contaminants. However, a
brief description of the Stage 2 analytical approach is presented in Section 5 and a detailed
description is presented in Appendix B. Also, to illustrate the types of occurrence findings
generated, a Stage 2 analysis of the DCPA degradates was conducted; summary findings are
presented in Section 7 and detailed results are presented in Appendix C of this report.
The two-stage analytical approach was previously developed for other EPA Office of
Ground Water and Drinking Water (OGWDW) national occurrence studies, including the first
Six-Year Review of National Primary Drinking Water Regulations (see USEPA, 2003a). This
data management and occurrence analytical approach was peer-reviewed for use under the Six-
Year Review. Partly to establish consistency across OGWDW occurrence assessment projects,
this two-stage analytical approach has been adapted here for the analyses of the UCMR 1
occurrence data. The UCMR 1 two-stage analytical approach and a draft report of analytical
findings based on that approach were also peer-reviewed. Comments from that peer-review have
been incorporated into this report.
These analyses are conservative in the sense that they are protective of human health (i.e., they are more likely to
overestimate risks to human health than underestimate them).
4 By definition, an analytical detection is a quantified concentration that is equal to or greater than the laboratory
method minimum reporting level (or limit), the MRL.
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
1.3 Analytical Tools
Database manipulation, data quality assurance checks, and overall data management were
conducted in Microsoft Access®. Most statistical analyses were conducted with SAS®
statistical software. Additionally, WinBUGS and R code were used to develop the Bayesian
hierarchical model that is the basis of the Stage 2 analysis. After analysis, results were typically
exported into Microsoft Excel® for development of report tables that present the occurrence
findings. Spatial and geographic analyses and presentations of contaminant occurrence were
conducted using Arc View Geographic Information System (GIS) version 3.3 (ESRI Software).
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
2. UCMR 1 Program Overview
2.1 UCMR 1 Design and Implementation
The UCMR 1 database is a compilation of PWS monitoring results for select unregulated
contaminants, collected under the authority of the SDWA and the UCMR. The 1999 UCMR (64
FR 50556) (UCMR 1) established a three-tiered approach for monitoring of contaminants, based
on the availability of analytical methods and information on contaminant properties. EPA placed
twelve contaminants, for which suitable laboratory methods were available, on List 1; these were
scheduled to undergo full "Assessment Monitoring." Thirteen chemical contaminants whose
laboratory methods were less widely available were placed on List 2; these were scheduled for a
"Screening Survey" at a smaller group of systems. The purpose of the Screening Survey is to
develop a preliminary assessment of national occurrence for contaminants of concern that may
be otherwise too difficult to monitor at a larger scale. EPA also specified one List 3 contaminant
(Lead-210); however, EPA did not implement the scheduled UCMR List 3 monitoring ("Pre-
Screen Testing").
1,3-Dichloropropene was not an officially listed UCMR 1 contaminant, but 1,3-
dichloropropene monitoring was conducted by the same UCMR 1 small systems that conducted
List 1 monitoring. Consequently, the 1,3-dichloropropene data presented in the UCMR 1 are
only from the List 1 small systems.
The UCMR operates on a five-year cycle, with the first cycle extending from 2001
through 2005, though most monitoring was conducted from 2001 to 2003. All large CWSs and
NTNCWSs (i.e., those serving more than 10,000 people), plus a statistically representative
national sample of small CWSs and NTNCWSs (i.e., those serving 10,000 people or less), were
required to monitor for the List 1 contaminants. This totaled an estimated 2,800 large systems
and 800 small systems (USEPA, 200la).5 The Screening Survey for List 2 contaminants was
designed to be conducted by a total of 300 systems (120 large systems and 180 small systems).
PWSs for List 2 monitoring were randomly selected from among the systems required to conduct
Assessment Monitoring.
To facilitate laboratory scheduling and other logistical considerations, one-third of the
selected small PWSs were required to sample in each year of the program (2001, 2002, and
2003). The small systems were designated to a sampling year by random selection, with a 33%
probability for each system to be selected in any of the three years. Because of issues arising
during monitoring (e.g., a few systems closing), some of the original 800 selected systems could
not conduct monitoring and were replaced with substitute systems (previously selected within the
proper system stratification). The large systems could conduct their required one year of
monitoring any time during the UCMR 1 cycle.
Surface water (SW) systems were required to sample four times per entry point over a
one-year period, while ground water (GW) systems had to sample only twice per entry point over
5 At the time of the UCMR 1 rule development, there were an estimated 2,800 large PWSs in the United States.
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
a one-year period.6 One of the quarterly (SW systems) or semi-annual (GW systems) sampling
events had to occur in the defined "vulnerable" period of May through July, or an alternate
vulnerable period designated by the State, to ensure monitoring of potentially higher contaminant
concentrations. (For example, pesticides often exhibit strong seasonal patterns in drinking water
because their application season is concentrated in the spring and early summer, coinciding with
annual runoff and recharge periods.) Surface water systems had to select either the first, second,
or third month of a quarter and then had to take the remaining required samples at three-month
intervals for the following three quarters of the monitoring year.7 Ground water systems were
required to sample during one month of the most vulnerable period and then during one month
five-to-seven months earlier or later.8
Sampling was conducted at the entry points to the distribution system (EPTDS) after
treatment. These entry points were to be representative of each principal non-emergency source
of water in use over the 12-month monitoring period. In some cases, EPA allowed monitoring at
source (raw) water sampling points (consistent with State-approved compliance monitoring
points in States that allow source water sampling.) If a UCMR 1 contaminant was detected in a
source water sample, the UCMR required that follow-up samples be collected at the EPTDS
(unless there was no treatment), at the monitoring frequency specified in the rule for the
contaminant and water source type.
Large PWSs were responsible for collecting all UCMR 1 samples in accordance with the
program requirements for timing, frequency, and sampling quality control (QC) procedures.
Once samples were collected, large PWSs were responsible for sending the samples to an EPA-
approved laboratory for analysis. Systems with their own laboratories approved to perform
UCMR 1 analysis on-site could analyze their samples following UCMR 1 methods and QC
requirements.
Small PWSs were also responsible for collecting all UCMR 1 samples in accordance with
the program requirements for timing, frequency, and sampling QC procedures. However, sample
collection for the small systems was conducted differently than the large systems. EPA provided
sampling kits to the small systems; in the majority of States, the States actually collected the
UCMR 1 samples for the small systems. A very limited number of laboratories were specified to
analyze the small system samples, and the small PWSs were responsible for ensuring that the
collected samples were sent to the EPA-specified laboratory for analysis. The UCMR 1 program
was designed so that EPA paid for the costs associated with shipping samples from small PWSs
to the specified contract laboratories, as well as with sample analysis.
Most UCMR 1 data were collected between 2001 and 2003, though some results were
reported as late as October 2005. For the large systems, the data submission approach was
6 Note that not all systems took the required number of samples. See Section 3.3.2 for details on completeness of
UCMR 1 sampling.
7
That is, surface water systems were required to monitor either in January, April, July, and October; or February,
May, August, and November; or March, June, September, and December.
8
For example, if a ground water system selected May as its "vulnerable" month to sample, then the system was
required to take its other sample either five to seven months earlier (i.e., Oct, Nov or Dec of the preceding year) or
five to seven months later (i.e., Oct, Nov or Dec of the same year).
7
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
electronic posting by laboratories directly to a web-enabled database that allowed PWSs to
review and subsequently approve their data and release it EPA, with concurrent review by the
States. In the case of small systems, the specified contract labs were required to submit the
laboratory findings electronically to EPA, with copies sent to the PWSs and States for review.
Exhibit 2.1 presents the list often of the CCL 2 contaminants monitored under UCMR 1.
DCPA mono-acid and di-acid degradates were monitored in aggregate, because the approved
UCMR 1 analytical methods do not differentiate between the two degradates. As stated earlier,
although 1,3-dichloropropene was not an official UCMR 1 analyte, it was monitored alongside
List 1 contaminants at small systems. No large-system monitoring of 1,3-dichloropropene was
conducted. 1,3-Dichloropropene data were needed because problematic sample preservatives had
potentially compromised some older 1,3-dichloropropene monitoring results. The new 1,3-
dichloropropene data collected by all UCMR 1 small systems were handled according to
improved protocols.
-------
EPA - OGWDW
Analysis of Occurrence Data from the UCMR 1 for CCL 2
June 2008
Exhibit 2.1: Contaminants Considered During CCL 2 Regulatory Determinations
That Were Monitored Under the UCMR 1
Contaminant Name
SDWIS
Number1
CAS
Number
Contaminant Use and Description
Analytical
Method
List 1 (Assessment Monitoring)
2,4-dinitrotoluene
2,6-dinitrotoluene
DCPA
mono-acid degradate 2
DCPA
di-acid degradate 2
4,4-DDE
EPIC
MTBE
Terbacil
2270
2266
NA
NA
2069
2052
2251
9125
121-14-2
606-20-2
887-54-7
2136-79-0
72-55-9
759-94.4
1634-04-4
5902-51-2
Used in the bedding & furniture industries, the
production of ammunition, explosives, and dyes;
also used in automobile air bags. Most
environmental releases through industrial
wastewater discharges & improper waste disposal.
Same as 2,4-dinitrotoluene (above).
DCPA is a pre-emergent herbicide used historically
on annual grasses & broadleaf weed species.
Degrades into a transitory form (mono-acid) & a
moderately persistent form (di-acid).
No commercial uses; only found in the environment
as a result of contamination or breakdown of parent
chemical, 1,1,1 -trichloro-2,2-bis(p-
chlorophenyl)ethane (DDT).
Selective herbicide mainly used for control of
weeds in the cultivation of beans, forage legumes,
potatoes, corn, & sweet potatoes.
Oxygenate commonly added to gasoline (until
recently) to improve air quality.
Selective herbicide, inhibits photosynthesis. Used
to control grasses & broad-leaf weeds in
agricultural fields & fruit & nut orchards.
525.2
525.2
515.1
515.2
515.3
515.4
508
508.1
525.2
507
525.2
502.2
524.2
507
525.2
List 2 (Screening Survey)
Fonofos
2570
944-22-9
Applied to soil to control insects around crops
(predominantly corn).
526
Non-List Monitoring3
1,3-dichloropropene
2413
542-75-6
Soil fumigant to control nematodes & other soil
pests, particularly for root predation.
524.2
1. "NA" indicates that there is no 4-digit Safe Drinking Water Information System (SDWIS) contaminant code for the contaminant.
2. The approved methods for the two DCPA degradates do not allow for the identification and quantification of the individual acids;
thus, a single analytical result was obtained and reported for total DCPA mono- and di-acid degradates.
3. Although 1,3-dichloropropene was not officially a UCMR 1 contaminant, EPA collected 1,3-dichloropropene data from the UCMR
1 small systems that sampled for the List 1 contaminants, using an appropriate analytical method that does not involve sample
preservatives sodium sulfate or sodium thiosulfate.
Two categories of PWSs were exempt from UCMR 1 monitoring. First, PWSs that
purchase their entire water supply from another PWS were not included since monitoring at these
systems could result in double-counting of estimated population exposure. Second, transient
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
non-community water systems (TNCWSs) were also excluded since estimating contaminant
exposure for transient populations can be difficult and inconclusive.
2.2 Large Systems (Serving > 10,000 People)
The UCMR 1 required that all CWSs and NTNCWSs that serve more than 10,000 people
and do not purchase all of their water from another system monitor their water for the presence
of the 12 List 1 contaminants. At the time of the UCMR 1 rule development, available data
indicated that there were an estimated 2,800 large PWSs eligible for monitoring in the United
States. However, the most recent Safe Drinking Water Accession and Review System
(SDWARS) data indicate that there are 3,100 large systems eligible for UCMR 1 large system
sampling. The final UCMR 1 list of large systems requiring monitoring included 3,100 systems.
For List 2 monitoring, a random sample of 120 large systems was selected from among the large
systems conducting List 1 monitoring.
2.3 Small Systems (Serving < 10,000 People)
EPA used a stratified random sample of 800 small systems to conduct Assessment
Monitoring for the List 1 contaminants. The sample size was determined by a combination of
statistical and budgetary considerations. A sample of 800 systems is more than the
approximately 720 systems (659 CWSs and 61 NTNCWSs) needed to meet necessary
programmatic data quality objectives (DQOs), and enables the selection of at least two PWSs in
each State to ensure a broad and diverse geographic coverage. For more detailed information on
the selection of the 800 PWSs, refer to "Statistical Design and Sample Selection for the
Unregulated Contaminant Monitoring Regulation" (USEPA, 200Ib) and "Unregulated
Contaminant Monitoring Regulation: Implementation Report" (The Cadmus Group, Inc., 2002).
Note that, for List 2 monitoring, an additional random sample of 180 small systems was selected
from among the 800 small systems conducting List 1 monitoring.
2.3.1 Stratified, Random, Statistically-Weighted Sample
The UCMR 1 small system monitoring program was designed to provide EPA with high
quality data about contaminant occurrence in finished drinking water from a nationally
representative sample of small PWSs. Such data support statistically valid estimates of national
occurrence at small systems. Combined with information about the size of the populations
served by these systems, the data also enable EPA to perform rudimentary exposure assessments.
The data also enable EPA to draw conclusions about some sub-categories of systems (e.g., those
served by ground water or surface water). While the small system sample is nationally
representative, the sample size does not provide representative occurrence findings at the State
level.
2.3.2 Sample Allocation of Systems to Strata and States/Territories
The UCMR 1 small system sample size of 800 was determined by a combination of
statistical and budgetary considerations. Systems were allocated by size categories, source water
types, system types, and location (in what State/Territory they were located). With 3 size
10
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
categories, 2 source water types, 2 system types, and 56 States and Territories, there were 672
strata (3x2x2x56 = 672) in which to allocate the 800 systems.
EPA used the following three steps to select the group of 800 small systems:
1. First, the 800 sample (system) allocations were distributed across the 56 States and
Territories. The allocation was proportional to population, but at least two systems were
allocated to each State or Territory. (Note: the District of Columbia was not included
because it has no small systems.)
2. Within each State or Territory, a probability was assigned to each of 12 system categories
(according to system size, source water type, and system type), based on available data.
3. Within each State or Territory, a category was selected at random for each allocated
system, using the probabilities computed in step 2. Within the selected category, a PWS
was selected at random (weighted by population served).
The first step was accomplished in the following manner: To obtain the most precise
national exposure estimates, EPA initially allocated systems to each State in proportion to the
State's population served. For example, Texas has about 8.9% of the population served by small
systems, so small systems in Texas would ideally constitute about 8.9% (-71) of the 800 systems
selected. However, this population-weighted allocation had two drawbacks: (1) States can be
assigned a fractional number of systems and (2) some small States can get less than two systems.
To address the drawbacks, all allocations were rounded up to the next integer, and any
allocation of less than two was increased to two. At this point, the total number of allocated
systems was more than 800. Systems were then removed one at a time from various States'
allocations, in such a way as to minimize the increase in variance of an overall statistical
estimate of exposure without reducing any State allocation below two, until the total allocation
was reduced again to 800. It should be noted that the results were very close to what one would
get by simply rounding the original population-weighted allocations to the nearest integers.
Given the small sample size for individual States, statistically valid conclusions on small
system occurrence at the State level are not possible. However, EPA still considered it important
that all States be represented and have the opportunity to participate in the UCMR 1. Some
contaminants, such as some pesticides, may only be used intensively in specific regions of the
country. It is possible that with the relatively small number of systems in the representative
sample, monitoring may miss contaminants with such targeted regional use patterns. However,
including systems from every State in approximate proportion to the population served should
ensure that contaminants with regional use patterns, to the extent that they potentially
contaminate water supplies, are proportionately represented by the national sampling design.
Also, because the large system UCMR 1 data were generated by a census of large systems, the
combined small and large system monitoring results can provide an approximation of occurrence
at the State level.
11
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
3. UCMR 1 Data Description
This section of the report describes the management of the UCMR 1 monitoring data
(also referred to as the contaminant sample data or analytical data), and the quality review
measures applied to the data. It also includes an assessment of the representativeness and
completeness of the data set, as well as various temporal, geographical, and other characteristics
of the data. The contaminant sampling data described in and used as the basis for this report are
available to the public on EPA's website at the National Contaminant Occurrence Database
(NCOD), available on the Internet at: http://www.epa.gov/safewater/data/ncod/index.html. Note
that the information presented in Sections 3.1-3.3.2 is relevant to all 26 contaminants9 with
UCMR 1 data. Sections 3.3.3-3.4.3 focus only on the ten contaminants considered during CCL 2
regulatory determinations.
The sampling data provided in this report reflect UCMR 1 analytical samples submitted
and quality-checked as of March 2006 and posted on EPA's NCOD in October of 2007. Data for
all 26 contaminants underwent quality control and quality assurance (QA/QC) procedures prior
to their upload to the NCOD and their use in the occurrence analyses presented in this report.
EPA routinely posted preliminary UCMR 1 data on EPA's NCOD to provide the public with
monitoring results as they were generated and quality-checked. However, any analyses based on
UCMR 1 data released prior to March 2006 should be interpreted with caution, as they were
conducted using a preliminary and incomplete UCMR 1 data set.
The UCMR 1 monitoring plan and implementation has been described in full in several
other published reports. Interested parties are referred to: the Federal Register announcement of
the UCMR (64 FR 50556); "Technical Background Information for the Unregulated
Contaminant Monitoring Regulation" (USEPA, 2000); "Reference Guide for the Unregulated
Contaminant Monitoring Regulation" (USEPA, 2001a); "Statistical Design and Sample Selection
for the Unregulated Contaminant Monitoring Regulation (1999)" (USEPA, 2001b); and the
"Unregulated Contaminant Monitoring Regulation: Implementation Report" (The Cadmus
Group, Inc., 2002).
3.1 Data Overview
This report used the essentially complete version of the UCMR 1 data set, the March
2006 version, which contains more than 400,000 individual sample analytical results for the 26
contaminants, including more than 240,000 sample results for ten of the CCL 2 contaminants
monitored under the UCMR 1. The data set includes contaminant sample analytical results for
all of the List 1 and List 2 chemical contaminants, with the following exceptions: alachlor ethane
sulfonic acid (ESA), Royal Demolition Explosive (RDX), and Polonium-210 (these were
excluded for lack of approved, cost-efficient analytical methods); 2-methyl-phenol was added,
and; DCPA mono- and di-acid degradates were combined into one parameter. Contaminant
samples were collected between May 1, 2000 and October 25, 2005, with almost 95% collected
between January 2001 and December 2003, the core three-year period of the UCMR 1. Samples
were collected from all 50 States, plus Washington D.C., Tribal Nations, Puerto Rico, the
American Virgin Islands, Guam, and the Commonwealth of the Northern Mariana Islands.
9 The 26 contaminants refer the 25 official UCMR 1 List 1 and List 2 contaminants plus 1,3-dichloropropene, which
was added as a non-list contaminant for monitoring by small systems.
12
-------
EPA - OGWDW
Analysis of Occurrence Data from the UCMR 1 for CCL 2
June 2008
3.2 Data Management
This section describes how the UCMR 1 data were collected, maintained, and organized
by EPA. Quality assurance/quality control (QA/QC) procedures are also described. Data
discussed in this section include the water sample analytical data (monitoring results that define
contaminant occurrence) and PWS inventory information (data that define characteristics of the
participating drinking water systems). Exhibit 3.2.1 shows the sample-level data elements and
Exhibit 3.2.2 shows the system-level data elements included in the UCMR 1 database.
Exhibit 3.2.1: UCMR 1 Data Elements Related to Analytical Samples
Data Element
PWSID
FacID
SPID
Sample_pt_type
EP
SR
Sample_collection_date
Sample_identification_number
Parameter
Results_sign
eq
It
Results_value
Analytical_result_ unit_measure
Analytical_method
MRL
MRL_unit
Data Type
Alpha-numeric
Alpha-numeric
Alpha-numeric
Alpha
Alpha
Alpha
Numeric
Alpha-numeric
Alpha
Alpha
Alpha
Alpha
Numeric
Alpha
Numeric
Numeric
Alpha
Description
9-digit identification number unique to each public
water system
5-digit identification number unique within each PWS
for each applicable facility
Sample point identification number
Type of sample point tested
Entry-point to the distribution system (sample
collection location)
Source water sample collection location (untreated
raw water)
Date sample was collected (month-day-year)
Identification number for each sample
Commonly used contaminant name
Code to determine if analysis result is greater than or
less than MRL
Result is greater than or equal to MRL
Result is less than MRL (or not detected)
Concentration of the sample
Reporting units of analytical result (e.g., ng/L)
EPA-approved analytical method used
Minimum Reporting Level for sample
Reporting units of MRL
13
-------
EPA - OGWDW
Analysis of Occurrence Data from the UCMR 1 for CCL 2
June 2008
Exhibit 3.2.2: UCMR 1 Data Elements Related to Systems (Inventory Information)
Data Element
PWSID
State
PWS_Name
Small_Large
Size_ Category
Very Small
Small
Medium
Large
Very Large
GW_SW
Water_Type
GW
GU
Mix
SW
SWP
PWS_Type
CWS
NTNCWS
Population served
Data Type
Alpha-numeric
Alpha
Alpha
Alpha
Alpha
Alpha
Alpha
Alpha
Alpha
Alpha
Alpha
Alpha
Alpha
Alpha
Alpha
Alpha
Alpha
Alpha
Alpha
Alpha
Numeric
Description
9-digit identification number unique to each public water
system
State or Territory identification abbreviation
Proper name of system or water source
Whether system sampled as a large system (census) or small
system (survey)
One of five size categories defining gross population served
Serving up to 500 people
Serving 501-3,300 people
Serving 3,301 - 10,000 people
Serving 10,001 - 50,000 people
Serving more than 50,000 people
Whether system was analyzed as a ground water or surface
water system
Source water type of system
Ground water
Ground water under the influence of surface water (classified
asSW)
Mix of ground water and surface water (classified as SW)
Surface Water
Purchased Surface Water (classified as SW)
Type of system
Community Water System
Non-Transient Non-Community Water System
Population served by the PWS
3.2.1 Quality Assessments for Submitted Data
There was some flexibility for PWSs in collecting and submitting UCMR 1 data. The
UCMR 1 data collection period officially began in January of 2001, but systems were allowed to
report results of previously collected drinking water contaminant data for any of the UCMR 1
contaminants, as long as the data met specific data quality requirements. Information on the
criteria for accepting historical data can be found in the "UCMR Reference Guide" (USEPA,
200 la).
Laboratories submitted UCMR 1 analytical results from large systems directly over the
Internet, through EPA's Central Data Exchange (CDX). The CDX served as a secure central
point where PWSs, laboratories, States, and EPA could submit, view, review, and approve
14
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
UCMR 1 data. Once data were submitted via CDX and approved, they were stored in
SDWARS/UCMR - the main database for the upload and reviewing of UCMR 1 data.
Numerous controls were established to prevent unauthorized entry into the CDX and the
SDWARS/UCMR storage system, and to prevent the potential loss of data or inappropriate
transformations. For example, CDX requires users to register prior to being allowed access to
data reporting and reviewing sections. PWSs and analytical laboratories were only allowed
access to their own information. While PWSs had the ability to review and approve data, they
did not have access to alter data. Furthermore, the SDWARS/UCMR system had a number of
electronic back-up provisions and a requirement for off-site storage and duplicate files, so there
was minimal risk that data sets would be lost to tampering, system failure, or physical
destruction. The UCMR 1 Program Implementation Manager was the controlling authority for
the storage of and access to UCMR 1 data prior to public release.
UCMR 1 large system data were checked and verified for accuracy. Error correction
before electronic submission of data was the responsibility of the analytical laboratory. Once the
laboratory submitted results to EPA via the CDX, the laboratory had to approve the results prior
to their release to PWSs. Each PWS then had 30 days after the month in which it received
results to review the data and approve it electronically. Further review, and changes, and final
approval of data by EPA, State, and PWS authorities was completed within 60 days of the
approval by the PWS. At no point were data accepted for inclusion in SDWARS/UCMR without
the direct verification of that data by the submitting authority.
UCMR 1 data that were ready for EPA review were extracted on a monthly basis from
the CDX. EPA reviewed all UCMR 1 data that had already passed all the laboratory and PWS
reviews. EPA developed an Access database that conducted an automated data review and
quality check that flagged records that met the following criteria:
Records with PWS IDs or Lab IDs that begin with "99" (test data);
• Records for PWSs with the same sample point IDs at multiple facilities;
Records with a result value of "N/A";
• Records that are duplicates (i.e., having the same PWSID, Facility ID, Sample Point ID,
parameter, and sample collection date)--this category includes both intentional duplicate
samples taken to test the sampling process and unintentional, mistaken duplicates;
• Records with batch accuracy less than 2%;
Records from laboratories not approved for UCMR 1 analyses;
• Records for systems reporting data with List 2 methods where the system is not required
to report List 2 data;
• Records for systems reporting data with List 1 methods where the system is not required
to report List 1 data;
15
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
Sample point locations not identical to the entry point to the distribution system (EP), or
the source sampling point for collection of untreated water (SR) where appropriate.
The process of upload, review, retrieval, and archiving for UCMR 1 small systems
differed slightly from that described above for large systems. The 1996 Amendments to the
SDWA, which established the UCMR, require EPA to organize and pay for the UCMR 1
sampling at small PWSs. As part of this requirement, EPA had small systems send their samples
to specific laboratories contracted by the EPA. These laboratories then reported results to EPA's
Technical Support Center (TSC) where the records were reviewed for quality under essentially
the same criteria as for large systems (see criteria above). TSC then approved the final records
and sent them to PWSs and States for review.
For the March 2006 UCMR 1 data set used to support the analyses in this report, data
submitted to EPA that failed UCMR 1 quality approval were deleted according to the described
criteria. Deleted records from large systems include the following (note that these are numbers
for all of the UCMR 1 contaminants, not just the CCL 2 contaminants monitored under UCMR
1):
• Records from non-approved labs were deleted (8 records);
If there were duplicate detections, the lesser of the two analytical results was deleted (21
records);
If there were a mix of non-detect and detect duplicates, the non-detect(s) was deleted (23
records);
• If there were duplicate non-detections, all but one of the duplicate records was deleted
(4,643 records);
• Records for systems reporting data with List 2 methods where the system is not required
to report List 2 data were deleted (776 records);
Records from CA4810015 were deleted because the system uses the same water source
as CA4810003, and including data from both systems would be double-sampling (44
records);
Records from the following five systems, because the size of the populations they served
had changed and they were no longer officially considered large systems: MA4261024,
PR0005226, PR0005246, PR0005617, and TX0150039 (115 records).
Two additional data management adjustments were made regarding sampling points. For
systems (typically ground water systems) identified as not requiring and not having treatment,
"SR" designated samples were changed to an "EP" designation. Also, approximately 6,000
16
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
samples reported as "MD," "LD," "MR" (all distribution system locations)10 or "UK"
(unknown) were changed to EP.
A total of 405,570 UCMR 1 analytical sample records passed quality checks and were
used for occurrence analyses. Originally 411,200 sample records were submitted, but 5,630
records (1.37%) were deleted because they failed data quality checks. No records were deleted
from UCMR 1 small systems. (For the ten contaminants considered during CCL 2 regulatory
determinations monitored under the UCMR 1, a total of 3,075 samples were removed (-1.25%)
from the original 245,702 sample results for those ten contaminants.) Subsequent to the QA/QC
effort, there was a total of 375,805 sample results for the List 1 Assessment Monitoring
contaminants, 29,765 sample results for the List 2 Screening Survey contaminants, and 3,719
sample results for 1,3-dichloropropene (non-list monitoring).
3.2.2 Spatial Data
Occurrence information was mapped to the greatest degree of geographic accuracy
possible with the available data. Facility location data were used to develop maps using
Arc View GIS software. All maps were created and edited using Arc View 3.3 GIS software.
The locational data enabled only general identification of locations for PWSs located in Alaska,
Hawaii, and Puerto Rico.
3.3 Assessments of Data Completeness and Representativeness
To ensure that occurrence estimates based on UCMR 1 data dependably reflect national
conditions, the completeness and representativeness of the UCMR 1 contaminant sample data
were assessed. Background discussions of data quality issues can be found in the UCMR 1
statistical design (USEPA, 200Ib) and the quality assurance project plan (QAPP) (USEPA,
2003b). The QAPP specified quantitative data quality objectives (DQOs) for the completeness
and representativeness of small system data collected under UCMR 1. The small system data in
the March 2006 data set satisfy those DQOs indicating the small system data are complete and
representative. Although no formal DQOs were established for large systems, the large system
census had a very high participation rate and a very large portion of the submitted data passed
the general data quality criteria checks described in Section 3.2.1 (above). These and other
quality assessments (described below) suggest the large system contaminant occurrence data are
dependable for national contaminant occurrence analyses, although there is some potential bias
for underestimation of occurrence in the large PWSs. More detailed discussions on these topics
continue below.
3.3.1 Data Completeness
Small Systems (Serving < 10,000 Persons)
For the statistical sample of small systems, there was a DQO for the completeness of
occurrence data reported to EPA, with two components. The DQO specified that 90% of data
These codes represent Aeromonas sampling locations (MD = a midpoint location in the distribution system with
typical disinfectant residual levels; MR = a location representing the maximum residence time in the distribution
system; and LD = a location in the distribution system with the lowest disinfectant residual).
17
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
submitted be acceptable (i.e., in conformance with QC criteria, with all data elements present and
accurate), and that acceptable data be obtained from 82.375% of selected PWSs (USEPA,
2003b). Although all selected PWSs were required to collect and report UCMR 1 monitoring
data, it was anticipated that in certain instances some systems may not have been able to
participate, that some samples may not have been collected, or that some results may have not
been reported. Achieving these DQOs ensures adequate data quality for end-use applications
while recognizing the practical realities of PWS monitoring that some required data will not be
collected and/or reported.
In the March 2006 data set, all small system data submitted (100%) conformed to every
QC criterion. (EPA and States maintained significant oversight in the implementation of
sampling at the relatively few small systems conducting UCMR 1 sampling, and only a small
number of laboratories conducted all the analyses of the UCMR 1 small systems data.) A total of
48,050 analytical sample records were submitted by small PWSs and no records were rejected
due to failing QA/QC criteria This significantly exceeds the DQO of 90% of acceptable data. Of
the statistical design total of 800 small PWSs, 797 (99.6%) collected and reported acceptable
data for the List 1 contaminants. This also surpasses the DQO goal of 82.375%. (Note: Only
796 systems reported data for 1,3-dichloropropene, MTBE, and nitrobenzene, reducing the
response rate slightly to 99.5%.)
The DQO to obtain acceptable data from 82.375% of small PWSs represents the smallest
number of PWSs that still allows a national occurrence estimate for small PWSs and maintain a
99% confidence interval with a 1% margin of error. Achieving these DQOs suggests that the
small system sample is representative and complete (with acceptable sampling error and/or bias).
Achieving and surpassing the completeness DQOs for small systems helps UCMR 1 meet its
other data quality goals as well.
Large Systems (Serving > 10,000 Persons)
No formal completeness DQO was established for the census of large systems. As of
March 2006, large PWSs submitted 363,150 analytical sample records; a total of 5,630 records
(1.6 %) were removed because they failed the QA/QC criteria described above. A total of 3,090
out of the 3,100 eligible large PWSs had submitted at least some UCMR 1 monitoring data,
giving an overall large system response rate of 99.7%. The geographic distribution of the 3,090
large systems that did provide UCMR 1 data is illustrated in Exhibit 3.3.1. The large system
response rates for individual contaminants are briefly described below in Section 3.3.2., and in
Section 6.
18
-------
EPA - OGWDW
Analysis of Occurrence Data from the UCMR 1 for CCL 2
June 2008
Exhibit 3.3.1: UCMR 1 Large Systems by Source Water Type
Ground Water Systems
Surface Water Systems
Additional measures of completeness
For additional measures of completeness, EPA assessed the proportion of small and large
facilities that had the required number of analytical sample records per contaminant (i.e., two
samples from each entry point in a GW facility and four samples from each entry point in a SW
facility).11 EPA made use of the traditional distinction between system types, where systems
with mixed GW and SW sources and/or GU (ground water under the influence of surface water)
sources are categorized as SW systems. Under the UCMR 1, however, this distinction was made
not only at the system-level, but also at the facility-level. For example, although a PWS is
designated as a SW PWS because it has one SW source and one GW source, if the water from
the two sources was treated by separate facilities, the system was permitted to monitor the water
from the GW source on the GW schedule (i.e., two times per year), while monitoring the water
from the SW source on the SW schedule (i.e., four times per year). This important detail affects
measures of UCMR 1 completeness. Therefore, the assessments of completeness for this report
were conducted at the facility-level rather than at the system-level.
The UCMR 1 data base (with final, quality-checked data used for occurrence analyses)
contains the required two samples for approximately 91% of small ground water facilities
(average of 1.93 samples per facility, compared with the ideal of 2), and the required four
samples per contaminant at 77% of small surface water facilities (average of 3.74 samples per
11 Generally, a facility is a treatment plant or ground water distribution plant without treatment. Several facilities can
be a part of a single system.
19
-------
EPA - OGWDW
Analysis of Occurrence Data from the UCMR 1 for CCL 2
June 2008
facility, compared with the ideal of 4). The database contains the required number of samples
per contaminant at 79% of large ground water facilities (average of 1.92 samples per facility) and
at 79% of large surface water facilities (average of 3.91 samples per facility). One likely reason
that not all required samples at all systems were collected is that no samples were collected at
facilities that were temporarily off-line due to seasonal use or maintenance.
3.3.2 Data Representativeness
Small Systems (Serving < 10,000 Persons)
The small system sampling design incorporated a stratified sampling approach to enable
statistically valid occurrence analyses according to system size (based on population served) and
water source type (surface water or ground water).12 This stratified, population-weighted,
random selection process is described in detail in USEPA (200Ib) and summarized in section
2.3, above. Statistical design, program DQOs, and cost/schedule considerations resulted in a
sample design that selected 800 small PWSs that collectively would provide nationally
representative contaminant occurrence data. Exhibit 3.3.2.a illustrates, by source water type, the
geographic distribution of the small PWSs that conducted and reported UCMR 1 monitoring.
Exhibit 3.3.2.a: UCMR 1 Small Systems by Source Water Type
Ground Water Systems
Surface Water Systems
12 The number of NTNCWSs designated and selected for UCMR 1 monitoring does not support a statistically valid
analysis of only NTNCWSs.
20
-------
EPA - OGWDW
Analysis of Occurrence Data from the UCMR 1 for CCL 2
June 2008
The UCMR 1 sample of small systems was designed to provide a national exposure
estimates with a 1% margin of error and 99% confidence. In other words, if the sampling plan
were to be repeated many times, the true occurrence and exposure values would fall within the
1% margin of error around the estimate in 99% of all cases.
Meeting the representativeness objective requires that the designated sample be stratified
and implemented correctly. In a small number of cases, the originally selected small systems
could not participate (due to closing, change in status, etc.) Multiple replacement systems were
statistically selected in the event that the original (or first or second replacement) system could
not participate. Two replacement systems for each original were selected from the appropriate
size and type stratum using the same process as that for selecting the original system in the
sample. A third, or general, list of replacement systems consisted of a randomly selected number
of PWSs from the remaining PWSs in the State, regardless of system size category, source water
type, and system type.
The designated and actual distribution of the small system sample across strata is shown
in Exhibit 3.3.2.b. The differences between the actual distribution and the designed distribution
primarily reflect an inability to get an adequate number of NTNCWSs, so a very small number of
similarly-sized CWSs were substituted. Exhibit 3.3.2.b shows the final allocation of systems
among source water type, system type, and system size categories. Of the 800 small PWSs
selected, three systems did not participate in the UCMR 1 small system monitoring. (Two small
systems in American Samoa were unable to ship samples back to approved labs within the
required "hold time" specified by the UCMR 1 laboratory analytical protocol. One system in
Florida could not collect List 1 data.) The resulting 797 participating small PWSs maintain the
1% margin of error with 99% confidence for CWSs while allowing the incorporation of
NTNCWSs into the design. These 797 small PWSs (that also meet the completeness DQOs
described above) provide a nationally representative sample of systems that provided UMCR 1
contaminant occurrence data.
Exhibit 3.3.2.b: Designed and Actual Small System Allocation for
Assessment Monitoring
System
Type
CWS
NTNCWS
Size Category
500 and Under
501 to 3,300
3,301 to 10,000
Total
500 and Under
501 to 3,300
3,301 to 10,000
Total
Ground Water
Systems
Designed
72
218
225
515
31
31
6
68
Actual
76
215
230
521
35
30
4
69
Surface Water
Systems
Designed
47
41
102
190
10
9
8
27
Actual
45
38
105
188
7
7
5
19
Total
Designed
119
259
327
705
41
40
14
95
Actual
123
253
335
711
43
37
9
89
21
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
Large Systems (Serving > 10,000 Persons)
No formal representativeness DQO was established for large system results. A census,
such as that required for all eligible large systems under the UCMR 1 Assessment Monitoring, is
by definition the most representative type of sample design. In the March 2006 data set, only 10
of the potential 3,100 large systems that were eligible for UCMR 1 did not submit any
monitoring data, resulting in a participation (response) rate of 99.7%. All 10 systems are CWSs
and all but one are categorized as a "large" system (serving between 10,001 and 50,000 people).
Six of the 10 systems were served by ground water while four were served by surface water.
The non-response systems were from four States (FL, ID, LA, and OK) and two Territories
(American Samoa and Puerto Rico). These 10 non-responsive systems represent approximately
0.3% of all the 3,100 UCMR 1 large systems, yet less than 0.15% of the population served by the
3,100 large systems.
The only pattern of the non-responsive PWSs is that they are predominantly "large"
systems (rather than "very large" systems serving more than 50,000 persons). Otherwise, these
systems are very few in number, are distributed across many different States and Territories, and
represent both source water types. However, there is a possibility of underestimation of national
occurrence due to the non-responsive PWSs. The maximum value of underestimation would be
defined by assuming that all non-responsive systems had detections of UCMR 1 contaminants.
(There is no information available to EPA that indicates whether this assumption might be true
or not.) The number of large PWSs that did not report UMCR 1 monitoring results differed for
the individual contaminants, ranging from 21 to 32 PWSs (10 large PWSs reported no data for
any of the UCMR 1 contaminants). The contaminant-specific cases of non-responsive systems,
and their implications regarding potential occurrence underestimations and analyses, are further
discussed in Section 6.
List 2 Screening Survey for Fonofos - Small and Large Systems
In addition to the UCMR 1 List 1 Assessment Monitoring, EPA required monitoring for
selected contaminants for which analytical methods were developed but not widely used. EPA
designed a random selection of 300 public water systems (180 small and 120 large systems) from
those systems conducting List 1 Assessment Monitoring to conduct the UCMR 1 "List 2
Screening Survey," which included monitoring for fonofos.
List 2 systems were selected from all the size and water source categories with each of
the five size categories (three small and two large) given equal importance.13 Therefore, 60
systems were selected from each size category, with the selected systems distributed evenly
between surface water and ground water systems, wherever possible. (See USEPA, 200Ib and
The Cadmus Group, 2002 for more details.) List 2 monitoring for fonofos was primarily
conducted in 2001 for small systems and 2002 for large systems.
13 Selection was not proportionately weighted by population served (as in Assessment Monitoring-List 1) or by the
proportion of systems in each size category. If the sample was weighted by population served, a disproportionate
number of large systems would be included in the Screening Surveys. If the sample were weighted by the number of
systems in each size category, a disproportionate number of small systems would be represented.
22
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
The DQOs for completeness were exceeded by the fonofos data. As of March 2006, a
total of 643 analytical sample records of fonofos were submitted by small PWSs and no records
from small PWSs were rejected because of failing QA/QC criteria. Of the statistical design total
of 180 small PWSs, 178 (98.9%) collected and reported acceptable data for fonofos. Large
PWSs submitted 1,711 analytical sample records for fonofos; a total of 48 records (2.8%) were
removed because they failed the QA/QC criteria described above. Fonofos data were submitted
by a total of 117 (97.5%) of the 120 large PWSs selected for List 2 monitoring.
The UCMR 1 fonofos data contain the required two samples for approximately 87% of
small ground water facilities (average of 1.87 samples per facility, compared with the ideal of 2),
and the required four samples per contaminant at 70% of small surface water facilities (average
of 3.60 samples per facility, compared with the ideal of 4). The data base contains the required
number of samples per contaminant at 76% of large ground water facilities (average of 1.82
samples per facility) and at 77% of large surface water facilities (average of 3.97 samples per
facility). One likely reason that not all required samples were collected at all systems is that no
samples were collected at facilities that were temporarily off-line due to seasonal use or
maintenance.
3.3.3 Other Characteristics of the UCMR 1 Monitoring Data (Focus Only on
Contaminants Considered for Regulatory Determinations)
The following four exhibits (3.3.3.a - d) characterize the data collected for the ten
contaminants considered during CCL 2 regulatory determinations by number of samples, number
of systems, source water type, system type, and system size (population served). (The data set
containing these ten contaminants will be referred to as the "9-Contaminant Data Set.") A
temporal characterization of data (samples by year and month) is presented separately in Section
3.4.2.
Exhibit 3.3.3.a. shows the number and percent of samples and systems according to
source water type in the 9-Contaminant data set. Source water types are stratified by all
classifications, and summaries of ground water and surface water groupings are also presented.
For analysis of UCMR 1 data, EPA followed its normal practice of treating mixed water sources
(Mix), ground water under the influence of surface water (GU), and purchased surface water
(SWP) as surface water.
23
-------
EPA - OGWDW
Analysis of Occurrence Data from the UCMR 1 for CCL 2
June 2008
Exhibit 3.3.3.a: Number of UCMR 1 Analytical Samples and Systems in the
9-Contaminant Data Set, by Source Water Type
System Size
Small
Large
Source Type
GW
GU
Mix
SW
SWP
Total
GW
GU
Mix
SW
SWP
Total
All GW sources
All SW sources
Total
Samples
Number
19,332
201
397
7,227
0
27,157
112,598
1,568
1,107
75,739
24,458
215,470
131,930
110,697
242,627
Percent
71 .2%
0.7%
1 .5%
26.6%
0.0%
100.0%
52.3%
0.7%
0.5%
35.2%
1 1 .4%
100.0%
54.4%
45.6%
100.0%
Systems
Number
590
4
6
197
0
797
1,392
25
15
1,391
265
3,088 1
1,983
1,904
3,885
Percent
74.0%
0.5%
0.8%
24.7%
0.0%
100.0%
45.1%
0.8%
0.5%
45.0%
8.6%
100.0%
510%
49.0%
100.0%
1. A total of 3,090 large systems submitted data for at least one of the 26 UCMR 1 contaminants; however,
only 3,088 large systems submitted data for at least one of the 10 contaminants considered during the CCL2
regulatory determinations.
Exhibit 3.3.3.b shows the number and percent of samples and systems in the 9-
Contaminant data set by system type. Eighty-nine percent of small systems in the data set are
CWSs. In the large system census, more than 99% of systems are CWSs, as there were only
eight large NTNCWSs. EPA did not include TNCWSs in UCMR 1, both because they compose
a small proportion of nationwide drinking water systems, and because they would complicate
evaluations for contaminant exposure due to the transient nature of the populations that these
sources of drinking water serve.
24
-------
EPA - OGWDW
Analysis of Occurrence Data from the UCMR 1 for CCL 2
June 2008
Exhibit 3.3.3.b: Number of UCMR 1 Analytical Samples and Systems in the
9-Contaminant Data Set, by System Type
System Size
Small
Large
Source Type
CWS
NTNCWS
Total
CWS
NTNCWS
Total
All CWS sources
All NTNCWS sources
Total
Samples
Number
25,245
1,912
27,157
215,183
287
215,470
240,428
2,199
242,627
Percent
92.96%
7.04%
100.00%
99.87%
0.13%
100.00%
99.09%
0.91%
100.00%
Systems
Number
709
88
797
3,080
8
3,088 1
3,789
96
3,885
Percent
89.0%
1 1 .0%
100.0%
99.7%
0.3%
100.0%
97.5%
2.5%
100.0%
1. A total of 3,090 large systems submitted data for at least one of the 26 UCMR 1 contaminants; however,
only 3,088 large systems submitted data for at least one of the 10 contaminants considered during the CCL2
regulatory determinations.
Exhibit 3.3.3.C is a map of all large and small systems that submitted UCMR 1 data. At
least two small systems were sampled in every State and most Territories. One large system and
two small systems from American Samoa were originally included in the sampling plan, but
none of these three systems provided data. Consequently, American Samoa has been removed
from all State-level analyses of the UCMR 1 data. Exhibit 3.3.3.d is a map of all large and small
systems that submitted fonofos (List 2) data. These systems represent a subset of the systems
presented in Exhibit 3.3.3.C.
25
-------
EPA - OGWDW
Analysis of Occurrence Data from the UCMR 1 for CCL 2
June 2008
Exhibit 3.3.3.c: All Public Water Systems with UCMR 1 Monitoring Results
o Small Systems
D Large Systems
Exhibit 3.3.3.d: All Public Water Systems with Fonofos (List 2) Monitoring Results
O Small Systems
n Large Systems
26
-------
EPA - OGWDW
Analysis of Occurrence Data from the UCMR 1 for CCL 2
June 2008
Various stratifications of UCMR 1 systems' characteristics are presented in Exhibits
3.3.3.e-g. Exhibit 3.3.3.e summarizes, by State (or Territory), the number of systems in each of
five system size classifications and the population served by those systems. Exhibit 3.3.3.f
stratifies the systems in each State (or Territory) by source water type, and Exhibit 3.3.3.g
stratifies the systems in each State (or Territory) by system type.
Exhibit 3.3.3.e: Distribution of PWSs in UCMR 1 by State & Size Category
State or Territory
Alabama
Alaska
Arizona
Arkansas
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Idaho
Illinois
Indiana
Iowa
Kansas
Kentucky
Louisiana
Maine
Maryland
Massachusetts
Michigan
Minnesota
Mississippi
Missouri
Montana
N. Mariana Is.
Nebraska
New Hampshire
New Jersey
New Mexico
New York
Nevada
North Carolina
Small Systems
< 500 customers
#
PWSs
1
3
2
2
17
1
1
0
1
4
7
0
0
2
0
2
3
2
1
4
4
2
0
5
4
2
5
2
0
2
1
3
3
6
1
4
Pop.
Served
360
454
212
670
4,473
400
72
0
300
490
1,807
0
0
850
0
914
968
330
256
1,460
665
412
0
926
774
510
2,471
845
0
350
200
600
770
1,315
463
526
501 - 3,300 customers
#
PWSs
3
1
3
3
12
4
3
0
0
9
6
0
1
1
12
3
12
5
2
13
1
4
4
12
5
22
7
2
1
3
4
4
5
11
3
6
Pop. Served
6,309
3,000
5,036
3,298
22,836
10,908
3,748
0
0
14,997
1 1 ,446
0
1,307
2,797
16,275
6,257
22,047
8,721
2,089
29,299
2,370
8,189
7,790
23,015
12,882
37,915
13,634
4,840
2,631
5,152
9,050
5,100
6,425
16,844
5,393
12,843
3,301 -10,000
customers
#
PWSs
11
0
7
8
19
5
2
0
1
18
9
1
2
5
16
15
1
5
6
10
1
2
8
7
7
6
8
2
1
3
1
9
0
12
0
12
Pop. Served
67,788
0
36,050
50,227
132,080
26,119
16,014
0
6,500
102,029
48,469
5,504
14,155
34,650
100,876
105,819
3,690
29,575
38,074
57,664
5,075
9,900
55,503
54,756
44,678
40,574
35,642
9,831
3,509
18,033
7,000
70,620
0
75,872
0
85,470
Large Systems 1
10,001 -50,000
customers
#
PWSs
72
4
37
29
220
32
25
0
3
141
62
3
11
11
89
53
22
23
63
45
12
21
103
37
55
40
39
4
1
10
13
93
20
101
3
76
Pop. Served
1 ,844,637
101,537
951 ,370
742,366
6,097,170
804,204
711,319
0
89,460
3,611,491
2,634,658
37,965
287,780
304,266
1,991,360
1,118,760
586,771
493,183
1 ,729,802
827,051
226,615
484,967
2,639,037
818,082
1 ,220,775
872,095
677,499
112,064
62,696
232,814
255,151
2,641,362
462,074
2,645,899
84,735
2,026,239
> 50,000 customers
#
PWSs
11
1
10
5
139
14
10
1
3
66
17
1
3
2
16
13
9
6
5
16
1
7
17
10
14
2
9
3
0
2
2
19
4
30
4
17
Pop. Served
2,047,714
135,000
3,254,264
599,674
26,881 ,229
3,243,821
1 ,658,947
927,055
440,000
1 1 ,594,779
4,053,865
61 ,750
807,484
238,351
5,537,436
2,307,971
1 ,073,244
1,207,516
1 ,728,876
2,347,815
113,560
4,173,168
3,754,044
4,596,152
1 ,726,673
322,468
2,889,857
222,735
0
709,420
223,000
5,404,980
643,300
17,216,421
1 ,535,200
2,968,658
27
-------
EPA - OGWDW
Analysis of Occurrence Data from the UCMR 1 for CCL 2
June 2008
State or Territory
North Dakota
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Vermont
Virgin Islands
Virginia
Washington
West Virginia
Wisconsin
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
Total
Small Systems
< 500 customers
#
PWSs
1
3
3
3
13
2
0
1
1
2
14
1
1
2
6
5
0
2
2
1
0
1
2
0
163
Pop.
Served
203
1,099
1,698
785
3,503
680
0
450
376
764
3,913
185
322
400
1,386
1,060
0
500
580
191
0
498
825
0
44,261
501 - 3,300 customers
#
PWSs
3
7
3
4
12
2
2
5
2
3
24
2
2
0
8
8
5
8
1
0
1
0
0
1
290
Pop. Served
7,416
13,553
6,420
4,104
19,105
3,215
4,740
7,022
5,480
4,033
49,857
4,217
1,827
0
1 2,742
1 2,546
1 1 ,958
1 3,944
1,100
0
2,300
0
0
3,200
533,222
3,301 -10,000
customers
#
PWSs
0
18
9
4
12
5
0
5
1
9
33
4
1
0
2
4
5
11
0
0
0
0
0
1
344
Pop. Served
0
108,467
58,921
27,004
70,057
32,756
0
42,632
4,300
68,418
197,303
28,300
9,020
0
8,800
28,230
22,803
74,330
0
0
0
0
0
10,000
2,183,087
Small Systems Total:
797 systems, 2,760,570 persons served
Large Systems 1
10,001 -50,000
customers
#
PWSs
8
102
29
36
99
61
8
38
11
76
152
33
5
2
30
53
22
43
7
0
0
0
0
1
2,389
Pop. Served
222,052
2,318,255
633,194
857,803
2,744,392
1 ,567,033
240,079
978,431
157,408
1,911,324
3,270,267
814,082
104,300
64,000
1,115,180
1 ,653,266
391 ,405
862,597
188,407
0
0
0
0
1 8,244
60,538,973
> 50,000 customers
#
PWSs
1
23
8
8
29
16
3
10
2
15
44
12
1
0
12
12
3
12
1
0
0
0
0
0
701
Pop. Served
90,599
6,100,615
1 ,520,991
1,626,166
6,171,071
3,228,427
579,233
1 ,640,733
185,983
2,285,334
13,223,062
1,164,251
1 04,970
0
3,999,833
2,795,149
355,659
1,818,525
55,608
0
0
0
0
0
763,592,636
Large Systems Total:
3,090 systems, 224,131,609 persons served
1. A total of 10 large systems that were eligible for UCMR 1 monitoring did not report any UCMR 1 results. These systems were
located in the following States/Territories: American Samoa (1), Florida (1), Idaho (1), Louisiana (1), Oklahoma (4), and Puerto Rico
(2).
28
-------
EPA - OGWDW
Analysis of Occurrence Data from the UCMR 1 for CCL 2
June 2008
Exhibit 3.3.3.f: Distribution of PWSs in UCMR 1 by State and Source Water Type
State or Territory
Alabama
Alaska
Arizona
Arkansas
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Idaho
Illinois
Indiana
Iowa
Kansas
Kentucky
Louisiana
Maine
Maryland
Massachusetts
Michigan
Minnesota
Mississippi
Missouri
Montana
N. Mariana Is.
Nebraska
New Jersey
New Mexico
New York
Nevada
North Carolina
North Dakota
Ohio
Oklahoma
Oregon
Pennsylvania
Small Systems
(< 10,000 customers)
Total
15
4
12
13
48
10
6
0
2
31
22
1
3
8
28
20
16
12
9
27
6
8
12
24
16
30
20
6
2
8
16
8
29
4
22
4
28
15
11
37
Ground
Water
12
2
11
9
26
3
3
0
2
31
14
0
3
6
26
19
12
10
2
23
4
7
10
21
16
30
17
4
1
8
14
6
21
3
12
3
24
7
6
21
Surface
Water
3
2
1
4
22
7
3
0
0
0
8
1
0
2
2
1
4
2
7
4
2
1
2
3
0
0
3
2
1
0
2
2
8
1
10
1
4
8
5
16
Large Systems
(> 10,000 customers)
Total
83
5
47
34
359
46
35
1
6
207
79
4
14
13
105
66
31
29
68
61
13
28
120
47
69
42
48
7
1
12
112
24
131
7
93
9
125
37
44
128
Ground
Water
30
2
34
14
152
12
8
0
2
189
24
1
12
11
58
45
15
13
6
38
2
11
58
17
59
40
26
2
1
10
74
19
50
1
26
3
61
8
14
22
Surface
Water
53
3
13
20
207
34
27
1
4
18
55
3
2
2
47
21
16
16
62
23
11
17
62
30
10
2
22
5
0
2
38
5
81
6
67
6
64
29
30
106
All Systems
Total
98
9
59
47
407
56
41
1
8
238
101
5
17
21
133
86
47
41
77
88
19
36
132
71
85
72
68
13
3
20
128
32
160
11
115
13
153
52
55
165
Ground
Water
42
4
45
23
178
15
11
0
4
220
38
1
15
17
84
64
27
23
8
61
6
18
68
38
75
70
43
6
2
18
88
25
71
4
38
6
85
15
20
43
Surface
Water
56
5
14
24
229
41
30
1
4
18
63
4
2
4
49
22
20
18
69
27
13
18
64
33
10
2
25
7
1
2
40
7
89
7
77
7
68
37
35
122
29
-------
EPA - OGWDW
Analysis of Occurrence Data from the UCMR 1 for CCL 2
June 2008
State or Territory
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Vermont
Virgin Islands
Virginia
Washington
West Virginia
Wisconsin
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
Total
Small Systems
(< 10,000 customers)
Total
9
2
11
4
14
71
7
4
2
16
17
10
21
3
1
1
1
2
2
797
Ground
Water
4
2
5
3
2
61
4
3
0
13
14
0
21
1
1
1
0
1
1
590
Surface
Water
5
0
6
1
12
10
3
1
2
3
3
10
0
2
0
0
1
1
1
207
Large Systems
(> 10,000 customers)
Total
77
11
48
13
91
196
45
6
2
42
65
25
55
8
0
0
0
0
1
3,090
Ground
Water
20
4
10
5
17
67
13
0
0
1
41
3
37
1
0
0
0
0
0
1,393
Surface
Water
57
7
38
8
74
129
32
6
2
41
24
22
18
7
0
0
0
0
1
1,697
All Systems
Total
86
13
59
17
105
267
52
10
4
58
82
35
76
11
1
1
1
2
3
3,887
Ground
Water
24
6
15
8
19
128
17
3
0
14
55
3
58
2
1
1
0
1
1
1,983
Surface
Water
62
7
44
9
86
139
35
7
4
44
27
32
18
9
0
0
1
1
2
1,904
30
-------
EPA - OGWDW
Analysis of Occurrence Data from the UCMR 1 for CCL 2
June 2008
Exhibit 3.3.3.g: Distribution of PWSs in UCMR 1 by State and System Type
State or Territory
Alabama
Alaska
Arizona
Arkansas
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Maine
Maryland
Massachusetts
Michigan
Minnesota
Mississippi
Missouri
Montana
N. Mariana Is.
Nebraska
New Hampshire
New Jersey
New Mexico
New York
Nevada
North Carolina
North Dakota
Ohio
Oklahoma
Oregon
Pennsylvania
Small Systems
(< 10,000 customers)
Total
15
4
12
13
48
10
6
0
2
31
22
1
3
16
8
28
20
12
9
27
6
8
12
24
16
30
20
6
2
8
6
16
8
29
4
22
4
28
15
11
37
cws
15
4
12
13
43
9
4
0
2
28
20
1
3
16
8
27
18
12
9
26
3
6
11
20
14
28
18
5
2
7
5
14
6
22
3
20
4
23
15
9
26
NTNCWS
0
0
0
0
5
1
2
0
0
3
2
0
0
0
0
1
2
0
0
1
3
2
1
4
2
2
2
1
0
1
1
2
2
7
1
2
0
5
0
2
11
Large Systems
(> 10,000 customers)
Total
83
5
47
34
359
46
35
1
6
207
79
4
14
31
13
105
66
29
68
61
13
28
120
47
69
42
48
7
1
12
15
112
24
131
7
93
9
125
37
44
128
CWS
83
5
46
34
358
45
35
1
6
207
79
4
14
31
13
105
66
29
68
61
13
28
120
47
69
42
48
7
1
12
15
112
24
129
7
93
9
124
37
44
128
NTNCWS
0
0
1
0
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
2
0
0
0
1
0
0
0
All Systems
Total
98
9
59
47
407
56
41
1
8
238
101
5
17
47
21
133
86
41
77
88
19
36
132
71
85
72
68
13
3
20
21
128
32
160
11
115
13
153
52
55
165
CWS
98
9
58
47
401
54
39
1
8
235
99
5
17
47
21
132
84
41
77
87
16
34
131
67
83
70
66
12
3
19
20
126
30
151
10
113
13
147
52
53
154
NTNCWS
0
0
1
0
6
2
2
0
0
3
2
0
0
0
0
1
2
0
0
1
3
2
1
4
2
2
2
1
0
1
1
2
2
9
1
2
0
6
0
2
11
31
-------
EPA - OGWDW
Analysis of Occurrence Data from the UCMR 1 for CCL 2
June 2008
State or Territory
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Vermont
Virgin Islands
Virginia
Washington
West Virginia
Wisconsin
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
Total
Small Systems
(< 10,000 customers)
Total
9
2
11
4
14
71
7
4
2
16
17
10
21
3
1
1
1
2
2
797
CWS
8
2
9
4
13
67
7
4
1
12
15
9
19
2
1
1
1
2
1
709
NTNCWS
1
0
2
0
1
4
0
0
1
4
2
1
2
1
0
0
0
0
1
88
Large Systems
(> 10,000 customers)
Total
77
11
48
13
91
196
45
6
2
42
65
25
55
8
0
0
0
0
1
3,090
CWS
77
11
47
13
91
196
44
6
2
42
65
25
55
8
0
0
0
0
1
3,082
NTNCWS
0
0
1
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
8
All Systems
Total
86
13
59
17
105
267
52
10
4
58
82
35
76
11
1
1
1
2
3
3,887
CWS
85
13
56
17
104
263
51
10
3
54
80
34
74
10
1
1
1
2
2
3,791
NTNCWS
1
0
3
0
1
4
1
0
1
4
2
1
2
1
0
0
0
0
1
96
3.4 Additional Data Management Considerations
A detailed QA/QC process was applied to the UCMR 1 dataset to evaluate many quality
aspects of the occurrence data and system inventory. The following sections address data
management steps taken with the UCMR 1 large-system population-served values as they relate
to consecutive systems, seller/purchaser relations, and the resulting potential double-counting of
populations served by systems. Temporal characterizations of the UCMR 1 occurrence data are
also presented in this section.
3.4.1 Population Adjustments
Population-served values for small systems (those serving 10,000 or fewer persons) were
extensively evaluated as part of the UCMR 1 program statistical design and initial
implementation in 1999 and 2000. This was necessary to define the universe of small PWSs
from which the statistical sample of representative UCMR 1 small PWSs was drawn. (Details
are presented in USEPA, 2001b.) Similarly detailed analysis of large PWSs was not performed
at that time. However, extensive work was undertaken subsequently to ensure that all large
PWSs (those serving more than 10,000 persons) could be dependably identified for inclusion in
the large PWS monitoring under UCMR 1. Large system population-served values were verified
and updated during the period of UCMR 1 monitoring through communications with EPA
regions, States, and systems. And during UCMR 1 occurrence data, EPA conducted a
comprehensive review of the 3,100 large systems' population served values.
32
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
This final review was conducted not only to establish current population-served values
for the large systems, but also to address the issue of potential double-counting of populations
exposed to contaminant occurrence found in "consecutive systems." In a typical consecutive
system arrangement, one system acting as a wholesale distributor sells water to another system
acting as the retail distributor to customers. If both systems conduct UCMR 1 monitoring and
find contaminant occurrence, simply adding up the nominal populations served by each system
would result in double-counting and overestimation of contaminant occurrence. To the extent
possible, population adjustments were made to large systems to reduce double-counting of
population served while ensuring that the populations served by large systems were appropriately
represented in UCMR 1 monitoring. A brief description of this process is described below; for
more details, please refer to Appendix D.
Two major sources of data were used to determine the population-served values for the
3,100 large systems monitoring under UCMR 1. Both data sets originated from the federal
version of SDWIS (SDWIS/Fed), but they represent different time periods and different levels of
QC and revision. The first source of data ("SDWISOO") was a copy of the 2nd quarter (June)
version (or "2nd quarter freeze") of SDWIS/Fed from 2000. Population-served values for a
portion of the systems within this data set had been updated at the request of regional offices, the
States, and/or individual systems. The second source ("SDWIS05") represents the 4th quarter
(December) version (or "4th quarter freeze") of SDWIS/Fed from 2004, with QC procedures
implemented in January 2005.
EPA employed a four-step process to adjust the population-served values for the large
systems (for further detail on the process, see Appendix D):
1. EPA modified the SDWIS05 population-served values to reduce double-counting by
wholesale and retail public water systems.
2. EPA performed a system-by-system comparison of population served between the
SDWISOO and SDWIS05 data.
3. EPA developed decision criteria to determine which of the two data sets provided a better
population estimate for each large system.
4. EPA identified systems for whom the previous steps returned problematic results (less
than 1% of the systems), and made system-specific inquiries to establish "final" best
estimates for those systems' population-served values.
It is important to note that the adjusted population-served estimates do not define the size
categories, nor do the size categories define limits on the adjusted population-served estimates.
Systems were assigned to population-served size categories14 prior to Rule implementation.
Because EPA adjusted the population-served values of large wholesale systems to prevent
double-counting, the final UCMR 1 population-served values listed for some systems may not
match their size classification. For example, a system with a retail population of 100 people that
also treats water resold to 20,000 people by another PWS would be classified as "large" (because
14
The two size categories for large systems are: "large" (systems serving between 10,001 and 50,000 people) and
"very large" (systems serving more than 50,000 people).
33
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
it nominally provides water to a population of more than 10,000), but it would be assigned an
adjusted population-served value of 100. The purpose of the size categories is to aid in analysis
and interpretation of results at the system level, and the categories adhere to the original
statistical design of the rule implementation. The purpose of the adjusted population-served
estimates is to provide a better estimate of potential human exposure to the monitored
contaminants, which requires reducing the double-counting inherent in typical consecutive
system arrangements.
The population adjustments serve to reduce over-estimation of the number of people
potentially exposed to drinking water contaminants monitored under the UCMR 1. The
adjustments were made prior to and independent of all the contaminant-specific occurrence
analyses, so the actual impact of the adjustments on exposure estimates for any specific
contaminant is not known. In principle, the adjustments would most affect exposure estimates
for contaminants with more occurrence in consecutive systems.
3.4.2 Temporal Information
Although samples submitted to EPA under the UCMR 1 were collected between May
2000 and October 2005, most were collected during the three core UCMR 1 sampling years of
2001-2003. Samples collected after December 2003 include samples from systems that began
monitoring late (e.g., as a result of a system substitution), systems that were required to re-
sample (e.g., to sample at an entry point following a detection in a source water sample), and
systems that were under Administrative Orders following EPA Regional enforcement actions for
failing to meet their monitoring and/or reporting requirements. Exhibit 3.4.2.a shows the total
number of systems collecting UCMR 1 data each year during the sampling period. (Note that
these numbers are only for the ten CCL 2 contaminants monitored under UCMR 1.)
Over the course of the monitoring period, the presence and concentration of individual
contaminants sometimes varied at individual systems. This variability in contaminant
occurrence can result from many factors. Changes in weather, precipitation, and water
movement (seasonally and from year-to-year) can affect the fate and transport of a contaminant,
and therefore its occurrence in drinking water. Changes in contaminant occurrence may also
reflect operational factors such as changed water sources or altered treatment practices. Some
systems use different sources of drinking water seasonally in reaction to different seasonal
demands and/or different seasonal availabilities of supply.
The UCMR 1 program was designed with concerns about temporal variability in mind.
The study design addressed temporal variability in contaminant occurrence by defining a
vulnerable period (i.e., the season of greatest likelihood of contaminant occurrence, generally the
months of late spring and early summer which are characterized by high volumes of surface
water runoff and ground water recharge) and requiring at least one UCMR 1 sample at each
system during that period. In addition, the monitoring periods for the large and small systems
were staggered over the three years of UCMR 1 monitoring. Approximately one-third of the
small UCMR 1 systems, spread across the country, were scheduled to conduct monitoring in
each of the three years of UCMR 1 monitoring. The monitoring schedules for these systems also
were staggered to ensure that results are collected from every month in every part of the country.
Large systems could conduct their one year of monitoring anytime during the UCMR 1 period
34
-------
EPA - OGWDW
Analysis of Occurrence Data from the UCMR 1 for CCL 2
June 2008
from 2001 to 2003. Like small systems, their monitoring schedules were spread throughout the
year and were to include one sample during what was considered the most vulnerable season. In
this way, the UCMR 1 results reflect multiple seasons and multiple years of climatic conditions
throughout the country and are not directly affected (or biased) by weather conditions of a single
season, year, or geographic region.
Exhibit 3.4.2.a: Number of PWSs collecting UCMR 1 Samples Each Year,
2000-2005
O)
_c
'
C
O
2,000
I1-
>
W 1,000
a)
0
2,152
1,193
11
1,795
382
57
2000 2001 2002 2003
Sampling Year
2004
2005
The sum of systems monitoring each year does not equal the total number of UCMR 1 systems because some systems' monitoring
schedules can overlap two consecutive calendar years.
Exhibit 3.4.2.b illustrates the distribution of ground water and surface water UCMR
samples from month to month. Seasonal fluctuation is evident for ground water sampling, which
was conducted biennially. Most ground water samples were collected in the summer months
(May, June, July) and the winter months (November, December, January). No distinct seasonal
pattern is evident in the surface water sampling, as those systems sampled on a quarterly
schedule.
-------
EPA - OGWDW
Analysis of Occurrence Data from the UCMR 1 for CCL 2
June 2008
Exhibit 3.4.2.b: Number of PWSs collecting UCMR 1 Samples Each Month,
2000-2005
(Top Graph: GW Systems; Bottom Graph: SW Systems)
300 -,
c 250
0
§ 200
to
I 150
W)
!£ 100
o
o 50
0
Jar
Ground water Systems
1.
n 11
ID 1 1
n
n
Ilin Lnnn
n nn.
>00 Jan-01 Jan-02 Jan-03 Jan-04 Jan-05
Sampling Period
400
o. 35°
Q 300
| 250
to
§ 200
to
>>
150
<:
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
in addition to the MRL gives additional information on the degree as well as the frequency of
contaminant occurrence, and helps to better characterize the distribution of occurrence.
EPA evaluated the best available, peer-reviewed assessments and studies to characterize
the human health effects that may result from exposure to individual contaminants when found in
drinking water. Based on this characterization, the Agency estimated an HRL for each
contaminant. (For MTBE, an HRL value was not available because the risk assessment had not
been finalized. Therefore, occurrence measures for MTBE were performed relative to the MRL
only.) For more details regarding the development of the HRLs, see Appendix E of this report.
A list of the contaminants with Stage 1 Analyses presented in this report, along with their
MRL and HRL values, is presented in Exhibit 3.4.3. For the contaminants whose MRLs are
greater than their HRLs (viz., DDE, 2,4- and 2,6-dinitrotoluene, and 1,3-dichloropropene), it is
possible that UCMR 1 monitoring did not detect all HRL exceedances at participating systems,
so analysis could only be performed at the level of the MRL. The MRLs for DDE, 2,4- and 2,6-
dinitrotoluene, and 1,3-dichloropropene are all within the 10"4 to the 10"6 cancer risk range,
which EPA considers an acceptable range for occurrence analysis of carcinogens. In the case of
1,3-dichloropropene, not a single detection was found under UCMR 1 sampling.
The Stage 1 analytical approach can not provide any direct measure of contaminant
occurrence at thresholds below the MRL. If warranted, however, the Stage 2 analytical
approach, which is based on probabilistic modeling, can be used to estimate system mean
concentrations at any level above or below the MRL. This provides occurrence analyses that are
less conservative than the Stage 1 analysis (since the Stage 2 analysis is based on estimated mean
concentrations rather than on maximum concentrations), and also provides occurrence analyses
that are more reflective of potential chronic exposure.
37
-------
EPA - OGWDW
Analysis of Occurrence Data from the UCMR 1 for CCL 2
June 2008
Exhibit 3.4.3: Contaminants Analyzed Using Stage 1 Methodology, Along with
Relevant Threshold Values
List Contaminant Name MRL (ug/L) HRL (ug/L)
Listl
(Assessment
Monitoring)
List 2
(Screening Survey)
Non-List Monitoring2
DCPA mono- and di-acid degradates
DDE
2,4-Dinitrotoluene
2,6-Dinitrotoluene
EPIC
MTBE
Terbacil
Fonofos
1,3-Dichloropropene
r
0.8
2
2
1
5
2
0.5
0.5
70 1
0.2
0.05
0.05
175
N/A
90
10
0.4
1 The approved methods for the two DCPA degradates did not permit the identification and quantification of the individual acids;
thus, a single analytical result was obtained and reported for the two degradates in aggregate.
2 Although 1,3-dichloropropene was not officially a UCMR 1 contaminant, EPA collected these data from UCMR 1 small system
samples alongside data for the regular List 1 contaminants.
38
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
39
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
4. Description of Stage 1 Analytical Methodology
The Stage 1 analysis consists of simple occurrence measures based on the UCMR 1 data.
If necessary, Stage 1 analyses can be followed by Stage 2 analyses for individual contaminants.
This chapter is a discussion of the Stage 1 analyses, while the next section (5) discusses Stage 2
analysis.
4.1 Stage 1 Analysis
The Stage 1 statistical analysis of the UCMR 1 data consists of simple counts and
descriptive statistics of analytical occurrence data for each of the contaminants. These
occurrence analyses are conducted at the level of samples, sample points, systems, and
population served. At the sample level, occurrence measures include: the number and percent of
samples for each contaminant with analytical detections, and the minimum, median, maximum,
and 99th percentile values of those detections. System-level occurrence measures include: the
number and percent of systems with one or more analytical detections, and the number and
percent of systems with two or more analytical detections of a given contaminant. Population-
served occurrence measures include: the number and percent of customers (population served)
by systems with one or more analytical detections, and the number and percent of population
served by systems with two or more analytical detections of a given contaminant. Sample-point-
level occurrence measures are discussed in Section 4.3, below.
4.2 Additional Considerations for Stage 1 Analysis
4.2.1 Ground Water and Surface Water Comparisons
Given the different sampling schedules of ground water systems (two samples per year)
and surface water systems (four samples per year), care must be taken regarding any sample-
level comparative analyses between the two source water types. For example, if the true rate of
detection for a given contaminant was identical for both GW and SW systems, one would expect
to see roughly twice the number of detections in the SW systems, simply because SW systems
collect twice as many samples. Estimating the percentage of detections by source water type
(i.e., dividing the raw number of detections by number of samples taken) corrects for this
difference and provides a fair comparison of detection rates across SW and GW systems.
System-level and population-served-level analyses also account for the different sampling
frequencies.
4.2.2 Large System and Small System Totals
When presenting the Stage 1 Analyses, it is sometimes useful to summarize the
occurrence of a contaminant as a single number or percentage. When doing so, however,
consideration should be given to the distinction between analytical results from the small system
sample and large system census. Simply adding the number of both small and large systems'
detections may undercount the actual number of detections at the nation's small systems. While
such simple summaries accurately present actual UCMR 1 monitoring results, extrapolation of
small system results is necessary to produce accurate national contaminant occurrence estimates.
40
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
4.2.3 Extrapolation of the Small System Survey Results
Under the UCMR 1, the 800 small systems (serving < 10,000 persons) selected to
conducting monitoring were a stratified, random, statistically-weighted sample of the nation's
small systems. These systems were chosen to represent the distribution of small system
characteristics found at the national level, as described in Section 2.3. Occurrence findings for
these 800 systems, consequently, are representative of occurrence at the 60,414 small systems
operating nationally. Moreover, the 2.7 million persons served by the 800 sampled systems are
representative of the over 45 million served by all small systems nationally.
In order to better compare contaminant occurrence measured in the small system sample
to that of the large system census, the number of small systems (and population served by those
systems) is extrapolated to the national level. These extrapolations are presented in summary
tables in Section 6. To calculate the extrapolations, the percent of systems (or population served)
at each source water-size category was multiplied times the total number of systems found
nationally in the same source water-size category (see Exhibit 4.2.3). Estimates of national
system and population-served numbers were taken from the "Drinking Water Baseline
Handbook, Fourth edition" (USEPA, 2003c).
For the Stage 1 estimates, the extrapolations are calculated for each category of small
systems (source water type/system size stratum) and are then summed to yield a single national
total for all small systems. In contrast, the extrapolation for the Stage 2 estimates is calculated
(statistically modeled) directly for the "total" estimate for all small systems (i.e., extrapolations
for individual categories are not summed to generate the total.) Extrapolations are conducted
differently for the Stage 2 results because the Stage 2 modeling provides better estimates when
all data points are included. Extrapolations provide the best available estimate of contaminant
occurrence in small systems on a nationwide scale.
Exhibit 4.2.3 illustrates the calculation of Stage 1 estimates of national contaminant
occurrence, using DCPA degradates as an example. To estimate the number of ground water
systems serving 500 people or less nationally expected to have detections of DCPA degradates,
the percentage of systems of that description with detections in UCMR 1 (0.9%) is multiplied by
the total number of ground water systems nationally that serve 500 people or less (41,415
systems). The result is an estimate of 373 systems (41,415 x 0.009 = 373). A similar process is
used to estimate the population served nationally by systems in that category, and to make the
corresponding extrapolations in each of the other five system type / system size categories. Then
the Stage 1 extrapolations are summed to yield a single national total for all small systems.
41
-------
EPA - OGWDW
Analysis of Occurrence Data from the UCMR 1 for CCL 2
June 2008
Exhibit 4.2.3: Calculating National Estimates (Extrapolations) Using DCPA
Degradates Stage 1 Occurrence Findings
Water
Type
Ground
Water
Surface
Water
System Size by
Population
Served
<500
501 - 3,300
3,301 -10,000
Total
<500
501 - 3,300
3,301 -10,000
Total
All Small Systems
National Inventory
Systems
41,415
12,128
2,529
56,072
1,639
1,659
1,044
4,342
60,414
Population
6,231 ,348
15,602,332
14,390,656
36,224,336
306,256
2,674,107
6,209,891
9,190,254
45,414,590
DCPA Degradates > MRL
Systems
0.9%
1.2%
5.1%
2.7%
0.0%
2.2%
0.0%
0.5%
2.1%
Population
1.8%
1.1%
5.5%
4.5%
0.0%
1.6%
0.0%
0.2%
3.2%
National Estimate
Systems
373
149
130
652
0
37
0
37
689
Population
113,000
166,000
795,000
1,074,000
0
44,000
0
44,000
1,118,000
4.2.4 Stage 1 Analyses and the Statistically-Weighted Sample of Small Systems
The Stage 1 occurrence results presented in this report are simple, non-parametric,
descriptive statistics based directly upon the UCMR 1 occurrence data. The approximately 800
small systems that conducted UCMR 1 monitoring and provided the occurrence data used in this
report were selected as a statistically-weighted (primarily population-weighted) stratified sample.
For several reasons, the occurrence findings presented here do not incorporate adjustments for
the statistically-weighted sample selection of the UCMR 1 small systems. For the three
contaminants with more than one analytical detection (the two DCPA degradates, reported in
aggregate, and MTBE), occurrence rates are higher in large systems than in small systems. This
large-system predominance is even greater when considered on a population-served basis.
Therefore, adjusting the occurrence findings to account for the statistically-weighted sample of
small systems would not be anticipated to significantly affect the occurrence findings presented
here. However, a sensitivity analysis was conducted on the 800 small systems to address this
issue.
The sensitivity analysis compared weighted and non-weighted mean population exposed
based on various detection rates.15 At each detection level, a number of systems was randomly
selected without replacement (8 systems selected under the 1% detection rate scenario, 16
selected at 2% detection rate, 24 at 3%, etc., to 80 systems at 10%, and 400 systems at 50%
detection rate). Weighted and non-weighted mean population-exposed values were calculated
for each system. In systems with no detections, the population exposed was set at zero.
Weighted and non-weighted means were then derived and compared using two-sample t-tests
This analysis was conducted independent of any particular contaminant. The aim was to determine whether or not
weighting made any difference (related to the mean population exposed) if there is x % of detections in the data. The
sensitivity analysis findings are applicable to all contaminants.
42
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
assuming both equal and unequal variances.16 At every single detection level, there was no
significant statistical difference between estimates of the weighted and unweighted means.
Additionally, weighted and non-weighted mean population-exposed values were compared at a
100% detection rate (i.e., a hypothetical scenario assuming detection of a contaminant at all 800
systems. Again, it was determined that the weighting did not significantly change population
means overall. For more details on this sensitivity analysis, please refer to Appendix F.
4.3 Sample-Point-Level Analyses
The basic Stage 1 analytical methodology is a conservative approach: occurrence
measures are based on simple counts of whether or not a PWS has at least one sample analytical
result greater than a specified concentration threshold. This is roughly analogous to a measure
based conservatively on peak contaminant occurrence (i.e., when a system's occurrence is
represented by the maximum sample value even if numerous other samples collected by the
system had lower concentrations or were non-detections). The approach incorporates another
conservative assumption that if a detection is found in a single entry (or sampling) point in a
system, then the entire population served by the system is exposed to the detected contaminant
(i.e., even if there are other entry points with no detections that might dilute the concentration
found in the single entry point sample). For example, if a PWS serves a population of 10,000
and found a detection of a UCMR 1 contaminant in one out of its two sampling points on one
occasion, the Stage 1 analytical methodology would estimate that the entire population served by
the system (10,000) was potentially exposed to the maximum detected levels of the contaminant.
In reality, many systems get water from multiple water sources (such as a mix of
purchased and non-purchased water, ground water and surface water, etc.). In systems with
multiple water sources or water intakes, contaminant occurrence in one source or entry point
does not necessarily mean occurrence in all sources or entry points that distribute water to
consumers. Given the detailed sample point information in the UCMR 1 data, additional Stage 1
analyses are conducted at the sample-point-level to provide additional details of contaminant
occurrence. Sample-point-level occurrence measures include: the number and percentage of
systems with analytical detections at two or more sample points, the number and percentage of
systems with two or more analytical detections at a single sample point, and a "proportional
population" occurrence assessment.
Systems were generally required to collect UCMR 1 samples at the entry points to the
distribution system (EP). Systems in some States, such as California and New York, were
allowed to collect source water (SR) samples for the UCMR 1 in a manner consistent with those
States' approved compliance monitoring sample locations and protocol. Source water samples
could also be collected in other States at (ground water) systems that have no treatment facilities.
Various occurrence analyses at the sample-point-level (which includes EPs and SRs) are possible
based on the occurrence and system inventory data that are available. This section presents the
following types of sample-point-level analysis
16 A two-sample t-test is conventionally used to test if an estimate (usually a mean) from one sample is statistically
different from the mean of another sample. It assumes that the two samples being tested are independent of each
other. Because there is no conventional way to test equality of means of the same sample with and without weights,
independence of the sample with and without weights was assumed.
43
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
Two Detections at One Sample Point (2D1SP)
The count of "2D1SP" identifies public water systems that have at least two analytical
detections at any single sample point in the system. By counting individual sample points with
at least two separate detections, the analysis provides an indication of persistent or recurring
contaminant occurrence over time at the particular sampling point location within the system.
In the 2D1SP analysis, if a system is identified with two or more detections at a sample
point, the maximum detected concentration is used in the analysis to estimate potential exposure
for the population served by that system.
One Detection at Two Sample Points (1D2SP)
Another sample-point-level analysis is an assessment of systems with at least one
analytical detection at two or more sample points. This measure addresses the distribution of a
contaminant's occurrence throughout a system. Similarly, the percentage of a system's sampling
point locations (EPs and/or SRs) that have one or more detections of the contaminant can be
measured. As in the 2D1SP analysis, the maximum detected concentration is used in the
analysis for estimating potential exposure for the population served by that system.
Note that when reviewing the percentage of systems with detections in two or more
sampling points, many UCMR 1 systems have only one sample point and thus must be
discounted. Approximately 1,861 systems (roughly half of all UCMR 1 systems) sampled only
at one sample point. By size category, 62% of all small systems and 44% of all large systems
sampled only at one sample point.
Proportional Populations
This occurrence measure is a less conservative estimate of the population served by a
system with a contaminant detection. To derive this less conservative, sample-point-level
measure, an assumption was necessary regarding populations served by individual entry points at
drinking water systems. Because the population served by each entry point is not known, EPA
assumed that the total population served by a particular system is equally distributed across all
entry (sampling) points. Therefore, the population served by an entry point with a detection of a
particular contaminant is calculated by multiplying the system's total population served by the
percentage of that PWS's sampling points with a contaminant detection. For example, if a PWS
serves a population of 30,000 and found detections of a UCMR 1 contaminant in one out of its
two sampling points, then a population of 15,000 (30,000 x Va, or 50%) would be estimated to be
potentially exposed to the contaminant.
As detailed as the UCMR 1 data are, no information is available on the exact populations
served by each sample point within a system. (This information is also not available in the
SDWIS/Fed database.) Therefore, the proportional population estimate is based on the
assumption that for every system, each sample point serves an equal portion of the system's total
population. How well this assumption reflects actual populations potentially exposed to
contaminant occurrence will depend on the distribution system and service population
configurations at individual systems. Also, the national extrapolations of the sample point
44
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
analyses assume that the sample points (contained in the statistical sample of small systems) are
nationally representative. This may not be the case since the UCMR 1 statistical design
addressed small systems, not small system sample points. However, for all practical purposes,
the national extrapolations of the small system sample point analyses are considered good
approximations of national occurrence since any effects on occurrence due to the difference of
system versus sample point representativeness should be minimal, particularly since large system
occurrence for DCPA degradates and MTBE tends to dominate over small system occurrence
(especially when measuring populations-served by systems).
An example can illustrate the differences between 2D1SP, 1D2SP, and proportional
population occurrence measures of potential exposure. Consider the case of a large PWS that
has four entry points to the distribution systems (4 UCMR 1 sample points) and serves a
population of 100,000. In this example, the PWS has two detections of a contaminant in one of
its four sample points (i.e., 25% of its sample points). The 2D1SP measure would estimate that
the entire population served by the system (100,000) was potentially exposed to detection levels
of the contaminant (because there is at least two detections in 1 sample point). The 1D2SP
measure would estimate no exposure to the contaminant at this system (exposure is defined by
this measure as a situation where two or more sample points at a PWS are identified with
detections). The proportional population approach would estimate that a population of 25,000
was potentially exposed to the contaminant (because 1 of 4 sample points, or 25%, were
identified with detections, and 25% of the PWS total population served is 25,000). These
various measures are presented to enable a broader consideration of occurrence and potential
exposure. Results of all three sample point analyses are presented for select contaminants (those
with multiple analytical detections) in Section 7.
45
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
5. Description of Stage 2 Analytical Methodology
EPA's two-stage analytical approach uses the occurrence estimates derived from the
Stage 1 analyses to determine if a more rigorous statistical analysis, the Stage 2 analysis, is
warranted. Stage 2 analyses are conducted when the Stage 1 findings indicate significant
contaminant occurrence at or near the HRL for any particular contaminant. The Stage 2
analytical approach employs probabilistic modeling to estimate system mean contaminant
concentrations and the percent of systems with means exceeding specified contaminant
concentration thresholds. This enables, for example, a direct estimate of the number of systems
(and population served by those systems) with mean concentrations greater than an HRL. The
probabilistic model used, a Bayesian-based hierarchical model, was initially developed and peer-
reviewed for use in occurrence estimations conducted for the first Six-Year Review of NPDWRs
(see USEPA, 2003a).
The Stage 2 probabilistic model was developed as part of the two-stage analytical
approach for use and consistency across various occurrence assessment projects for the Office of
Ground Water and Drinking Water. The Stage 2 analysis generates an estimated number of
systems with an annual (or longer-term) mean contaminant concentration exceeding a specified
threshold, and includes measures of uncertainty (corresponding confidence intervals based on
calculated standard errors). The Stage 2 model includes confidence intervals around each mean,
enables estimates of mean contaminant concentrations below the MRL, and directly uses non-
detections (censored data) in estimating systems' mean concentrations (so therefore can generate
contaminant occurrence estimates even when a high proportion of non-detection data are
present). The model was used to generate the contaminant occurrence estimates for 60 regulated
contaminants for the first Six-Year Review of NPDWRs. For a more detailed, technical
description of the Stage 2 analysis and model, please refer to Appendix B.
The use of the Bayesian-based probabilistic model with the UCMR 1 data has also been
peer-reviewed. This model can be directly used with the UCMR 1 large system (census)
occurrence data. For use with the UCMR 1 small system sample data, weighting adjustments are
added to the model so that model estimates generated account for the UCMR 1 statistically-
weighted sample of small systems.
EPA did not need to perform Stage 2 analysis on any of the contaminants evaluated in
this report because none of the contaminants occurred at or above their respective HRLs and/or
the contaminants may potentially have acute (rather than chronic) effects such that Stage 2 would
not have been appropriate.17 However, to fully illustrate the two-stage occurrence analysis
approach, a Stage 2 analysis is conducted on the DCPA degradates. Summary results of this
analysis are presented in Section 7 of this report and the detailed DCPA degradate occurrence
findings generated by the Stage 2 analysis are presented in Appendix C.
17 Stage 2 analyses provide occurrence information that is more reflective of potential chronic exposure.
46
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
47
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
6. Stage 1 Occurrence Estimates
This section presents summary occurrence findings for the ten CCL 2 contaminants
monitored under UCMR 1. The following exhibits, evaluated together with the other analytical
and graphical results included within this report (and report appendices), provide a multi-faceted
overview of the frequency, degree, and distribution of the occurrence of those contaminants.
The results presented here are Stage 1 analyses of the UCMR 1 data. Note that many of the
summary tables included in this section of the report do not present a full breakdown of results
by system size category; for that level of detail, please refer to Appendix G. Additionally, brief
summaries of the occurrence findings for the other 16 UCMR 1 contaminants (i.e., those not
being considered during CCL 2 regulatory determinations) are included in Appendix A. Results
of the example Stage 2 analysis for DCPA degradates are presented in Section 7, and graphical
assessments of occurrence distribution are presented in Section 8.
In many of the following exhibits (as well as those in Section 8 and the Appendices),
numbers of detections in small and large systems are combined for summary purposes. It is
important to note, however, that while these combined small and large system summaries
accurately present actual UCMR 1 monitoring results (such as the percent of systems with
detections), the total number of systems with detections does not accurately represent national
occurrence. Because UCMR 1 small system data were collected from a representative sample of
small systems, these data must be extrapolated to generate estimates of national occurrence (see
Section 4.2.3). Those exhibits that do include extrapolated small system data are clearly
identified.
Summary tables of basic occurrence information on all ten CCL 2 contaminants are
presented in Exhibits 6.a and 6.b. (Exhibit 6. a presents a breakdown of the occurrence data by
system size, while Exhibit 6.b presents a breakdown by source water type.) Five out of the ten
contaminants (1,3-dichloropropene, 2,6-dinitrotoluene, EPTC, fonofos, and terbacil) had no
analytical detections in any of the large or small systems that sampled under the UCMR 1. Two
of the ten contaminants (DDE and 2,4-dinitrotoluene) had only a single detection while another
three contaminants (DCPA degradates, reported in aggregate, and MTBE) had multiple
detections in small and large systems. The maximum concentrations of DCPA degradates and
MTBE detected were 190 |ig/L and 49 |ig/L, respectively. Overall, system detection rates
(percentage of PWSs with at least one analytical detection) were 4.57% for DCPA degradates
and 0.49% for MTBE.
Summaries of sample-point-level results (as opposed to sample-level or system-level
results) are also included in Section 6. These analyses were only conducted for the three CCL 2
contaminants with multiple detections (DCPA degradates and MTBE). Note that only the
national extrapolation values are presented for the small systems, not the actual, raw numerical
counts from the UCMR 1 data set. For more detailed sample-point-level tables presenting
occurrence findings (including raw counts of sample-point-level detections at small systems),
please refer to Appendix H.
48
-------
EPA - OGWDW
Analysis of Occurrence Data from the UCMR 1 for CCL 2
June 2008
Exhibit 6.a: Stage 1 Summary of UCMR 1 Occurrence of Ten CCL 2 Contaminants Monitored Under UCMR 1
(by System Size)
Contaminant
DCPA mono & di-acid
degradates
4,4-DDE
1 ,3-dichloropropene
2,4-dinitrotoluene
2,6-dinitrotoluene
EPIC
Fonofos
MTBE
Terbacil
System Size
Small
Large
All (Small + Large)
Small
Large
All (Small + Large)
Small
Large
All (Small + Large)
Small
Large
All (Small + Large)
Small
Large
All (Small + Large)
Small
Large
All (Small + Large)
Small
Large
All (Small + Large)
Small
Large
All (Small + Large)
Small
Large
All (Small + Large)
Sample Level
Number of
Samples
3,272
30,638
33,910
3,251
30,546
33,797
3,719
0
3,779
3,251
30,513
33,764
3,251
30,514
33,765
3,251
30,547
33,798
643
1,663
2,306
3,268
30,500
33,768
3,251
30,549
33,800
Detections
Number
38
738
776
--
1
1
--
--
--
--
1
1
--
--
--
--
--
--
--
--
--
3
23
26
--
--
--
Percent
1.16%
2.41%
2.29%
--
<0.01%
<0.01%
--
--
--
--
<0.01%
<0.01%
--
--
--
--
--
--
--
--
--
0.09%
0.08%
0.08%
--
--
--
System-level
Number of
Systems
Sampled
797
3,079
3,876
797
3,077
3,874
796
0
796
797
3,076
3,873
797
3,076
3,873
797
3,076
3,873
178
117
295
796
3,075
3,871
797
3,076
3,873
Systems with
> 1 Detection(s)
Number
17
160
177
--
1
1
--
--
--
--
1
1
--
--
--
--
--
--
--
--
--
3
16
19
--
--
--
Percent
2.13%
5.20%
4.57%
--
0.03%
0.03%
--
--
--
--
0.03%
0.03%
--
--
--
--
--
--
--
--
--
0.38%
0.52%
0.49%
--
--
--
Concentrations of Analytical Detections
(in ng/L)
Minimum
1
1
1
--
3
3
--
--
--
--
333
333
--
--
--
--
--
--
--
--
--
6
5
5
--
--
--
Median
2
2
2
--
3
3
--
--
--
--
333
333
--
--
--
--
--
--
--
--
--
13
9
9
--
--
--
99th %
190
16
19
--
3
3
--
--
--
--
333
333
--
--
--
--
--
--
--
--
--
49
48
49
--
--
--
Maximum
190
39
190
--
3
3
--
--
--
--
333
333
--
--
--
--
--
--
--
--
--
49
48
49
--
--
--
While the combined small and large system summary numbers in this table accurately present actual UCMR 1 monitoring results (e.g., percent of systems with detections), the total
number of systems with detections does not accurately represent national occurrence. The statistical sample of small UCMR 1 systems must be extrapolated to generate estimates of
national occurrence (see Section 4.2.3). NOTE:"--" indicates no result (no detection of contaminant).
49
-------
EPA - OGWDW
Analysis of Occurrence Data from the UCMR 1 for CCL 2
June 2008
Exhibit 6.b: Stage 1 Summary of UCMR 1 Occurrence of Ten CCL 2 Contaminants Monitored Under UCMR 1
(by Source Water Type)
Contaminant
DCPA mono & di-acid
degradates
DDE
1 ,3-Dichloropropene
2,4-Dinitrotoluene
2,6-Dinitrotoluene
EPIC
Fonofos
MTBE
Terbacil
Source Water Type
GW
SW
All (GW + SW)
GW
SW
All (GW + SW)
GW
SW
All (GW + SW)
GW
SW
All (GW + SW)
GW
SW
All (GW + SW)
GW
SW
All (GW + SW)
GW
SW
All (GW + SW)
GW
SW
All (GW + SW)
GW
SW
All (GW + SW)
Sample-level
Number of
Samples
18.451
15,459
33,910
18,256
15,541
33,797
2,556
1,163
3,719
18,286
15,478
33,764
18,288
15,477
33,765
18,289
15,509
33,798
1,263
1,043
2,306
18,265
15,503
33,768
18,276
15,524
33,800
Detections
Number
524
252
776
1
—
1
-
—
-
-
1
1
—
—
—
—
__
—
—
__
-
20
6
26
-
—
--
Percent
2.84%
1 .63%
2.29%
0.01 %
—
<0.01%
-
—
-
-
0.01 %
<0.01%
—
—
—
—
__
—
—
__
-
0.11%
0.04%
0.08%
-
—
--
System-level
Number of
Systems
Sampled
1.979
1,897
3,876
1,971
1,903
3,874
589
207
796
1,970
1,903
3,873
1,970
1,903
3,873
1,970
1,903
3,873
164
131
295
1,970
1,901
3,871
1,970
1,903
3,873
Systems with
> 1 Detection (s)
Number
125
52
177
1
—
1
-
—
-
-
1
1
—
—
—
—
__
—
—
__
-
15
4
19
-
—
--
Percent
6.32%
2.74%
4.57%
0.05%
—
0.03%
-
—
-
-
0.05%
0.03%
—
—
—
—
__
—
—
__
-
0.76%
0.21%
0.49%
-
—
--
Concentrations of Analytical Detections
(in ng/L)
Minimum
1
1
1
3
—
3
-
—
-
-
333
333
—
—
—
—
__
—
—
__
-
5
8
5
-
—
--
Median
2
2
2
3
—
3
-
—
-
-
333
333
—
—
—
—
__
—
—
__
-
8
9
9
-
—
--
99th %
16
24
19
3
—
3
-
—
-
-
333
333
—
—
—
—
__
—
—
__
-
49
33
49
-
—
--
Maximum
190
39
190
3
—
3
-
—
-
-
333
333
—
—
—
—
__
—
—
__
-
49
33
49
-
—
--
While the combined small and large system summary numbers in this table accurately present actual UCMR 1 monitoring results (e.g., percent of systems with detections), the total
number of systems with detections does not accurately represent national occurrence. The statistical sample of small UCMR 1 systems must be extrapolated to generate estimates of
national occurrence (see Section 4.2.3). NOTE:"--" indicates no result (no detection of contaminant).
50
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
6.1 DCPA Mono- and Di-Acid Degradates
UCMR 1 monitoring identified 776 analytical detections of the DCPA degradates (i.e., at
or above the MRL of 1 |ig/L) in 33,910 samples collected. DCPA degradates appear to have a
relatively wide occurrence in both ground water and surface water drinking sources (Exhibit
6.1.a), as evidenced by the relatively high percentage of samples and PWSs with analytical
detections. UCMR 1 monitoring found DCPA degradate detections at 177 PWSs located in 24
States and 1 Territory. DCPA degradates were found to occur in ground water PWSs at a rate
approximately three times that in surface water PWSs, and to occur in large systems at a rate
approximately two times that in small systems regardless of source water type. The percentage
of all (large and small) UCMR 1 systems with at least one detection of DCPA degradates was
4.57%. The average value among DCPA degradate detections was 3.48 |ig/L and the median
value was 2.00 |ig/L.
DCPA degradate occurrence was also measured relative to the 1A HRL (35 |ig/L) and
HRL (70 |ig/L) (Exhibits 6.1.b and 6.1.c). While DCPA degradate occurrence was relatively
widespread, the degree of occurrence (the typical concentration levels found) was low. Only two
PWSs (one small system and one large system) detected concentrations greater than the 1A HRL,
and only one small PWS detected concentrations greater than the HRL. Extrapolating these
findings suggests that an estimated 12.3 million persons are served by systems with detections of
DCPA degradates nationally, while only an estimated 113,000 are served by systems with DCPA
degradate concentrations greater than the HRL. (See Section 4 for an explanation of small
system national extrapolations.)
DCPA degradate data were collected and reported by 797 (99.6% of) small PWSs with
100% of the small system data determined to be acceptable based on data quality QA/QC
criteria. This high response rate and high data quality satisfy data quality objectives for
representativeness and completeness in the small system statistical survey, meaning that we can
have reasonable confidence in the extrapolated estimate of national occurrence at small systems.
DCPA degradate data were collected by 3,079 (99.3% of) large PWSs with 98.8% of the
large system data determined to be acceptable based on the data quality criteria. The large
system census is therefore slightly incomplete (with a system non-response rate of 0.7%).
Sixteen of the 21 large systems not reporting UCMR 1 results (the "non-responsive systems")
were from the "large" size category (serving between 10,001 and 50,000 people), and 5 systems
were from the "very large" size category (serving over 50,000 people). There were nearly an
equal number of ground water and surface water non-responsive systems. The State with the
greatest number of large systems that were non-responsive for DCPA degradates was Louisiana
(7 of the 21 non-responsive systems). Of the 55 large and very large PWSs in Louisiana that did
provide DCPA degradate data, none found any detections of DCPA degradates. (Nationally,
5.20% of large and very large systems found DCPA degradate detections.) The non-response
rate is very slightly higher when assessed on a potential exposure (population-served) basis: Of
the total population served by all eligible UCMR 1 large systems, approximately 0.9% is served
by the 21 non-responsive systems. If any of these non-responsive systems actually had DCPA
degradates in their water, the UCMR 1 national occurrence results would underestimate actual
occurrence at large systems. The maximum value (upper bound) of the potential underestimation
of population-served by large systems with potential DCPA degradates is 0.9%.
51
-------
EPA - OGWDW
Analysis of Occurrence Data from the UCMR 1 for CCL 2
June 2008
Exhibit 6.1.a: Summary of Stage 1 Occurrence Measures of DCPA Mono-and
Di-Acid Degradates
Water Type
Sample-level
Number of
Samples
Detections
#
%
System-level
Number of
Systems with
1 Detection
#
%
Systems with
2 or more Detections
#
%
Small Systems (Statistical Sample)
GW
SW
All
2,345
927
3,272
37
1
38
1 .58%
0.11%
1.16%
590
207
797
16
1
17
2.71%
0.48%
2.13%
12
0
12
2.03%
0.00%
1 .51 %
Large Systems (Census)
GW
SW
All
16,106
1 4,532
30,638
487
251
738
3.02%
1 .73%
2.41%
1,389
1,690
3,079
109
51
160
7.85%
3.02%
5.20%
74
41
115
5.27%
2.43%
3.73%
All Systems
Total Water II
Systems1 || 33'910
776
2.29%
3,876
177
4.57%
127
3.28%
Note that small water systems (population served < 10,000) conducting UCMR 1 monitoring represent a statistically representative
sub-sample of all small systems, while the UCMR 1 large water systems (population served > 10,000) represent a census of all
large systems. Comparisons and totals of raw data collected by small and large systems may not accurately represent national
occurrence.
52
-------
EPA - OGWDW
Analysis of Occurrence Data from the UCMR 1 for CCL 2
June 2008
Exhibit 6.1.b: National Extrapolation of Stage 1 Occurrence Measures of DCPA Mono- and Di-Acid
Degradates in Small PWSs
Water
Type
System Size
by
Population
Served
Total Number
Sys
Pop
Detections (> MRL) 1
UCMR1
Sys
Pop
Percentage
Sys
Pop
National
Extrapolation
Sys
Pop
Detections (> 1/2 HRL) 1
UCMR1
Sys
Pop
Percentage
Sys
Pop
National
Extrapolation
Sys
Pop
Detections (> HRL) 1
UCMR1
Sys
Pop
Percentage
Sys
Pop
National
Extrapolation
Sys
Pop
Small Systems
GW
sw
<500
501 - 3,300
3,301 - 10,000
Total
<500
501 - 3,300
3,301 - 10,000
Total
All Small Systems
111
245
234
590
52
45
110
207
797
27,599
441 ,499
1,470,717
1,939,815
16,662
91,723
712,370
820,755
2,760,570
1
3
12
16
1
1
17
500
4,692
81,241
86,433
-
1,500
-
1,500
87,933
0.90%
1 .22%
5.13%
2.71%
-
2.22%
-
0.48%
2.13%
1.81%
1 .06%
5.52%
4.46%
-
1 .64%
-
0.18%
3.19%
373
149
130
652
-
37
-
37
689
113,000
166,000
795,000
1,074,000
-
44,000
-
44,000
1,118,000
1
--
1
--
--
1
500
-
-
500
-
-
-
-
500
0.90%
-
-
0.17%
-
-
-
-
0.13%
1.81%
-
-
0.03%
-
-
-
-
0.02%
373
-
-
373
-
-
-
-
373
113,000
-
-
113,000
-
-
-
-
113,000
1
--
1
--
--
1
500
-
-
500
-
-
-
-
500
0.90%
-
-
0.17%
-
-
-
-
0.13%
1 .81 %
-
-
0.03%
-
-
-
-
0.02%
373
-
-
373
-
-
-
-
373
113,000
-
-
113,000
-
-
-
-
113,000
NOTE:"--" indicates no result (no systems, or population served by systems, with detections).
1 MRL for DCPA degradates is 1 ng/L and the HRL is 70 ng/L
53
-------
EPA - OGWDW
Analysis of Occurrence Data from the UCMR 1 for CCL 2
June 2008
Exhibit 6.1.c: Stage 1 National Occurrence Measures of DCPA Mono- and Di-Acid Degradates Based on UCMR 1
Small System Extrapolated Data and Large System Census Data
Water Type
System Size by
Population Served
Detections (> MRL) 1
Number
Sys
Pop
Percentage
Sys
Pop
Detections (> 1/2 HRL) 1
Number
Sys
Pop
Percentage
Sys
Pop
Detections (> HRL) 1
Number
Sys
Pop
Percentage
Sys
Pop
Small Systems
Ground
Water
Surface
Water
<500
501 - 3,300
3,301 -10,000
Total
<500
501 - 3,300
3,301 -10,000
Total
All Small Systems
373
149
130
652
-
37
-
37
689
113,000
166,000
795,000
1 ,074,000
-
44,000
-
44,000
1,118,000
0.90%
1 .22%
5.13%
2.71%
-
2.22%
-
0.48%
2.13%
1.81%
1 .06%
5.52%
4.46%
-
1 .64%
-
0.18%
3.19%
373
-
-
373
-
-
-
-
373
113,000
-
-
113,000
-
-
-
-
113,000
0.90%
-
-
0.17%
-
-
-
-
0.13%
1.81%
-
-
0.03%
-
-
-
-
0.02%
373
-
-
373
-
-
-
-
373
113,000
-
-
113,000
-
-
-
-
113,000
0.90%
-
-
0.17%
-
-
-
-
0.13%
1 .81 %
-
-
0.03%
-
-
-
-
0.02%
Large Systems
Ground
Water
Surface
Water
10,001 -50,000
> 50,000
Total
10,001 -50,000
> 50,000
Total
All Large Systems
87
22
109
34
17
51
160
2,095,370
3,987,609
6,082,979
1,136,909
4,049,548
5,186,457
1 1 ,269,436
7.26%
1 1 .58%
7.85%
2.87%
3.35%
3.02%
5.20%
7.74%
15.06%
1 1 .36%
3.41%
2.99%
3.07%
5.07%
-
-
-
-
1
1
1
-
-
-
-
738,337
738,337
738,337
-
-
-
-
0.20%
0.06%
0.03%
-
-
-
-
0.55%
0.44%
0.33%
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
All Systems (National Extrapolation plus Census)
Total Water Systems
849
12,387,436
4.57%
5.05%
374
851,337
0.05%
0.33%
373
113,000
0.03%
< 0.01%
NOTE:"--" indicates no result (no systems, or populations served by systems, with detections).
1 MRL for DCPA degradates is 1 ng/L and the HRL is 70 ng/L.
54
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
Exhibit 6.1.d presents a summary of the sample-point-level analysis of DCPA degradate
occurrence. Incorporating small system national extrapolations, almost 3% of all PWSs, serving
3.6% of the total population, are estimated to have multiple detections of DCPA degradates at a
single sampling point. A slightly smaller percentage of PWSs and population served nationally
is estimated to have DCPA degradate detections at multiple sampling points. Using another
measure of occurrence, the sampling point (SP) proportional population, it is estimated that
approximately 1.4% of the population served by PWSs nationally is served by an entry
point/sample point with detections of DCPA degradates. (This proportional population served
by sample points with detections, a less conservative measure of occurrence, is calculated by
multiplying a PWS's total population served by the percentage of that PWS's sampling points
with a contaminant detection. Refer to Section 4.3 for more details regarding the proportional
population analysis.)
55
-------
EPA - OGWDW
Analysis of Occurrence Data from the UCMR 1 for CCL 2
June 2008
Exhibit 6.1.d: Summary of Sample-Point-Level Occurrence Measures of DCPA Mono- and Di-Acid Degradates Based
on UCMR 1 Small System Extrapolated Data and Large System Census Data
Water
Type
Total
Sys
SPs
Pop
At Least 2 Detections
at 1 SP
Systems
#
%
Population
#
%
At Least 1 Detect
at 2 SPs
Systems
#
%
Population
#
%
SP Proportional Population With
At Least One Detection
SPs 1
#
%
Population 2
#
%
Small Systems
GW
SW
All
590
207
797
1,211
243
1,454
1,939,815
820,755
2,760,570
558
0
558
1 .86%
0.00%
1 .38%
727,000
0
727,000
2.86%
0.00%
2.01%
93
0
93
0.85
0.00%
0.63%
346,000
0
346,000
1.51%
0.00%
1 .06%
843
46
889
1 .90%
0.41 %
1 .65%
554,000
44,000
598,000
1 .90%
0.18%
1 .39%
Large Systems
GW
SW
All
1,389
1,690
3,079
8,241
5,284
13,525
53,537,353
168,728,855
222,266,208
66
36
102
4.75%
2.13%
3.31%
4,363,000
3,649,000
8,011,000
8.15%
2.16%
3.60%
56
25
81
4.03%
1 .48%
2.63%
3,931 ,000
3,422,000
7,353,000
7.34%
2.03%
3.31%
300
125
425
3.64%
2.37%
3.14%
1,465,000
1,584,000
3,049,000
2.74%
0.94%
1 .37%
All Small plus Large Systems
All
Systems
3,876
14,979
225,026,778
660
2.92%
8,738,000
3.58%
174
2.22%
7,699,000
3.28%
1,314
3.00%
3,647,000
1 .37%
All Population values are rounded to the nearest thousand.
1 The extrapolated number of small system sample points with a contaminant detection was estimated by multiplying the percentage of UCMR 1 small system sample points with a
contaminant detection by the total number of sample points nationally. The national number of small system sample points was estimated by multiplying the average number of sample
points for a system water type category by the total number of systems nationally in that category. (The average number of sampling points per system was obtained from the Community
Water System Survey 2000, Volume II Detailed Tables and Survey Methodology.) The large system sample point numbers presented in this table are direct counts of the UCMR 1 large
system data (no extrapolations are necessary).
2 Sample point proportional population was calculated by multiplying each system's total population served by the percentage of that PWS's sampling points found with a contaminant
detection.
56
-------
EPA - OGWDW
Analysis of Occurrence Data from the UCMR 1 for CCL 2
June 2008
Most UCMR 1 systems have multiple SPs, and DCPA degradates may not be present in
all SPs at a system (even if one or more SPs at a system does have DCPA degradate occurrence).
Exhibit 6.1.e illustrates the proportion of systems detecting the DCPA degradates in various
percentages of their SPs. Fifty-five (55) percent of systems with DCPA degradate detections had
detections in more than 25% of their SPs, and 22% of systems with detections had detections in
more than 50% of their SPs. (Note that for all UCMR 1 systems with DCPA degradate
detections, 9.1% had only 1 SP.)
Exhibit 6.1.e: Percentage of SPs with Detections of DCPA Mono- and Di-Acid
Degradates (Among Systems with At Least One Detection)
45% of PWSs had
detections in
< 25% of SPs
32% of PWSs had
detections in
25%-50% of SPs
19% of PWSs had
detections in
75%-100%ofSPs
5% of PWSs had
detections in
50%-75% of SPs
57
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
6.2 DDE
DDE was only detected (at or above the MRL of 0.8 |ig/L) in one sample in all of the
UCMR 1 sampling (see Exhibit 6.2). The single detection of 3 |ig/L was in a ground water
sample in Alabama. The population served by this large system was 17,670, which thus also
represents the total estimated national population served by systems with detectable levels of
DDE. The overall occurrence rate of DDE in all public water systems that participated in
UCMR 1 monitoring is 0.03%.
DDE data were collected and reported by 797 (99.6% of) small PWSs, with all the small
system data determined to be acceptable based on data quality QA/QC criteria. This high
response rate and high proportion of acceptable data satisfies data quality objectives for
representativeness and completeness in the small system statistical survey, meaning that we can
have reasonable confidence in an extrapolated estimate of national occurrence (in this case, the
data indicate that DDE is not likely to be present in the nation's small systems).
DDE data were collected by 3,077 (99.3% of) large PWSs with 98.2% of the large system
data determined to be acceptable based on the data quality QA/QC. The large system census is
therefore slightly incomplete, with a system non-response rate of 0.7%. Eighty-seven percent of
the 23 non-responsive large systems were from the "large" size category (serving between
10,001 and 50,000 people); the remaining 13% were from the "very large" size category (serving
over 50,000 people). Seventy-eight percent of the non-responsive systems were served by
ground water. The State with the greatest number of large systems that were non-responsive for
DDE was Louisiana (12 of the 23 non-responsive systems). The non-response rate is smaller
when assessed on a potential exposure (population served) basis. Of the total population served
by all eligible UCMR 1 large systems, approximately 0.4% is served by the 23 non-responsive
systems. If any of these non-responsive systems actually had DDE in their water, the UCMR 1
national results would underestimate actual occurrence at large systems. The maximum value
(upper bound) of the potential underestimation of the population-served by large systems with
detections of DDE is 0.4%.
Because the HRL for DDE (0.2 |ig/L) is lower than the MRL used for monitoring (0.8
|ig/L), EPA used the MRL value for formal evaluation of occurrence and exposure assessments.
The MRL is within the 10"4 to the 10"6 cancer risk range for DDE.18
18 When EPA specified the analytical methods and the MRL for the monitoring of DDE in UCMR 1, the Agency
chose an MRL that was within the capabilities of the most commonly used methods for drinking water laboratories
at that time. The DDE MRL of 0.8 ug/L is within the 10~4 to the 10~6 cancer risk range, which is considered an
acceptable range by the Agency for occurrence evaluation of carcinogens.
58
-------
EPA - OGWDW
Analysis of Occurrence Data from the UCMR 1 for CCL 2
June 2008
Exhibit 6.2.a: Summary of Stage 1 Occurrence Measures of DDE
Water Type
Sample-level
Number of
Samples
Detections
#
%
System -level
Number of
Systems with
1 Detection
#
%
Systems with
2 or more Detections
#
%
Small Systems (Statistical Sample)
GW
SW
All
2,342
909
3,251
0
0
0
0.00%
0.00%
0.00%
590
207
797
0
0
0
0.00%
0.00%
0.00%
0
0
0
0.00%
0.00%
0.00%
Large Systems (Census)
GW
SW
All
15,914
1 4,632
30,546
1
0
1
0.01%
0.00%
O.01 %
1,381
1,696
3,077
1
0
1
0.07%
0.00%
0.03%
0
0
0
0.00%
0.00%
0.00%
All Systems
Total Water |
Systems1 || 33'797
1
O.01 %
3,874
1
0.03%
0
0.00%
1 Note that small water systems (population served < 10,000) conducting UCMR 1 monitoring represent a statistically representative
sub-sample of all small systems, while the UCMR 1 large water systems (population served > 10,000) represent a census of all
large systems. Comparisons and totals of raw data collected by small and large systems may not accurately represent national
occurrence.
59
-------
EPA - OGWDW
Analysis of Occurrence Data from the UCMR 1 for CCL 2
June 2008
6.3 1,3-Dichloropropene
1,3-Dichloropropene was not detected at or above the MRL of 0.05 |ig/L in any of the
3,719 samples for which it was tested (see Exhibit 6.3). 1,3-Dichloropropene was monitored and
reported by a total of 796 (99.5% of) small PWSs with all the small system data determined to be
acceptable based on data quality QA/QC criteria. This high response rate and high data quality
satisfies data quality objectives for representativeness and completeness in the small system
statistical survey, meaning that we can have reasonable confidence in an extrapolated estimate of
national occurrence. (In this case, the data indicate that 1,3-dichloropropene is not likely to be
present in the nation's small systems.) Of the 796 PWSs, 589 relied on ground water sources
and 207 on surface water sources.
1,3-Dichloropropene was not officially on the UCMR 1 monitoring list, but was added as
an extra contaminant for monitoring by the participating small systems; UCMR 1 large systems
did not monitor for 1,3-dichloropropene. Note that although the HRL for 1,3-dichloropropene
(0.4 |ig/L) is lower than the MRL used for monitoring (0.5 |ig/L), the MRL is within the 10"4 to
the 10"6 cancer risk range for 1,3-dichloropropene.19
Exhibit 6.3: Summary of Stage 1 Occurrence Measures of 1,3-Dichloropropene
Water Type
Sample-level
Number of
Samples
Detections
#
%
System -level
Number of
Systems with
1 Detection
#
%
Systems with
2 or more Detections
#
%
Small Systems (Statistical Sample)
GW
SW
All
2,556
1,163
3,719
0
0
0
0.00%
0.00%
0.00%
589
207
796
0
0
0
0.00%
0.00%
0.00%
0
0
0
0.00%
0.00%
0.00%
When EPA specified the analytical methods and the MRL for the monitoring of 1,3-dichloropropene in UCMR 1,
the Agency chose an MRL that was within the capabilities of the most commonly used methods for drinking water
laboratories at that time. The 1,3-dichloropropene MRL of 0.5ug/L is within the 10~4 to 10~6 cancer risk range, which
is considered an acceptable risk range by the Agency for occurrence analyses for carcinogens.
60
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
6.4 2,4-Dinitrotoluene
2,4-Dinitrotoluene (2,4-DNT) was detected (at or above the MRL of 2 |ig/L) in only one
sample in all of the UCMR 1 sampling (Exhibit 6.4). This single detection of 333 |ig/L was in a
surface water sample taken from an entry point source at a large system in the State of
Tennessee. The population served by this system was 37,811, which thus also represents the
total estimated national population served by systems with detections of 2,4-dinitrotoluene. The
overall occurrence rate of 2,4-dinitrotoluene in all public water systems that participated in
UCMR 1 monitoring is 0.03%. This single detection concentration was above the HRL (0.05
|ig/L) for 2,4-dinitrotoluene.
2,4-DNT data were collected and reported by 797 (99.6% of) small PWSs with all the
small system data determined to be acceptable based on data quality QA/QC criteria. This high
response rate and high data quality satisfies data quality objectives for representativeness and
completeness in the small system statistical survey, meaning that we can have reasonable
confidence in an extrapolated estimate of national occurrence (in this case, the data indicate that
2,4-DNT is not likely to be present in the nation's small systems).
2,4-DNT data were collected by 3,076 (99.2% of) large PWSs with 98.8% of large
system data determined to be acceptable based on data quality QA/QC criteria. The large system
census is therefore slightly incomplete, with a system non-response rate of 0.8%. Eighty-eight
percent of the 24 non-responsive large systems were from the "large" size category (serving
between 10,001 and 50,000 people); the remaining systems were from the "very large" size
category (serving over 50,000 people). Seventy-nine percent of the non-responsive systems were
served by ground water. The State with the greatest number of large systems that were non-
responsive for 2,4-dinitrotoluene was Louisiana (13 of the 24 non-responsive systems). The
non-response rate is smaller when assessed on a potential exposure (population-served) basis: Of
the total population served by all eligible UCMR 1 large systems, approximately 0.4% is served
by the 24 non-responsive systems. If any of these non-responsive systems actually had
detectable levels of 2,4-DNT, the UCMR 1 national results would underestimate actual
occurrence at large systems. The maximum value (upper bound) of the potential underestimation
of population served by large systems with 2,4-DNT is 0.4%.
Because the HRL for 2,4-DNT (0.05 |ig/L) is lower than the MRL used for monitoring (2
|ig/L), EPA used the MRL to formally evaluate occurrence and exposure. The MRL is within
the 10"4 to the 10"6 cancer risk range for 2,4-DNT.20
20 When EPA specified the analytical methods and the MRL for the monitoring of 2,4- and 2,6-DNT in UCMR 1,
the Agency chose an MRL that was within the capabilities of the most commonly used methods for drinking water
laboratories at that time. The 2,4- and 2,6-DNT MRL of 2 ug/L is within the 10~4 to 10~6 cancer risk range, which is
considered an acceptable risk range by the Agency for carcinogens.
61
-------
EPA - OGWDW
Analysis of Occurrence Data from the UCMR 1 for CCL 2
June 2008
Exhibit 6.4: Summary of Stage 1 Occurrence Measures of 2,4-Dinitrotoluene
Water Type
Sample-level
Number of
Samples
Detections
#
%
System -level
Number of
Systems with
1 Detection
#
%
Systems with
2 or more Detections
#
%
Small Systems (Statistical Sample)
GW
SW
All
2,342
909
3,251
0
0
0
0.00%
0.00%
0.00%
590
207
797
0
0
0
0.00%
0.00%
0.00%
0
0
0
0.00%
0.00%
0.00%
Large Systems (Census)
GW
SW
All
1 5,944
1 4,569
30,513
0
1
1
0.00%
0.01%
O.01 %
1,380
1,696
3,076
0
1
1
0.00%
0.06%
0.03%
0
0
0
0.00%
0.00%
0.00%
All Systems
Total Water II ,, TC .
Systems1 | 33'764
1
O.01 %
3,873
1
0.03%
0
0.00%
1 Note that small water systems (population served < 10,000) conducting UCMR 1 monitoring represent a statistically representative
sub-sample of all small systems, while the UCMR 1 large water systems (population served > 10,000) represent a census of all
large systems. Comparisons and totals of raw data collected by small and large systems may not accurately represent national
occurrence.
62
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
6.5 2,6-Dinitrotoluene
2,6-Dinitrotoluene (2,6-DNT) was not detected at or above the MRL of 2.0 |ig/L in any
of the 33,765 samples for which it was tested (see Exhibit 6.5). A total of 3,873 PWSs were
tested for 2,6-dinitrotoluene, of which 1,970 relied on ground water sources and 1,903 on surface
water sources.
2,6-DNT data were collected and reported by 797 (99.6% of) small PWSs with all the
small system data determined to be acceptable based on data quality QA/QC criteria. This high
response rate and high data quality satisfies data quality objectives for representativeness and
completeness in the small system statistical survey, meaning that we can have reasonable
confidence in an extrapolated estimate of national occurrence (in this case, the data indicate that
2,6-DNT is not likely to be present in the nation's small systems).
2,6-DNT data were collected by 3,076 (99.2% of) large PWSs with 98.8% of large
system data determined to be acceptable based on data quality QA/QC criteria. The large system
census is therefore slightly incomplete, with a system non-response rate of 0.8%. Eighty-eight
percent of the 24 non-responsive large systems were from the "large" size category (serving
between 10,001 and 50,000 people); the remaining systems were in from the "very large" size
category (serving over 50,000 people). Seventy-nine percent of the non-responsive systems were
served by ground water. The State with the greatest number of large systems that were non-
responsive for 2,6-dinitrotoluene was Louisiana (13 of the 24 non-responsive systems). The
large system non-response rate is smaller when assessed on a potential exposure (population-
served) basis: of the total population served by all eligible UCMR 1 large systems,
approximately 0.4% is served by the 24 non-responsive systems. If any of these non-responsive
systems actually had detectable levels of 2,6-DNT, the UCMR 1 national occurrence results
would underestimate actual occurrence at large systems. The maximum value (upper bound) of
the potential underestimation of the population served by large systems with 2,6-DNT is 0.4%.
Because the HRL for 2,6-DNT (0.05 |ig/L) is lower than the MRL used for monitoring (2
|ig/L), EPA used the MRL to formally evaluate occurrence and exposure. The MRL is within
the 10"4 to the 10"6 cancer risk range for 2,6-DNT.21
21 When EPA specified the analytical methods and the MRL for the monitoring of 2,4- and 2,6-DNT in UCMR 1,
the Agency chose an MRL that was within the capabilities of the most commonly used methods for drinking water
laboratories at that time. The 2,4- and 2,6-DNT MRL of 2 ug/L is within the 10~4 to 10~6 cancer risk range, which is
considered an acceptable risk range by the Agency for carcinogens.
63
-------
EPA - OGWDW
Analysis of Occurrence Data from the UCMR 1 for CCL 2
June 2008
Exhibit 6.5: Summary of Stage 1 Occurrence Measures of 2,6-Dinitrotoluene
Water Type
Sample-level
Number of
Samples
Detections
#
%
System -level
Number of
Systems with
1 Detection
#
%
Systems with
2 or more Detections
#
%
Small Systems (Statistical Sample)
GW
SW
All
2,342
909
3,251
0
0
0
0.00%
0.00%
0.00%
590
207
797
0
0
0
0.00%
0.00%
0.00%
0
0
0
0.00%
0.00%
0.00%
Large Systems (Census)
GW
SW
All
1 5,946
1 4,568
30,514
0
0
0
0.00%
0.00%
0.00%
1,380
1,696
3,076
0
0
0
0.00%
0.00%
0.00%
0
0
0
0.00%
0.00%
0.00%
All Systems
Total Water II ,, 7Rt.
Systems1 | 33'765
0
0.00%
3,873
0
0.00%
0
0.00%
1 Note that small water systems (population served < 10,000) conducting UCMR 1 monitoring represent a statistically representative
sub-sample of all small systems, while the UCMR 1 large water systems (population served > 10,000) represent a census of all
large systems. Comparisons and totals of raw data collected by small and large systems may not accurately represent national
occurrence.
64
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
6.6 EPTC
EPIC was not detected at or above the MRL of 1.0 jig/L in any of the 33,798 samples for
which it was tested (Exhibit 6.6). A total of 3,873 PWSs were tested for EPTC, of which 1,970
relied on ground water sources and 1,903 on surface water sources.
EPTC data were collected and reported by 797 (99.6% of) small PWSs with all the small
system data determined to be acceptable based on data quality QA/QC criteria. This high
response rate and high data quality satisfies data quality objectives for representativeness and
completeness in the small system statistical survey, meaning that we can have reasonable
confidence in an extrapolated estimate of national occurrence (in this case, the data indicate that
EPTC is not likely to be present in the nation's small systems).
EPTC data were collected by 3,076 (99.2% of) large PWSs with 98.4% of large system
data determined to be acceptable based on data quality QA/QC criteria. The large system census
is therefore slightly incomplete, with a system non-response rate of 0.8%. Eighty-eight percent
of the 24 non-responsive large systems were from the "large" size category (serving between
10,001 and 50,000 people); the remaining systems were from the "very large" size category
(serving over 50,000 people). Seventy-nine percent of the non-responsive systems were served
by ground water. The State with the greatest number of large systems that were non-responsive
for EPTC was Louisiana (13 of the 24 non-responsive systems). The large system non-response
rate is smaller when assessed on a potential exposure (population-served) basis. Of the total
population served by all eligible UCMR 1 large systems, approximately 0.4% is served by the 24
non-responsive systems. If any of these non-responsive systems actually had detectable levels of
the EPTC, the UCMR 1 national occurrence results would underestimate actual occurrence at
large systems. The maximum value (upper bound) of the potential underestimation of population
served by large systems with EPTC is 0.4%.
65
-------
EPA - OGWDW
Analysis of Occurrence Data from the UCMR 1 for CCL 2
June 2008
Exhibit 6.6: Summary of Stage 1 Occurrence Measures of EPTC
Water Type
Sample-level
Number of
Samples
Detections
#
%
System -level
Number of
Systems with
1 Detection
#
%
Systems with
2 or more Detections
#
%
Small Systems (Statistical Sample)
GW
SW
All
2,342
909
3,251
0
0
0
0.00%
0.00%
0.00%
590
207
797
0
0
0
0.00%
0.00%
0.00%
0
0
0
0.00%
0.00%
0.00%
Large Systems (Census)
GW
SW
All
1 5,947
1 4,600
30,547
0
0
0
0.00%
0.00%
0.00%
1,380
1,696
3,076
0
0
0
0.00%
0.00%
0.00%
0
0
0
0.00%
0.00%
0.00%
All Systems
Total Water II
Systems1 | 33'798
0
0.00%
3,873
0
0.00%
0
0.00%
1 Note that small water systems (population served < 10,000) conducting UCMR 1 monitoring represent a statistically representative
sub-sample of all small systems, while the UCMR 1 large water systems (population served > 10,000) represent a census of all
large systems. Comparisons and totals of raw data collected by small and large systems may not accurately represent national
occurrence.
66
-------
EPA - OGWDW
Analysis of Occurrence Data from the UCMR 1 for CCL 2
June 2008
6.7 Fonofos
Fonofos was not detected at or above the MRL of 0.5 jig/L in any of the 2,306 samples
for which it was tested (see Exhibit 6.7). A total of 295 PWSs collected occurrence data for
fonofos, of which 164 relied on ground water sources and 131 on surface water sources. Testing
for fonofos was part of the List 2 Screening Survey, which is why far fewer systems were
sampled for fonofos than for the other contaminants discussed in this chapter, which were all List
1 contaminants. Of the 180 small PWSs selected for List 2 monitoring, 178 (98.9%) collected
and reported occurrence data for fonofos with all the small system data determined to be
acceptable based on data quality QA/QC criteria. Fonofos data were submitted by a total of 117
(97.5%) of the 120 large PWSs selected for List 2 monitoring with 2.8% of the large system
records removed because they did not meet QA/QC criteria. This high response rate and high
data quality indicates that these List 2 results for fonofos provide reasonable confidence in an
extrapolated estimate of national occurrence (in this case, the data indicate that fonofos is not
likely to be present in the nation's small or large systems).
Exhibit 6.7: Summary of Stage 1 Occurrence Measures of Fonofos
Water Type
Sample-level
Number of
Samples
Detections
#
%
System -level
Number of
Systems with
1 Detection
#
%
Systems with
2 or more Detections
#
%
Small Systems (Statistical Sample)1
GW
SW
All
380
263
643
0
0
0
0.00%
0.00%
0.00%
114
64
178
0
0
0
0.00%
0.00%
0.00%
0
0
0
0.00%
0.00%
0.00%
Large Systems (Statistical Sample)2
GW
SW
All
883
780
1,663
0
0
0
0.00%
0.00%
0.00%
50
67
117
0
0
0
0.00%
0.00%
0.00%
0
0
0
0.00%
0.00%
0.00%
All Systems
Total Water II
Systems || 2'306
0
0.00%
295
0
0.00%
0
0.00%
1 The 178 small water systems (population served < 10,000) conducting UCMR 1 List 2 monitoring represent a statistically
representative sub-sample of the 800 small systems selected to participate in List 1 monitoring.
2 The 117 large water systems (population served > 10,000) conducting UCMR 1 List 2 monitoring represent a statistically
representative sub-sample of the 3,100 large systems that participated in List 1 monitoring.
67
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
6.8 MTBE
MTBE was detected at or above the MRL of 5 |ig/L in 26 (0.08%) of 33,768 samples
collected. MTBE occurred in both ground water and surface water systems, but was more
prevalent in ground water (see Exhibit 6.8.a). Occurrence rates in small systems (0.38%) and
large systems (0.52%) were not markedly different, with an overall (small and large system) rate
of 0.49%. UCMR 1 monitoring identified MTBE occurrence at 19 PWSs located in 14 States.
Seven of those 19 PWSs had multiple detections of this contaminant. Extrapolated to the
national level, these findings suggest that approximately 900,000 persons were served by
drinking water systems with detectable levels of MTBE (see Exhibit 6.8.c). (See Section 4 for
an explanation of small system national extrapolations.) The average value among MTBE
detections was 15.2 |ig/L and the median value was 9.2 |ig/L. There currently is no HRL
available for MTBE, so occurrence was assessed only relative to the MRL.
MTBE data were collected by 796 (99.5% of) small PWSs with all the small system data
determined to be acceptable based on data quality QA/QC criteria. This high response rate and
high data quality satisfies data quality objectives for representativeness and completeness in the
small system statistical survey, meaning that we can have reasonable confidence in the
extrapolated estimate of national occurrence at small systems.
MTBE data were collected by 3,075 (99.2% of) large PWSs with 98.8% of large system
data determined to be acceptable based on data quality QA/QC criteria. The large system census
is therefore slightly incomplete, with a system non-response rate of 0.8%. Eighty-four percent of
the 25 non-responsive large systems were from the "large" size category (serving between
10,001 and 50,000 people), and the remaining 16% were from the "very large" size category
(serving more than 50,000 people). Seventy-two percent of the non-responsive systems were
served by ground water (the source water type with higher MTBE occurrence). The States with
the greatest number of large systems that were non-responsive for MTBE were Louisiana and
New Jersey (each State had 5 of the 25 non-responsive systems). None of the 57 large and very
large PWSs that did report MTBE results in Louisiana had any detections of MTBE. Of the 107
large and very large PWSs in New Jersey that did report MTBE results, about 1.9% found
MTBE detections. (Nationally, 0.52% of large and very large systems found MTBE detections.)
The large system non-response rate is smaller when assessed on a potential exposure
(population-served) basis. Of the total population served by all eligible UCMR 1 large systems,
approximately 0.5% is served by the 25 non-responsive systems. If any of these non-responsive
systems actually had detectable levels of MTBE, UCMR 1 results would underestimate actual
MTBE occurrence at large systems. The maximum value (upper bound) of the potential
underestimation of population served by large systems with MTBE is 0.5%.
68
-------
EPA - OGWDW
Analysis of Occurrence Data from the UCMR 1 for CCL 2
June 2008
Exhibit 6.8.a: Summary of Stage 1 Occurrence Measures of MTBE
Water Type
Sample-level
Number of
Samples
Detections
#
%
System-level
Number of
Systems with
1 Detection
#
%
Systems with
2 or more Detections
#
%
Small Systems (Statistical Sample)
GW
SW
All
2,341
927
3,268
3
0
3
0.13%
0.00%
0.09%
589
207
796
3
0
3
0.51%
0.00%
0.38%
0
0
0
0.00%
0.00%
0.00%
Large Systems (Census)
GW
SW
All
15,924
1 4,576
30,500
17
6
23
0.11%
0.04%
0.08%
1,381
1,694
3,075
12
4
16
0.87%
0.24%
0.52%
5
2
7
0.36%
0.12%
0.23%
All Systems
Total Water II
Systems1 | 33'768
26
0.08%
3,871
19
0.49%
7
0.18%
1 Note that small water systems (population served < 10,000) conducting UCMR 1 monitoring represent a statistically representative
sub-sample of all small systems, while the UCMR 1 large water systems (population served > 10,000) represent a census of all
large systems. Comparisons and totals of raw data collected by small and large systems may not accurately represent national
occurrence.
Exhibit 6.8.b: National Extrapolation of Stage 1 Occurrence Measures of
MTBE in Small PWSs
Water
Type
System Size
by Population
Served
Total Number
Sys
Pop
Detections (> MRL)
UCMR 1 Data
Sys
Pop
Percentage
Sys
Pop
National
Extrapolation
Sys
Pop
Small Systems
GW
SW
<500
501 - 3,300
3,301 -10,000
Total
<500
501 - 3,300
3,301 -10,000
Total
All Small Systems
111
244
234
589
52
45
110
207
796
27,599
439,011
1,470,717
1,937,327
16,662
91,723
712,370
820,755
2,758,082
0
3
0
3
0
0
0
0
3
0
4,150
0
4,150
0
0
0
0
4,150
0.00%
1 .23%
0.00%
0.51%
0.00%
0.00%
0.00%
0.00%
0.38%
0.00%
0.95%
0.00%
0.21%
0.00%
0.00%
0.00%
0.00%
0.15%
0
149
0
149
0
0
0
0
149
0
147,000
0
147,000
0
0
0
0
147,000
No HRL has been established for MTBE.
69
-------
EPA - OGWDW
Analysis of Occurrence Data from the UCMR 1 for CCL 2
June 2008
Exhibit 6.8.c: Stage 1 National Occurrence Measures of MTBE Based on UCMR 1
Large System and Extrapolated Small System Data
Water Type
System Size by
Population
Served
Detections (> MRL)
Number
Sys
Pop
Percentage
Sys
Pop
Small Systems
GW
SW
<500
501 - 3,300
3,301 - 10,000
Total
<500
501 - 3,300
3,301 -10,000
Total
All Small Systems
0
149
0
149
0
0
0
0
149
0
147,000
0
147,000
0
0
0
0
147,000
0.00%
1 .23%
0.00%
0.51%
0.00%
0.00%
0.00%
0.00%
0.38%
0.00%
0.95%
0.00%
0.21%
0.00%
0.00%
0.00%
0.00%
0.15%
Large Systems
GW
SW
10,001 -50,000
> 50,000
Total
10,001 -50,000
> 50,000
Total
All Large Systems
9
3
12
2
2
4
16
179,894
241 ,292
421,186
55,388
272,909
328,297
749,483
0.76%
1 .59%
0.87%
0.17%
0.39%
0.24%
0.52%
0.67%
0.92%
0.79%
0.17%
0.20%
0.19%
0.34%
All Systems (National Extrapolation plus Census)
Total Water Systems
165
896,483
0.49%
0.33%
No HRL has been established for MTBE.
Sample-point-level occurrence analyses for MTBE are presented in Exhibit 6.8.d. No
small systems had more than a single detection at a single SP. A total of 4 large PWSs, serving
approximately 97,000 persons, had multiple detections of MTBE at a single sampling point.
Three large PWSs, serving 99,000 persons, had MTBE detections at multiple SPs. Using another
measure of occurrence, the sampling point (SP) proportional population, it is estimated that
approximately 0.1% of the population served by PWSs nationally, or 199,000 persons, is served
by entry points/sample points with detections of MTBE. (This proportional population served by
sample points with detections, a less conservative measure of occurrence, is calculated by
multiplying a PWS's total population served by the percentage of that PWS's sampling points
with a contaminant detection. Refer to Section 4.3 for more details regarding the proportional
population analysis.)
70
-------
EPA - OGWDW
Analysis of Occurrence Data from the UCMR 1 for CCL 2
June 2008
Exhibit 6.8.d: Summary of Sample-Point-Level Occurrence Measures of MTBE Based on UCMR 1 Small System
Extrapolated Data and Large System Census Data
Water
Type
Total
Sys
SPs
Pop
At Least 2 Detections
at 1 SP
Systems
#
%
Population
#
%
At Least 1 Detect
at 2 SPs
Systems
#
%
Population
#
%
SP Proportional Population With
At Least One Detection
SPs 1
#
%
Population 2
#
%
Small Systems
GW
SW
All
589
207
796
1,207
243
1,450
1,937,327
820,755
2,758,082
0
0
0
0.00%
0.00%
0.00%
0
0
0
0.00%
0.00%
0.00%
0
0
0
0.00%
0.00%
0.00%
0
0
0
0.00%
0.00%
0.00%
147
0
147
0.25%
0.00%
0.21%
87,000
0
87,000
0.13%
0.00%
0.09%
Large Systems
GW
SW
All3
1,381
1,694
3,075
8,161
5,281
13,442
53,273,126
169,958,828
223,231,954
3
1
4
0.22%
0.06%
0.13%
74,000
22,000
97,000
0.14%
0.01 %
0.04%
2
1
3
0.14%
0.06%
0.10%
30,000
69,000
99,000
0.06%
0.04%
0.04%
14
5
19
0.17%
0.09 %
0.14%
77,000
35,000
112,000
0.14%
0.02%
0.05%
All Small plus Large Systems
All
Systems
3,871
14,892
225,990,036
4
0.10%
97,000
0.04%
3
0.08%
99,000
0.04%
166
0.15%
199,000
0.05%
All Population values are rounded to the nearest thousand.
1 The extrapolated number of small system sample points with a contaminant detection was estimated by multiplying the percentage of UCMR 1 small system sample points with a
contaminant detection by the total number of sample points nationally. The national number of small system sample points was estimated by multiplying the average number of sample
points for a system water type category by the total number of systems nationally in that category. (The average number of sampling points per system was obtained from the Community
Water System Survey 2000, Volume II Detailed Tables and Survey Methodology.) The large system sample point numbers presented in this table are direct counts of the UCMR 1 large
system data (no extrapolations are necessary).
2 Sample point proportional population was calculated by multiplying each system's total population served by the percentage of that PWS's sampling points found with a contaminant
detection.
3 Due to rounding, the GW and SW population values do not add up to the total population value.
71
-------
EPA - OGWDW
Analysis of Occurrence Data from the UCMR 1 for CCL 2
June 2008
Exhibit 6.8.e illustrates the proportion of systems with MTBE detections in various
percentages of their SPs. Note that there were only 19 systems with detections of MTBE. Sixty-
three (63) percent of systems with detections of MTBE had detections in 25% of their SPs or
less. Only 11% of systems with detections had detections in more than 50% of their SPs. When
MTBE was detected, it was more often than not detected in only one SP. (Note that for all
UCMR 1 systems with MTBE detections, 11% had only 1 SP.)
Exhibit 6.8.e: Percentage of SPs with Detections of MTBE (Among Systems with
At Least One Detection)
63% of PWSs had
detections in
< 25% of SPs
26% of PWSs had
detections in
25% - 50% of SPs
11% of PWSs had
detections in
75%-100%ofSPs
0% of PWSs had
detections in
50% - 75% of SPs
72
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
6.9 Terbacil
Terbacil was not detected at or above the MRL of 2.0 jig/L in any of the 33,800 samples
for which it was tested (see Exhibit 6.9). A total of 3,873 PWSs were tested for terbacil, of
which 1,970 relied on ground water sources and 1,903 on surface water sources.
Terbacil data were collected by 797 (99.6% of) small PWSs and all small system data for
terbacil were determined to be acceptable based on data quality QA/QC criteria. This high
response rate satisfies data quality objectives for representativeness and completeness in the
small system statistical survey, meaning that we can have reasonable confidence in an
extrapolated estimate of national occurrence (in this case, the data indicate that terbacil is not
likely to be present in the nation's small systems).
Terbacil data were collected by 3,076 (99.2% of) large PWSs with 98.4% of large system
data determined to be acceptable based on data quality QA/QC criteria. The large system census
is therefore slightly incomplete, with a system non-response rate of 0.8%. Eighty-eight percent
of the 24 non-responsive large systems were from the "large" size category (serving between
10,001 and 50,000 people); the remaining systems were from the "very large" size category.
Seventy-nine percent of the non-responsive systems were served by ground water. The State
with the greatest number of large systems that were non-responsive for terbacil was Louisiana
(13 of the 24 non-responsive systems). The non-response rate is smaller when assessed on a
potential exposure (population-served) basis. Of the total population served by all eligible
UCMR 1 large systems, approximately 0.4% is served by the 24 non-responsive systems. If any
of these non-responsive systems actually had terbacil occurrence, the UCMR results would
underestimate actual occurrence. The maximum value (upper bound) of the potential
underestimation of the population served by systems with detections of terbacil is 0.4%.
73
-------
EPA - OGWDW
Analysis of Occurrence Data from the UCMR 1 for CCL 2
June 2008
Exhibit 6.9: Summary of Stage 1 Occurrence Measures of Terbacil
Water Type
Sample-level
Number of
Samples
Detections
#
%
System -level
Number of
Systems with
1 Detection
#
%
Systems with
2 or more Detections
#
%
Small Systems (Statistical Sample)
GW
SW
All
2,342
909
3,251
0
0
0
0.00%
0.00%
0.00%
590
207
797
0
0
0
0.00%
0.00%
0.00%
0
0
0
0.00%
0.00%
0.00%
Large Systems (Census)
GW
SW
All
15,934
14,615
30,549
0
0
0
0.00%
0.00%
0.00%
1,380
1,696
3,076
0
0
0
0.00%
0.00%
0.00%
0
0
0
0.00%
0.00%
0.00%
All Systems
Total Water II
Systems1 | 33'800
0
0.00%
3,873
0
0.00%
0
0.00%
1 Note that small water systems (population served < 10,000) conducting UCMR 1 monitoring represent a statistically representative
sub-sample of all small systems, while the UCMR 1 large water systems (population served > 10,000) represent a census of all
large systems. Comparisons and totals of raw data collected by small and large systems may not accurately represent national
occurrence.
74
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
75
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
7. Stage 2 Occurrence Estimates ~ An Example
At this time, EPA has concluded that none of the UCMR 1 contaminants assessed for
regulatory determination warrant a Stage 2 analysis of occurrence. This conclusion is based on
either Stage 1 analytical findings (Section 6) that indicate no significant occurrence at or near the
HRLs and/or the contaminant may potentially have acute (rather than chronic) effects such that
Stage 2 would not have been appropriate. Therefore, the additional effort to conduct the Stage 2
analyses is not warranted. However, to illustrate the second stage of the two-stage occurrence
analytical approach, a Stage 2 analysis is conducted on DCPA degradates. Summary findings
are presented below and detailed Stage 2 occurrence findings tables are included in Appendix C.
7.1 DCPA Mono- and Di-Acid Degradates
The Stage 2 occurrence findings for DCPA degradates are presented in Exhibits 7.1 .a and
7.1 .b. These are best estimates of the number and percent of PWSs with estimated DCPA
degradate mean concentrations greater than or equal to the MRL and greater than /^ the HRL and
HRL. The Stage 2 findings are based on estimated PWS annual mean concentrations of a
contaminant and therefore reflect long-term occurrence. The statistically modeled best estimate
values, including 90% and 95% confidence interval ranges around the best estimate value, are
presented in Appendix C. (For more details regarding the Stage 2 analytical approach, refer to
Appendix B of this report and USEPA, 2003a.)
Sixty-eight small PWSs nationally serving 21,500 persons are estimated to have a mean
concentration of DCPA mono- and di-acid degradates exceeding the HRL of 70 |ig/L (Exhibit
7.1.a). Approximately 75 small PWSs nationally serving 23,500 persons are expected to have an
estimated mean concentration exceeding the 1A HRL of 35 |ig/L. A total of 645 small PWSs
nationally serving 571,300 persons are estimated to have a mean concentration exceeding 1
|ig/L. A significantly higher proportion of small ground water PWSs are expected to have mean
concentrations with exceedances compared to small surface PWSs water systems.
76
-------
EPA - OGWDW
Analysis of Occurrence Data from the UCMR 1 for CCL 2
June 2008
Exhibit 7.1.a: DCPA Degradates Stage 2 Occurrence Results for Small Systems
Source Water
Type
Ground Water
Threshold
(H9/L)
70
35
1
Small Systems Estimated
to Exceed Threshold
Number1'2
86
94
789
Percent
0.15%
0.17%
1.41%
Population Served by Small Systems
Estimated to Exceed Threshold
Number 1'2
26,200
28,700
687,400
Percent
0.07%
0.08%
1.90%
Surface Water
70
35
1
0
0
4
0.00%
0.00%
0.10%
0
0
4,200
0.00%
0.00%
0.05%
Total
(Ground Water +
Surface Water)
70
35
1
68
75
645
0.11%
0.12%
1.07%
21,500
23,500
571,300
0.05%
0.05%
1 .26%
1 The number of systems and population served by systems presented in this table reflect national extrapolations.
2 These probabilistic estimates are modeled separately for each level of aggregation (e.g., ground water, surface water, and total
ground water plus surface water). Therefore, model estimates for the individual source water stratum will not sum to the Total
Ground Water + Surface Water estimate because the separate stratified and total estimates are based on a different number of
samples (different "n" for each estimate). The Total Ground & Surface Water estimate is based on the higher number of samples so
likely represents the more robust estimate.
An even smaller number of large systems are estimated to have mean concentrations of
the DCPA mono- and di-acid degradates exceeding 35 |ig/L or 70 |ig/L (Exhibit 7.1.b). In
contrast, based on simple detections (concentrations above 1 |ig/L), model estimated occurrence
in large PWSs is greater than that for small PWSs. Sixty-two large PWSs nationally serving 4.6
million persons are estimated to have a mean concentration exceeding 1 |ig/L. Similar to the
small PWSs, more large ground water systems are expected to have mean concentrations with
exceedances compared to large surface water systems.
77
-------
EPA - OGWDW
Analysis of Occurrence Data from the UCMR 1 for CCL 2
June 2008
Exhibit 7.1.b: DCPA Degradates Stage 2 Occurrence Results for Large Systems
Source Water
Type
Ground Water
Threshold
(H9/L)
70
35
1
Large Systems Estimated
to Exceed Threshold
Number1
0
0
41
Percent 2
<0.01%
<0.01%
2.95%
Population Served by Large Systems
Estimated to Exceed Threshold
Number1
0
0
1,589,600
Percent 2
<0.01%
<0.01%
2.97%
Surface Water
70
35
1
0
0
21
0.00%
<0.01%
1 .27%
0
0
2,117,100
0.00%
<0.01%
1 .26%
Total
(Ground Water +
Surface Water)
70
35
1
0
0
62
<0.01%
<0.01%
2.03%
0
0
4,589,600
<0.01%
<0.01%
2.07%
1 These probabilistic estimates are modeled separately for each level of aggregation (e.g., ground water, surface water, and total
ground water plus surface water). Therefore, model estimates for the individual source water stratum will not sum to the Total
Ground Water + Surface Water estimate because the separate stratified and total estimates are based on a different number of
samples (different "n" for each estimate). The "Total (Ground Water + Surface Water)" estimate is based on the higher number of
samples so likely represents the more robust estimate.
2
Percentage values less than 0.01 % are effectively equal to zero (0) when carried through in the Stage 2 computations.
Exhibits 7.1.c and 7.1.d present a comparison of the Stage 1 findings to the Stage 2 best
estimate findings for the small systems and large systems, respectively. Note that this table
compares the two different types of analytical findings of the Stage 1 (non-parametric "peak"
concentration values) and the Stage 2 (parametric "long-term" mean concentration values)
analyses. This comparison is included as a general, qualitative evaluation of the Stage 2 model
as well as a means to develop a sense of how straightforward Stage 1 findings relate to the
statistically modeled Stage 2 findings. For the small systems, the Stage 1 findings (percent of
systems with at least one analytical result greater than a specified threshold) are always higher
than the Stage 2 findings (percent of systems with an estimated mean concentration greater than
the threshold). Similarly, the large system Stage 1 findings are consistently higher than the large
system Stage 2 findings. The one apparent exception is the percentage of systems and
population served by systems with mean concentrations greater than 70 |ig/L. The Stage 2
model estimates an extremely small proportion of large systems that apparently have a mean
concentration greater than this threshold while the Stage 1 analysis found that no large systems
had any results greater than 70 |ig/L. The Stage 2 percentage findings, however, are effectively
zero, reflecting less that 1 system and less than 5,000 population served.
78
-------
EPA - OGWDW
Analysis of Occurrence Data from the UCMR 1 for CCL 2
June 2008
Exhibit 7.1.c: Comparison of DCPA Degradates Stage 1 and Stage 2 Occurrence
Results for Small Systems
Threshold
Number > Threshold 1
Stage 1
Stage 2
Percent > Threshold
Stage 1
Stage 2
Systems
70 ng/L (HRL)
35 ng/L (1/2 HRL)
1 ng/L (MRL)
373
373
689
68
75
645
0.13%
0.13%
2.13%
0.11%
0.12%
1.07%
Population Served
70 ng/L (HRL)
35 ng/L (1/2 HRL)
1 |ig/L (MRL)
112,900
112,900
1,117,300
21,500
23,500
571,300
0.018%
0.018%
3.19%
0.047%
0.052%
1 .28%
1 These numbers are national estimates (i.e., they have been extrapolated). Note that the Stage 1 extrapolations were generated by
extrapolating each individual strata and then adding up those extrapolations to yield the total (presented here). The Stage 2
extrapolations, however, were directly calculated for all strata, including the "total" level presented here.
Exhibit 7.1.d: Comparison of DCPA Degradates Stage 1 and Stage 2 Occurrence
Results for Large Systems
Threshold
Number > Threshold
Stage 1
Stage 2
Percent > Threshold
Stage 1
Stage 2 1
Systems
70 ng/L (HRL)
35 ng/L (1/2 HRL)
1 ng/L (MRL)
0
1
158
0
0
62
0.00%
0.033%
5.14%
<0.01%
<0.01%
2.03%
Population Served
70 ng/L (HRL)
35 ng/L (1/2 HRL)
1 ng/L (MRL)
0
738,337
11,220,836
0
0
4,589,600
0.00%
0.33%
5.05%
<0.01%
<0.01%
2.07%
Percentage values less than 0.01 % are effectively equal to zero (0) when carried through in the Stage 2 computations.
79
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
8. Spatial and Graphical Assessments of Contaminants
Up to three of the contaminants considered during CCL 2 regulatory determinations
monitored under UCMR 1 were detected in multiple PWSs. Spatial and graphical assessments
are provided in this section for these three contaminants (DCPA mono- and di-acid degradates,
reported in aggregate, and MTBE). DDE and 2,4-dinitrotoluene were each detected only once;
thus no spatial assessments are presented for those two. Breakdowns of sampling efforts by
State for each of the ten contaminants considered during CCL 2 regulatory determinations can be
found in Appendix G.
8.1 DCPA Mono- and Di-Acid Degradates
Public water systems with DCPA degradate detections (at concentrations > 1 |ig/L) were
distributed across 24 States and the Territory of Guam (Exhibit 8.1.a). Systems with detections
were found in four general State/region groupings: California and the western Rocky Mountain
States, the Southeast, the Northeast, and the upper Midwest. These States cover a broad enough
area that no geological or hydrological trend unites them all; however, the United States
Geological Survey (USGS, 2004) identified similar States in its map of estimated annual
agricultural uses of DCPA.22 (Generally, areas of high use were located along the entire eastern
seaboard, in the Great Lakes States, and in a large, ten-State area of the west, stretching from
Washington and Idaho to California, Colorado, and Texas.) While many States had detections of
the DCPA degradates, only one State, Michigan, had a detected concentration above the HRL of
70 |ig/L; the concentration of this detection was 190 |ig/L. The following maps, based on
UCMR 1 data, give an indication of the geographic distribution of DCPA degradate occurrence
in drinking water. Exhibit 8.1.a shows the distribution of States with at least one detection.
Exhibit S.l.b shows the relative frequency of detection in those States.
DCPA has historically been used as a selective pre-emergence weed control on ornamental turf and plants,
strawberries, seeded and transplanted vegetables, cotton, and field beans (USEPA, 1998).
80
-------
EPA - OGWDW
Analysis of Occurrence Data from the UCMR 1 for CCL 2
June 2008
Exhibit 8.1.a: Geographic Distribution of the DCPA Degradates - States
with At Least One Detection Equal to or Above the MRL (> 1 ug/L)
• Guam U Mariana Is.
(~l Virgin Is. [~] Puerto Rico
D Tribes
Entities with No Ort&ctions
i-ntilws with DHtediwiM"-- I I
Exhibit 8.1.b: Geographic Distribution of the DCPA Degradates - State
Percentage of PWSs with At Least One Detection Equal to or Above the
MRL (> 1 ug/L)
[-. n
• Guam L Mariana Is.
LJ Virgin Is. LJ Puerto Rico
l~ Tribes
Ertitiw with No Oet«bws
Entities wim Oststlions at 0 01 - 5.00 % of PWSs
tnlilies witti Dstections al 5 01 • It 00 % Ol PWSs
Ent*85 with Detedions at 15 01 - 42 00 % ot PWSs
Note: This map depicts UCMR 1 results from both small systems and large systems. The statistical selection of
UCMR 1 small systems was designed to be representative at the national level, but not at the State level. Therefore,
this map should only be considered an approximation of State-level patterns of contaminant occurrence.
81
-------
EPA - OGWDW
Analysis of Occurrence Data from the UCMR 1 for CCL 2
June 2008
Exhibit S.l.c illustrates the geographic distribution of PWSs that detected DCPA
degradates at various concentrations. Specifically, this map shows the maximum concentration
of the DCPA degradates at each system where DCPA degradates were found in UCMR 1
sampling. This map shows that the 177 systems with detections of the DCPA degradates are
generally restricted to a few areas: California and Arizona, the Salt Lake City region, Nebraska,
the Minneapolis-St. Paul metropolitan area, southern Lake Michigan, and the broad area from
Philadelphia to New York City and southern New England. The densest grouping of high-
concentration detections is in the Philadelphia to New York City vicinity. It is important to note,
however, that all the DCPA degradate detections - with the exception of a single detection in
Michigan - have concentrations below the HRL of 70 |ig/L.
Exhibit 8.1.c: System-Level Geographic Distribution of the DCPA Degradates-
Maximum Concentration of Detections per System
82
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
8.2 MTBE
MTBE was detected in 14 States and no territories (see Exhibit 8.2.a). No strong
geographic trend is apparent, though many States in the Northeast detected MTBE. The
Northeast States, plus California and Missouri, broadly constitute the areas of the United States
where MTBE use as a gasoline additive has been greatest due to requirements of the Federal
Reformulated Gasoline (RFG) Program. For more information on uses of MTBE, refer to
USEPA (2008b). The four States with the highest percentage of systems with MTBE detections
were New Hampshire, New Mexico, South Dakota and West Virginia. New Hampshire has a
well-documented history of MTBE contamination as a result of oxygenated fuels and New
Mexico (specifically, the city of Albuquerque) used MTBE as a fuel additive due to its
participation in the Winter Oxygenated Fuel Program (USEPA, 200Ic). However, neither South
Dakota nor West Virginia participated in the RFG or Winter Oxyfuel Programs (USEPA, 200Ic
and 2005). Until 2001, South Dakota allowed MTBE to be mixed with gasoline up to 2% by
volume; now there is a ban limiting MTBE concentrations in gasoline to trace amounts (0.5% by
volume) (USEPA, 2004). West Virginia has not placed any statewide limitations on the use of
MTBE in gasoline. Exhibit 8.2.a shows the distribution of States with at least one detection.
Exhibit 8.2.b shows the relative frequency of detection in those States.
83
-------
EPA - OGWDW
Analysis of Occurrence Data from the UCMR 1 for CCL 2
June 2008
Exhibit 8.2.a: Geographic Distribution of MTBE - States with At Least One
Detection Equal to or Above the MRL (> 5 ug/L)
1i n
CCD
[ I Guam G Mariana Is.
D Virgin Is. n Puerto Rico
U Tribes
) lEnlHies wilh No Detections
• Eritiitv, vviltl Detections I? 5 ug/L)
Exhibit 8.2.b: Geographic Distribution of MTBE - State Percentage of PWSs with
At Least One Detection Equal to or Above the MRL (> 5 ug/L)
! 1 Guam D Mariana It.
D Virgin Is. D Puerto Rico
U Tribes
Q]Entllioswi»lD«l!DO)- !00%oIPW3s
| EnXliss wilh Detections 8t1.01-2.W%0f PWSs
• Mitres wilh Deteciions el J 51 - 10 00 % of PWSs
Note: This map depicts UCMR 1 results from both small systems and large systems. The statistical selection of
UCMR 1 small systems was designed to be representative at the national level, but not at the State level. Therefore,
this map should only be considered an approximation of State-level patterns of contaminant occurrence.
84
-------
EPA - OGWDW
Analysis of Occurrence Data from the UCMR 1 for CCL 2
June 2008
Exhibit 8.2.c shows the maximum concentration at each system where MTBE was
detected. No particular geographic pattern is evident.
Exhibit 8.2.c: System-Level Geographic Distribution of MTBE -
Maximum Concentration of Detections per System
85
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
9. Summary of Findings
The most current and complete version of the UCMR 1 data set, the March 2006 version,
contains more than 400,000 individual sample analytical results for a total of 26 contaminants.
Ten of those contaminants (those that were considered during CCL 2 regulatory determinations
monitored under the UCMR 1) are described in detail in this report. Contaminant samples were
collected between May 2000 and October 2005, with almost 95% collected between January
2001 and December 2003. Data were collected from all 50 States, plus Washington D.C., Tribal
Nations, Puerto Rico, the American Virgin Islands, Guam, and the Commonwealth of the
Northern Mariana Islands. List 1 Assessment Monitoring was completed by 797 (99.6%) of the
800 selected small systems and 3,090 (99.7%) of the complete census of 3,100 large systems.
List 2 Screening Survey monitoring was completed by 178 (98.9%) of the 180 selected small
systems and 117 (97.5%) of the 120 selected large systems.
Five of the ten CCL 2 contaminants monitored under UCMR 1 were not detected at all.
These included fonofos (results from 295 large and small systems), 1,3-dichloropropene (results
from 796 small systems), and 2,6-dinitrotoluene, EPTC, and terbacil (results from 3,873 large
and small systems). DDE and 2,4-dinitrotoluene, monitored at 3,874 and 3,873 systems,
respectively, were each detected exactly once. DDE was detected in one large ground water
system in Alabama at a concentration of 3 |ig/L. 2,4-Dinitrotoluene was detected in one large
surface water system in Tennessee at a concentration of 333 |ig/L. Up to three contaminants (the
two DCPA degradates, reported in aggregate, and MTBE) had multiple detections in multiple
States, and these are discussed in more detail below.
The DCPA degradates were detected in approximately 4.57% of all participating large
and small systems (776 detections at 177 PWSs). This corresponds to an estimated 849 systems
serving approximately 12.4 million people nationally. The maximum detected concentration of
the DCPA degradates was 190 |ig/L, the 99th percentile concentration among detections was 18
|ig/L, the average concentration among detections was 3.48 |ig/L and the median concentration
among detections was 2.00 |ig/L. The highest concentration detected among large systems was
39 |ig/L. Only two PWSs (one small system and one large system) detected concentrations
greater than 35 |ig/L (1A HRL), and only one small PWS detected concentrations greater than 70
|ig/L (the HRL).
MTBE was detected in both ground water and surface water, but was more prevalent in
ground water. Approximately 0.49% of all large and small participating systems had at least one
detection of MTBE (a total of 26 detections from 19 PWSs). This corresponds to an estimated
165 systems serving approximately 896,000 people nationally. The maximum detected
concentration of MTBE was 49 |ig/L, the 99l percentile concentration among detections was 49
|ig/L, the average concentration among detections was 15.2 |ig/L, and the median concentration
among detections was 9.2 |ig/L. There is currently no HRL for MTBE.
86
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
87
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
10. References
The Cadmus Group, Inc. 2002. Unregulated Contaminant Monitoring Regulation:
Implementation Report. Draft report submitted to EPA for review March 20, 2002.
Lockwood, J.R. Ill, MJ. Schervish, P. Gurian, andMJ. Small. 2001. Characterization of
Arsenic Occurrence in US Drinking Water Treatment Facility Source Waters. Journal of
the American Statistical Association, Vol. 96, 2001.
Ott, W.R. 1995. Environmental Statistics and Data Analysis. Boca Raton, FL: Lewis
Publishers.
USEPA. 1999. Revisions to the Unregulated Contaminant Monitoring Regulation for Public
Water Systems. Federal Register. Vol. 64, no. 180, p. 50556, September 17, 1999.
USEPA. 2000. Technical Background Information for the Unregulated Contaminant
Monitoring Regulation. Office of Water. 69pp. Available on the Internet at:
http://www.epa.gov/safewater/ucmr/ucmrl/pdfs/guidance_ucmr l_tech_background.pdf
USEPA. 200la. Reference Guide for the Unregulated Contaminant Monitoring Regulation.
EPA815-R-01-023. Office of Water. 65pp. Available on the Internet at:
http://www.epa.gov/OGWDW/ucmr/ucmr 1 /pdfs/guidance_ucmr 1 _ref_gui de.pdf.
USEPA. 2001b. Statistical Design and Sample Selection for the Unregulated Contaminant
Monitoring Regulation (1999). EPA 815-R-01-004. Office of Water. 36pp.
USEPA. 200 Ic. State Winter Oxygenated Fuel Program Requirements for Attainment or
Maintenance of CO NAAQS. Office of Transportation and Air Quality. 4 pp. Available
on the Internet at: http://www.epa.gov/otaq/regs/fuels/oxy-area.pdf.
USEPA. 2003 a. Occurrence Estimation Methodology and Occurrence Findings for Six-Year
Review of National Primary Drinking Water Regulations. EPA 815-R-03-006. Office of
Water.
USEPA. 2003b. Quality Assurance Project Plan for the Implementation of the Unregulated
Contaminant Monitoring Regulation. Draft EPA Report. Office of Water.
USEPA. 2003c. Drinking Water Baseline Handbook, Fourth edition.
USEPA. 2004. State Actions Banning MTBE (Statewide). 3 pp. Available on the Internet at:
http://www.epa.gov/mtbe/420b04009.pdf.
USEPA. 2005. Where You Live [Webpage]. Available on the Internet at:
http://www.epa.gov/otaq/rfg/whereyoulive.htm. Accessed May 24, 2005. Last updated
May 13, 2005.
-------
EPA - OGWDW Analysis of Occurrence Data from the UCMR 1 for CCL 2 June 2008
USEPA. 2008a. The Analysis of Occurrence Data from the Unregulated Contaminant
Monitoring (UCM) Program and National Inorganics and Radionuclides Survey (MRS)
in Support of Regulatory Determinations for the Second Drinking Water Contaminant
Candidate List. EPA 815-R-08-014. June 2008.
USEPA. 2008b. Regulatory Determinations Support Document for Selected Contaminants from
the Second Drinking Water Contaminant Candidate List (CCL 2). EPA 815-R-08-012.
June 2008.
United States Geological Survey (USGS). 2004. Annual Use Maps. Available on the Internet
at: http://ca.water.usgs.gov/pnsp/use92/dcpa.html. Accessed October 24, 2005.
89
-------
APPENDICES
Appendix A.
Appendix B.
Appendix C.
Appendix D.
Appendix E.
Appendix F.
Appendix G.
Appendix H.
Stage 1 Occurrence Measures for All Other UCMR 1
Contaminants (Non-CCL 2 Regulatory Determination
Contaminants)
Detailed Description of Stage 2 (Bayesian-Based) Hierarchical
Model
Stage 2 Occurrence Measures for DCPA Degradates
Detailed Description of UCMR Large System Population-Served
Adjustments
Development of Health Reference Levels (HRLs)
Detailed Description of the Sensitivity Analysis Comparing
Adjusted/Unadjusted Findings
Stage 1 Occurrence Measures for All CCL 2 Regulatory
Determination Contaminants Monitored Under UCMR 1
Sample-Point Level Occurrence Measures
-------
-------
Appendix A. Stage 1 Occurrence Measures for
All Other UCMR Contaminants
Table Al.a Acetochlor - Occurrence Based on Samples, Systems, and Population Served
(UCMR 1 March 2006 Data)
Table Al .b Acetochlor - Number of PWSs by State (UCMR 1 March 2006 Data)
Table Al .c Acetochlor - Total Population-Served by State (UCMR 1 March 2006 Data)
Table A2.a Aeromonas - Occurrence Based on Samples, Systems, and Population Served
(UCMR 1 March 2006 Data)
Table A2.b Aeromonas - Statistics for All Detections (UCMR 1 March 2006 Data)
Table A2.c Aeromonas - System Level Occurrence by State and Size Category
(UCMR 1 March 2006 Data)
Table A2.d Aeromonas - System Level Occurrence by State and Source Water Type
(UCMR 1 March 2006 Data)
Table A2.e Aeromonas - Statistics for All Detections by State (UCMR 1 March 2006 Data)
Table A2.f Aeromonas - Population Served Level Occurrence by State & Size Category
(UCMR 1 March 2006 Data)
Table A2.g Aeromonas - Population Served Level Occurrence by State & Source Water Type
(UCMR 1 March 2006 Data)
Table A3.a Diazinon - Occurrence Based on Samples, Systems, and Population Served
(UCMR 1 March 2006 Data)
Table A3.b Diazinon - Number of PWSs by State (UCMR 1 March 2006 Data)
Table A3 .c Diazinon - Total Population-Served by State (UCMR 1 March 2006 Data)
Table A4.a 2,4-Dichlorophenol - Occurrence Based on Samples, Systems, and Population
Served (UCMR 1 March 2006 Data)
Table A4.b 2,4-Dichlorophenol - Number of PWSs by State (UCMR 1 March 2006 Data)
Table A4.c 2,4-Dichlorophenol - Total Population-Served by State (UCMR 1 March 2006
Data)
Table A5.a 2,4-Dinitrophenol - Occurrence Based on Samples, Systems, and Population
Served (UCMR 1 March 2006 Data)
Table A5.b 2,4-Dinitrophenol - Number of PWSs by State (UCMR 1 March 2006 Data)
Table A5.c 2,4-Dinitrophenol - Total Population-Served by State (UCMR 1 March 2006
Data)
Table A6.a 1,2-Diphenylhydrazine - Occurrence Based on Samples, Systems, and Population
Served (UCMR 1 March 2006 Data)
Table A6.b 1,2-Diphenylhydrazine - Number of PWSs by State (UCMR 1 March 2006 Data)
Table A6.c 1,2-Diphenylhydrazine - Total Population-Served by State (UCMR 1 March 2006
Data)
-------
Table A7.a Disulfoton - Occurrence Based on Samples, Systems, and Population Served
(UCMR 1 March 2006 Data)
Table A7.b Disulfoton - Number of PWSs by State (UCMR 1 March 2006 Data)
Table A7.c Disulfoton - Total Population-Served by State (UCMR 1 March 2006 Data)
Table A8.a Diuron - Occurrence Based on Samples, Systems, and Population Served
(UCMR 1 March 2006 Data)
Table A8.b Diuron - Number of PWSs by State (UCMR 1 March 2006 Data)
Table A8.c Diuron - Total Population-Served by State (UCMR 1 March 2006 Data)
Table A9.a Linuron - Occurrence Based on Samples, Systems, and Population Served
(UCMR 1 March 2006 Data)
Table A9.b Linuron - Number of PWSs by State (UCMR 1 March 2006 Data)
Table A9.c Linuron - Total Population-Served by State (UCMR 1 March 2006 Data)
Table AlO.a LL-Nitrobenzene - Occurrence Based on Samples, Systems, and Population
Served (UCMR 1 March 2006 Data)
Table AlO.b LL-Nitrobenzene - Number of PWSs by State (UCMR 1 March 2006 Data)
Table AlO.c LL-Nitrobenzene - Total Population-Served by State (UCMR 1 March 2006 Data)
Table Al La 2-Methyl-phenol - Occurrence Based on Samples, Systems, and Population
Served (UCMR 1 March 2006 Data)
Table Al 1 .b 2-Methyl-phenol - Number of PWSs by State (UCMR 1 March 2006 Data)
Table Al 1 .c 2-Methyl-phenol - Total Population-Served by State (UCMR 1 March 2006 Data)
Table A12.a Molinate - Occurrence Based on Samples, Systems, and Population Served
(UCMR 1 March 2006 Data)
Table A12.b Molinate - Number of PWSs by State (UCMR 1 March 2006 Data)
Table A12.c Molinate - Total Population-Served by State (UCMR 1 March 2006 Data)
Table A13.a Nitrobenzene - Occurrence Based on Samples, Systems, and Population Served
(UCMR 1 March 2006 Data)
Table A13.b Nitrobenzene - Number of PWSs by State (UCMR 1 March 2006 Data)
Table A13.c Nitrobenzene - Total Population-Served by State (UCMR 1 March 2006 Data)
Table A14.a Prometon - Occurrence Based on Samples, Systems, and Population Served
(UCMR 1 March 2006 Data)
Table A14.b Prometon - Number of PWSs by State (UCMR 1 March 2006 Data)
Table A14.c Prometon - Total Population-Served by State (UCMR 1 March 2006 Data)
Table AlS.a Terbufos - Occurrence Based on Samples, Systems, and Population Served
(UCMR 1 March 2006 Data)
Table Al 5 .b Terbufos - Number of PWSs by State (UCMR 1 March 2006 Data)
Table Al 5 .c Terbufos - Total Population-Served by State (UCMR 1 March 2006 Data)
-------
Table A16.a 2,4,6-Trichlorophenol - Occurrence Based on Samples, Systems, and Population
Served (UCMR 1 March 2006 Data)
Table A16.b 2,4,6-Trichlorophenol - Number of PWSs by State (UCMR 1 March 2006 Data)
Table A16.c 2,4,6-Trichlorophenol - Total Population-Served by State (UCMR 1 March 2006
Data)
-------
-------
Table A1.a. Acetochlor - Occurrence Based on Samples, Systems, and Population Served (UCMR 1 March 2006 Data)
Water Type
System Size by
Population Served
Sample Level
Total Number
of Samples
Detections
Number
Percent
System Level
Total Number
of Systems
Sampled
Systems with Detections
Number
Percent
Population Served-Level
Total
Population
Served
Pop. Served by
Systems with Detections
Number
Percent
Small Systems (Statistical Sample)
Ground
Water
Surface
Water
25 - 500
501 - 3,300
3,301 -10,000
Total
25 - 500
501 - 3,300
3,301 -10,000
Total
All Small Systems
259
879
1,204
2,342
220
181
508
909
3,251
0
0
0
0.00%
0.00%
0.00%
111
245
234
590
52
45
110
207
797
0
0
0
0.00%
0.00%
0.00%
27,599
441 ,499
1,470,717
1,939,815
16,662
91 ,723
712,370
820,755
2,760,570
0
0
0
0.00%
0.00%
0.00%
Large Systems (Census)
Ground
Water
Surface
Water
10,001 -50,000
> 50,000
Total
10,001 -50,000
> 50,000
Total
All Large Systems
10,514
5,412
15,926
7,425
7,176
14,601
30,527
0
0
0
0.00%
0.00%
0.00%
1,186
190
1,376
1,187
509
1,696
3,072
0
0
0
0.00%
0.00%
0.00%
26,849,175
26,476,158
53,325,333
33,405,163
136,681,205
170,086,368
223,411,701
0
0
0
0.00%
0.00%
0.00%
All Systems
Total Water Systems1
33,778
0
0.00%
3,869
0
0.00%
226,172,271
0
0.00%
1 The UCMR small water systems (population served < 10,000) are a statistical, representative sample of all national small systems while the UCMR large water systems (population
served > 10,000) represent a census of all large systems. Combined small and large system occurrence summaries accurately present the actual UCMR monitoring results. However,
only the summary findings expressed as percentages accurately reflect national occurrence; combined large and small summaries based on numerical counts of detections at the sample,
system, and population-served levels do not accurately represent national occurrence.
A-1
-------
Appendix A. Stage 1 Occurrence Measures for All Other UCMR 1 Contaminants
Table A1 .b. Acetochlor - Number of PWSs by State (UCMR 1 March 2006 Data)
State 1 2
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
lotal
Total Number
of Samples
53
809
236
1,314
8,548
396
370
8
102
1,165
568
275
394
213
248
749
397
247
343
320
1,137
175
89
371
434
457
137
527
125
1,042
41
230
135
1,051
362
71
2,327
549
317
351
1,260
717
109
292
103
542
1,750
466
298
28
40
687
552
152
69
2
2
4
6
16
33,778
Total Number
of PWSs
9
98
47
59
407
56
41
1
8
238
101
5
17
47
21
133
86
41
77
72
132
36
19
71
85
68
3
72
13
115
13
20
21
128
32
11
160
153
52
55
165
85
13
59
17
105
266
52
58
4
10
82
76
35
11
1
1
1
2
3
3,869
No. of Small Systems
GW
2
12
9
11
26
3
3
2
31
14
3
12
6
26
19
10
2
23
10
7
4
21
16
17
1
30
4
12
3
8
4
14
6
3
21
24
7
6
21
4
2
5
3
2
61
4
13
3
14
21
1
1
1
1
1
590
SW
2
3
4
1
22
7
3
8
1
4
2
2
1
2
7
4
2
1
2
3
3
1
2
10
1
2
2
2
1
8
4
8
5
16
5
6
1
12
10
3
3
2
1
3
10
2
1
1
1
207
No. of Large Systems
GW
2
30
14
34
152
12
8
2
189
24
1
12
15
11
58
45
13
6
22
58
11
2
17
59
26
1
40
2
26
3
10
4
74
19
1
50
61
8
14
22
20
4
10
5
17
66
13
1
41
37
3
1
1,376
SW
3
53
20
13
207
34
27
1
4
18
55
3
2
16
2
47
21
16
62
23
62
17
11
30
10
22
2
5
67
6
2
11
38
5
6
81
64
29
30
106
56
7
38
8
74
129
32
41
2
6
24
18
22
7
1
1,696
The UCMR data are not representative at the state-level.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
A-2
-------
Appendix A. Stage 1 Occurrence Measures for All Other UCMR 1 Contaminants
Table A1.c. Acetochlor - Total Population-Served by State (UCMR 1 March 2006 Data)
State 1 2
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
lotal
Total Number
of PWSs
9
98
47
59
407
56
41
1
8
238
101
5
17
47
21
133
86
41
77
72
132
36
19
71
85
68
3
72
13
115
13
20
21
128
32
11
160
153
52
55
165
85
13
59
17
105
266
52
58
4
10
82
76
35
11
1
1
1
2
3
3,869
Total
Population
Served
239,991
3,966,808
1,396,235
4,246,932
33,137,788
4,085,452
2,390,100
927,055
536,260
15,323,786
6,750,245
105,219
1,110,726
1,686,720
580,914
7,645,947
3,539,721
1,739,325
3,499,097
2,605,619
6,456,374
4,676,636
348,285
5,492,931
3,005,782
3,619,103
68,836
1 ,273,562
350,315
5,093,736
320,270
965,769
494,401
8,122,662
1,112,569
1,625,791
19,956,351
8,541 ,989
2,221,224
2,515,862
9,008,128
4,782,110
824,052
2,669,268
353,547
4,269,873
16,732,165
2,011,035
5,137,941
64,400
220,439
4,490,251
2,769,896
781,825
245,695
191
2,300
498
825
31 ,444
226,172,271
Pop. Served by
Small Systems
GW
3,092
67,068
35,209
39,692
85,318
12,175
1,309
6,800
117,516
28,636
15,462
19,916
35,100
106,661
104,078
27,481
7,622
75,303
50,393
12,301
2,955
57,873
58,334
38,276
2,631
78,999
10,314
47,141
7,416
23,535
10,620
60,020
6,625
5,393
45,407
104,131
23,784
12,378
42,012
24,631
4,740
14,485
9,780
2,533
228,336
16,417
13,849
2,149
38,029
88,774
1,100
191
2,300
325
3,200
1,939,815
SW
362
7,389
18,986
1,606
74,071
25,252
18,525
33,086
5,504
6,789
3,197
10,490
8,912
11,145
32,797
13,120
12,900
6,200
5,155
20,824
13,471
3,509
5,202
51 ,698
203
5,630
16,300
570
463
48,624
18,988
43,255
19,515
50,653
12,020
35,619
376
70,682
22,737
16,285
9,079
400
9,020
3,807
34,761
580
498
500
10,000
820,755
Pop. Served by
Large Systems
GW
58,600
703,125
334,297
1,561,412
7,011,747
294,405
121,731
53,330
12,383,938
715,555
12,500
1,010,064
515,056
342,565
1,536,074
1,195,492
299,868
179,924
726,919
1,392,955
522,337
27,040
624,720
1 ,695,267
767,067
62,696
872,095
85,782
663,985
67,034
410,925
76,400
2,086,167
948,281
17,000
3,493,019
1,683,901
166,635
390,600
442,445
445,558
94,000
213,706
72,760
1,078,175
2,851,292
351,194
40,715
1,516,949
1,022,486
60,546
24,999
53,325,333
SW
177,937
3,189,226
1,007,743
2,644,222
25,966,652
3,753,620
2,248,535
927,055
476,130
2,822,332
5,972,968
87,215
85,200
1,144,959
200,052
5,992,722
2,231,239
1 ,400,831
3,278,754
1,790,277
5,000,126
4,135,798
313,135
4,789,514
1,252,181
2,800,289
322,468
249,017
4,330,912
245,617
531 ,309
401,751
5,960,175
157,093
1,602,935
16,369,301
6,734,969
1 ,987,550
2,093,369
8,473,018
4,299,901
725,312
2,405,458
270,631
3,118,483
13,629,800
1,627,139
5,074,298
64,000
209,270
2,931,466
1 ,658,636
686,518
219,016
18,244
170,086,368
The UCMR data are not representative at the state-level.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
A-3
-------
Appendix A. Stage 1 Occurrence Measures for All Other UCMR 1 Contaminants
Table A2.a. Aeromonas - Occurrence Based on Samples, Systems, and Population Served (UCMR 1 March 2006 Data)
Water
Type
System Size by
Population
Served
Sample Level
Total # of
Samples
Detections
#
%
System Level
Total # of
Systems
Detections
Systems with
One or More
#
%
Systems with
Two or More
#
%
Population-Served Level
Total Pop.
Served by
Systems
Detections
Pop. Served by
Systems with
One or More
#
%
Pop. Served by
Systems with
Two or More
#
%
Small Systems (Statistical Sample)
GW
SW
25 - 500
501 - 3,300
3,301 -10,000
Total
25 - 500
501 - 3,300
3,301 -10,000
Total
All Small Systems
595
852
586
2,033
260
229
434
923
2,956
28
35
23
86
14
5
19
105
4.71%
4.11%
3.92%
4.23%
5.38%
1.15%
2.06%
3.55%
36
50
34
120
15
14
25
54
174
6
13
4
23
3
3
6
29
16.67%
26.00%
1 1 .76%
19.17%
20.00%
12.00%
11.11%
16.67%
4
5
3
12
1
1
2
14
11.11%
10.00%
8.82%
10.00%
6.67%
4.00%
3.70%
8.05%
7,223
88,167
242,928
338,318
5,776
29,230
153,671
188,677
526,995
1,265
23,149
28,243
52,657
1,139
24,796
25,935
78,592
17.51%
26.26%
1 1 .63%
15.56%
19.72%
16.14%
13.75%
14.91%
729
9,020
23,098
32,847
460
8,000
8,460
41 ,307
10.09%
10.23%
9.51%
9.71%
7.96%
5.21%
4.48%
7.84%
Large Systems (Statistical Sample)
GW
SW
10,001 -50,000
> 50,000
Total
10,001 -50,000
> 50,000
Total
All Large Systems
466
459
925
603
564
1,167
2,092
2
7
9
8
8
16
25
0.43%
1 .53%
0.97%
1 .33%
1 .42%
1 .37%
1 .20%
26
26
52
34
32
66
118
2
6
8
2
3
5
13
7.69%
23.08%
15.38%
5.88%
9.38%
7.58%
11.02%
1
1
2
1
3
4
3.85%
1 .92%
5.88%
3.13%
4.55%
3.39%
663,464
5,586,543
6,250,007
1 ,284,768
17,867,890
19,152,658
25,402,665
49,300
1,155,698
1 ,204,998
67,171
4,655,200
4,722,371
5,927,369
7.43%
20.69%
19.28%
5.23%
26.05%
24.66%
23.33%
56,315
56,315
67,171
979,000
1,046,171
1,102,486
1.01%
0.90%
5.23%
5.48%
5.46%
4.34%
All (Small & Large) Systems
Total Water Systems
5,048
130
2.58%
292
42
14.38%
18
6.16%
25,929,660
6,005,961
23.16%
1,143,793
4.41%
A-4
-------
Appendix A. Stage 1 Occurrence Measures for All Other UCMR 1 Contaminants
Table A2.b. Aeromonas - Statistics for All Detections (UCMR 1 March 2006 Data)
Water Type
System Size by
Population
Served
Total # of
Detections
Statistics for All Recorded Values Equal to or Above the Detection Limit (in CFU/100
mL)
Minimum | Median | 99th Percentile | Maximum
Small Systems (Statistical Sample)
GW
SW
25 - 500
501 - 3,300
3,301 - 10,000
Total
25 - 500
501 - 3,300
3,301 - 10,000
Total
All Small Systems
28
35
23
86
14
0
5
19
105
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
3.1
0.6
1.2
1.3
3.0
1.8
2.7
1.6
380.0
40.0
69.0
140.0
800.0
28.0
800.0
680
380.0
40.0
69.0
380.0
800.0
28.0
800.0
800
Large Systems (Statistical Sample)
GW
SW
10,001 -50,000
> 50,000
Total
10,001 -50,000
> 50,000
Total
II Large Systems
2
7
9
8
8
16
25
0.2
0.2
0.2
0.6
0.2
0.2
0.2
1.1
0.2
0.2
3.8
2.5
2.7
1.6
2.0
2.6
2.6
880.0
52.8
880.0
880.0
2.0
2.6
2.6
880.0
52.8
880.0
880.0
All (Small & Large) Systems
Total Water Systems
130
0.2
1.6
800.0
880.0
A-5
-------
Appendix A. Stage 1 Occurrence Measures for All Other UCMR 1 Contaminants
Table A2.c. Aeromonas - System Level Occurrence by State and Size Category (UCMR 1 March 2006 Data)
State 1 2
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
Total
Total #
Samples
18
53
124
70
425
51
18
18
271
139
54
120
51
268
126
79
53
139
135
69
54
158
121
70
48
29
230
18
72
18
90
54
224
175
68
59
90
36
18
90
18
70
424
36
89
35
158
108
53
36
18
5,048
Total # PWSs
Total
1
3
7
4
25
3
1
1
16
8
3
7
3
15
7
5
3
8
8
4
3
9
7
4
3
2
13
1
4
1
5
3
13
10
4
4
5
2
1
5
1
4
25
2
5
2
9
7
3
2
1
292
Small
1
2
4
3
10
2
1
1
4
6
1
5
1
6
4
3
2
6
2
3
1
7
4
4
3
2
6
1
4
1
2
2
10
4
3
4
3
1
0
4
1
3
14
2
3
1
6
5
3
2
1
174
Large
0
1
3
1
15
1
0
0
12
2
2
2
2
9
3
2
1
2
6
1
2
2
3
0
0
0
7
0
0
0
3
1
3
6
1
0
2
1
1
1
0
1
11
0
2
1
3
2
0
0
0
118
# PWSs with Detections
Total
1
3
1
5
1
1
1
3
1
2
1
2
2
1
1
1
1
1
2
1
1
2
1
1
1
2
2
42
Small
1
0
1
0
1
1
1
0
1
2
1
2
2
1
0
1
1
1
2
0
1
2
1
1
1
2
2
29
Large
0
3
0
5
0
0
0
3
0
0
0
0
0
0
1
0
0
0
0
1
0
0
0
0
0
0
0
13
% PWSs with Detections
Total
25.00%
12.00%
33.33%
31 .25%
12.50%
6.67%
12.50%
37.50%
25.00%
22.22%
14.29%
50.00%
66.67%
50.00%
7.69%
25.00%
20.00%
7.69%
50.00%
20.00%
50.00%
40.00%
25.00%
4.00%
20.00%
22.22%
28.57%
14.38%
Small
33.33%
0.00%
50.00%
0.00%
16.67%
16.67%
16.67%
0.00%
33.33%
28.57%
25.00%
50.00%
66.67%
50.00%
0.00%
25.00%
50.00%
10.00%
50.00%
0.00%
100.00%
50.00%
33.33%
7.14%
33.33%
33.33%
40.00%
16.67%
Large
0.00%
20.00%
0.00%
41 .67%
0.00%
0.00%
0.00%
50.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
14.29%
0.00%
0.00%
0.00%
0.00%
50.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
1 1 .02%
The UCMR data are not representative at the state-level.
' States are arranged alphabetically based on their 2-digit State abbreviation.
A-6
-------
Appendix A. Stage 1 Occurrence Measures for All Other UCMR 1 Contaminants
Table A2.d. Aeromonas - System Level Occurrence by State and Source Water Type (UCMR 1 March 2006 Data)
State 1 2
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
Total
Total # PWSs
Total
1
3
7
4
25
3
1
1
16
8
3
7
3
15
7
5
3
8
8
4
3
9
7
4
3
2
13
1
4
1
5
3
13
10
4
4
5
2
1
5
1
4
25
2
5
2
9
7
3
2
1
292
GW
1
2
4
3
11
0
1
1
15
4
3
4
3
8
6
2
1
6
4
4
1
8
6
3
3
2
2
1
4
0
2
2
9
5
1
2
1
0
1
2
0
0
16
1
2
1
6
7
0
0
1
172
sw
0
1
3
1
14
3
0
0
1
4
0
3
0
7
1
3
2
2
4
0
2
1
1
1
0
11
0
0
1
3
1
4
5
3
2
4
2
0
3
1
4
9
1
3
1
3
0
3
2
120
# PWSs with Detections
Total
1
3
1
5
1
1
1
3
1
2
1
2
2
1
1
1
1
1
2
1
1
2
1
1
1
2
2
42
GW
1
2
0
5
1
1
1
1
1
2
1
2
2
1
0
1
0
1
2
0
0
1
0
1
0
2
2
31
SW
0
1
1
0
0
0
0
2
0
0
0
0
0
0
1
0
1
0
0
1
1
1
1
0
1
0
0
11
% PWSs with Detections
Total
25.00%
12.00%
33.33%
31.25%
12.50%
6.67%
12.50%
37.50%
25.00%
22.22%
14.29%
50.00%
66.67%
50.00%
7.69%
25.00%
20.00%
7.69%
50.00%
20.00%
50.00%
40.00%
25.00%
4.00%
20.00%
22.22%
28.57%
14.38%
GW
33.33%
18.18%
0.00%
33.33%
25.00%
12.50%
16.67%
25.00%
25.00%
25.00%
16.67%
66.67%
66.67%
50.00%
0.00%
25.00%
0.00%
11.11%
100.00%
0.00%
0.00%
50.00%
0.00%
6.25%
0.00%
33.33%
28.57%
18.02%
SW
0.00%
7.14%
33.33%
0.00%
0.00%
0.00%
0.00%
50.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
9.09%
0.00%
33.33%
0.00%
0.00%
25.00%
50.00%
33.33%
25.00%
0.00%
33.33%
0.00%
0.00%
9.17%
The UCMR data are not representative at the state-level.
" States are arranged alphabetically based on their 2-digit State abbreviation.
A-7
-------
Appendix A. Stage 1 Occurrence Measures for All Other UCMR 1 Contaminants
Table A2.e. Aeromonas - Statistics for All Detections by State (UCMR 1 March 2006 Data)
State 1 2
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
Total
Total #
Detections
1
8
1
6
6
6
1
8
1
3
3
4
2
3
2
10
3
1
10
1
12
2
1
1
1
26
7
130
Statistics for Detections (in CFU/100 mL)
Minimum
0.2
0.2
13.4
0.2
17
0.2
0.4
0.6
0.2
0.2
5.6
0.2
0.8
0.2
0.6
0.2
1.8
1
0.2
5
0.2
0.2
0.4
2.8
0.2
0.2
0.2
0.2
Median
0.2
1.2
13.4
0.2
66
4.6
0.4
27.8
0.2
0.2
7.2
0.4
1
0.2
2.7
1
12
1
2.6
5
2.95
0.3
0.4
2.8
0.2
1.6
0.8
1.6
99th
Percentile
0.2
12.8
13.4
2.6
380
69
0.4
880
0.2
29
27
0.4
1.2
0.2
4.8
11
28
1
40
5
800
0.4
0.4
2.8
0.2
25.4
6.4
800
Maximum
0.2
12.8
13.4
2.6
380
69
0.4
880
0.2
29
27
0.4
1.2
0.2
4.8
11
28
1
40
5
800
0.4
0.4
2.8
0.2
25.4
6.4
880
The UCMR data are not representative at the state-level.
' States are arranged alphabetically based on their 2-digit State abbreviation.
A-8
-------
Appendix A. Stage 1 Occurrence Measures for All Other UCMR 1 Contaminants
Table A2.f. Aeromonas - Population Served Level Occurrence by State & Size Category (UCMR 1 March 2006 Data)
State 1 2
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
Total
Total #
PWSs
1
3
7
4
25
3
1
1
16
8
3
7
3
15
7
5
3
8
8
4
3
9
7
4
3
2
13
1
4
1
5
3
13
10
4
4
5
2
1
5
1
4
25
2
5
2
9
7
3
2
1
292
Total Population Served by PWSs
Total
92
40,908
396,347
1,212,061
3,578,339
23,900
72
300
1,599,335
54,583
764,305
45,673
76,757
673,952
234,348
241,915
108,547
409,491
2,267,247
253,162
125,435
3,547,569
75,414
1 1 ,203
3,333
4,840
1,331,680
2,267
10,647
3,000
464,100
43,826
1,366,143
1,310,635
289,388
7,945
1,705,419
29,928
17,500
33,898
376
63,653
1,909,121
7,937
853,573
19,500
591,766
107,397
9,928
580
325
25,929,660
Small
92
12,108
22,294
12,061
24,825
3,900
72
300
23,095
14,323
9,147
5,098
8,500
23,395
30,930
10,241
7,604
12,620
2,390
3,562
250
7,992
1 1 ,501
1 1 ,203
3,333
4,840
18,518
2,267
10,647
3,000
8,100
2,825
25,587
24,038
13,388
7,945
17,098
460
0
1 1 ,628
376
15,533
45,239
7,937
1,799
1,000
3,249
29,852
9,928
580
325
526,995
Large
0
28,800
374,053
1 ,200,000
3,553,514
20,000
0
0
1 ,576,240
40,260
755,158
40,575
68,257
650,557
203,418
231,674
100,943
396,871
2,264,857
249,600
125,185
3,539,577
63,913
0
0
0
1,313,162
0
0
0
456,000
41,001
1 ,340,556
1 ,286,597
276,000
0
1,688,321
29,468
17,500
22,270
0
48,120
1 ,863,882
0
851,774
18,500
588,517
77,545
0
0
0
25,402,665
Population Served by PWSs
with Detections
Total
2,880
1,515,011
400
639,687
91
7,104
1,328
2,074,709
336
3,318
279
6,300
3,033
2,500
21,762
8,000
8,000
670
1,865
1 ,676,200
460
9,711
7,985
5,145
279
714
8,194
6,005,961
Small
2,880
0
400
0
91
7,104
1,328
0
336
3,318
279
6,300
3,033
2,500
0
8,000
8,000
670
1,865
0
460
9,711
7,985
5,145
279
714
8,194
78,592
Large
0
1,515,011
0
639,687
0
0
0
2,074,709
0
0
0
0
0
0
21,762
0
0
0
0
1 ,676,200
0
0
0
0
0
0
0
5,927,369
% Population Served by
PWSs with Detections
Total
0.24%
42.34%
1 .67%
40.00%
0.17%
1 .05%
0.32%
91.51%
0.13%
0.09%
0.37%
56.23%
91 .00%
51 .65%
1 .63%
75.14%
1.72%
0.05%
23.47%
98.29%
1 .54%
28.65%
12.54%
0.27%
0.03%
0.12%
7.63%
23.16%
Small
23.88%
0.00%
10.26%
0.00%
0.64%
30.37%
10.52%
0.00%
9.43%
41.52%
2.43%
56.23%
91 .00%
51 .65%
0.00%
75.14%
98.77%
2.62%
23.47%
0.00%
100.00%
83.51%
51.41%
11.37%
15.51%
21.98%
27.45%
14.91%
Large
0.00%
42.63%
0.00%
40.58%
0.00%
0.00%
0.00%
91 .60%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
1 .66%
0.00%
0.00%
0.00%
0.00%
99.28%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
23.33%
The UCMR data are not representative at the state-level.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
A-9
-------
Appendix A. Stage 1 Occurrence Measures for All Other UCMR 1 Contaminants
Table A2.g. Aeromonas - Population Served Level Occurrence by State & Source Water Type (UCMR 1 March 2006 Data)
State 1 2
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
Total
Total Population Served by PWSs
Total
92
40,908
396,347
1,212,061
3,578,339
23,900
72
300
1,599,335
54,583
764,305
45,673
76,757
673,952
234,348
241,915
108,547
409,491
2,267,247
253,162
125,435
3,547,569
75,414
1 1 ,203
3,333
4,840
1,331,680
2,267
10,647
3,000
464,100
43,826
1,366,143
1,310,635
289,388
7,945
1,705,419
29,928
17,500
33,898
376
63,653
1,909,121
7,937
853,573
19,500
591,766
107,397
9,928
580
325
25,929,660
GW
92
12,108
46,969
12,061
892,662
0
72
300
1,572,687
43,351
764,305
30,735
76,757
230,700
198,098
8,345
100,943
397,472
104,190
253,162
250
68,610
43,352
7,100
3,333
4,840
2,795
2,267
10,647
0
15,100
2,825
1,092,121
124,270
188
1,865
8,373
0
17,500
2,367
0
0
116,379
1,637
1,520
1,000
207,255
107,397
0
0
325
6,588,325
SW
0
28,800
349,378
1 ,200,000
2,685,677
23,900
0
0
26,648
11,232
0
14,938
0
443,252
36,250
233,570
7,604
12,019
2,163,057
0
125,185
3,478,959
32,062
4,103
0
0
1 ,328,885
0
0
3,000
449,000
41,001
274,022
1,186,365
289,200
6,080
1 ,697,046
29,928
0
31,531
376
63,653
1,792,742
6,300
852,053
18,500
384,511
0
9,928
580
0
19,341,335
Population Served by PWSs
with Detections
Total
2,880
1,515,011
400
639,687
91
7,104
1,328
2,074,709
336
3,318
279
6,300
3,033
2,500
21,762
8,000
8,000
670
1,865
1 ,676,200
460
9,711
7,985
5,145
279
714
8,194
6,005,961
GW
2,880
536,01 1
0
639,687
91
7,104
1,328
29,300
336
3,318
279
6,300
3,033
2,500
0
8,000
0
670
1,865
0
0
900
0
5,145
0
714
8,194
1,257,655
SW
0
979,000
400
0
0
0
0
2,045,409
0
0
0
0
0
0
21,762
0
8,000
0
0
1 ,676,200
460
8,811
7,985
0
279
0
0
4,748,306
% Pop. Served by PWSs with Detections
Total
0.24%
42.34%
1 .67%
40.00%
0.17%
1 .05%
0.32%
91.51%
0.13%
0.09%
0.37%
56.23%
91 .00%
51 .65%
1 .63%
75.14%
1.72%
0.05%
23.47%
98.29%
1 .54%
28.65%
12.54%
0.27%
0.03%
0.12%
7.63%
23.16%
GW
23.88%
60.05%
0.00%
40.67%
0.21%
3.08%
0.33%
28.12%
0.13%
4.84%
0.64%
88.73%
91 .00%
51 .65%
0.00%
75.14%
0.00%
0.06%
100.00%
0.00%
0.00%
38.02%
0.00%
4.42%
0.00%
0.34%
7.63%
19.09%
SW
0.00%
36.45%
1 .67%
0.00%
0.00%
0.00%
0.00%
94.56%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
1 .64%
0.00%
1.78%
0.00%
0.00%
98.77%
1 .54%
27.94%
12.54%
0.00%
0.03%
0.00%
0.00%
24.55%
The UCMR data are not representative at the state-level.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
A-10
-------
Appendix A. Stage 1 Occurrence Measures for All Other UCMR 1 Contaminants
Table A3.a. Diazinon - Sample-, System-, and Population Served-Level Occurrence (UCMR 1 March 2006 Data)
Water Type
System Size by
Population Served
Sample Level
Total Number
of Samples
Detections
Number
Percent
System Level
Total Number
of Systems
Sampled
Systems with Detections
Number
Percent
Population Served-Level
Total
Population
Served
Pop. Served by
Systems with Detections
Number
Percent
Small Systems (Statistical Sample)
Ground
Water
Surface
Water
25 - 500
501 - 3,300
3,301 -10,000
Total
25 - 500
501 - 3,300
3,301 -10,000
Total
All Small Systems
95
151
134
380
65
64
134
263
643
0
0
0
0.00%
0.00%
0.00%
43
43
28
114
17
17
30
64
178
0
0
0
0.00%
0.00%
0.00%
10,296
79,739
185,150
275,185
4,744
29,902
198,305
232,951
508,136
0
0
0
0.00%
0.00%
0.00%
Large Systems (Statistical Sample)
Ground
Water
Surface
Water
10,001 -50,000
> 50,000
Total
10,001 -50,000
> 50,000
Total
All Large Systems
272
611
883
199
581
780
1,663
0
0
0
0.00%
0.00%
0.00%
28
22
50
34
33
67
117
0
0
0
0.00%
0.00%
0.00%
792,573
7,207,549
8,000,122
1,291,958
30,967,264
32,259,222
40,259,344
0
0
0
0.00%
0.00%
0.00%
All Systems
Total Water Systems
2,306
0
0.00%
295
0
0.00%
40,767,480
0
0.00%
A-11
-------
Appendix A. Stage 1 Occurrence Measures for All Other UCMR 1 Contaminants
Table A3.b. Diazinon - Number of PWSs by State (UCMR 1 March 2006 Data)
State 1 2
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
lotal
Total Number of
Samples
2
12
21
35
765
32
21
98
24
2
46
2
2
18
9
33
53
29
6
30
33
34
7
28
16
52
4
18
10
51
78
4
122
20
10
12
76
45
11
13
6
51
217
4
8
12
46
66
8
4
2,306
Total Number of
PWSs
1
3
5
2
39
6
2
15
8
1
7
1
1
5
3
7
9
5
2
8
6
4
2
7
3
9
1
2
2
10
8
1
12
7
3
3
17
6
2
4
2
9
19
1
3
4
6
9
2
1
295
No. of Small Systems
GW
1
2
5
1
6
6
1
4
1
1
3
2
6
2
1
6
3
1
1
6
1
3
1
1
5
3
1
2
3
1
8
1
1
1
1
8
2
2
3
7
114
SW
1
1
2
1
8
3
1
2
1
1
2
1
1
1
1
1
1
4
1
2
1
1
1
2
4
2
2
5
4
1
1
1
2
1
64
No. of Large Systems
GW
1
13
9
2
1
1
1
2
1
1
3
3
4
2
1
1
2
1
1
50
SW
1
1
13
2
1
1
4
1
3
1
1
2
1
2
1
2
5
1
1
1
4
3
2
1
1
2
5
2
1
1
67
The UCMR data are not representative at the state-level.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
A-12
-------
Appendix A. Stage 1 Occurrence Measures for All Other UCMR 1 Contaminants
Table A3.c. Diazinon - Total Population-Served by State (UCMR 1 March 2006 Data)
State 1 2
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
lotal
Total Number of
PWSs
1
3
5
2
39
6
2
15
8
1
7
1
1
5
3
7
9
5
2
8
6
4
2
7
3
9
1
2
2
10
8
1
12
7
3
3
17
6
2
4
2
9
19
1
3
4
6
9
2
1
295
Total Population
Served
188
50,304
231,182
22,606
9,456,619
1,415,583
48,908
3,085,161
12,586
5,008
118,082
450
970
298,249
12,552
416,408
300,226
176,784
265
62,019
581 ,274
1,591,818
6,140
48,956
34,328
255,993
203
510,453
28,200
491,189
498,770
1,383
7,327,997
1,752,015
17,740
32,860
185,358
1 ,691 ,960
459,312
52,976
28,958
783,081
6,382,552
9,800
5,258
62,749
1,254,766
953,848
2,895
498
40,767,480
Pop. Served by
Small Systems
GW
6,150
8,639
12,314
5,758
13,345
5,180
5,008
8,533
450
970
15,938
3,303
23,544
10,400
185
12,908
13,150
2,118
2,631
8,988
445
3,104
4,033
200
1 1 ,200
3,200
1,383
740
10,086
110
10,957
7,616
2,886
4,300
1,526
15,786
1,258
1,149
10,289
25,405
275,185
SW
188
2,154
6,656
1,606
23,867
10,495
8,500
7,406
2,580
9,249
8,089
4,500
80
9,006
5,200
3,509
4,802
18,365
203
570
8,888
7,000
1,780
6,200
10,601
7,376
9,350
28,669
7,556
9,800
4,000
1,313
2,895
498
232,951
Pop. Served by
Large Systems
GW
21,000
1 ,053,905
3,071,816
106,969
39,000
22,428
62,210
119,440
39,968
28,000
93,489
495,000
644,310
82,783
16,000
654,267
1,374,537
22,000
53,000
8,000,122
SW
42,000
215,887
8,366,533
1 ,399,330
40,408
243,311
385,891
209,972
166,384
40,105
448,684
1 ,584,500
29,081
234,524
506,420
386,500
6,674,059
1,652,146
15,850
26,660
147,800
1 ,676,968
459,312
40,740
24,658
98,619
4,984,673
61,600
1,221,164
875,443
32,259,222
The UCMR data are not representative at the state-level.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
A-13
-------
Appendix A. Stage 1 Occurrence Measures for All Other UCMR 1 Contaminants
Table A4.a. 2,4-Dichlorophenol - Sample-, System-, and Population Served-Level Occurrence (UCMR 1 March 2006 Data )
Water Type
System Size by
Population Served
Sample Level
Total Number
of Samples
Detections
Number
Percent
System Level
Total Number
of Systems
Sampled
Systems with Detections
Number
Percent
Population Served-Level
Total
Population
Served
Pop. Served by
Systems with Detections
Number
Percent
Small Systems (Statistical Sample)
Ground
Water
Surface
Water
25 - 500
501 - 3,300
3,301 -10,000
Total
25 - 500
501 - 3,300
3,301 -10,000
Total
All Small Systems
95
148
138
381
67
66
137
270
651
0
0
0
0.00%
0.00%
0.00%
43
43
28
114
17
17
30
64
178
0
0
0
0.00%
0.00%
0.00%
10,296
79,739
185,150
275,185
4,744
29,902
198,305
232,951
508,136
0
0
0
0.00%
0.00%
0.00%
Large Systems (Statistical Sample)
Ground
Water
Surface
Water
10,001 -50,000
> 50,000
Total
10,001 -50,000
> 50,000
Total
All Large Systems
249
584
833
199
570
769
1,602
0
0
0
0.00%
0.00%
0.00%
28
22
50
34
32
66
116
0
0
0
0.00%
0.00%
0.00%
792,573
7,207,549
8,000,122
1,291,958
30,869,424
32,161,382
40,161,504
0
0
0
0.00%
0.00%
0.00%
All Systems
Total Water Systems
2,253
0
0.00%
294
0
0.00%
40,669,640
0
0.00%
A-14
-------
Appendix A. Stage 1 Occurrence Measures for All Other UCMR 1 Contaminants
Table A4.b. 2,4-Dichlorophenol - Number of PWSs by State (UCMR 1 March 2006 Data)
State 1 2
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
lotal
Total Number of
Samples
2
12
22
37
725
32
22
95
24
8
46
2
2
18
10
33
49
29
6
29
32
32
13
28
16
52
4
18
10
47
75
4
115
20
10
11
75
48
11
14
6
51
210
4
8
12
46
66
8
4
2,253
Total Number of
PWSs
1
3
5
2
38
6
2
15
8
1
7
1
1
5
3
7
9
5
2
8
6
4
2
7
3
9
1
2
2
10
8
1
12
7
3
3
17
6
2
4
2
9
19
1
3
4
6
9
2
1
294
No. of Small Systems
GW
1
2
5
1
6
6
1
4
1
1
3
2
6
2
1
6
3
1
1
6
1
3
1
1
5
3
1
2
3
1
8
1
1
1
1
8
2
2
3
7
114
SW
1
1
2
1
8
3
1
2
1
1
2
1
1
1
1
1
1
4
1
2
1
1
1
2
4
2
2
5
4
1
1
1
2
1
64
No. of Large Systems
GW
1
13
9
2
1
1
1
2
1
1
3
3
4
2
1
1
2
1
1
50
SW
1
1
12
2
1
1
4
1
3
1
1
2
1
2
1
2
5
1
1
1
4
3
2
1
1
2
5
2
1
1
66
The UCMR data are not representative at the state-level.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
A-15
-------
Appendix A. Stage 1 Occurrence Measures for All Other UCMR 1 Contaminants
Table A4.c. 2,4-Dichlorophenol - Total Population-Served by State (UCMR 1 March 2006 Data)
State 1 2
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
lotal
Total Number of
PWSs
1
3
5
2
38
6
2
15
8
1
7
1
1
5
3
7
9
5
2
8
6
4
2
7
3
9
1
2
2
10
8
1
12
7
3
3
17
6
2
4
2
9
19
1
3
4
6
9
2
1
294
Total Population
Served
188
50,304
231,182
22,606
9,358,779
1,415,583
48,908
3,085,161
12,586
5,008
118,082
450
970
298,249
12,552
416,408
300,226
176,784
265
62,019
581 ,274
1,591,818
6,140
48,956
34,328
255,993
203
510,453
28,200
491,189
498,770
1,383
7,327,997
1,752,015
17,740
32,860
185,358
1 ,691 ,960
459,312
52,976
28,958
783,081
6,382,552
9,800
5,258
62,749
1,254,766
953,848
2,895
498
40,669,640
Pop. Served by
Small Systems
GW
6,150
8,639
12,314
5,758
13,345
5,180
5,008
8,533
450
970
15,938
3,303
23,544
10,400
185
12,908
13,150
2,118
2,631
8,988
445
3,104
4,033
200
1 1 ,200
3,200
1,383
740
10,086
110
10,957
7,616
2,886
4,300
1,526
15,786
1,258
1,149
10,289
25,405
275,185
SW
188
2,154
6,656
1,606
23,867
10,495
8,500
7,406
2,580
9,249
8,089
4,500
80
9,006
5,200
3,509
4,802
18,365
203
570
8,888
7,000
1,780
6,200
10,601
7,376
9,350
28,669
7,556
9,800
4,000
1,313
2,895
498
232,951
Pop. Served by
Large Systems
GW
21,000
1 ,053,905
3,071,816
106,969
39,000
22,428
62,210
119,440
39,968
28,000
93,489
495,000
644,310
82,783
16,000
654,267
1,374,537
22,000
53,000
8,000,122
SW
42,000
215,887
8,268,693
1 ,399,330
40,408
243,311
385,891
209,972
166,384
40,105
448,684
1 ,584,500
29,081
234,524
506,420
386,500
6,674,059
1,652,146
15,850
26,660
147,800
1 ,676,968
459,312
40,740
24,658
98,619
4,984,673
61,600
1,221,164
875,443
32,161,382
The UCMR data are not representative at the state-level.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
A-16
-------
Appendix A. Stage 1 Occurrence Measures for All Other UCMR 1 Contaminants
Table A5.a. 2,4-Dinitrophenol - Sample-, System-, and Population Served-Level Occurrence (UCMR 1 March 2006 Data )
Water Type
System Size by
Population Served
Sample Level
Total Number
of Samples
Detections
Number
Percent
System Level
Total Number
of Systems
Sampled
Systems with Detections
Number
Percent
Population Served-Level
Total
Population
Served
Pop. Served by
Systems with Detections
Number
Percent
Small Systems (Statistical Sample)
Ground
Water
Surface
Water
25 - 500
501 - 3,300
3,301 -10,000
Total
25 - 500
501 - 3,300
3,301 -10,000
Total
All Small Systems
95
148
138
381
67
66
137
270
651
0
0
0
0.00%
0.00%
0.00%
43
43
28
114
17
17
30
64
178
0
0
0
0.00%
0.00%
0.00%
10,296
79,739
185,150
275,185
4,744
29,902
198,305
232,951
508,136
0
0
0
0.00%
0.00%
0.00%
Large Systems (Statistical Sample)
Ground
Water
Surface
Water
10,001 -50,000
> 50,000
Total
10,001 -50,000
> 50,000
Total
All Large Systems
249
584
833
199
567
766
1,599
0
0
0
0.00%
0.00%
0.00%
28
22
50
34
32
66
116
0
0
0
0.00%
0.00%
0.00%
792,573
7,207,549
8,000,122
1,291,958
30,869,424
32,161,382
40,161,504
0
0
0
0.00%
0.00%
0.00%
All Systems
Total Water Systems
2,250
0
0.00%
294
0
0.00%
40,669,640
0
0.00%
A-17
-------
Appendix A. Stage 1 Occurrence Measures for All Other UCMR 1 Contaminants
Table A5.b. 2,4-Dinitrophenol - Number of PWSs by State (UCMR 1 March 2006 Data)
State 1 2
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
lotal
Total Number of
Samples
2
12
22
37
725
29
22
95
24
8
46
2
2
18
10
33
49
29
6
29
32
32
13
28
16
52
4
18
10
47
75
4
115
20
10
11
75
48
11
14
6
51
210
4
8
12
46
66
8
4
2,250
Total Number of
PWSs
1
3
5
2
38
6
2
15
8
1
7
1
1
5
3
7
9
5
2
8
6
4
2
7
3
9
1
2
2
10
8
1
12
7
3
3
17
6
2
4
2
9
19
1
3
4
6
9
2
1
294
No. of Small Systems
GW
1
2
5
1
6
6
1
4
1
1
3
2
6
2
1
6
3
1
1
6
1
3
1
1
5
3
1
2
3
1
8
1
1
1
1
8
2
2
3
7
114
SW
1
1
2
1
8
3
1
2
1
1
2
1
1
1
1
1
1
4
1
2
1
1
1
2
4
2
2
5
4
1
1
1
2
1
64
No. of Large Systems
GW
1
13
9
2
1
1
1
2
1
1
3
3
4
2
1
1
2
1
1
50
SW
1
1
12
2
1
1
4
1
3
1
1
2
1
2
1
2
5
1
1
1
4
3
2
1
1
2
5
2
1
1
66
The UCMR data are not representative at the state-level.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
A-18
-------
Appendix A. Stage 1 Occurrence Measures for All Other UCMR 1 Contaminants
Table A5.c. 2,4-Dinitrophenol - Total Population-Served by State (UCMR 1 March 2006 Data)
State 1 2
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
lotal
Total Number of
PWSs
1
3
5
2
38
6
2
15
8
1
7
1
1
5
3
7
9
5
2
8
6
4
2
7
3
9
1
2
2
10
8
1
12
7
3
3
17
6
2
4
2
9
19
1
3
4
6
9
2
1
294
Total Population
Served
188
50,304
231,182
22,606
9,456,619
1,415,583
48,908
3,085,161
12,586
5,008
118,082
450
970
298,249
12,552
416,408
300,226
176,784
265
62,019
581 ,274
1,591,818
6,140
48,956
34,328
255,993
203
510,453
28,200
491,189
498,770
1,383
7,327,997
1,752,015
17,740
32,860
185,358
1 ,691 ,960
459,312
52,976
28,958
783,081
6,382,552
9,800
5,258
62,749
1,254,766
953,848
2,895
498
40,767,480
Pop. Served by
Small Systems
GW
6,150
8,639
12,314
5,758
13,345
5,180
5,008
8,533
450
970
15,938
3,303
23,544
10,400
185
12,908
13,150
2,118
2,631
8,988
445
3,104
4,033
200
1 1 ,200
3,200
1,383
740
10,086
110
10,957
7,616
2,886
4,300
1,526
15,786
1,258
1,149
10,289
25,405
275,185
SW
188
2,154
6,656
1,606
23,867
10,495
8,500
7,406
2,580
9,249
8,089
4,500
80
9,006
5,200
3,509
4,802
18,365
203
570
8,888
7,000
1,780
6,200
10,601
7,376
9,350
28,669
7,556
9,800
4,000
1,313
2,895
498
232,951
Pop. Served by
Large Systems
GW
21,000
1 ,053,905
3,071,816
106,969
39,000
22,428
62,210
119,440
39,968
28,000
93,489
495,000
644,310
82,783
16,000
654,267
1,374,537
22,000
53,000
8,000,122
SW
42,000
215,887
8,268,693
1 ,399,330
40,408
243,311
385,891
209,972
166,384
40,105
448,684
1 ,584,500
29,081
234,524
506,420
386,500
6,674,059
1,652,146
15,850
26,660
147,800
1 ,676,968
459,312
40,740
24,658
98,619
4,984,673
61,600
1,221,164
875,443
32,161,382
The UCMR data are not representative at the state-level.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
A-19
-------
Appendix A. Stage 1 Occurrence Measures for All Other UCMR 1 Contaminants
Table A6.a. 1,2-Diphenylhydrazine - Sample-, System-, and Population Served-Level Occurrence (UCMR 1 March 2006 Data)
Water Type
System Size by
Population Served
Sample Level
Total Number
of Samples
Detections
Number
Percent
System Level
Total Number
of Systems
Sampled
Systems with Detections
Number
Percent
Population Served-Level
Total
Population
Served
Pop. Served by
Systems with Detections
Number
Percent
Small Systems (Statistical Sample)
Ground
Water
Surface
Water
25 - 500
501 - 3,300
3,301 -10,000
Total
25 - 500
501 - 3,300
3,301 -10,000
Total
All Small Systems
95
151
134
380
65
64
134
263
643
0
0
0
0.00%
0.00%
0.00%
43
43
28
114
17
17
30
64
178
0
0
0
0.00%
0.00%
0.00%
10,296
79,739
185,150
275,185
4,744
29,902
198,305
232,951
508,136
0
0
0
0.00%
0.00%
0.00%
Large Systems (Statistical Sample)
Ground
Water
Surface
Water
10,001 -50,000
> 50,000
Total
10,001 -50,000
> 50,000
Total
All Large Systems
272
611
883
199
581
780
1,663
0
0
0
0.00%
0.00%
0.00%
28
22
50
34
33
67
117
0
0
0
0.00%
0.00%
0.00%
792,573
7,207,549
8,000,122
1,291,958
30,967,264
32,259,222
40,259,344
0
0
0
0.00%
0.00%
0.00%
S
Total Water Systems
2,306
0
0.00%
295
0
0.00%
40,767,480
0
0.00%
A-20
-------
Appendix A. Stage 1 Occurrence Measures for All Other UCMR 1 Contaminants
Table A6.b. 1,2-Diphenylhydrazine - Number of PWSs by State (UCMR 1 March 2006 Data]
State 1 2
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
lotal
Total Number of
Samples
2
12
21
35
765
32
21
98
24
2
46
2
2
18
9
33
53
29
6
30
33
34
7
28
16
52
4
18
10
51
78
4
122
20
10
12
76
45
11
13
6
51
217
4
8
12
46
66
8
4
2,306
Total Number of
PWSs
1
3
5
2
39
6
2
15
8
1
7
1
1
5
3
7
9
5
2
8
6
4
2
7
3
9
1
2
2
10
8
1
12
7
3
3
17
6
2
4
2
9
19
1
3
4
6
9
2
1
295
No. of Small Systems
GW
1
2
5
1
6
6
1
4
1
1
3
2
6
2
1
6
3
1
1
6
1
3
1
1
5
3
1
2
3
1
8
1
1
1
1
8
2
2
3
7
114
SW
1
1
2
1
8
3
1
2
1
1
2
1
1
1
1
1
1
4
1
2
1
1
1
2
4
2
2
5
4
1
1
1
2
1
64
No. of Large Systems
GW
1
13
9
2
1
1
1
2
1
1
3
3
4
2
1
1
2
1
1
50
SW
1
1
13
2
1
1
4
1
3
1
1
2
1
2
1
2
5
1
1
1
4
3
2
1
1
2
5
2
1
1
67
The UCMR data are not representative at the state-level.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
A-21
-------
Appendix A. Stage 1 Occurrence Measures for All Other UCMR 1 Contaminants
Table A6.c. 1,2-Diphenylhydrazine - Total Population-Served by State (UCMR 1 March 2006 Data
State 1 2
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
lotal
Total Number of
PWSs
1
3
5
2
39
6
2
15
8
1
7
1
1
5
3
7
9
5
2
8
6
4
2
7
3
9
1
2
2
10
8
1
12
7
3
3
17
6
2
4
2
9
19
1
3
4
6
9
2
1
295
Total Population
Served
188
50,304
231,182
22,606
9,456,619
1,415,583
48,908
3,085,161
12,586
5,008
118,082
450
970
298,249
12,552
416,408
300,226
176,784
265
62,019
581 ,274
1,591,818
6,140
48,956
34,328
255,993
203
510,453
28,200
491,189
498,770
1,383
7,327,997
1,752,015
17,740
32,860
185,358
1 ,691 ,960
459,312
52,976
28,958
783,081
6,382,552
9,800
5,258
62,749
1,254,766
953,848
2,895
498
40,767,480
Pop. Served by
Small Systems
GW
6,150
8,639
12,314
5,758
13,345
5,180
5,008
8,533
450
970
15,938
3,303
23,544
10,400
185
12,908
13,150
2,118
2,631
8,988
445
3,104
4,033
200
1 1 ,200
3,200
1,383
740
10,086
110
10,957
7,616
2,886
4,300
1,526
15,786
1,258
1,149
10,289
25,405
275,185
SW
188
2,154
6,656
1,606
23,867
10,495
8,500
7,406
2,580
9,249
8,089
4,500
80
9,006
5,200
3,509
4,802
18,365
203
570
8,888
7,000
1,780
6,200
10,601
7,376
9,350
28,669
7,556
9,800
4,000
1,313
2,895
498
232,951
Pop. Served by
Large Systems
GW
21,000
1 ,053,905
3,071,816
106,969
39,000
22,428
62,210
119,440
39,968
28,000
93,489
495,000
644,310
82,783
16,000
654,267
1,374,537
22,000
53,000
8,000,122
SW
42,000
215,887
8,366,533
1 ,399,330
40,408
243,311
385,891
209,972
166,384
40,105
448,684
1 ,584,500
29,081
234,524
506,420
386,500
6,674,059
1,652,146
15,850
26,660
147,800
1 ,676,968
459,312
40,740
24,658
98,619
4,984,673
61,600
1,221,164
875,443
32,259,222
The UCMR data are not representative at the state-level.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
A-22
-------
Appendix A. Stage 1 Occurrence Measures for All Other UCMR 1 Contaminants
Table A7.a. pisuifoton - Sample-, System-, and Population Served-Level Occurrence (UCMR 1 March 2006 Data )
Water Type
System Size by
Population Served
Sample Level
Total Number
of Samples
Detections
Number
Percent
System Level
Total Number
of Systems
Sampled
Systems with Detections
Number
Percent
Population Served-Level
Total
Population
Served
Pop. Served by
Systems with Detections
Number
Percent
Small Systems (Statistical Sample)
Ground
Water
Surface
Water
25 - 500
501 - 3,300
3,301 -10,000
Total
25 - 500
501 - 3,300
3,301 -10,000
Total
All Small Systems
95
151
134
380
65
64
134
263
643
0
0
0
0.00%
0.00%
0.00%
43
43
28
114
17
17
30
64
178
0
0
0
0.00%
0.00%
0.00%
10,296
79,739
185,150
275,185
4,744
29,902
198,305
232,951
508,136
0
0
0
0.00%
0.00%
0.00%
Large Systems (Statistical Sample)
Ground
Water
Surface
Water
10,001 -50,000
> 50,000
Total
10,001 -50,000
> 50,000
Total
All Large Systems
272
610
882
198
577
775
1,657
0
0
0
0.00%
0.00%
0.00%
28
22
50
34
33
67
117
0
0
0
0.00%
0.00%
0.00%
792,573
7,207,549
8,000,122
1,291,958
30,967,264
32,259,222
40,259,344
0
0
0
0.00%
0.00%
0.00%
All Systems
Total Water Systems
2,300
0
0.00%
295
0
0.00%
40,767,480
0
0.00%
A-23
-------
Appendix A. Stage 1 Occurrence Measures for All Other UCMR 1 Contaminants
Table A7.b. Disulfoton - Number of PWSs by State (UCMR 1 March 2006 Data)
State 1 2
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
lotal
Total Number of
Samples
2
12
21
35
765
32
21
98
24
2
46
2
2
18
9
33
53
29
6
30
33
34
7
28
16
52
4
18
10
51
78
4
122
20
10
12
76
45
11
13
6
51
212
4
8
12
46
65
8
4
2,300
Total Number of
PWSs
1
3
5
2
39
6
2
15
8
1
7
1
1
5
3
7
9
5
2
8
6
4
2
7
3
9
1
2
2
10
8
1
12
7
3
3
17
6
2
4
2
9
19
1
3
4
6
9
2
1
295
No. of Small Systems
GW
1
2
5
1
6
6
1
4
1
1
3
2
6
2
1
6
3
1
1
6
1
3
1
1
5
3
1
2
3
1
8
1
1
1
1
8
2
2
3
7
114
SW
1
1
2
1
8
3
1
2
1
1
2
1
1
1
1
1
1
4
1
2
1
1
1
2
4
2
2
5
4
1
1
1
2
1
64
No. of Large Systems
GW
1
13
9
2
1
1
1
2
1
1
3
3
4
2
1
1
2
1
1
50
SW
1
1
13
2
1
1
4
1
3
1
1
2
1
2
1
2
5
1
1
1
4
3
2
1
1
2
5
2
1
1
67
The UCMR data are not representative at the state-level.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
A-24
-------
Appendix A. Stage 1 Occurrence Measures for All Other UCMR 1 Contaminants
Table A7.c. Disulfoton - Total Population-Served by State (UCMR 1 March 2006 Data)
State 1 2
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
lotal
Total Number of
PWSs
1
3
5
2
39
6
2
15
8
1
7
1
1
5
3
7
9
5
2
8
6
4
2
7
3
9
1
2
2
10
8
1
12
7
3
3
17
6
2
4
2
9
19
1
3
4
6
9
2
1
295
Total Population
Served
188
50,304
231,182
22,606
9,456,619
1,415,583
48,908
3,085,161
12,586
5,008
118,082
450
970
298,249
12,552
416,408
300,226
176,784
265
62,019
581 ,274
1,591,818
6,140
48,956
34,328
255,993
203
510,453
28,200
491,189
498,770
1,383
7,327,997
1,752,015
17,740
32,860
185,358
1 ,691 ,960
459,312
52,976
28,958
783,081
6,382,552
9,800
5,258
62,749
1,254,766
953,848
2,895
498
40,767,480
Pop. Served by
Small Systems
GW
6,150
8,639
12,314
5,758
13,345
5,180
5,008
8,533
450
970
15,938
3,303
23,544
10,400
185
12,908
13,150
2,118
2,631
8,988
445
3,104
4,033
200
1 1 ,200
3,200
1,383
740
10,086
110
10,957
7,616
2,886
4,300
1,526
15,786
1,258
1,149
10,289
25,405
275,185
SW
188
2,154
6,656
1,606
23,867
10,495
8,500
7,406
2,580
9,249
8,089
4,500
80
9,006
5,200
3,509
4,802
18,365
203
570
8,888
7,000
1,780
6,200
10,601
7,376
9,350
28,669
7,556
9,800
4,000
1,313
2,895
498
232,951
Pop. Served by
Large Systems
GW
21,000
1 ,053,905
3,071,816
106,969
39,000
22,428
62,210
119,440
39,968
28,000
93,489
495,000
644,310
82,783
16,000
654,267
1,374,537
22,000
53,000
8,000,122
SW
42,000
215,887
8,366,533
1 ,399,330
40,408
243,311
385,891
209,972
166,384
40,105
448,684
1 ,584,500
29,081
234,524
506,420
386,500
6,674,059
1,652,146
15,850
26,660
147,800
1 ,676,968
459,312
40,740
24,658
98,619
4,984,673
61,600
1,221,164
875,443
32,259,222
The UCMR data are not representative at the state-level.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
A-25
-------
Appendix A. Stage 1 Occurrence Measures for All Other UCMR 1 Contaminants
Table A8.a. Diuron - Sample-, System-, and Population Served-Level Occurrence (UCMR 1 March 2006 Data)
Water Type
System Size by
Population Served
Sample Level
Total Number
of Samples
Detections1
Number
Percent
System Level
Total Number
of Systems
Sampled
Systems with Detections
Number
Percent
Population Served-Level
Total
Population
Served
Pop. Served by
Systems with Detections
Number
Percent
Small Systems (Statistical Sample)
Ground
Water
Surface
Water
25 - 500
501 - 3,300
3,301 -10,000
Total
25 - 500
501 - 3,300
3,301 -10,000
Total
All Small Systems
94
160
145
399
68
67
149
284
683
0
1
1
1
0.00%
1 .49%
0.35%
0.15%
43
43
28
114
17
17
30
64
178
0
1
1
1
0.00%
5.88%
1 .56%
0.56%
10,296
79,739
185,150
275,185
4,744
29,902
198,305
232,951
508,136
0
800
800
800
0.00%
2.68%
0.34%
0.16%
Large Systems (Statistical Sample)
Ground
Water
Surface
Water
10,001 -50,000
> 50,000
Total
10,001 -50,000
> 50,000
Total
All Large Systems
262
596
858
198
575
773
1,631
0
0
0
0.00%
0.00%
0.00%
27
22
49
33
33
66
115
0
0
0
0.00%
0.00%
0.00%
770,573
7,207,549
7,978,122
1,253,958
30,967,264
32,221 ,222
40,199,344
0
0
0
0.00%
0.00%
0.00%
All Systems
Total Water Systems
2,314
1
0.04%
293
1
0.34%
40,707,480
800
0.002%
1 The single detection of diuron (equal to 2.1 ug/L) was found in a NTNCWS in California.
A-26
-------
Appendix A. Stage 1 Occurrence Measures for All Other UCMR 1 Contaminants
Table A8.b. Diuron - Number of PWSs by State (UCMR 1 March 2006 Data)
State 1 2
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
lotal
Total Number of
Samples
2
12
22
34
737
32
22
98
24
8
46
2
2
18
8
34
60
29
6
29
33
36
21
28
16
52
4
18
10
53
79
4
135
20
8
12
76
49
12
14
6
52
226
4
8
12
23
66
8
4
2,314
Total Number of
PWSs
1
3
5
2
39
6
2
15
8
1
7
1
1
5
3
7
9
5
2
8
6
4
2
7
3
9
1
2
2
10
8
1
11
7
3
3
17
6
2
4
2
9
19
1
3
4
5
9
2
1
293
No. of Small Systems
GW
1
2
5
1
6
6
1
4
1
1
3
2
6
2
1
6
3
1
1
6
1
3
1
1
5
3
1
2
3
1
8
1
1
1
1
8
2
2
3
7
114
SW
1
1
2
1
8
3
1
2
1
1
2
1
1
1
1
1
1
4
1
2
1
1
1
2
4
2
2
5
4
1
1
1
2
1
64
No. of Large Systems
GW
1
13
9
2
1
1
1
2
1
1
3
3
4
2
1
1
2
1
49
SW
1
1
13
2
1
1
4
1
3
1
1
2
1
2
1
2
4
1
1
1
4
3
2
1
1
2
5
2
1
1
66
The UCMR data are not representative at the state-level.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
A-27
-------
Appendix A. Stage 1 Occurrence Measures for All Other UCMR 1 Contaminants
Table A8.c. Diuron - Total Population-Served by State (UCMR 1 March 2006 Data]
State 1 2
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
lotal
Total Number of
PWSs
1
3
5
2
39
6
2
15
8
1
7
1
1
5
3
7
9
5
2
8
6
4
2
7
3
9
1
2
2
10
8
1
11
7
3
3
17
6
2
4
2
9
19
1
3
4
5
9
2
1
293
Total Population
Served
188
50,304
231,182
22,606
9,456,619
1,415,583
48,908
3,085,161
12,586
5,008
118,082
450
970
298,249
12,552
416,408
300,226
176,784
265
62,019
581 ,274
1,591,818
6,140
48,956
34,328
255,993
203
510,453
28,200
491,189
498,770
1,383
7,289,997
1,752,015
17,740
32,860
185,358
1 ,691 ,960
459,312
52,976
28,958
783,081
6,382,552
9,800
5,258
62,749
1,232,766
953,848
2,895
498
40,707,480
Pop. Served by
Small Systems
GW
6,150
8,639
12,314
5,758
13,345
5,180
5,008
8,533
450
970
15,938
3,303
23,544
10,400
185
12,908
13,150
2,118
2,631
8,988
445
3,104
4,033
200
1 1 ,200
3,200
1,383
740
10,086
110
10,957
7,616
2,886
4,300
1,526
15,786
1,258
1,149
10,289
25,405
275,185
SW
188
2,154
6,656
1,606
23,867
10,495
8,500
7,406
2,580
9,249
8,089
4,500
80
9,006
5,200
3,509
4,802
18,365
203
570
8,888
7,000
1,780
6,200
10,601
7,376
9,350
28,669
7,556
9,800
4,000
1,313
2,895
498
232,951
Pop. Served by
Large Systems
GW
21,000
1 ,053,905
3,071,816
106,969
39,000
22,428
62,210
119,440
39,968
28,000
93,489
495,000
644,310
82,783
16,000
654,267
1,374,537
53,000
7,978,122
SW
42,000
215,887
8,366,533
1 ,399,330
40,408
243,311
385,891
209,972
166,384
40,105
448,684
1 ,584,500
29,081
234,524
506,420
386,500
6,636,059
1,652,146
15,850
26,660
147,800
1 ,676,968
459,312
40,740
24,658
98,619
4,984,673
61,600
1,221,164
875,443
32,221,222
The UCMR data are not representative at the state-level.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
A-28
-------
Appendix A. Stage 1 Occurrence Measures for All Other UCMR 1 Contaminants
Table A9.a. |_inuron - Sample-, System-, and Population Served-Level Occurrence (UCMR 1 March 2006 Data)
Water Type
System Size by
Population Served
Sample Level
Total Number
of Samples
Detections
Number
Percent
System Level
Total Number
of Systems
Sampled
Systems with Detections
Number
Percent
Population Served-Level
Total
Population
Served
Pop. Served by
Systems with Detections
Number
Percent
Small Systems (Statistical Sample)
Ground
Water
Surface
Water
25 - 500
501 - 3,300
3,301 -10,000
Total
25 - 500
501 - 3,300
3,301 -10,000
Total
All Small Systems
94
160
145
399
68
67
149
284
683
0
0
0
0.00%
0.00%
0.00%
43
43
28
114
17
17
30
64
178
0
0
0
0.00%
0.00%
0.00%
10,296
79,739
185,150
275,185
4,744
29,902
198,305
232,951
508,136
0
0
0
0.00%
0.00%
0.00%
Large Systems (Statistical Sample)
Ground
Water
Surface
Water
10,001 -50,000
> 50,000
Total
10,001 -50,000
> 50,000
Total
All Large Systems
259
596
855
198
575
773
1,628
0
0
0
0.00%
0.00%
0.00%
27
22
49
33
33
66
115
0
0
0
0.00%
0.00%
0.00%
770,573
7,207,549
7,978,122
1,253,958
30,967,264
32,221 ,222
40,199,344
0
0
0
0.00%
0.00%
0.00%
All Systems
Total Water Systems
2,311
0
0.00%
293
0
0.00%
40,707,480
0
0.00%
A-29
-------
Appendix A. Stage 1 Occurrence Measures for All Other UCMR 1 Contaminants
Table A9.b. Linuron - Number of PWSs by State (UCMR March 2006 Data)
State 1 2
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
lotal
Total Number of
Samples
2
12
22
34
737
32
22
98
24
8
46
2
2
18
8
34
60
29
6
29
33
36
21
28
16
52
4
18
10
53
79
4
132
20
8
12
76
49
12
14
6
52
226
4
8
12
23
66
8
4
2,311
Total Number of
PWSs
1
3
5
2
39
6
2
15
8
1
7
1
1
5
3
7
9
5
2
8
6
4
2
7
3
9
1
2
2
10
8
1
11
7
3
3
17
6
2
4
2
9
19
1
3
4
5
9
2
1
293
No. of Small Systems
GW
1
2
5
1
6
6
1
4
1
1
3
2
6
2
1
6
3
1
1
6
1
3
1
1
5
3
1
2
3
1
8
1
1
1
1
8
2
2
3
7
114
SW
1
1
2
1
8
3
1
2
1
1
2
1
1
1
1
1
1
4
1
2
1
1
1
2
4
2
2
5
4
1
1
1
2
1
64
No. of Large Systems
GW
1
13
9
2
1
1
1
2
1
1
3
3
4
2
1
1
2
1
49
SW
1
1
13
2
1
1
4
1
3
1
1
2
1
2
1
2
4
1
1
1
4
3
2
1
1
2
5
2
1
1
66
The UCMR data are not representative at the state-level.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
A-30
-------
Appendix A. Stage 1 Occurrence Measures for All Other UCMR 1 Contaminants
Table A9.c. Linuron - Total Population-Served by State (UCMR March 2006 Data)
State 1 2
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
lotal
Total Number of
PWSs
1
3
5
2
39
6
2
15
8
1
7
1
1
5
3
7
9
5
2
8
6
4
2
7
3
9
1
2
2
10
8
1
11
7
3
3
17
6
2
4
2
9
19
1
3
4
5
9
2
1
293
Total Population
Served
188
50,304
231,182
22,606
9,456,619
1,415,583
48,908
3,085,161
12,586
5,008
118,082
450
970
298,249
12,552
416,408
300,226
176,784
265
62,019
581 ,274
1,591,818
6,140
48,956
34,328
255,993
203
510,453
28,200
491,189
498,770
1,383
7,289,997
1,752,015
17,740
32,860
185,358
1 ,691 ,960
459,312
52,976
28,958
783,081
6,382,552
9,800
5,258
62,749
1,232,766
953,848
2,895
498
40,707,480
Pop. Served by
Small Systems
GW
6,150
8,639
12,314
5,758
13,345
5,180
5,008
8,533
450
970
15,938
3,303
23,544
10,400
185
12,908
13,150
2,118
2,631
8,988
445
3,104
4,033
200
1 1 ,200
3,200
1,383
740
10,086
110
10,957
7,616
2,886
4,300
1,526
15,786
1,258
1,149
10,289
25,405
275,185
SW
188
2,154
6,656
1,606
23,867
10,495
8,500
7,406
2,580
9,249
8,089
4,500
80
9,006
5,200
3,509
4,802
18,365
203
570
8,888
7,000
1,780
6,200
10,601
7,376
9,350
28,669
7,556
9,800
4,000
1,313
2,895
498
232,951
Pop. Served by
Large Systems
GW
21,000
1 ,053,905
3,071,816
106,969
39,000
22,428
62,210
119,440
39,968
28,000
93,489
495,000
644,310
82,783
16,000
654,267
1,374,537
53,000
7,978,122
SW
42,000
215,887
8,366,533
1 ,399,330
40,408
243,311
385,891
209,972
166,384
40,105
448,684
1 ,584,500
29,081
234,524
506,420
386,500
6,636,059
1,652,146
15,850
26,660
147,800
1 ,676,968
459,312
40,740
24,658
98,619
4,984,673
61,600
1,221,164
875,443
32,221,222
The UCMR data are not representative at the state-level.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
A-31
-------
Appendix A. Stage 1 Occurrence Measures for All Other UCMR 1 Contaminants
Table A10.a. LL-Nitrobenzene - Sample-, System-, and Population Served-Level Occurrence (UCMR 1 March 2006 Data)
Water Type
System Size by
Population Served
Sample Level
Total Number
of Samples
Detections
Number
Percent
System Level
Total Number
of Systems
Sampled
Systems with Detections
Number
Percent
Population Served-Level
Total
Population
Served
Pop. Served by
Systems with Detections
Number
Percent
Small Systems (Statistical Sample)
Ground
Water
Surface
Water
25 - 500
501 - 3,300
3,301 -10,000
Total
25 - 500
501 - 3,300
3,301 -10,000
Total
All Small Systems
95
151
134
380
65
64
134
263
643
0
0
0
0.00%
0.00%
0.00%
43
43
28
114
17
17
30
64
178
0
0
0
0.00%
0.00%
0.00%
10,296
79,739
185,150
275,185
4,744
29,902
198,305
232,951
508,136
0
0
0
0.00%
0.00%
0.00%
Large Systems (Statistical Sample)
Ground
Water
Surface
Water
10,001 -50,000
> 50,000
Total
10,001 -50,000
> 50,000
Total
All Large Systems
272
611
883
199
581
780
1,663
0
0
0
0.00%
0.00%
0.00%
28
22
50
34
33
67
117
0
0
0
0.00%
0.00%
0.00%
792,573
7,207,549
8,000,122
1,291,958
30,967,264
32,259,222
40,259,344
0
0
0
0.00%
0.00%
0.00%
All Systems
Total Water Systems
2,306
0
0.00%
295
0
0.00%
40,767,480
0
0.00%
A-32
-------
Appendix A. Stage 1 Occurrence Measures for All Other UCMR 1 Contaminants
Table A10.b. LL-Nitrobenzene - Number of PWSs by State (UCMR 1 March 2006 Data)
State 1 2
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
lotal
Total Number of
Samples
2
12
21
35
765
32
21
98
24
2
46
2
2
18
9
33
53
29
6
30
33
34
7
28
16
52
4
18
10
51
78
4
122
20
10
12
76
45
11
13
6
51
217
4
8
12
46
66
8
4
2,306
Total Number of
PWSs
1
3
5
2
39
6
2
15
8
1
7
1
1
5
3
7
9
5
2
8
6
4
2
7
3
9
1
2
2
10
8
1
12
7
3
3
17
6
2
4
2
9
19
1
3
4
6
9
2
1
295
No. of Small Systems
GW
1
2
5
1
6
6
1
4
1
1
3
2
6
2
1
6
3
1
1
6
1
3
1
1
5
3
1
2
3
1
8
1
1
1
1
8
2
2
3
7
114
SW
1
1
2
1
8
3
1
2
1
1
2
1
1
1
1
1
1
4
1
2
1
1
1
2
4
2
2
5
4
1
1
1
2
1
64
No. of Large Systems
GW
1
13
9
2
1
1
1
2
1
1
3
3
4
2
1
1
2
1
1
50
SW
1
1
13
2
1
1
4
1
3
1
1
2
1
2
1
2
5
1
1
1
4
3
2
1
1
2
5
2
1
1
67
The UCMR data are not representative at the state-level.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
A-33
-------
Appendix A. Stage 1 Occurrence Measures for All Other UCMR 1 Contaminants
Table A10.C. LL-Nitrobenzene - Total Population-Served by State (UCMR 1 March 2006 Data)
State 1 2
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
lotal
Total Number of
PWSs
1
3
5
2
39
6
2
15
8
1
7
1
1
5
3
7
9
5
2
8
6
4
2
7
3
9
1
2
2
10
8
1
12
7
3
3
17
6
2
4
2
9
19
1
3
4
6
9
2
1
295
Total Population
Served
188
50,304
231,182
22,606
9,456,619
1,415,583
48,908
3,085,161
12,586
5,008
118,082
450
970
298,249
12,552
416,408
300,226
176,784
265
62,019
581 ,274
1,591,818
6,140
48,956
34,328
255,993
203
510,453
28,200
491,189
498,770
1,383
7,327,997
1,752,015
17,740
32,860
185,358
1 ,691 ,960
459,312
52,976
28,958
783,081
6,382,552
9,800
5,258
62,749
1,254,766
953,848
2,895
498
40,767,480
Pop. Served by
Small Systems
GW
6,150
8,639
12,314
5,758
13,345
5,180
5,008
8,533
450
970
15,938
3,303
23,544
10,400
185
12,908
13,150
2,118
2,631
8,988
445
3,104
4,033
200
1 1 ,200
3,200
1,383
740
10,086
110
10,957
7,616
2,886
4,300
1,526
15,786
1,258
1,149
10,289
25,405
275,185
SW
188
2,154
6,656
1,606
23,867
10,495
8,500
7,406
2,580
9,249
8,089
4,500
80
9,006
5,200
3,509
4,802
18,365
203
570
8,888
7,000
1,780
6,200
10,601
7,376
9,350
28,669
7,556
9,800
4,000
1,313
2,895
498
232,951
Pop. Served by
Large Systems
GW
21,000
1 ,053,905
3,071,816
106,969
39,000
22,428
62,210
119,440
39,968
28,000
93,489
495,000
644,310
82,783
16,000
654,267
1,374,537
22,000
53,000
8,000,122
SW
42,000
215,887
8,366,533
1 ,399,330
40,408
243,311
385,891
209,972
166,384
40,105
448,684
1 ,584,500
29,081
234,524
506,420
386,500
6,674,059
1,652,146
15,850
26,660
147,800
1 ,676,968
459,312
40,740
24,658
98,619
4,984,673
61,600
1,221,164
875,443
32,259,222
The UCMR data are not representative at the state-level.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
A-34
-------
Appendix A. Stage 1 Occurrence Measures for All Other UCMR 1 Contaminants
Table A11.a. 2-Methyl-phenol - Sample-, System-, and Population Served-Level Occurrence (UCMR 1 March 2006 Data)
Water Type
System Size by
Population Served
Sample Level
Total Number
of Samples
Detections
Number
Percent
System Level
Total Number
of Systems
Sampled
Systems with Detections
Number
Percent
Population Served-Level
Total
Population
Served
Pop. Served by
Systems with Detections
Number
Percent
Small Systems (Statistical Sample)
Ground
Water
Surface
Water
25 - 500
501 - 3,300
3,301 -10,000
Total
25 - 500
501 - 3,300
3,301 -10,000
Total
All Small Systems
95
148
138
381
67
66
137
270
651
0
0
0
0.00%
0.00%
0.00%
43
43
28
114
17
17
30
64
178
0
0
0
0.00%
0.00%
0.00%
10,296
79,739
185,150
275,185
4,744
29,902
198,305
232,951
508,136
0
0
0
0.00%
0.00%
0.00%
Large Systems (Statistical Sample)
Ground
Water
Surface
Water
10,001 -50,000
> 50,000
Total
10,001 -50,000
> 50,000
Total
All Large Systems
249
584
833
199
570
769
1,602
0
0
0
0.00%
0.00%
0.00%
28
22
50
34
32
66
116
0
0
0
0.00%
0.00%
0.00%
792,573
7,207,549
8,000,122
1,291,958
30,869,424
32,161,382
40,161,504
0
0
0
0.00%
0.00%
0.00%
All Systems
Total Water Systems
2,253
0
0.00%
294
0
0.00%
40,669,640
0
0.00%
A-35
-------
Appendix A. Stage 1 Occurrence Measures for All Other UCMR 1 Contaminants
Table A11.b. 2-Methyl-phenol - Number of PWSs by State (UCMR 1 March 2006 Data)
State 1 2
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
lotal
Total Number of
Samples
2
12
22
37
725
32
22
95
24
8
46
2
2
18
10
33
49
29
6
29
32
32
13
28
16
52
4
18
10
47
75
4
115
20
10
11
75
48
11
14
6
51
210
4
8
12
46
66
8
4
2,253
Total Number of
PWSs
1
3
5
2
38
6
2
15
8
1
7
1
1
5
3
7
9
5
2
8
6
4
2
7
3
9
1
2
2
10
8
1
12
7
3
3
17
6
2
4
2
9
19
1
3
4
6
9
2
1
294
No. of Small Systems
GW
1
2
5
1
6
6
1
4
1
1
3
2
6
2
1
6
3
1
1
6
1
3
1
1
5
3
1
2
3
1
8
1
1
1
1
8
2
2
3
7
114
SW
1
1
2
1
8
3
1
2
1
1
2
1
1
1
1
1
1
4
1
2
1
1
1
2
4
2
2
5
4
1
1
1
2
1
64
No. of Large Systems
GW
1
13
9
2
1
1
1
2
1
1
3
3
4
2
1
1
2
1
1
50
SW
1
1
12
2
1
1
4
1
3
1
1
2
1
2
1
2
5
1
1
1
4
3
2
1
1
2
5
2
1
1
66
The UCMR data are not representative at the state-level.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
A-36
-------
Appendix A. Stage 1 Occurrence Measures for All Other UCMR 1 Contaminants
Table A11.C. 2-Methyl-phenol - Total Population-Served by State (UCMR 1 March 2006 Data;
State 1 2
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
lotal
Total Number of
PWSs
1
3
5
2
38
6
2
15
8
1
7
1
1
5
3
7
9
5
2
8
6
4
2
7
3
9
1
2
2
10
8
1
12
7
3
3
17
6
2
4
2
9
19
1
3
4
6
9
2
1
294
Total Population
Served
188
50,304
231,182
22,606
9,456,619
1,415,583
48,908
3,085,161
12,586
5,008
118,082
450
970
298,249
12,552
416,408
300,226
176,784
265
62,019
581 ,274
1,591,818
6,140
48,956
34,328
255,993
203
510,453
28,200
491,189
498,770
1,383
7,327,997
1,752,015
17,740
32,860
185,358
1 ,691 ,960
459,312
52,976
28,958
783,081
6,382,552
9,800
5,258
62,749
1,254,766
953,848
2,895
498
40,767,480
Pop. Served by
Small Systems
GW
6,150
8,639
12,314
5,758
13,345
5,180
5,008
8,533
450
970
15,938
3,303
23,544
10,400
185
12,908
13,150
2,118
2,631
8,988
445
3,104
4,033
200
1 1 ,200
3,200
1,383
740
10,086
110
10,957
7,616
2,886
4,300
1,526
15,786
1,258
1,149
10,289
25,405
275,185
SW
188
2,154
6,656
1,606
23,867
10,495
8,500
7,406
2,580
9,249
8,089
4,500
80
9,006
5,200
3,509
4,802
18,365
203
570
8,888
7,000
1,780
6,200
10,601
7,376
9,350
28,669
7,556
9,800
4,000
1,313
2,895
498
232,951
Pop. Served by
Large Systems
GW
21,000
1 ,053,905
3,071,816
106,969
39,000
22,428
62,210
119,440
39,968
28,000
93,489
495,000
644,310
82,783
16,000
654,267
1,374,537
22,000
53,000
8,000,122
SW
42,000
215,887
8,268,693
1 ,399,330
40,408
243,311
385,891
209,972
166,384
40,105
448,684
1 ,584,500
29,081
234,524
506,420
386,500
6,674,059
1,652,146
15,850
26,660
147,800
1 ,676,968
459,312
40,740
24,658
98,619
4,984,673
61,600
1,221,164
875,443
32,161,382
The UCMR data are not representative at the state-level.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
A-37
-------
Appendix A. Stage 1 Occurrence Measures for All Other UCMR 1 Contaminants
Table A12.a. Molinate - Occurrence Based on Samples, Systems, and Population Served (UCMR 1 March 2006 Data)
Water Type
System Size by
Population Served
Sample Level
Total Number
of Samples
Detections1
Number
Percent
System Level
Total Number
of Systems
Sampled
Systems with Detections
Number
Percent
Population Served-Level
Total
Population
Served
Pop. Served by
Systems with Detections
Number
Percent
Small Systems (Statistical Sample)
Ground
Water
Surface
Water
25 - 500
501 - 3,300
3,301 -10,000
Total
25 - 500
501 - 3,300
3,301 -10,000
Total
All Small Systems
259
879
1,204
2,342
220
181
508
909
3,251
0
0
0
0.00%
0.00%
0.00%
111
245
234
590
52
45
110
207
797
0
0
0
0.00%
0.00%
0.00%
27,599
441 ,499
1,470,717
1,939,815
16,662
91 ,723
712,370
820,755
2,760,570
0
0
0
0.00%
0.00%
0.00%
Large Systems (Census)
Ground
Water
Surface
Water
10,001 -50,000
> 50,000
Total
10,001 -50,000
> 50,000
Total
All Large Systems
10,525
5,422
15,947
7,425
7,176
14,601
30,548
1
1
0
1
0.02%
0.01%
0.00%
0.00%
1,190
190
1,380
1,187
509
1,696
3,076
1
1
0
1
0.53%
0.07%
0.00%
0.03%
26,929,381
26,476,158
53,405,539
33,405,163
136,681,205
170,086,368
223,491,907
457,51 1
457,51 1
0
457,51 1
1.73%
0.86%
0.00%
0.20%
All Systems
Total Water Systems2
33,799
1
0.003%
3,873
1
0.03%
226,252,477
457,51 1
0.20%
1 The single detection of molinate (equal to 5.7 ug/L) was found in a CWS in California.
2 The UCMR small water systems (population served < 10,000) are a statistical, representative sample of all national small systems while the UCMR large water systems (population
served > 10,000) represent a census of all large systems. Combined small and large system occurrence summaries accurately present the actual UCMR monitoring results. However,
only the summary findings expressed as percentages accurately reflect national occurrence; combined large and small summaries based on numerical counts of detections at the sample,
system, and population-served levels do not accurately represent national occurrence.
A-38
-------
Appendix A. Stage 1 Occurrence Measures for All Other UCMR 1 Contaminants
Table A12.b. Molinate - Number of PWSs by State (UCMR 1 March 2006 Data)
State 1 2
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
lotal
Total Number of
Samples
53
809
239
1,314
8,567
396
370
8
102
1,166
568
275
394
213
248
749
400
247
344
319
1,135
175
89
371
434
457
137
527
126
1,042
41
230
135
1,051
362
71
2,325
548
317
351
1,260
717
109
292
106
542
1,750
466
298
28
40
683
552
152
69
2
2
4
6
16
33,799
Total Number of
PWSs
9
98
47
59
407
56
41
1
8
238
101
5
17
47
21
133
86
41
77
76
132
36
19
71
85
68
3
72
13
115
13
20
21
128
32
11
160
153
52
55
165
85
13
59
17
105
266
52
58
4
10
82
76
35
11
1
1
1
2
3
3,873
No. of Small Systems
GW
2
12
9
11
26
3
3
2
31
14
3
12
6
26
19
10
2
23
10
7
4
21
16
17
1
30
4
12
3
8
4
14
6
3
21
24
7
6
21
4
2
5
3
2
61
4
13
3
14
21
1
1
1
1
1
590
SW
2
3
4
1
22
7
3
8
1
4
2
2
1
2
7
4
2
1
2
3
3
1
2
10
1
2
2
2
1
8
4
8
5
16
5
6
1
12
10
3
3
2
1
3
10
2
1
1
1
207
No. of Large Systems
GW
2
30
14
34
152
12
8
2
189
24
1
12
15
11
58
45
13
6
26
58
11
2
17
59
26
1
40
2
26
3
10
4
74
19
1
50
61
8
14
22
20
4
10
5
17
66
13
1
41
37
3
1
1,380
SW
3
53
20
13
207
34
27
1
4
18
55
3
2
16
2
47
21
16
62
23
62
17
11
30
10
22
2
5
67
6
2
11
38
5
6
81
64
29
30
106
56
7
38
8
74
129
32
41
2
6
24
18
22
7
1
1,696
The UCMR data are not representative at the state-level.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
A-39
-------
Appendix A. Stage 1 Occurrence Measures for All Other UCMR 1 Contaminants
Table A12.C. Molinate - Total Population-Served by State (UCMR 1 March 2006 Data]
State 1 2
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
lotal
Total Number of
PWSs
9
98
47
59
407
56
41
1
8
238
101
5
17
47
21
133
86
41
77
76
132
36
19
71
85
68
3
72
13
115
13
20
21
128
32
11
160
153
52
55
165
85
13
59
17
105
266
52
58
4
10
82
76
35
11
1
1
1
2
3
3,873
Total Population
Served
239,991
3,966,808
1,396,235
4,246,932
33,137,788
4,085,452
2,390,100
927,055
536,260
15,323,786
6,750,245
105,219
1,110,726
1,686,720
580,914
7,645,947
3,539,721
1,739,325
3,499,097
2,685,825
6,456,374
4,676,636
348,285
5,492,931
3,005,782
3,619,103
68,836
1 ,273,562
350,315
5,093,736
320,270
965,769
494,401
8,122,662
1,112,569
1,625,791
19,956,351
8,541 ,989
2,221,224
2,515,862
9,008,128
4,782,110
824,052
2,669,268
353,547
4,269,873
16,732,165
2,011,035
5,137,941
64,400
220,439
4,490,251
2,769,896
781,825
245,695
191
2,300
498
825
31 ,444
226,252,477
Pop. Served by
Small Systems
GW
3,092
67,068
35,209
39,692
85,318
12,175
1,309
6,800
117,516
28,636
15,462
19,916
35,100
106,661
104,078
27,481
7,622
75,303
50,393
12,301
2,955
57,873
58,334
38,276
2,631
78,999
10,314
47,141
7,416
23,535
10,620
60,020
6,625
5,393
45,407
104,131
23,784
12,378
42,012
24,631
4,740
14,485
9,780
2,533
228,336
16,417
13,849
2,149
38,029
88,774
1,100
191
2,300
325
3,200
1,939,815
SW
362
7,389
18,986
1,606
74,071
25,252
18,525
33,086
5,504
6,789
3,197
10,490
8,912
11,145
32,797
13,120
12,900
6,200
5,155
20,824
13,471
3,509
5,202
51 ,698
203
5,630
16,300
570
463
48,624
18,988
43,255
19,515
50,653
12,020
35,619
376
70,682
22,737
16,285
9,079
400
9,020
3,807
34,761
580
498
500
10,000
820,755
Pop. Served by
Large Systems
GW
58,600
703,125
334,297
1,561,412
7,011,747
294,405
121,731
53,330
12,383,938
715,555
12,500
1,010,064
515,056
342,565
1,536,074
1,195,492
299,868
179,924
807,125
1,392,955
522,337
27,040
624,720
1 ,695,267
767,067
62,696
872,095
85,782
663,985
67,034
410,925
76,400
2,086,167
948,281
17,000
3,493,019
1,683,901
166,635
390,600
442,445
445,558
94,000
213,706
72,760
1,078,175
2,851,292
351,194
40,715
1,516,949
1,022,486
60,546
24,999
53,405,539
SW
177,937
3,189,226
1,007,743
2,644,222
25,966,652
3,753,620
2,248,535
927,055
476,130
2,822,332
5,972,968
87,215
85,200
1,144,959
200,052
5,992,722
2,231,239
1 ,400,831
3,278,754
1,790,277
5,000,126
4,135,798
313,135
4,789,514
1,252,181
2,800,289
322,468
249,017
4,330,912
245,617
531 ,309
401,751
5,960,175
157,093
1,602,935
16,369,301
6,734,969
1 ,987,550
2,093,369
8,473,018
4,299,901
725,312
2,405,458
270,631
3,118,483
13,629,800
1,627,139
5,074,298
64,000
209,270
2,931,466
1 ,658,636
686,518
219,016
18,244
170,086,368
The UCMR data are not representative at the state-level.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
A-40
-------
Appendix A. Stage 1 Occurrence Measures for All Other UCMR 1 Contaminants
Table A13.a. Nitrobenzene - Occurrence Based on Samples, Systems, and Population Served (UCMR 1 March 2006 Data)
Water Type
System Size by
Population Served
Sample Level
Total Number
of Samples
Detections1
Number
Percent
System Level
Total Number
of Systems
Sampled
Systems with Detections
Number
Percent
Population Served-Level
Total
Population
Served
Pop. Served by
Systems with Detections
Number
Percent
Small Systems (Statistical Sample)
Ground
Water
Surface
Water
25 - 500
501 - 3,300
3,301 -10,000
Total
25 - 500
501 - 3,300
3,301 -10,000
Total
All Small Systems
259
871
1,211
2,341
224
183
520
927
3,268
0
0
0
0.00%
0.00%
0.00%
111
244
234
589
52
45
110
207
796
0
0
0
0.00%
0.00%
0.00%
27,599
439,01 1
1,470,717
1 ,937,327
16,662
91 ,723
712,370
820,755
2,758,082
0
0
0
0.00%
0.00%
0.00%
Large Systems (Census)
Ground
Water
Surface
Water
10,001 -50,000
> 50,000
Total
10,001 -50,000
> 50,000
Total
All Large Systems
10,328
5,524
15,852
7,347
7,109
14,456
30,308
1
1
1
1
2
0.01%
0.01%
0.01 %
0.01%
0.01 %
1,186
189
1,375
1,182
508
1,690
3,065
1
1
1
1
2
0.08%
0.07%
0.20%
0.06%
0.07%
26,796,362
26,361,273
53,157,635
33,201,855
136,615,205
169,817,060
222,974,695
16,990
16,990
238,368
238,368
255,358
0.06%
0.03%
0.17%
0.14%
0.11%
All Systems
Total Water Systems2
33,576
2
0.01%
3,861
2
0.05%
225,732,777
255,358
0.11%
1 The two detections of nitrotbenzene were found in CWSs in Florida. The GW detection was equal to 21.6 ug/L; the SW detection was equal to 100.0 ug/L.
2 The UCMR small water systems (population served < 10,000) are a statistical, representative sample of all national small systems while the UCMR large water systems (population
served > 10,000) represent a census of all large systems. Combined small and large system occurrence summaries accurately present the actual UCMR monitoring results. However,
only the summary findings expressed as percentages accurately reflect national occurrence; combined large and small summaries based on numerical counts of detections at the sample,
system, and population-served levels do not accurately represent national occurrence.
A-41
-------
Appendix A Stage 1 Occurrence Measures for All Other UCMR 1 Contaminants
Table A13.b. Nitrobenzene - Number of PWSs by State (UCMR 1 March 2006 Data)
State 1 2
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
lotal
Total Number of
Samples
53
614
229
1,278
8,568
397
370
8
102
1,162
564
267
392
213
247
745
410
248
354
477
1,125
172
91
363
431
452
19
525
141
1,046
41
231
134
1,014
353
73
2,364
544
320
355
1,258
720
104
288
101
546
1,721
475
297
26
40
684
552
171
70
2
2
4
6
17
33,576
Total Number of
PWSs
9
88
47
59
407
56
41
1
8
238
99
5
17
47
21
133
86
41
77
84
132
36
19
71
85
68
2
72
13
115
13
20
21
123
32
11
160
153
52
55
165
85
13
59
17
105
264
52
58
4
10
82
76
35
11
1
1
1
2
3
3,861
No. of Small Systems
GW
2
12
9
11
26
3
3
2
31
13
3
12
6
26
19
10
2
23
10
7
4
21
16
17
1
30
4
12
3
8
4
14
6
3
21
24
7
6
21
4
2
5
3
2
61
4
13
3
14
21
1
1
1
1
1
589
SW
2
3
4
1
22
7
3
8
1
4
2
2
1
2
7
4
2
1
2
3
3
1
2
10
1
2
2
2
1
8
4
8
5
16
5
6
1
12
10
3
3
2
1
3
10
2
1
1
1
207
No. of Large Systems
GW
2
24
14
34
152
12
8
2
189
23
1
12
15
11
58
45
13
6
34
58
11
2
17
59
26
40
2
26
3
10
4
70
19
1
50
61
8
14
22
20
4
10
5
17
65
13
1
41
37
3
1
1,375
SW
3
49
20
13
207
34
27
1
4
18
55
3
2
16
2
47
21
16
62
23
62
17
11
30
10
22
2
5
67
6
2
11
37
5
6
81
64
29
30
106
56
7
38
8
74
128
32
41
2
6
24
18
22
7
1
1,690
The UCMR data are not representative at the state-level.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
A-42
-------
Appendix A Stage 1 Occurrence Measures for All Other UCMR 1 Contaminants
Table A13.C. Nitrobenzene - Total Population-Served by State (UCMR 1 March 2006 Data]
State 1 2
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
lotal
Total Number of
PWSs
9
88
47
59
407
56
41
1
8
238
99
5
17
47
21
133
86
41
77
84
132
36
19
71
85
68
2
72
13
115
13
20
21
123
32
11
160
153
52
55
165
85
13
59
17
105
264
52
58
4
10
82
76
35
11
1
1
1
2
3
3,861
Total Population
Served
239,991
3,709,549
1,396,235
4,246,932
33,137,788
4,085,452
2,390,100
927,055
536,260
15,323,786
6,732,757
105,219
1,110,726
1,686,720
580,914
7,645,947
3,539,721
1,739,325
3,499,097
2,818,393
6,456,374
4,676,636
348,285
5,492,931
3,005,782
3,619,103
6,140
1 ,273,562
350,315
5,093,736
320,270
965,769
494,401
7,839,337
1,112,569
1,625,791
19,956,351
8,541 ,989
2,221,224
2,515,862
9,008,128
4,782,110
824,052
2,669,268
353,547
4,269,873
16,700,665
2,011,035
5,137,941
64,400
220,439
4,490,251
2,769,896
781,825
245,695
191
2,300
498
825
31 ,444
225,732,777
Pop. Served by
Small Systems
GW
3,092
67,068
35,209
39,692
85,318
12,175
1,309
6,800
117,516
26,148
15,462
19,916
35,100
106,661
104,078
27,481
7,622
75,303
50,393
12,301
2,955
57,873
58,334
38,276
2,631
78,999
10,314
47,141
7,416
23,535
10,620
60,020
6,625
5,393
45,407
104,131
23,784
12,378
42,012
24,631
4,740
14,485
9,780
2,533
228,336
16,417
13,849
2,149
38,029
88,774
1,100
191
2,300
325
3,200
1,937,327
SW
362
7,389
18,986
1,606
74,071
25,252
18,525
33,086
5,504
6,789
3,197
10,490
8,912
11,145
32,797
13,120
12,900
6,200
5,155
20,824
13,471
3,509
5,202
51 ,698
203
5,630
16,300
570
463
48,624
18,988
43,255
19,515
50,653
12,020
35,619
376
70,682
22,737
16,285
9,079
400
9,020
3,807
34,761
580
498
500
10,000
820,755
Pop. Served by
Large Systems
GW
58,600
587,634
334,297
1,561,412
7,011,747
294,405
121,731
53,330
12,383,938
700,555
12,500
1,010,064
515,056
342,565
1,536,074
1,195,492
299,868
179,924
939,693
1,392,955
522,337
27,040
624,720
1 ,695,267
767,067
872,095
85,782
663,985
67,034
410,925
76,400
1,910,382
948,281
17,000
3,493,019
1,683,901
166,635
390,600
442,445
445,558
94,000
213,706
72,760
1,078,175
2,839,792
351,194
40,715
1,516,949
1,022,486
60,546
24,999
53,157,635
SW
177,937
3,047,458
1,007,743
2,644,222
25,966,652
3,753,620
2,248,535
927,055
476,130
2,822,332
5,972,968
87,215
85,200
1,144,959
200,052
5,992,722
2,231,239
1 ,400,831
3,278,754
1,790,277
5,000,126
4,135,798
313,135
4,789,514
1,252,181
2,800,289
322,468
249,017
4,330,912
245,617
531 ,309
401,751
5,852,635
157,093
1,602,935
16,369,301
6,734,969
1 ,987,550
2,093,369
8,473,018
4,299,901
725,312
2,405,458
270,631
3,118,483
13,609,800
1,627,139
5,074,298
64,000
209,270
2,931,466
1 ,658,636
686,518
219,016
18,244
169,817,060
The UCMR data are not representative at the state-level.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
A-43
-------
Appendix A. Stage 1 Occurrence Measures for All Other UCMR 1 Contaminants
Table A14.a. Prometon - Sample-, System-, and Population Served-Level Occurrence (UCMR 1 March 2006 Data)
Water Type
System Size by
Population Served
Sample Level
Total Number
of Samples
Detections
Number
Percent
System Level
Total Number
of Systems
Sampled
Systems with Detections
Number
Percent
Population Served-Level
Total
Population
Served
Pop. Served by
Systems with Detections
Number
Percent
Small Systems (Statistical Sample)
Ground
Water
Surface
Water
25 - 500
501 - 3,300
3,301 -10,000
Total
25 - 500
501 - 3,300
3,301 -10,000
Total
All Small Systems
95
151
134
380
65
64
134
263
643
0
0
0
0.00%
0.00%
0.00%
43
43
28
114
17
17
30
64
178
0
0
0
0.00%
0.00%
0.00%
10,296
79,739
185,150
275,185
4,744
29,902
198,305
232,951
508,136
0
0
0
0.00%
0.00%
0.00%
Large Systems (Statistical Sample)
Ground
Water
Surface
Water
10,001 -50,000
> 50,000
Total
10,001 -50,000
> 50,000
Total
All Large Systems
272
611
883
199
581
780
1,663
0
0
0
0.00%
0.00%
0.00%
28
22
50
34
33
67
117
0
0
0
0.00%
0.00%
0.00%
792,573
7,207,549
8,000,122
1,291,958
30,967,264
32,259,222
40,259,344
0
0
0
0.00%
0.00%
0.00%
All Systems
Total Water Systems
2,306
0
0.00%
295
0
0.00%
40,767,480
0
0.00%
A-44
-------
Appendix A. Stage 1 Occurrence Measures for All Other UCMR 1 Contaminants
Table A14.b. Prometon - Number of PWSs by State (UCMR 1 March 2006 Data)
State 1 2
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
lotal
Total Number of
Samples
2
12
21
35
765
32
21
98
24
2
46
2
2
18
9
33
53
29
6
30
33
34
7
28
16
52
4
18
10
51
78
4
122
20
10
12
76
45
11
13
6
51
217
4
8
12
46
66
8
4
2,306
Total Number of
PWSs
1
3
5
2
39
6
2
15
8
1
7
1
1
5
3
7
9
5
2
8
6
4
2
7
3
9
1
2
2
10
8
1
12
7
3
3
17
6
2
4
2
9
19
1
3
4
6
9
2
1
295
No. of Small Systems
GW
1
2
5
1
6
6
1
4
1
1
3
2
6
2
1
6
3
1
1
6
1
3
1
1
5
3
1
2
3
1
8
1
1
1
1
8
2
2
3
7
114
SW
1
1
2
1
8
3
1
2
1
1
2
1
1
1
1
1
1
4
1
2
1
1
1
2
4
2
2
5
4
1
1
1
2
1
64
No. of Large Systems
GW
1
13
9
2
1
1
1
2
1
1
3
3
4
2
1
1
2
1
1
50
SW
1
1
13
2
1
1
4
1
3
1
1
2
1
2
1
2
5
1
1
1
4
3
2
1
1
2
5
2
1
1
67
The UCMR data are not representative at the state-level.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
A-45
-------
Appendix A. Stage 1 Occurrence Measures for All Other UCMR 1 Contaminants
Table A14.C. Prometon - Total Population-Served by State (UCMR 1 March 2006 Data)
State 1 2
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
lotal
Total Number of
PWSs
1
3
5
2
39
6
2
15
8
1
7
1
1
5
3
7
9
5
2
8
6
4
2
7
3
9
1
2
2
10
8
1
12
7
3
3
17
6
2
4
2
9
19
1
3
4
6
9
2
1
295
Total Population
Served
188
50,304
231,182
22,606
9,456,619
1,415,583
48,908
3,085,161
12,586
5,008
118,082
450
970
298,249
12,552
416,408
300,226
176,784
265
62,019
581 ,274
1,591,818
6,140
48,956
34,328
255,993
203
510,453
28,200
491,189
498,770
1,383
7,327,997
1,752,015
17,740
32,860
185,358
1 ,691 ,960
459,312
52,976
28,958
783,081
6,382,552
9,800
5,258
62,749
1,254,766
953,848
2,895
498
40,767,480
Pop. Served by
Small Systems
GW
6,150
8,639
12,314
5,758
13,345
5,180
5,008
8,533
450
970
15,938
3,303
23,544
10,400
185
12,908
13,150
2,118
2,631
8,988
445
3,104
4,033
200
1 1 ,200
3,200
1,383
740
10,086
110
10,957
7,616
2,886
4,300
1,526
15,786
1,258
1,149
10,289
25,405
275,185
SW
188
2,154
6,656
1,606
23,867
10,495
8,500
7,406
2,580
9,249
8,089
4,500
80
9,006
5,200
3,509
4,802
18,365
203
570
8,888
7,000
1,780
6,200
10,601
7,376
9,350
28,669
7,556
9,800
4,000
1,313
2,895
498
232,951
Pop. Served by
Large Systems
GW
21,000
1 ,053,905
3,071,816
106,969
39,000
22,428
62,210
119,440
39,968
28,000
93,489
495,000
644,310
82,783
16,000
654,267
1,374,537
22,000
53,000
8,000,122
SW
42,000
215,887
8,366,533
1 ,399,330
40,408
243,311
385,891
209,972
166,384
40,105
448,684
1 ,584,500
29,081
234,524
506,420
386,500
6,674,059
1,652,146
15,850
26,660
147,800
1 ,676,968
459,312
40,740
24,658
98,619
4,984,673
61,600
1,221,164
875,443
32,259,222
The UCMR data are not representative at the state-level.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
A-46
-------
Appendix A. Stage 1 Occurrence Measures for All Other UCMR 1 Contaminants
Table A15.a. jerbufos - Sample-, System-, and Population Served-Level Occurrence (UCMR 1 March 2006 Data)
Water Type
System Size by
Population Served
Sample Level
Total Number
of Samples
Detections
Number
Percent
System Level
Total Number
of Systems
Sampled
Systems with Detections
Number
Percent
Population Served-Level
Total
Population
Served
Pop. Served by
Systems with Detections
Number
Percent
Small Systems (Statistical Sample)
Ground
Water
Surface
Water
25 - 500
501 - 3,300
3,301 -10,000
Total
25 - 500
501 - 3,300
3,301 -10,000
Total
All Small Systems
95
151
134
380
65
64
134
263
643
0
0
0
0.00%
0.00%
0.00%
43
43
28
114
17
17
30
64
178
0
0
0
0.00%
0.00%
0.00%
10,296
79,739
185,150
275,185
4,744
29,902
198,305
232,951
508,136
0
0
0
0.00%
0.00%
0.00%
Large Systems (Statistical Sample)
Ground
Water
Surface
Water
10,001 -50,000
> 50,000
Total
10,001 -50,000
> 50,000
Total
All Large Systems
272
611
883
198
577
775
1,658
0
0
0
0.00%
0.00%
0.00%
28
22
50
34
33
67
117
0
0
0
0.00%
0.00%
0.00%
792,573
7,207,549
8,000,122
1,291,958
30,967,264
32,259,222
40,259,344
0
0
0
0.00%
0.00%
0.00%
All Systems
Total Water Systems
2,301
0
0.00%
295
0
0.00%
40,767,480
0
0.00%
A-47
-------
Appendix A. Stage 1 Occurrence Measures for All Other UCMR 1 Contaminants
Table A15.b. Terbufos - Number of PWSs by State (UCMR 1 March 2006 Data)
State 1 2
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
lotal
Total Number of
Samples
2
12
21
35
765
32
21
98
24
2
46
2
2
18
9
33
53
29
6
30
33
34
7
28
16
52
4
18
10
51
78
4
122
20
10
12
76
45
11
13
6
51
212
4
8
12
46
66
8
4
2,301
Total Number of
PWSs
1
3
5
2
39
6
2
15
8
1
7
1
1
5
3
7
9
5
2
8
6
4
2
7
3
9
1
2
2
10
8
1
12
7
3
3
17
6
2
4
2
9
19
1
3
4
6
9
2
1
295
No. of Small Systems
GW
1
2
5
1
6
6
1
4
1
1
3
2
6
2
1
6
3
1
1
6
1
3
1
1
5
3
1
2
3
1
8
1
1
1
1
8
2
2
3
7
114
SW
1
1
2
1
8
3
1
2
1
1
2
1
1
1
1
1
1
4
1
2
1
1
1
2
4
2
2
5
4
1
1
1
2
1
64
No. of Large Systems
GW
1
13
9
2
1
1
1
2
1
1
3
3
4
2
1
1
2
1
1
50
SW
1
1
13
2
1
1
4
1
3
1
1
2
1
2
1
2
5
1
1
1
4
3
2
1
1
2
5
2
1
1
67
The UCMR data are not representative at the state-level.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
A-48
-------
Appendix A. Stage 1 Occurrence Measures for All Other UCMR 1 Contaminants
Table A15.C. Terbufos - Total Population-Served by State (UCMR 1 March 2006 Data)
State 1 2
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
lotal
Total Number of
PWSs
1
3
5
2
39
6
2
15
8
1
7
1
1
5
3
7
9
5
2
8
6
4
2
7
3
9
1
2
2
10
8
1
12
7
3
3
17
6
2
4
2
9
19
1
3
4
6
9
2
1
295
Total Population
Served
188
50,304
231,182
22,606
9,456,619
1,415,583
48,908
3,085,161
12,586
5,008
118,082
450
970
298,249
12,552
416,408
300,226
176,784
265
62,019
581 ,274
1,591,818
6,140
48,956
34,328
255,993
203
510,453
28,200
491,189
498,770
1,383
7,327,997
1,752,015
17,740
32,860
185,358
1 ,691 ,960
459,312
52,976
28,958
783,081
6,382,552
9,800
5,258
62,749
1,254,766
953,848
2,895
498
40,767,480
Pop. Served by
Small Systems
GW
6,150
8,639
12,314
5,758
13,345
5,180
5,008
8,533
450
970
15,938
3,303
23,544
10,400
185
12,908
13,150
2,118
2,631
8,988
445
3,104
4,033
200
1 1 ,200
3,200
1,383
740
10,086
110
10,957
7,616
2,886
4,300
1,526
15,786
1,258
1,149
10,289
25,405
275,185
SW
188
2,154
6,656
1,606
23,867
10,495
8,500
7,406
2,580
9,249
8,089
4,500
80
9,006
5,200
3,509
4,802
18,365
203
570
8,888
7,000
1,780
6,200
10,601
7,376
9,350
28,669
7,556
9,800
4,000
1,313
2,895
498
232,951
Pop. Served by
Large Systems
GW
21,000
1 ,053,905
3,071,816
106,969
39,000
22,428
62,210
119,440
39,968
28,000
93,489
495,000
644,310
82,783
16,000
654,267
1,374,537
22,000
53,000
8,000,122
SW
42,000
215,887
8,366,533
1 ,399,330
40,408
243,311
385,891
209,972
166,384
40,105
448,684
1 ,584,500
29,081
234,524
506,420
386,500
6,674,059
1,652,146
15,850
26,660
147,800
1 ,676,968
459,312
40,740
24,658
98,619
4,984,673
61,600
1,221,164
875,443
32,259,222
The UCMR data are not representative at the state-level.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
A-49
-------
Appendix A. Stage 1 Occurrence Measures for All Other UCMR 1 Contaminants
Table A16.a. 2,4,6-Trichlorophenol - Sample-, System-, and Population Served-Level Occurrence (UCMR 1 March 2006 Data )
Water Type
System Size by
Population Served
Sample Level
Total Number
of Samples
Detections
Number
Percent
System Level
Total Number
of Systems
Sampled
Systems with Detections
Number
Percent
Population Served-Level
Total
Population
Served
Pop. Served by
Systems with Detections
Number
Percent
Small Systems (Statistical Sample)
Ground
Water
Surface
Water
25 - 500
501 - 3,300
3,301 -10,000
Total
25 - 500
501 - 3,300
3,301 -10,000
Total
All Small Systems
95
148
138
381
67
66
137
270
651
0
0
0
0.00%
0.00%
0.00%
43
43
28
114
17
17
30
64
178
0
0
0
0.00%
0.00%
0.00%
10,296
79,739
185,150
275,185
4,744
29,902
198,305
232,951
508,136
0
0
0
0.00%
0.00%
0.00%
Large Systems (Statistical Sample)
Ground
Water
Surface
Water
10,001 -50,000
> 50,000
Total
10,001 -50,000
> 50,000
Total
All Large Systems
249
584
833
199
570
769
1,602
0
0
0
0.00%
0.00%
0.00%
28
22
50
34
32
66
116
0
0
0
0.00%
0.00%
0.00%
792,573
7,207,549
8,000,122
1,291,958
30,869,424
32,161,382
40,161,504
0
0
0
0.00%
0.00%
0.00%
All Systems
Total Water Systems
2,253
0
0.00%
294
0
0.00%
40,669,640
0
0.00%
A-50
-------
Appendix A. Stage 1 Occurrence Measures for All Other UCMR 1 Contaminants
Table A16.b. 2,4,6-Trichlorophenol - Number of PWSs by State (UCMR 1 March 2006 Data)
State 1 2
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
lotal
Total Number of
Samples
2
12
22
37
725
32
22
95
24
8
46
2
2
18
10
33
49
29
6
29
32
32
13
28
16
52
4
18
10
47
75
4
115
20
10
11
75
48
11
14
6
51
210
4
8
12
46
66
8
4
2,253
Total Number of
PWSs
1
3
5
2
38
6
2
15
8
1
7
1
1
5
3
7
9
5
2
8
6
4
2
7
3
9
1
2
2
10
8
1
12
7
3
3
17
6
2
4
2
9
19
1
3
4
6
9
2
1
294
No. of Small Systems
GW
1
2
5
1
6
6
1
4
1
1
3
2
6
2
1
6
3
1
1
6
1
3
1
1
5
3
1
2
3
1
8
1
1
1
1
8
2
2
3
7
114
SW
1
1
2
1
8
3
1
2
1
1
2
1
1
1
1
1
1
4
1
2
1
1
1
2
4
2
2
5
4
1
1
1
2
1
64
No. of Large Systems
GW
1
13
9
2
1
1
1
2
1
1
3
3
4
2
1
1
2
1
1
50
SW
1
1
12
2
1
1
4
1
3
1
1
2
1
2
1
2
5
1
1
1
4
3
2
1
1
2
5
2
1
1
66
The UCMR data are not representative at the state-level.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
A-51
-------
Appendix A. Stage 1 Occurrence Measures for All Other UCMR 1 Contaminants
Table A16.C. 2,4,6-Trichlorophenol - Total Population-Served by State (UCMR 1 March 2006 Data;
State 1 2
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
lotal
Total Number of
PWSs
1
3
5
2
38
6
2
15
8
1
7
1
1
5
3
7
9
5
2
8
6
4
2
7
3
9
1
2
2
10
8
1
12
7
3
3
17
6
2
4
2
9
19
1
3
4
6
9
2
1
294
Total Population
Served
188
50,304
231,182
22,606
9,358,779
1,415,583
48,908
3,085,161
12,586
5,008
118,082
450
970
298,249
12,552
416,408
300,226
176,784
265
62,019
581 ,274
1,591,818
6,140
48,956
34,328
255,993
203
510,453
28,200
491,189
498,770
1,383
7,327,997
1,752,015
17,740
32,860
185,358
1 ,691 ,960
459,312
52,976
28,958
783,081
6,382,552
9,800
5,258
62,749
1,254,766
953,848
2,895
498
40,669,640
Pop. Served by
Small Systems
GW
6,150
8,639
12,314
5,758
13,345
5,180
5,008
8,533
450
970
15,938
3,303
23,544
10,400
185
12,908
13,150
2,118
2,631
8,988
445
3,104
4,033
200
1 1 ,200
3,200
1,383
740
10,086
110
10,957
7,616
2,886
4,300
1,526
15,786
1,258
1,149
10,289
25,405
275,185
SW
188
2,154
6,656
1,606
23,867
10,495
8,500
7,406
2,580
9,249
8,089
4,500
80
9,006
5,200
3,509
4,802
18,365
203
570
8,888
7,000
1,780
6,200
10,601
7,376
9,350
28,669
7,556
9,800
4,000
1,313
2,895
498
232,951
Pop. Served by
Large Systems
GW
21,000
1 ,053,905
3,071,816
106,969
39,000
22,428
62,210
119,440
39,968
28,000
93,489
495,000
644,310
82,783
16,000
654,267
1,374,537
22,000
53,000
8,000,122
SW
42,000
215,887
8,268,693
1 ,399,330
40,408
243,311
385,891
209,972
166,384
40,105
448,684
1 ,584,500
29,081
234,524
506,420
386,500
6,674,059
1,652,146
15,850
26,660
147,800
1 ,676,968
459,312
40,740
24,658
98,619
4,984,673
61,600
1,221,164
875,443
32,161,382
The UCMR data are not representative at the state-level.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
A-52
-------
Appendix B. Detailed Description of Stage 2
(Bayesian-Based) Hierarchical Model
-------
-------
Appendix B. Detailed Description of the Stage 2 Analysis
Appendix B. Detailed Description of the Stage 2 Analysis ~
The Bayesian-Based Hierarchical Model1
General Description ofBayesian Statistics
Bayesian statistics are named after the English mathematician Reverend Thomas Bayes,
who first used probability inductively and established a mathematical basis for probability
inference and information updating. Although Rev. Bayes' original work was not intended for
combining information, the Bayesian approach is nevertheless most suitable for combining
information contained in the single experiment data as well as knowledge accumulated before
the experiment. The core Bayesian definition of a subjective probability (probability is defined
as the degree of belief) enables the Bayesian to update information and combine information
from different, but related, situations or experiments. This type of approach considers not only
what information is contained in the specific situation (or data) directly being assessed, but what
outside expertise or information might also contribute to an understanding of the situation being
assessed (a priori information or the prior). Considering prior information is consistent with the
common scientific approach. A scientific study always starts with a summary of existing
knowledge of the subject matter to propose a new hypothesis. Data are then collected to test the
hypothesis. New conclusions are drawn based on the results.
Because of the subjective probability definition, Bayesian inference is best suited to
problems that involve making decisions under uncertainty. Uncertain knowledge is summarized
in terms of prior probability in Bayes' Theorem. In the context of statistical modeling, this prior
knowledge is typically in the form of a probability density function, a mathematical expression
that defines the likelihood of an event occurring. The prior knowledge can be based on the
results of other experiments, on expert opinion, or actual existing data. The Bayesian analytical
approach starts with initial or prior knowledge and then uses data to improve upon the initial
state of knowledge.
In the context of statistical estimations of occurrence of the unregulated contaminants
being assessed under the UCMR, there is little prior information. Consequently, a special class
of prior distributions that represents no or little information is used. The information in the data
is expressed in terms of a likelihood function, which is a mathematical expression about the
probability of observing the data. Using Bayes' Theorem, the priors and the likelihood are
combined to yield posterior distributions. A posterior distribution represents what is now
believed about the original parameter (the prior) in light of the supplemental data. The posterior
distribution can be used as prior for a future similar study.
Estimating System Mean Concentrations
It is a common assumption that water data follow a log-normal distribution (Ott, 1995).
The Bayesian-based model described here is based on the assumption that the contaminant
concentrations at each system are log-normally distributed with an unknown mean and unknown
variance. The priors in this analysis are the probability distributions for the system means and
Full references for all cited documents are included in the body of the report.
B-l
-------
Appendix B. Detailed Description of the Stage 2 Analysis
variances. Once the prior distribution has been established, a two-level statistical model is built.
The lower-level features the observed concentrations (analytical detections and non-detections),
which are treated as coming from a log-normal distribution. The upper-level features the
unknown parameters (system mean and within-system variance) of the log-normal probability
distribution of each system, whose values are estimated based on the detections and non-
detections. These system means are further summarized to develop the national distribution of
system means with two additional parameters (mean of the system means and between-system
variance). Thus, the Bayesian-based approach allows the model to produce a conditional
distribution of occurrence characteristics that are currently unknown (system mean, within-
system variance, mean of system mean, and between-system variance) as a function of the
known data (the analytical detections and non-detections).2
By pooling evidence (data) from many observations for hundreds or thousands of
PWSIDs, this model estimates the mean concentration and standard deviation for each system
using a Bayesian-based approach. An advantage of this model is that it allows for "borrowing of
strength" in estimation between neighboring strata (Lockwood et al. 2001). For example, when a
particular stratum (say, ground water systems serving less than 500 people) has either no or very
few observations, its parameter estimates are shrunk toward the nearest strata that have data (e.g.,
ground water systems serving between 501-3,301 people). Thus, this process improves estimates
for all strata.
A historical limitation of using Bayesian methods was that analytical solutions for the
required computations were available for a limited number of parameters (The Cadmus Group,
2001). The amount of parameters in this analysis exceeded this limit, making it impossible to
generate estimates by use of Bayes' Theorem. However, the advent of fast and inexpensive
computing has promoted the development of several methods of performing Bayesian inference
(The Cadmus Group, 2001). The method used for this analysis is based on Monte Carlo
sampling.
The Monte Carlo method is, in general terms, any technique using random numbers to
model some sort of a process. (This technique works particularly well when the process is one
where the underlying probability distributions are known, but the results are more difficult to
determine.) In a Monte Carlo simulation, the value used for each variable is selected randomly
from the defined probability distribution. Many simulations are then performed and the desired
result is taken as an average over the number of observations (which may be a single observation
or perhaps millions of observations).
A Markov chain Monte Carlo method was used for this analysis. Markov chain Monte
Carlo (MCMC) is an important technique used with Bayesian statistics to sample from the
posterior distribution. MCMC generates a chain that converges, in distribution, on the posterior
parameter distribution, that can be regarded as a sample from the posterior distribution (The
Cadmus Group, 2001). Using these samples, it is then possible to calculate the statistics of
interest (mean concentration and standard deviation). This technique also provides a means to
generate a random sequence of model output that may be used to make inferences about the
model uncertainties that derive from measurement uncertainties.
2
Although actual numerical values are unknown for the non-detections, they are known to be less than the MRL.
B-2
-------
Appendix B. Detailed Description of the Stage 2 Analysis
This Bayesian-based hierarchical model can be summarized by the following equations:
, <7fe2)I(, Chljk)
where Y^k is the log of the kih concentration value in they'th system in the /'th category in the hih
stratum (if Y^K is a non-detect, the value Chijk is the detection limit or MRL), Oh,2 is the common
within-system variance for the /'th category in the Mi stratum. The system mean jUhy is further
modeled as from another normal distribution:
juhlj ~ Normal(//fe, a2)
where //& represents the mean of system means for the /'th category and Mi stratum (or the
category mean), and cr/,2 is the between-system variance. The full hierarchical model further
constrains the mean parameter ///„• by using two higher-level normal distributions:
jUhi ~ Normalt///,, cr2)
and
jUh ~ Normal(//, T2)
where ///, is the mean of category means for the Mi stratum (or the stratum mean), c? is the
between category variance, and //, T2 are the hyper-parameters that define the distribution of
stratum mean. When evaluating the national distribution of system means, we use the estimated
system means jiihij to form empirical CDFs. Because the arithmetic system mean is of interest,
the estimated arithmetic mean is /4yA = exp(//fey+ 0.5 cr/,2). When each system is sampled with
an equal weight, the estimated //^A values are treated equally. For example, the empirical CDF
can be estimated by calculating the fraction of systems with estimated mean less than a given
concentration value. When the systems are sampled with unequal weights, the empirical CDF at
a given concentration value is the sum of the weights of those systems with an estimated mean
less than the concentration value. Because the model parameters are estimated using a Markov
chain Monte Carlo (MCMC) simulation method, the same CDF is estimated repeatedly. Each
iteration represents a possible estimate of the CDF. Consequently, each iteration can be used to
summarize uncertainty in the estimated CDF. The exceedance probability is (1 - CDF value)
estimated at the threshold concentration. When the empirical CDF is estimated separately for
each category and each stratum, category- and stratum-specific exceedance probabilities can be
estimated.
B-3
-------
Appendix B. Detailed Description of the Stage 2 Analysis
Computer Code
The actual Bayesian-based, probabilistic modeling code used for UCMR 1 Stage 2 DCPA
degradate occurrence analyses is presented in full below.
setwd(base)
dataDir <_ paste(base, "Data", sep="/")
library(R2WinBUGS)
library(BRugs)
## my bugs files ##
source("c:/users/song/mybugs.r")
##
DCPA.small<_read.table(paste(dataDir, "DCPASmall.csv", sep=7"), header=T, sep=",")
DCPA.large<_ read.table(paste(dataDir, "DCPALarge2.csv", sep="/"), header=T, sep=",")
names(DCPA.small)
# [1] "State" "PWSID" "Weights" "Size"
#[5]"GW.SW" "PopServed" "Results.sign" "Results.value"
# [9] "FacID" "SPID" "Sample.pt.type" "Sample.ID"
#[13] "Parameter" "PWS.Type" "Date" "Analytical.meth"
#sub.data<_list()
#for (i in l:length(unique(allUCMR.data$Contaminant))){
# sub.data[[i]] <_ allUCMR.data[
allUCMR.data$Contaminant==sort(unique(allUCMR.data$Contaminant))[i], ]
#}
## find a unique stratum_category identification:
# state + system type(CSW or NTNCWS) + Source type (GW or SW) +
# Size (1, 2, 3 for the weight file and SizeCatl 1 .pt for the actual data set
# substring (levels(SizeCatll.pt), 1, 1) == a b, c|d, e )
bugsin.UCMR <_ function(infile = DCPAsmall){
# This version sorts the data by system id (pwsid)
# for calculating both strata means and systems means.
# cuts: concentration range where CDF will be estimated
# cr: critical values in original scale
oo <_ order(infile$PWSID)
infile <_ infile[oo, ]
Y <_ log(infile$Results.value)
n <_ length(y)
Source <_as.numeric(ordered(substring(infile$GW.SW,l,l))) # 1=G, 2=S
I <_ length(unique(Source))
pops <_ substring(infile$Size,l,l)
Strata <_ paste(pops, Source, sep = ".")
M <_ length(unique(Strata))
Strata <_ as.numeric(ordered(Strata))
pwsid <_ as.numeric(ordered(infile$PWSID))
npwsid <_ as.vector(table(pwsid))
B-4
-------
Appendix B. Detailed Description of the Stage 2 Analysis
mstrata <_ Strata[cumsum(npwsid)]
L <_ length(unique(pwsid))
cj<_y
y[infile$Results.sign=="lt"] <_ NA
bugs.dat <_ list(n = n, M = M, L = L, y = y, cj = cj, strata = mstrata, pwsid = pwsid)
yi <_ cj
yi[infile$Results.sign=="eq"] <_ NA
initl <_ list(y = 0.5*yi, munation = 0, prec = rep(9, M+2), musys = rep(_l, L), mustrata = rep( 1, M))
init2 <_ list(y = 0.4*yi, munation = 1, prec = rep(2, M+2), musys = rep(0 , L), mustrata = rep( 0, M))
initS <_ list(y = 0.3*yi, munation =_1, prec = rep(l, M+2), musys = rep(l , L), mustrata = rep(_l, M))
inits <_ list (initl, init2, initS)
parameters <_ elimination","mustrata","musys","sigma")
# BUGS files
return(list(para=parameters, data=bugs.dat, inits=inits))
#######################################################################
## BRugs
#input.to.bugs <_ bugsin.UCMR (infile=DCPA.small)
#bugsoutDCPA.small <_ my.bugs(input.to.bugs$data, input.to.bugs$inits)
n.chains <_ 3
n.iter<_50000
n .burnin<_floor(n. iter/2)
para <_ elimination", "mustrata", "cbar")
modelCheck(paste(base, "censorUCMR.txt",sep="/")) ##Checks model _ equivalent to check model
button
modelData("data.txt") ##Checks data _ equivalent to load data button
modelCompile(numChains = n.chains)
modellnits('initsl .txt') ##Checks initial values _ equivalent to load inits button
modellnits('inits2.txt')
modellnits('inits3 .txt')
sample s Set(para)
modelUpdate (numUpdate s=n .iter)
samplesCoda("*", stem="./", beg = floor(n.iter / 2),
thin = max(l, floor(n.chains * (niter _ n.burnin) / 1500)))
bugsout.small <_ my.sims(parameters.to.save=para,
n.chains=3, n.iter=n.iter, n.burnin=floor(n.iter/2),
n.thin=max(l, floor(n.chains * (n.iter _ n.burnin) / 1500)), DIG = TRUE)
#input.to.bugs <_ bugsin.UCMR (infile=DCPA.large)
#bugsoutDCPA.large <_ my.bugs(input.to.bugs$data, input.to.bugs$inits)
B-5
-------
Appendix B. Detailed Description of the Stage 2 Analysis
modelCheck(paste(base, "censorUCMR.txt",sep="/")) ##Checks model _ equivalent to check model
button
modelData("data.txt") ##Checks data _ equivalent to load data button
modelCompile(numChains = n.chains)
modellnits('initsl .txt') ##Checks initial values _ equivalent to load inits button
modellnits('inits2.txt')
modellnits('inits3 .txt')
sample sSet(para)
modelUpdate (numUpdate s=n .iter)
samplesCoda("*", stem="./", beg = floor(n.iter / 2),
thin = max(l, floor(n.chains * (niter _ n.burnin) / 1500)))
bugsout.large <_ my.sims(parameters.to.save=para,
n.chains=3, n.iter=n.iter, n.burnin=floor(n.iter/2),
n.thin=max(l, floor(n.chains * (n.iter _ n.burnin) / 1500)), DIG = TRUE)
###############
4 BRugsFit
samplesHistoryC'*", mfrow = c(4, 2)) # plot the chain,
samplesDensityC'alpha") # plot the densities,
samplesBgr("alpha[l:6]") # plot the bgr statistics, and
samplesAutoC("alpha[l:6]", 1) # plot autocorrelations of 1st chain
## switch back to the previous working directory:
setwd(oldwd)
## Not run:
# Getting more (online_)help:
help.BRugsQ
## End(Not run)
#####################################################################################
dataset <_ "DCPA"
cr<_c(l,35, 70)##DCPA
Strata.ID <_ function(infile){
oo <_ order(infile$PWSID)
temp <_infile[oo, ]
Source <_as.numeric(ordered(substring(temp$GW.SW,l,l))) # 1=G, 2=S
pops <_ substring(temp$Size,l,l)
Strata<_as.numeric(ordered(paste(pops, Source, sep = ".")))
pwsid <_ as.numeric(ordered(temp$PWSID))
npwsid <_ as.vector(table(pwsid))
mstrata <_ Strata[cumsum(npwsid)]
return(mstrata)
stratalD.small <_ Strata.ID(infile=DCPA.small)
stratalD.large <_ Strata.ID(infile=DCPA.large)
B-6
-------
Appendix B. Detailed Description of the Stage 2 Analysis
## sProb should be part of each input data set
# small systems
small.sims <_ bugsout.small$sims.list$cbar
temp.small <_strataID.small==l strataID.small==3 | strataID.small==5
temp <_apply(small.sims[,temp.small], 1, FUN=function(x, CR, sProb){# function(x, CR){ ## FUN
prob<_ numeric()
for(iinl:length(CR)){
#prob[i] <_ sum(x>=CR[i])/length(x)
## For sampling probability correction:
prob[i] <_ sum(sProb[x>=CR[i]])/sum(sProb)
## sProb[] is the sampling probability vector
}
return(prob)
}, CR=cr, sProb)
GW.small.All <_ apply(temp, 1, FUN=function(x)return(c(mean(x, na.rm=T), sd(x,
na.rm=T)/sqrt(length(x)), quantile(x, prob=c(0.025, 0.05, 0.5, 0.95, 0.975)))))
temp.small.i <_ strataID.small==l
temp <_apply(small.sims[,temp.small.i], 1, FUN=function(x, CR){
prob<_ numeric()
for(iinl:length(CR)){
prob[i] <_ sum(x>=CR[i])/length(x)
}
return(prob)
}, CR=cr)
GW.small. 1 <_ apply(temp, 1, FUN=runction(x)return(c(mean(x, na.rm=T), sd(x,
na.rm=T)/sqrt(length(x)), quantile(x, prob=c(0.025, 0.05, 0.5, 0.95, 0.975)))))
temp.small.i <_ strataID.small==3
temp <_apply(small.sims[,temp.small.i], 1, FUN=function(x, CR){
prob<_ numeric()
for (i in l:length(CR)){
prob[i] <_ sum(x>=CR[i])/length(x)
}
return(prob)
}, CR=cr)
GW.small.2 <_ apply(temp, 1, FUN=function(x)return(c(mean(x, na.rm=T), sd(x,
na.rm=T)/sqrt(length(x)), quantile(x, prob=c(0.025, 0.05, 0.5, 0.95, 0.975)))))
temp.small.i <_ strataID.small==5
temp <_apply(small.sims[,temp.small.i], 1, FUN=function(x, CR){
prob<_ numericO
for (i in l:length(CR)){
prob[i] <_ sum(x>=CR[i])/length(x)
}
return(prob)
}, CR=cr)
GW.small.3 <_ apply(temp, 1, FUN=function(x)return(c(mean(x, na.rm=T), sd(x,
na.rm=T)/sqrt(length(x)), quantile(x, prob=c(0.025, 0.05, 0.5, 0.95, 0.975)))))
B-7
-------
Appendix B. Detailed Description of the Stage 2 Analysis
temp <_apply(small.sims[,!temp.small], 1, FUN=function(x, CR){
prob<_ numericO
for(iinl:length(CR)){
prob[i] <_ sum(x>=CR[i])/length(x)
}
return(prob)
}, CR=cr)
SW.small.All <_ apply(temp, 1, FUN=function(x)return(c(mean(x, na.rm=T), sd(x,
na.rm=T)/sqrt(length(x)), quantile(x, prob=c(0.025, 0.05, 0.5, 0.95, 0.975)))))
temp.small.i <_ strataID.small==2
temp <_apply(small.sims[,temp.small.i], 1, FUN=function(x, CR){
prob<_ numeric()
for (i in l:length(CR)){
prob[i] <_ sum(x>=CR[i])/length(x)
}
return(prob)
}, CR=cr)
SW.small. 1 <_ apply(temp, 1, FUN=function(x)return(c(mean(x, na.rm=T), sd(x,
na.rm=T)/sqrt(length(x)), quantile(x, prob=c(0.025, 0.05, 0.5, 0.95, 0.975)))))
temp.small.i <_ strataID.small==4
temp <_apply(small.sims[,temp.small.i], 1, FUN=function(x, CR){
prob<_ numericO
for(iinl:length(CR)){
prob[i] <_ sum(x>=CR[i])/length(x)
}
return(prob)
}, CR=cr)
SW.small.2 <_ apply(temp, 1, FUN=function(x)return(c(mean(x, na.rm=T), sd(x,
na.rm=T)/sqrt(length(x)), quantile(x, prob=c(0.025, 0.05, 0.5, 0.95, 0.975)))))
temp.small.i <_ strataID.small==6
temp <_apply(small.sims[,temp.small.i], 1, FUN=function(x, CR){
prob<_ numeric()
for(iinl:length(CR)){
prob[i] <_ sum(x>=CR[i])/length(x)
}
return(prob)
}, CR=cr)
SW.small.3 <_ apply(temp, 1, FUN=function(x)return(c(mean(x, na.rm=T), sd(x,
na.rm=T)/sqrt(length(x)), quantile(x, prob=c(0.025, 0.05, 0.5, 0.95, 0.975)))))
temp <_apply(small.sims, 1, FUN=function(x, CR){
prob<_ numericO
for (i in l:length(CR)){
prob[i] <_ sum(x>=CR[i])/length(x)
B-8
-------
Appendix B. Detailed Description of the Stage 2 Analysis
return(prob)
}, CR=cr)
small.All <_ apply(temp, 1, FUN=f\mction(x)return(c(mean(x, na.rm=T), sd(x, na.rm=T)/sqrt(length(x)),
quantile(x, prob=c(0.025, 0.05, 0.5, 0.95, 0.975)))))
# large systems
large.sims <_ bugsout.large$sims.list$cbar
temp .large <_ stratalD .large== 1 stratalD .large==3
temp <_ apply (large, sims [,temp. large], 1, FUN=function(x, CR){
prob<_ numeric()
for(iinl:length(CR)){
prob[i] <_ sum(x>=CR[i])/length(x)
}
return(prob)
}, CR=cr)
GW.large.All <_ apply(temp, 1, FUN=runction(x)return(c(mean(x, na.rm=T), sd(x,
na.rm=T)/sqrt(length(x)), quantile(x, prob=c(0.025, 0.05, 0.5, 0.95, 0.975)))))
temp.large.i <_ stratalD.large==l
temp <_apply(large.sims[,temp.large.i], 1, FUN=function(x, CR){
prob<_ numeric()
for(iinl:length(CR)){
prob[i] <_ sum(x>=CR[i])/length(x)
}
return(prob)
}, CR=cr)
GW.large.l <_ apply(temp, 1, FUN=runction(x)return(c(mean(x, na.rm=T), sd(x,
na.rm=T)/sqrt(length(x)), quantile(x, prob=c(0.025, 0.05, 0.5, 0.95, 0.975)))))
temp.large.i <_ stratalD.large==3
temp <_apply(large.sims[,temp.large.i], 1, FUN=function(x, CR){
prob<_ numeric()
for(iinl:length(CR)){
prob[i] <_ sum(x>=CR[i])/length(x)
}
return(prob)
}, CR=cr)
GW.large.2 <_ apply(temp, 1, FUN=runction(x)return(c(mean(x, na.rm=T), sd(x,
na.rm=T)/sqrt(length(x)), quantile(x, prob=c(0.025, 0.05, 0.5, 0.95, 0.975)))))
temp <_apply(large.sims[,!temp.large], 1, FUN=function(x, CR){
prob<_ numeric()
for (i in l:length(CR)){
prob[i] <_ sum(x>=CR[i])/length(x)
}
return(prob)
}, CR=cr)
B-9
-------
Appendix B. Detailed Description of the Stage 2 Analysis
SW.large.All <_ apply(temp, 1, FUN=function(x)return(c(mean(x, na.rm=T), sd(x,
na.rm=T)/sqrt(length(x)), quantile(x, prob=c(0.025, 0.05, 0.5, 0.95, 0.975)))))
temp.large.i <_ strataID.large==2
temp <_apply(large.sims[,temp.large.i], 1, FUN=function(x, CR){
prob<_ numeric()
for(iinl:length(CR)){
prob[i] <_ sum(x>=CR[i])/length(x)
}
return(prob)
}, CR=cr)
SW.large.l <_ apply(temp, 1, FUN=runction(x)return(c(mean(x, na.rm=T), sd(x,
na.rm=T)/sqrt(length(x)), quantile(x, prob=c(0.025, 0.05, 0.5, 0.95, 0.975)))))
temp.large.i <_ strataID.large==4
temp <_apply(large.sims[,temp.large.i], 1, FUN=function(x, CR){
prob<_ numeric()
for(iinl:length(CR)){
prob[i] <_ sum(x>=CR[i])/length(x)
}
return(prob)
}, CR=cr)
SW.large.2 <_ apply(temp, 1, FUN=runction(x)return(c(mean(x, na.rm=T), sd(x,
na.rm=T)/sqrt(length(x)), quantile(x, prob=c(0.025, 0.05, 0.5, 0.95, 0.975)))))
temp <_apply(large.sims, 1, FUN=function(x, CR){
prob<_ numeric()
for(iinl:length(CR)){
prob[i] <_ sum(x>=CR[i])/length(x)
}
return(prob)
}, CR=cr)
large .All <_ apply(temp, 1, FUN=runction(x)return(c(mean(x, na.rm=T), sd(x, na.rm=T)/sqrt(length(x)),
quantile(x, prob=c(0.025, 0.05, 0.5, 0.95, 0.975)))))
write(t(GW.small.All), file=paste(dataset, "smallGW2.txt", sep=""), ncol=dim(GW.small.All)[2],
append=F)
write(t(GW.small.l), file=paste(dataset, "smallGW2.txt", sep=""), ncol=dim(GW.small.l)[2], append=T)
write(t(GW.small.2), file=paste(dataset, "smallGW2.txt", sep=""), ncol=dim(GW.small.2)[2], append=T)
write(t(GW.small.3), file=paste(dataset, "smallGW2.txt", sep=""), ncol=dim(GW.small.3)[2], append=T)
write(t(SW. small .All), file=paste(dataset, "smallSW2.txt", sep=""), ncol=dim(SW.small.All)[2],
append=F)
write(t(SW.small.l), file=paste(dataset, "smallSW2.txt", sep=""), ncol=dim(SW.small.l)[2], append=T)
write(t(SW.small.2), file=paste(dataset, "smallSW2.txt", sep=""), ncol=dim(SW.small.2)[2], append=T)
write(t(SW.small.3), file=paste(dataset, "smallSW2.txt", sep=""), ncol=dim(SW.small.3)[2], append=T)
B-10
-------
Appendix B. Detailed Description of the Stage 2 Analysis
write(t(GW.large.All), file=paste(dataset, "largeGW2.txt", sep=""), ncol=dim(GW.large.All)[2],
append=F)
write(t(GW.large.l), file=paste(dataset, "largeGW2.txt", sep=""), ncol=dim(GW.large.l)[2], append=T)
write(t(GW.large.2), file=paste(dataset, "largeGW2.txt", sep=""), ncol=dim(GW.large.2)[2], append=T)
write(t(SW.large.All), file=paste(dataset, "largeSW2.txt", sep=""), ncol=dim(SW.large.All)[2],
append=F)
write(t(SW.large.l), file=paste(dataset, "largeSW2.txt", sep=""), ncol=dim(SW.large.l)[2], append=T)
write(t(SW.large.2), file=paste(dataset, "largeSW2.txt", sep=""), ncol=dim(SW.large.2)[2], append=T)
write(t(large.All), file=paste(dataset, "A112.txt", sep=""), ncol=dim(large.All)[2], append=F)
write(t(small.All), file=paste(dataset, "A112.txt", sep=""), ncol=dim(small.All)[2], append=T)
B-ll
-------
-------
Appendix C. Stage 2 Occurrence Measures for DCPA Degradates
Table Cl .a
Table C 1 .b
Table C 1 .c
Table C 1 .d
Table Cl .e
Table C 1 .f
Table C 1 .g
Table C 1 .h
DCPA Degradates - Stage 2 Occurrence Results - Best Estimate and Confidence
Intervals Based on the Number of SMALL Systems (UCMR 1 March 2006 data)
DCPA Degradates - SMALL Systems - National Best Estimate Including
Estimate Range Based on Confidence Intervals (Threshold = 70 |ig/L)
DCPA Degradates - SMALL Systems - National Best Estimate Including
Estimate Range Based on Confidence Intervals (Threshold = 35 |ig/L)
DCPA Degradates - SMALL Systems - National Best Estimate Including
Estimate Range Based on Confidence Intervals (Threshold = 1 |ig/L)
DCPA Degradates - Stage 2 Occurrence Results - Best Estimate and Confidence
Intervals Based on the Population Served by SMALL Systems (UCMR 1 March
2006 data)
DCPA Degradates - Population Served by SMALL Systems - National Best
Estimate Including Estimate Range Based on Confidence Intervals (Threshold =
70
DCPA Degradates - Population Served by SMALL Systems - National Best
Estimate Including Estimate Range Based on Confidence Intervals (Threshold
35
DCPA Degradates - Population Served by SMALL Systems - National Best
Estimate Including Estimate Range Based on Confidence Intervals (Threshold
Table C2.a DCPA Degradates - Stage 2 Occurrence Results - Best Estimate and Confidence
Intervals Based on the Number of LARGE Systems (UCMR 1 March 2006 data)
Table C2.b DCPA Degradates - LARGE Systems - National Best Estimate Including
Estimate Range Based on Confidence Intervals (Threshold = 70 |ig/L)
Table C2.c DCPA Degradates - LARGE Systems - National Best Estimate Including
Estimate Range Based on Confidence Intervals (Threshold = 35 |ig/L)
Table C2.d DCPA Degradates - LARGE Systems - National Best Estimate Including
Estimate Range Based on Confidence Intervals (Threshold = 1 |ig/L)
-------
Table C2.e DCPA Degradates - Stage 2 Occurrence Results - Best Estimate and Confidence
Intervals Based on the Population Served by LARGE Systems (UCMR 1 March
2006 data)
Table C2.f DCPA Degradates - Population Served by LARGE Systems - National Best
Estimate Including Estimate Range Based on Confidence Intervals (Threshold =
70
Table C2.g DCPA Degradates - Population Served by LARGE Systems - National Best
Estimate Including Estimate Range Based on Confidence Intervals (Threshold
35
Table C2.h DCPA Degradates - Population Served by LARGE Systems - National Best
Estimate Including Estimate Range Based on Confidence Intervals (Threshold = 1
-------
Appendix C. Stage 2 Occurrence Measures
Table C1.a. DCPA Degradates - Stage 2 Occurrence Results - Best Estimate and Confidence Intervals Based on the Number of SMALL Systems
Source Water
Type
Ground Water
Population
Served
<500
501 - 3,300
3,301 -10,000
Total
Mean
Probability of
Exceeding
Threshold
95%
Confidence Interval
90%
Confidence Interval
Threshold = 70 ug/L
0%
0%
0.81%
0.15%
0% - 0%
0% - 0%
0.80% - 0.83%
0.15% - 0.16%
0% - 0%
0% - 0%
0.80% - 0.83%
0.15% - 0.16%
Mean
Probability of
Exceeding
Threshold
95%
Confidence Interval
90%
Confidence Interval
Threshold = 35 ug/L
0%
0%
0.89%
0.17%
0% - 0%
0% - 0%
0.88% - 0.89%
0.17% - 0.17%
0% - 0%
0% - 0%
0.89% - 0.89%
0.17% - 0.17%
Mean
Probability of
Exceeding
Threshold
95%
Confidence Interval
90%
Confidence Interval
Threshold = 1 ug/L
2.2%
0.71%
1.2%
1.4%
2.2% - 2.3%
0.69% - 0.73%
1.2% - 1.3%
1.4% - 1.4%
2.2% - 2.3%
0.69% - 0.72%
1.2% - 1.2%
1.4% - 1.4%
Surface Water
<500
501 - 3,300
3,301 -10,000
Total
0%
0%
0%
0%
0% - 0%
0% - 0%
0% - 0%
0% - 0%
0% - 0%
0% - 0%
0% - 0%
0% - 0%
0%
0%
0%
0%
0% - 0%
0% - 0%
0% - 0%
0% - 0%
0% - 0%
0% - 0%
0% - 0%
0% - 0%
0.00061%
0.45%
0.0026%
0.099%
0% - 0.0018%
0.40% - 0.50%
0% - 0.0061%
0.088% - 0.11%
0% - 0.0016%
0.41 % - 0.49%
0% - 0.0055%
0.090% - 0.11%
All Small Systems - Combined
Ground & Surface Water
0.11%
0.11% - 0.12%
0.11% - 0.11%
0.12%
0.12% - 0.12%
0.12% - 0.12%
1.1%
1.1% - 1.1%
1.1% - 1.1%
The Stage 2 occurrence estimates are based on the July 2005 UCMR 1 data.
C-1
-------
Appendix C. Stage 2 Occurrence Measures
Table C1.b. DCPA Degradates - SMALL Systems - National Best Estimate Including Estimate Range
Based on Confidence Intervals (Threshold = 70 ug/L)
Source Water
Type
Ground Water
Surface Water
Population Served
<500
501 -3,300
3,301 -10,000
Total Number of
Small Systems
Nationally
41,415
12,128
2,529
National Estimate of Small Systems Exceeding the Specified Threshold 1'2
using best
estimate
0
0
21
using 95%
Confidence Interval
0 - 0
0 - 0
20 - 21
using 90%
Confidence Interval
0 - 0
0 - 0
20 - 21
GW Total3 56,072 86 84 - 87 85 - 87
<500
501 -3,300
3,301 -10,000
SW Total 3
Total Ground & Surface Water 3
1,639
1,659
1,044
4,342
60,414
0
0
0
0
68
0 - 0
0 - 0
0 - 0
0 - 0
67 - 70
0 - 0
0 - 0
0 - 0
0 - 0
68 - 69
1 National estimates are based on extrapolated small system data.
2 System estimates are rounded to the nearest whole number.
3 Estimates are generated separately for each level of aggregation. Therefore, estimates for the individual size stratum will not
add to estimated totals at the source water level of aggregation, and estimates for the source water strata ("GW Total" and "SW
Total") will not add to the total estimated for all systems ("Total Ground & Surface Water").
C-2
-------
Appendix C. Stage 2 Occurrence Measures
Table C1.c. DCPA Degradates - SMALL Systems - National Best Estimate Including Estimate Range
Based on Confidence Intervals (Threshold = 35 ug/L)
Source Water
Type
Ground Water
Surface Water
Population Served
<500
501 -3,300
3,301 -10,000
Total Number of
Small Systems
Nationally
41,415
12,128
2,529
National Estimate of Small Systems Exceeding the Specified Threshold 1'2
using best
estimate
0
0
22
using 95%
Confidence Interval
0 - 0
0 - 0
22 - 23
using 90%
Confidence Interval
0 - 0
0 - 0
22 - 23
GW Total3 56,072 94 93 - 94 93 - 94
<500
501 -3,300
3,301 -10,000
SW Total 3
Total Ground & Surface Water 3
1,639
1,659
1,044
4,342
60,414
0
0
0
0
75
0 - 0
0 - 0
0 - 0
0 - 0
74 - 75
0 - 0
0 - 0
0 - 0
0 - 0
74 - 75
1 National estimates are based on extrapolated small system data.
2 System estimates are rounded to the nearest whole number.
3 Estimates are generated separately for each level of aggregation. Therefore, estimates for the individual size stratum will not
add to estimated totals at the source water level of aggregation, and estimates for the source water strata ("GW Total" and "SW
Total") will not add to the total estimated for all systems ("Total Ground & Surface Water").
C-3
-------
Appendix C. Stage 2 Occurrence Measures
Table C1.d. DCPA Degradates - SMALL Systems - National Best Estimate Including Estimate Range
Based on Confidence Intervals (Threshold = 1 ug/L)
Source Water
Type
Ground Water
Surface Water
Population Served
<500
501 -3,300
3,301 -10,000
Total Number of
Small Systems
Nationally
41,415
12,128
2,529
National Estimate of Small Systems Exceeding the Specified Threshold 1'2
using best
estimate
923
86
31
using 95%
Confidence Interval
911 - 935
83 - 88
30 - 32
using 90%
Confidence Interval
913 - 933
84 - 88
30 - 32
GW Total3 56,072 789 781 - 797 782 - 796
<500
501 -3,300
3,301 -10,000
SW Total 3
Total Ground & Surface Water 3
1,639
1,659
1,044
4,342
60,414
0
7
0
4
645
0 - 0
7 - 8
0 - 0
4 - 5
638 - 652
0 - 0
7 - 8
0 - 0
4 - 5
639 - 651
1 National estimates are based on extrapolated small system data.
2 System estimates are rounded to the nearest whole number.
3 Estimates are generated separately for each level of aggregation. Therefore, estimates for the individual size stratum will not
add to estimated totals at the source water level of aggregation, and estimates for the source water strata ("GW Total" and "SW
Total") will not add to the total estimated for all systems ("Total Ground & Surface Water").
C-4
-------
Appendix C. Stage 2 Occurrence Measures
Table C1.e. DCPA Degradates - Stage 2 Occurrence Results - Best Estimate and Confidence Intervals Based on the Population Served by SMALL Systems
Source Water
Type
Ground Water
Population
Served
<500
501 - 3,300
3,301 - 10,000
Total
Mean
Probability of
Exceeding
Threshold
95%
Confidence Interval
90%
Confidence Interval
Threshold = 70 ug/L
0%
0%
0.35%
0.07%
0% - 0%
0% - 0%
0.34% - 0.35%
0.07% - 0.07%
0% - 0%
0% - 0%
0.34% - 0.35%
0.07% - 0.07%
Mean
Probability of
Exceeding
Threshold
95%
Confidence Interval
90%
Confidence Interval
Threshold = 35 ug/L
0%
0%
0.38%
0.08%
0% - 0%
0% - 0%
0.38% - 0.38%
0.08% - 0.08%
0% - 0%
0% - 0%
0.38% - 0.38%
0.08% - 0.08%
Mean
Probability of
Exceeding
Threshold
95%
Confidence Interval
90%
Confidence Interval
Threshold = 1 ug/L
2.8%
1.75%
0.7%
1.9%
2.7% - 2.8%
1.69% - 1.81%
0.6% - 0.8%
1 .9% - 1 .9%
2.7% - 2.8%
1 .70% - 1 .80%
0.6% - 0.8%
1 .9% - 1 .9%
Surface Water
<500
501 - 3,300
3,301 - 10,000
Total
0%
0%
0%
0%
0% - 0%
0% - 0%
0% - 0%
0% - 0%
0% - 0%
0% - 0%
0% - 0%
0% - 0%
0%
0%
0%
0%
0% - 0%
0% - 0%
0% - 0%
0% - 0%
0% - 0%
0% - 0%
0% - 0%
0% - 0%
0.00024%
0.22%
0.0011%
0.045%
0% - 0.0007%
0.19% - 0.25%
0% - 0.0027%
0.039% - 0.05%
0% - 0.0006%
0.19% - 0.25%
0% - 0.0024%
0.040% - 0.05%
All Small Systems - Combined
Ground & Surface Water
0.05%
0.05% - 0.05%
0.05% - 0.05%
0.05%
0.05% - 0.05%
0.05% - 0.05%
1.3%
1.2% - 1.3%
1 .2% - 1 .3%
The Stage 2 occurrence estimates are based on the July 2005 UCMR 1 data.
C-5
-------
Appendix C. Stage 2 Occurrence Measures
Table C1.f. DCPA Degradates - Population Served by SMALL Systems - National Best Estimate Including
Estimate Range Based on Confidence Intervals (Threshold = 70 ug/L)
Source
Water Type
Ground
Water
Surface
Water
Population Served
<500
501 -3,300
3,301 -10,000
Total Pop.
Served by Small
Systems
Nationally
6,231,348
15,602,332
14,390,656
National Estimate of Population Served by Small Systems
Exceeding the Specified Threshold 1'2
using best
estimate
0
0
50,200
using 95%
Confidence Interval
0 - 0
0 - 0
49,300 - 51,000
using 90%
Confidence Interval
0 - 0
0 - 0
49,500 - 50,900
GW Total3 36,224,336 26,200 25,800 - 26,700 25,900 - 26,600
<500
501 -3,300
3,301 -10,000
SW Total 3
Total Ground & Surface Water 3
306,256
2,674,107
6,209,891
9,190,254
45,414,590
0
0
0
0
21,500
0 - 0
0 - 0
0 - 0
0 - 0
21,200 - 21,900
0 - 0
0 - 0
0 - 0
0 - 0
21,200 - 21,800
1 National estimates are based on extrapolated small system data.
2 Population served estimates are rounded to the nearest hundred.
3 Estimates are generated separately for each level of aggregation. Therefore, estimates for the individual size stratum will not
add to estimated totals at the source water level of aggregation, and estimates for the source water strata ("GW Total" and "SW
Total") will not add to the total estimated for all systems ("Total Ground & Surface Water").
C-6
-------
Appendix C. Stage 2 Occurrence Measures
Table C1.g. DCPA Degradates - Population Served by SMALL Systems - National Best Estimate
Including Estimate Range Based on Confidence Intervals (Threshold = 35 ug/L)
Source
Water Type
Ground
Water
Surface
Water
Population Served
<500
501 -3,300
3,301 -10,000
Total Pop.
Served by Small
Systems
Nationally
6,231,348
15,602,332
14,390,656
National Estimate of Population Served by Small Systems
Exceeding the Specified Threshold 1'2
using best
estimate
0
0
54,800
using 95%
Confidence Interval
0 - 0
0 - 0
54,500 - 55,200
using 90%
Confidence Interval
0 - 0
0 - 0
54,600 - 55,100
GW Total3 36,224,336 28,700 28,500 - 28,800 28,500 - 28,800
<500
501 -3,300
3,301 -10,000
SW Total 3
Total Ground & Surface Water 3
306,256
2,674,107
6,209,891
9,190,254
45,414,590
0
0
0
0
23,500
0 - 0
0 - 0
0 - 0
0 - 0
23,400 - 23,700
0 - 0
0 - 0
0 - 0
0 - 0
23,400 - 23,600
1 National estimates are based on extrapolated small system data.
2 Population served estimates are rounded to the nearest hundred.
3 Estimates are generated separately for each level of aggregation. Therefore, estimates for the individual size stratum will not
add to estimated totals at the source water level of aggregation, and estimates for the source water strata ("GW Total" and "SW
Total") will not add to the total estimated for all systems ("Total Ground & Surface Water").
C-7
-------
Appendix C. Stage 2 Occurrence Measures
Table C1.h. DCPA Degradates - Population Served by SMALL Systems - National Best Estimate
Including Estimate Range Based on Confidence Intervals (Threshold = 1 ug/L)
Source
Water Type
Ground
Water
Surface
Water
Population Served
<500
501 -3,300
3,301 -10,000
Total Pop.
Served by Small
Systems
Nationally
6,231,348
15,602,332
14,390,656
National Estimate of Population Served by Small Systems
Exceeding the Specified Threshold 1'2
using best
estimate
171,400
273,700
105,100
using 95%
Confidence Interval
167,000 - 175,800
264,300 - 283,100
90,600 - 119,700
using 90%
Confidence Interval
167,800 - 175,100
265,800 - 281,600
92,900 - 117,400
GWTotal3 36,224,336 687,400 672,600 - 702,300 675,100 - 699,800
<500
501 -3,300
3,301 -10,000
SW Total 3
Total Ground & Surface Water 3
306,256
2,674,107
6,209,891
9,190,254
45,414,590
0
5,800
0
4,200
571,300
0 - 0
5,000 - 6,700
0 - 0
3,600 - 4,800
559,100 - 583,500
0 - 0
5,100 - 6,600
0 - 0
3,700 - 4,700
561,100 - 581,500
1 National estimates are based on extrapolated small system data.
2 Population served estimates are rounded to the nearest hundred.
3 Estimates are generated separately for each level of aggregation. Therefore, estimates for the individual size stratum will not
add to estimated totals at the source water level of aggregation, and estimates for the source water strata ("GWTotal" and "SW
Total") will not add to the total estimated for all systems ("Total Ground & Surface Water").
C-8
-------
Appendix C. Stage 2 Occurrence Measures
Table C2.a. DCPA Degradates - Stage 2 Occurrence Results - Best Estimate and Confidence Intervals Based on the Number of LARGE Systems
Source Water
Type
Ground Water
Population
Served
10,001 -50,000
> 50,000
Total
Mean
Probability of
Exceeding
Threshold
95%
Confidence Interval
90%
Confidence Interval
Threshold = 70 ug/L
0.00011%
0%
0.000096%
0% - 0.00027%
0% - 0%
0% - 0.00023%
0% - 0.00024%
0% - 0%
0% - 0.00021%
Mean
Probability of
Exceeding
Threshold
95%
Confidence Interval
90%
Confidence Interval
Threshold = 35 ug/L
0.00061%
0.0024%
0.00086%
0.00025% - 0.00098%
0.00063% - 0.0042%
0.00047% - 0.0013%
0.00031% - 0.00092%
0.00092% - 0.0039%
0.00053% - 0.0012%
Mean
Probability of
Exceeding
Threshold
95%
Confidence Interval
90%
Confidence Interval
Threshold = 1 ug/L
3.0%
2.5%
3.0%
3.0% - 3.0%
2.4% - 2.5%
2.9% - 3.0%
3.0% - 3.0%
2.5% - 2.5%
2.9% - 3.0%
Surface Water
10,001 -50,000
> 50,000
Total
0%
0%
0%
0% - 0%
0% - 0%
0% - 0%
0% - 0%
0% - 0%
0% - 0%
0.00011%
0.00013%
0.00012%
0% - 0.00027%
0% - 0.00039%
0% - 0.00025%
0% - 0.00024%
0% - 0.00035%
0.0000064% - 0.00023%
1.4%
1.0%
1.3%
1.4% - 1.4%
1.0% - 1.0%
1.3% - 1.3%
1.4% - 1.4%
1.0% - 1.0%
1.3% - 1.3%
All Small Systems - Combined
Ground & Surface Water
0.000043%
0% - 0.00010%
0% - 0.000094%
0.00046%
0.00026% - 0.00065%
0.00029% - 0.00062%
2.0%
2.0% - 2.0%
2.0% - 2.0%
The Stage 2 occurrence estimates are based on the July 2005 UCMR 1 data.
C-9
-------
Appendix C. Stage 2 Occurrence Measures
Table C2.b. DCPA Degradates - LARGE Systems - National Best Estimate Including Estimate Range Based on Confidence
Intervals
(Threshold = 70 ug/L)
Source Water Type
Ground Water
Surface Water
Population Served
10,001 -50,000
> 50,000
Total Number
of Large
Systems with
DCPA Data
1,194
190
National Estimate of Large Systems Exceeding the Specified Threshold 1'2
using best
estimate
0
0
using 95% Confidence Interval
0 - 0
0 - 0
using 90% Confidence Interval
0 - 0
0 - 0
GW Total3 1,384 0 0-0 0-0
10,001 -50,000
> 50,000
SW Total 3
Total Ground & Surface Water 3
1,180
507
1,687
3,071
0
0
0
0
0 - 0
0 - 0
0 - 0
0 - 0
0 - 0
0 - 0
0 - 0
0 - 0
1 National estimates are based on actual UCMR large system data (not extrapolations).
2 System estimates are rounded to the nearest whole number.
3 Estimates are generated separately for each level of aggregation. Therefore, estimates for the individual size stratum will not add to estimated totals at
the source water level of aggregation, and estimates for the source water strata ("GW Total" and "SW Total") will not add to the total estimated for all
systems ("Total Ground & Surface Water").
C-10
-------
Appendix C. Stage 2 Occurrence Measures
Table C2.c. DCPA Degradates - LARGE Systems - National Best Estimate Including Estimate Range Based on Confidence
Intervals
(Threshold = 35 ug/L)
Source Water Type
Ground Water
Surface Water
Population Served
10,001 -50,000
> 50,000
Total Number
of Large
Systems with
DCPA Data
1,194
190
National Estimate of Large Systems Exceeding the Specified Threshold 1'2
using best
estimate
0
0
using 95% Confidence Interval
0 - 0
0 - 0
using 90% Confidence Interval
0 - 0
0 - 0
GW Total3 1,384 0 0-0 0-0
10,001 -50,000
> 50,000
SW Total 3
Total Ground & Surface Water 3
1,180
507
1,687
3,071
0
0
0
0
0 - 0
0 - 0
0 - 0
0 - 0
0 - 0
0 - 0
0 - 0
0 - 0
1 National estimates are based on actual UCMR large system data (not extrapolations).
2 System estimates are rounded to the nearest whole number.
3 Estimates are generated separately for each level of aggregation. Therefore, estimates for the individual size stratum will not add to estimated totals at
the source water level of aggregation, and estimates for the source water strata ("GW Total" and "SW Total") will not add to the total estimated for all
systems ("Total Ground & Surface Water").
C-11
-------
Appendix C. Stage 2 Occurrence Measures
Table C2.d. DCPA Degradates - LARGE Systems - National Best Estimate Including Estimate Range Based on Confidence
Intervals
(Threshold = 1 ug/L)
Source Water Type
Ground Water
Surface Water
Population Served
10,001 -50,000
> 50,000
Total Number
of Large
Systems with
DCPA Data
1,194
190
National Estimate of Large Systems Exceeding the Specified Threshold 1'2
using best
estimate
36
5
using 95% Confidence Interval
36 - 36
5 - 5
using 90% Confidence Interval
36 - 36
5 - 5
GW Total3 1,384 41 41 41 41 41
10,001 -50,000
> 50,000
SW Total 3
Total Ground & Surface Water 3
1,180
507
1,687
3,071
16
5
21
62
16 - 17
5 - 5
21 - 22
62 - 63
16 - 17
5 - 5
21 - 22
62 - 63
1 National estimates are based on actual UCMR large system data (not extrapolations).
2 System estimates are rounded to the nearest whole number.
3 Estimates are generated separately for each level of aggregation. Therefore, estimates for the individual size stratum will not add to estimated totals at
the source water level of aggregation, and estimates for the source water strata ("GW Total" and "SW Total") will not add to the total estimated for all
systems ("Total Ground & Surface Water").
C-12
-------
Appendix C. Stage 2 Occurrence Measures
Table C2.e. DCPA Degradates - Stage 2 Occurrence Results - Best Estimate and Confidence Intervals Based on the Population Served by LARGE Systems
Source Water
Type
Ground Water
Population
Served
10,001 -50,000
> 50,000
Total
Mean
Probability of
Exceeding
Threshold
95%
Confidence Interval
90%
Confidence Interval
Threshold = 70 ug/L
0.000050%
0%
0.000044%
0% - 0.00012%
0% - 0%
0% - 0.00011%
0% - 0.00011%
0% - 0%
0% - 0.00010%
Mean
Probability of
Exceeding
Threshold
95%
Confidence Interval
90%
Confidence Interval
Threshold = 35 ug/L
0.00033%
0.0017%
0.00049%
0.00012% - 0.00053%
0.00043% - 0.0029%
0.00026% - 0.00072%
0.00016% - 0.00050%
0.00063% - 0.0027%
0.00030% - 0.00069%
Mean
Probability of
Exceeding
Threshold
95%
Confidence Interval
90%
Confidence Interval
Threshold = 1 ug/L
3.1%
2.2%
3.0%
3.1% - 3.1%
2.1% - 2.2%
3.0% - 3.0%
3.1% - 3.1%
2.1% - 2.2%
3.0% - 3.0%
Surface Water
10,001 -50,000
> 50,000
Total
0%
0%
0%
0% - 0%
0% - 0%
0% - 0%
0% - 0%
0% - 0%
0% - 0%
0.000068%
0.00013%
0.000085%
0% - 0.00016%
0% - 0.00038%
0% - 0.00018%
0% - 0.00015%
0% - 0.00034%
0.0000029% - 0.00017%
1.1%
1.6%
1.3%
1.1% - 1.1%
1.6% - 1.6%
1.2% - 1.3%
1.1% - 1.1%
1.6% - 1.6%
1.2% - 1.3%
All Large Systems - Combined
Ground & Surface Water
0.000021%
0% - 0.000050%
0% - 0.000045%
0.00028%
0.00016% - 0.00040%
0.00018% - 0.00038%
2.1%
2.1% - 2.1%
2.1% - 2.1%
The Stage 2 occurrence estimates are based on the July 2005 UCMR 1 data.
C-13
-------
Appendix C. Stage 2 Occurrence Measures
Table C2.f. DCPA Degradates - Population Served by LARGE Systems - National Best Estimate Including
Estimate Range Based on Confidence Intervals (Threshold = 70 ug/L)
Source Water Type
Ground Water
Surface Water
Population Served
10,001 -50,000
> 50,000
Total Pop.
Served by Large
Systems with
DCPA Data
26,958,656
26,476,158
National Estimate of Population Served by Large Systems
Exceeding the Specified Threshold 1'2
using best
estimate
0
0
using 95% Confidence Interval
0 - 0
0 - 0
using 90% Confidence Interval
0 - 0
0 - 0
GW Total3 53,434,814 0 0-0 0-0
10,001 -50,000
> 50,000
SW Total 3
All Large Systems 3
33,230,082
135,389,905
168,619,987
222,054,801
0
0
0
0
0 - 0
0 - 0
0 - 0
0 - 0
0 - 0
0 - 0
0 - 0
0 - 0
1 National estimates are based on actual UCMR large system data (not extrapolations).
2 Population served estimates are rounded to the nearest hundred.
3 Estimates are generated separately for each level of aggregation. Therefore, estimates for the individual size stratum will not add to
estimated totals at the source water level of aggregation, and estimates for the source water strata ("GW Total" and "SW Total") will not
add to the total estimated for all systems ("Total Ground & Surface Water").
C-14
-------
Appendix C. Stage 2 Occurrence Measures
Table C2.g. DCPA Degradates - Population Served by LARGE Systems - National Best Estimate Including
Estimate Range Based on Confidence Intervals (Threshold = 35 ug/L)
Source Water Type
Ground Water
Surface Water
Population Served
10,001 -50,000
> 50,000
Total Pop.
Served by Large
Systems with
DCPA Data
26,958,656
26,476,158
National Estimate of Population Served by Large Systems
Exceeding the Specified Threshold 1'2
using best
estimate
0
0
using 95% Confidence Interval
0 - 0
0 - 0
using 90% Confidence Interval
0 - 0
0 - 0
GW Total3 53,434,814 0 0-0 0-0
10,001 -50,000
> 50,000
SW Total 3
All Large Systems 3
33,230,082
135,389,905
168,619,987
222,054,801
0
0
0
0
0 - 0
0 - 0
0 - 0
0 - 0
0 - 0
0 - 0
0 - 0
0 - 0
1 National estimates are based on actual UCMR large system data (not extrapolations).
2 Population served estimates are rounded to the nearest hundred.
3 Estimates are generated separately for each level of aggregation. Therefore, estimates for the individual size stratum will not add to
estimated totals at the source water level of aggregation, and estimates for the source water strata ("GW Total" and "SW Total") will not
add to the total estimated for all systems ("Total Ground & Surface Water").
C-15
-------
Appendix C. Stage 2 Occurrence Measures
Table C2.h. DCPA Degradates - Population Served by LARGE Systems - National Best Estimate Including
Estimate Range Based on Confidence Intervals (Threshold = 1 ug/L)
Source Water Type
Ground Water
Surface Water
Population Served
10,001 -50,000
> 50,000
Total Pop.
Served by Large
Systems with
DCPA Data
26,958,656
26,476,158
National Estimate of Population Served by Large Systems
Exceeding the Specified Threshold 1'2
using best
estimate
832,800
571,200
using 95% Confidence Interval
826,900 - 838,700
561,700 - 580,700
using 90% Confidence Interval
827,900 - 837,700
563,200 - 579,200
GW Total3 53,434,814 1,589,600 1,579,000 - 1,600,100 1,580,800 - 1,598,400
10,001 -50,000
> 50,000
SW Total 3
All Large Systems 3
33,230,082
135,389,905
168,619,987
222,054,801
370,700
2,183,900
2,117,100
4,589,600
365,900 - 375,400
2,163,400 - 2,204,400
2,098,200 - 2,136,000
4,565,500 - 4,613,800
366,700 - 374,700
2,166,800 - 2,201,000
2,101,300 - 2,132,900
4,569,400 - 4,609,900
1 National estimates are based on actual UCMR large system data (not extrapolations).
2 Population served estimates are rounded to the nearest hundred.
3 Estimates are generated separately for each level of aggregation. Therefore, estimates for the individual size stratum will not add to
estimated totals at the source water level of aggregation, and estimates for the source water strata ("GW Total" and "SW Total") will not
add to the total estimated for all systems ("Total Ground & Surface Water").
C-16
-------
Appendix D. Detailed Description of
UCMR Large System Population-Served Adjustments
-------
-------
Appendix D. Assessing and Refining Population-Served Values for UCMR 1 Large Systems
Appendix D. Assessing and Refining Population-Served Values for
UCMR 1 Large Systems
Population-served values for UCMR 1 small systems were first extensively evaluated
during the statistical design and initial implementation phases of the UCMR 1 program in 1999
and 2000. This was necessary to define the universe of small PWSs (i.e., those serving 10,000
persons or fewer) from which the statistical sample of representative UCMR 1 small PWSs was
drawn. (Details are presented in USEPA, lOOlb.1) Additional work was subsequently conducted
to confirm the population-served values and other inventory information of small systems.
Defining the universe of small systems also served to define the universe of large systems
(i.e., those serving greater than 10,000 persons) eligible for the UCMR 1 large system census.
Verification and updating of large system population-served values and other systems inventory
information began later, while UCMR monitoring was underway, in communications between
EPA's Technical Service Center (TSC), EPA regions, States, and systems. EPA conducted a
comprehensive check of inventory information (water source type, size category, population-
served values, etc.) of the 3,100 large systems participating in UCMR 1.
Further efforts, presented here, were undertaken to establish the most current population-
served values for the large systems and to address the issue of potential double-counting of
populations exposed to contaminants found in "consecutive systems." Consecutive systems are
systems that purchase finished drinking water from other systems; this might involve a simple
seller-purchaser relationship, or one large wholesale distributor selling water to multiple systems
that act as retail distributors to customers, or more complex arrangements like chains or
reciprocal relationships among systems. In general, the system that provides water directly to a
customer is considered the "retail" system, and any system the treats water eventually purchased
by the retail system is considered a "wholesale" system. To the extent possible, population-
served values of large UCMR 1 systems were adjusted to ensure that customers served by large
consecutive systems were counted as belonging to the population served by the retail system, or
a wholesale system, but not both.
Whenever possible, customers (populations-served) were assigned to the retail system on
the principle that the UCMR 1 monitoring results from a PWS that is a retail seller are likely to
better characterize the quality of water delivered to the consumer than will UCMR 1 monitoring
results from an "upstream" wholesaler. An additional assumption is made that the UCMR 1
monitoring results from a PWS retail seller adequately reflect any blending of wholesale
(purchased) water and self-sourced (non-purchased) water that is distributed to consumers.
Two major sources of data were used to determine the most accurate population-served
values for the large systems. Both data sets originated from the Safe Drinking Water Information
System/Federal Version (SDWIS/FED) database, but they represent different time periods and
different levels of quality control and revision. The first source of data ("SDWISOO") represents
The complete reference for USEPA (200 Ib) is included in the body of the report.
D-l
-------
Appendix D. Assessing and Refining Population-Served Values for UCMR 1 Large Systems
the 2nd quarter (June) version of SDWIS/FED from 2000. (This is the same data set that was
used as the basis for categorizing systems as small or large at the beginning of the UCMR
project.) Population-served values for a large portion of systems in this data set were updated
during the implementation of the UCMR 1 program at the request of regional offices, the States,
and/or individual systems. This effort to update population-served values in the SDWISOO data
set was very broad, but it was not comprehensive. The second source ("SDWIS05") represents
the 4th quarter (December) version of SDWIS/FED from 2004; the data were extensively quality-
checked in January 2005. This version of SDWIS/FED benefited from the extensive, systematic
quality-control procedures that are typically applied to the data collected in the last quarter of
each year.
For the purposes of UCMR 1, the population-served value of a participating large system
should include the system's retail population (those customers served directly by the system) and
its wholesale population (those served indirectly by the system, via intermediary systems who
purchase the water), with the exception of those customers in the wholesale population who are
already represented in the retail population of another UCMR-participating system. For example,
if system A sold water to system B, system A's population-served value for purposes of UCMR
1 exposure analysis should only include the population of system B if system B itself did not
participate in UCMR 1 monitoring.
Starting with the SDWIS05 data set, EPA used an additive process to construct the
appropriate population-served values for UCMR 1 large systems. The population-served values
in the SDWIS05 data set are generally understood to include retail customers only. Wholesale
values were derived from a master list of 13,029 purchased-water relationships. Each
relationship consisted of one seller and one purchaser. The master list also indicated, in each
case, whether the relationship represented 100% of the purchaser's water supply. The following
criteria were used to reduce the list of wholesale relationships to those whose inclusion would
not result in double-counting of populations:
• Wholesale relationships were excluded if the purchasing system was considered as a
small system for the purposes of UCMR 1 (i.e., if it had been determined to serve a
population of 10,000 or less). The retail populations of small systems are accounted for in
the UCMR 1 small system occurrence analysis. To assign these populations to wholesale
systems would constitute double-counting. This step removed 10,670 relationships.
• Wholesale relationships were excluded if the purchaser was a large system that purchased
less than 100% of its water, and therefore was among the 3,100 large systems that
participated in UCMR 1 monitoring. The retail customers of these systems are already
accounted for in the UCMR 1 large system data set. This step removed 638 relationships.
• Wholesale relationships were excluded if the purchaser was a large system that purchased
100% of its water, according to the wholesale relationship list, but nevertheless
conducted UCMR 1 monitoring. Large systems that purchase 100% of their water were
not required to participate in UCMR 1 monitoring. That several apparently did participate
might be attributable to a misunderstanding of program requirements, or a change in
D-2
-------
Appendix D. Assessing and Refining Population-Served Values for UCMR 1 Large Systems
system operating characteristics (e.g., a system might have purchased less than 100% of
its water when the UCMR 1 program began, and then purchased 100% of its water at the
time the list of wholesale relationships was compiled), or some other cause. In any case,
the retail customers of these systems are already accounted for in the UCMR 1 large
system data set, so including them among the population served by a wholesale system
would constitute double-counting. This step removed 16 relationships.
• In addition, wholesale relationships were excluded if the purchaser was listed as "closed"
by SDWIS/FED. If a purchaser is no longer active as a water provider, its population
should not be included in the totals either as a retail or a wholesale population.
(Presumably, former customers of such a system are now served by another system, and
are accounted for in that system's population-served value.) This step removed 81
relationships.
Of the initial list of 13,029 purchased-water relationships, 927 relationships remained.
The result of the exclusions described above was that the remaining relationships involved only
purchasers who are active large systems that did not participate in UCMR 1 monitoring because
they purchase 100% of their water from other systems. There were 722 of these purchasing
systems, and they purchased their water from 447 wholesale systems. Of these wholesale
systems, 347 were large systems that participated in UCMR 1 monitoring. For these 347
systems, total population-served values were obtained by adding one or more wholesale
populations to their their retail population. That left 2,763 of the 3,100 large UCMR 1 systems
that required no purchasing-population adjustment; these could be fairly represented by their
retail populations alone.
The final SDWIS05 population-served values, derived as described above, are based on
the most current quality-assured version of SDWIS/FED and include purchased water while
controlling for double-counting; thus, the SDWIS05 numbers likely represent the "best estimate"
of total population-served.
To validate these population estimates, the (adjusted) SDWIS05 numbers were compared
to the SDWISOO numbers. Systems were divided into five different "bins" which categorized the
difference between the two sets of population estimates (Exhibit D. 1). Since 10,000 is the
population-served threshold that separates small and large systems, it was used as a reference
point for defining the bins. Note that a system could technically be defined as "large" yet have a
population-served value of less than 10,000 when double-counting is adjusted. (I.e., a system
could be defined as large for the UCMR 1 program based on its total retail plus wholesale
population, but its retail population alone may be less than 10,000.) Large differences between
SDWISOO and SDWIS05 population estimates were often due to the fact that the adjusted
SDWIS05 values eliminated double-counting. As presented in Exhibit D.2, "Bin 5," the largest,
was stratified further based on the order of magnitude of the difference between the population-
served values (i.e., log (SDWIS05 - SDWISOO)).
D-3
-------
Appendix D. Assessing and Refining Population-Served Values for UCMR 1 Large Systems
Exhibit D.1. Division of large systems into "bins" for comparison of
SDWIS05 populations and SDWISOO populations
Bin
1
2
3
4
5
Definition
System's pop listed as < 10 in SDWIS05
System's pop listed as > 10,000 in SDWISOO
System's pop listed as between 10 and 10,000 in SDWIS05
System's pop listed as > 10,000 in SDWISOO
System's pop listed as < 10,000 in both SDWISOO and SDWIS05
System's pop listed as > 10,000 in SDWIS05
System's pop listed as < 10,000 in SDWISOO
System's pop listed as > 10,000 in both SDWISOO and SDWIS05
Number of
Systems in Bin
14
77
23
23
2.973
Exhibit D.2. Division of "Bin 5" systems by order-of-magnitude difference between
the SDWIS05 population and the SDWISOO population
Order-of-Magnitude
Difference
7
6
5
4
3
2
1
0
Difference between SDWIS05
& SDWISOO Populations
5, 000, 000 to 50,000, 000
500,000 to 5,000, 000
50,000 to 500,000
5, 000 to 50,000
500 to 5,000
50 to 500
5 to 50
1 to 5
None
Number of
Systems
1
21
195
859
915
169
15
3
795
The SDWIS05 values were used as the "default" or "best estimate" population-served
values except in cases where it was clear that the SDWISOO populations were a better or more
conservative population estimate. Part of this evaluation involved looking at the "absolute
purchasing population" (APP)--the total population of all systems that have purchased from a
selling system. The APP is the starting point for calculating a wholesale population-served value
by a subtractive method, e.g., by taking into account double-counting, systems' closings, etc. The
D-4
-------
Appendix D. Assessing and Refining Population-Served Values for UCMR 1 Large Systems
following four decision-criteria were ultimately used to pick the best population-served estimate
for each of the 3,100 large systems:
1. If the SDWIS05 population is 10,000 or less and has an APP of zero (i.e., the system does
not sell to others), and the SDWISOO population is greater than 10,000, use the SDWISOO
population.
2. If the SDWIS05 population is 10,000 or less and has an APP of zero, and the SDWISOO
population is also 10,000 or less, use the SDWIS05 population.
3. In all other cases, use the SDWIS05 population.
4. If the chosen population is zero or one, increase it to 50 to represent a nominal sum.
After following these four steps for all 3,100 large systems, a final analysis was
conducted to determine whether the decision-criteria "fairly" resolved all population
discrepancies. Particular attention was paid to those systems that fell into Bins 1 through 4 and
those from Bin 5 with differences of between five and seven orders of magnitude. A total of 26
systems required further investigation (see Exhibit D.3).
To provide further information in these cases, the population-served estimates from the
2001 Needs Survey2 and the Disinfection Byproducts Information Collection Rule (ICR)3 were
also consulted when available. For each system, the population chosen by following the
previously-outlined decision-criteria was compared to the other population estimates available.
In many cases, additional information was gathered via the Internet, from EPA regional offices,
and from State and Local resources. After this thorough analysis and comparison, EPA decided
that the decision criteria produced the best population-served value for all but five of the above
systems (see Exhibit D.4).
The "Needs Survey" is a national survey of drinking water infrastructure needs that is a joint effort of the nation's
drinking water utilities, State drinking water regulatory agencies, representatives of American Indians and Alaska
Natives, the Indian Health Service, and the U.S. EPA. For more details, see Drinking Water Infrastructure Needs
Survey: Second Report to Congress (EPA Report 816-R-01-004, 2001).
3 The Disinfection Byproducts (DBFs) ICR required only large public water systems to collect data. Surface water
systems serving more than 100,000 people and ground water systems serving more than 50,000 people had to
monitor for DBFs (61 FR 24354).
D-5
-------
Appendix D. Assessing and Refining Population-Served Values for UCMR 1 Large Systems
Exhibit D.3. Twenty-six systems requiring further investigation before selecting a
population-served value
PWSID
CA1 51 0040
CA1910087
CA1910128
CA341 0030
CA361 0006
CA3610019
CA4810015
CA491 0020
FL2550908
FL4431490
FL4431891
FL4434383
FL6277059
GU0000016
IA7727001
LA1079016
MA6000000
M 10006310
OH390261 1
OH7608112
OH8301412
PR0002000
PR0003313
TX0670019
TX1010429
WV33031 1 1
PWS Name
Kern County Water Agency (KCWA)
Metropolitan Water District of S. CA
Covina Irrigation Company
City of Folsom - Ashland
Water Facilities Authority - JPA
San Bernardino Valley Water District
Travis Air Force Base - Vallejo
Sonoma County Water Agency
Ponte Vedra Beach Water Department
Martin County Utilities - South
Martin County Utilities - North
Martin County Utilities - Martin Downs
Hernando County Utilities - West
Earth Tech, Inc.
Des Moines Waterworks - Maffitt
City of Pineville
MA Water Resources Authority
Saint Joseph
Village of New London - Plant #2
Canton Public Water System
Village of Springboro - Chautaqua
Super Acueducto
Anasco
Eastland County Water Supply District #1
CNP Utility District
Morgantown Utility Board
SDWISOO
100,000
16,000,000
85,000
25,674
400,000
90,460
32,000
487,254
4,700
13,900
16,100
10,350
26,192
12,500
193,189
228,000
2,000,000
32,431
52,000
1 ,400,000
123,000
750,000
25,524
25
101,956
464,947
SDWIS05
(50)
767,682
(50)
2,152
(50)
(50)
3
500
4,700
72,641
72,641
72,641
127,977
0
25
22,716
3,673,378
8,789
6,000
140,000
13,200
50,001
4,188
25
1 1 ,934
47,147
Absolute
Purchasing
Population
0
0
0
2,152
0
0
3
500
4,700
72,641
72,641
72,641
127,977
0
25
22,716
2,383,302
8,789
6,000
140,000
13,200
50,001
4,188
25
1 1 ,934
47,147
Needs
Survey
103,481
18,000,000
216,000
N/A
374,715
625,000
N/A
500,000
N/A
N/A
N/A
N/A
42,751
N/A
N/A
24,000
2,200,000
32,000
N/A
140,000
16,800
750,000
4,108
N/A
N/A
65,000
ICR
N/A
5,445,793
N/A
N/A
356,667
N/A
N/A
487,254
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
1 ,642,866
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A = Data not available
Numbers selected for systems in accordance with the decision criteria are highlighted in grey.
The systems for which the decision criteria were not followed are indicated in bold and italics.
There were five exceptions to the decision criteria (see Exhibit D.4); these represent the
most extreme cases where there was compelling evidence that the estimate chosen by the
decision criteria (either the SDWISOO or SDWIS05) was clearly the inferior of the two. In the
case of the Metropolitan Water District of Southern California, neither the SDWISOO nor
D-6
-------
Appendix D. Assessing and Refining Population-Served Values for UCMR 1 Large Systems
SDWIS05 population estimate represented the true population-served. Additional research was
necessary to establish an accurate estimate.
Exhibit D.4. Five systems for which the decision criteria yielded inadequate results
PWSID
CA1910087
FL4431490
FL4431891
FL4434383
MA6000000
PWS Name
Metropolitan Water
District of Southern
California
Martin County Utilities -
South
Martin County Utilities -
North
Martin County Utilities -
Martin Downs
MA Water Resources
Authority
Population
Chosen
3,399,581
13,900
16,100
10,350
2,000,000
Rationale for Exception
Total wholesale population is ~ 17.2 million. However, this
includes extensive double-counting of purchasing systems
that also submitted unique UCMR results. Eliminating the
double-counting yields the resulting population estimate of
3,399,581.
Since all three systems had the same SDWIS05 population, it
was clear that the total population-served value of the
combined utility had been erroneously reported for all three
individual systems. SDWISOO populations were confirmed by
Florida Department of Environmental Protection.
EPA confirmed that this system reported to SDWIS its retail
plus wholesale population as its retail population. Thus, the
SDWIS05 population double-counted the wholesale
population.
The resulting large system population values, combined with the previously-established
small system population values, constitute the full set of population values for the UCMR 1
contaminant exposure analysis. As of March 2006, a total of 3,887 systems (797 small and 3,090
large) have submitted results for UCMR 1. The total population served by all these systems is
226,892,179 (2,760,570 persons served by small systems and 224,131,609 persons served by
large systems).
Exhibit D.5. Adjusted UCMR 1 population-served estimates
System Size
Small
Large
Total
Number of Systems
in UCMR 1
797
3,090
3,887
Adjusted UCMR 1
Population Served
2,760,570
224,131,609
226,892,179
Although populations served by PWSs vary over time, the population-served size
categories determined as part of the initial implementation of the UCMR 1 are, for purposes of
D-7
-------
Appendix D. Assessing and Refining Population-Served Values for UCMR 1 Large Systems
UCMR 1 exposure analysis, fixed. Large PWSs are subdivided into two finer size categories:
"large" (systems serving between 10,001 and 50,000 persons) and "very large" (systems serving
more than 50,000 persons). It is important to note that the new (adjusted) population-served
estimates for each system, as described in this appendix, may not always agree with the system's
previously-defined size category. The new (adjusted) population-served estimates do not define
the size categories, nor do the size categories define limits on the population-served estimates.
The purpose of the size categories is to aid in analysis and interpretation of results at the system
level, while the purpose of the population-served estimates is to provide as realistic an estimate
as possible of the extent of human exposure to the monitored contaminants.
The population adjustments discussed in this appendix served to reduce double-counting
of populations exposed to contaminants in consecutive systems where both the seller and buyer
of water conducted UCMR 1 monitoring. The adjustments should result in a reduction of over-
estimates of populations potentially exposed to contaminants in drinking water monitored under
the UCMR 1. The adjustments were made prior to and independent of all the contaminant-
specific occurrence analyses, so the actual impact of the adjustments on exposure estimates for
any specific contaminant is not known. In principle, the adjustments would most affect exposure
estimates for contaminants occurring more commonly in large consecutive systems.
D-8
-------
Appendix E. Development of Health Reference Levels (HRLs)
-------
-------
Appendix E. Development of Health Reference Levels
Appendix E. Development of Health Reference Levels
Section 1412(b)(l)(A)(i) of SDWA requires EPA to determine whether each candidate
contaminant may have an adverse effect on public health. This appendix describes the overall
process the Agency used to evaluate health effects information, the approach used to estimate a
contaminant health reference level or HRL (a benchmark against which to conduct the initial
evaluation of the occurrence data), and the approach used to identify and evaluate information on
hazard and dose-response for the contaminants under consideration.
There are two different approaches to the derivation of an HRL. One approach is used for
chemicals that cause cancer and exhibit a linear response to dose and the other applies to non-
carcinogens and carcinogens evaluated using a non-linear approach.
Use of Carcinogenicity Data for the Derivation of a Health Reference Level
Five of the contaminants discussed in this report had data available to classify them as
likely or probable human carcinogens. These five contaminants (DDE, 1,3-dichloropropene, 2,4-
dinitrotoluene, 2,6-dinitrotoluene, and 1,1,2,2-tetrachloroethane) are also the only contaminants
for which low dose linear extrapolations were performed. For these contaminants, EPA
evaluated data on the mode of action of the chemical to determine the method of low dose
extrapolation. When this analysis indicates that a linear low dose extrapolation is appropriate or
when data on the mode of action are lacking, EPA uses a low dose linear extrapolation to
calculate risk-specific doses. The risk-specific doses are the estimated oral exposures associated
with lifetime excess risk levels that range from one cancer in ten thousand (10"4) to one cancer in
a million (10"6). The risk-specific doses (expressed as mg/kg of body weight per day) are
combined with adult body weight and drinking water consumption data to estimate drinking
water concentrations corresponding to this risk range. EPA generally used the one-in-a-million
(10"6) cancer risk in the initial screening of the occurrence data for carcinogens evaluated using
linear low dose extrapolation.
Use of Non-carcinogenic Health Effects Data for Derivation of a Health Reference Level
The remaining six contaminants (boron, DCPA mono- and di-acid degradates,1 EPTC,
fonofos and terbacil) have not been identified as known, likely or probable carcinogens. For
these contaminants, EPA calculated a reference dose (RfD). An RfD is an estimate of a daily
oral exposure to the human population (including sensitive subgroups) that is likely to be without
an appreciable risk of deleterious effects during a lifetime. It can be derived from either a "no-
observed-adverse-effect level" (NOAEL), a "lowest-observed-adverse-effect level" (LOAEL), or
a benchmark dose, with uncertainty factors applied to reflect limitations of the data used.
EPA used uncertainty factors (UFs) to address uncertainty resulting from incompleteness
of the toxicological database. The individual UFs (usually applied as integers of 1, 3, or 10) were
1 The HRL for the two DCPA degradates is based on the HRL value derived for the DCPA parent following the
guidance provided by EPA's Office of Pesticide Programs.
E-l
-------
Appendix E. Development of Health Reference Levels
multiplied together and used to derive the RfD from experimental data. Individual UFs are
intended to account for:
(1) the variation in sensitivity among the members of the human population (i.e.,
intraspecies variability);
(2) the uncertainty in extrapolating animal data to humans (i.e., interspecies variability);
(3) the uncertainty in extrapolating from data obtained in a study with less-than-lifetime
exposure to lifetime exposure (i.e., extrapolating from subchronic to chronic exposure);
(4) the uncertainty in extrapolating from a LOAEL rather than from a NOAEL; and/or
(5) the uncertainty associated with an incomplete database.
EPA derived the HRLs using the RfD approach as follows:
HRL = [(RfD x BW)/DWI] x RSC
Where:
RfD = Reference Dose
BW = Body Weight for an adult, assumed to be 70 kilograms (kg)
DWI = Drinking Water Intake, assumed to be 2 L/day (90th percentile)
RSC = Relative Source Contribution, or the level of exposure believed to result from drinking
water when compared to other sources (e.g., food, ambient air). A 20 percent RSC is being used
to estimate the HRL and screen the occurrence data because it is the lowest and most
conservative RSC used in the derivation of a maximum contaminant level goal (MCLG) for
drinking water.
For each of the six aforementioned non-carcinogenic compounds for which the Agency
has made regulatory determination in this action, EPA used the RfD in conjunction with a 20
percent RSC to derive a conservative HRL estimate and perform an initial screening of the
drinking water occurrence data. Since the initial screening of the occurrence data at this
conservative HRL value resulted in negligible occurrence findings for each of these six
compounds, EPA recognized that it was not necessary to further evaluate the RSC in making the
regulatory determination.
E-2
-------
Appendix F. Detailed Description of the Sensitivity Analysis
Comparing Adjusted/Unadjusted Findings
-------
-------
Appendix F. Detailed Description of the Sensitivity Analysis Comparing A djusted/Unadjusted Findings
Appendix F. Detailed Description of the Sensitivity Analysis
Comparing Adjusted/Unadjusted Findings
Calculation of Probability-Weighted Estimation of Population Served
All probabilities of unit selection within each state were divided by 56 to obtain the
probability of unit selection from any of the combined strata (56 states x 2 system types x 2
source types x 3 system sizes). Probabilities from Appendix B of "Statistical Design and Sample
Selection for the Unregulated Contaminant Monitoring Regulation" (USEPA, 200 Ib), calculated
using the requirement of at least 2 systems per State, were used in this analysis; thus, it was not
necessary to revisit the constraint of at least two systems per State. Within each stratum, an
individual unit's probability of selection is proportional to its strata population contribution.
Thus, each stratum probability was multiplied by the ratio of the unit population and total
stratum population. Obtained weights were adjusted such that they added to 1 for all 800 selected
units by dividing each weight by the total of all 800 weights. Finally, the weighted mean was
estimated as:
=
i=l to
800 Wi X Pop; X
where W is the calculated weight for a unit i, Pop is population served by a unit i, and y is the
indicator equal to 1 if the contaminant occurs at any time in system i, or 0 otherwise.
Sensitivity Analysis of Weighting versus Non-Weighting
The sensitivity analysis compared weighted and non-weighted mean population-served
by systems with detections based on various detection rates. * At each detection rate, a number of
systems was randomly selected without replacement (8 systems at thel% detection rate scenario,
16 at the 2% detection rate scenario, 24 at 3%,. ..,80 at 10%, and 400 at 50% detection rate).
Weighted and non-weighted mean populations-served were calculated for each system. In
systems with no detections, the population-served value was set to zero. The calculated weighted
and non-weighted means were compared using two-sample t-tests assuming both equal and
unequal variances.2 At every single detection level, there was no significant statistical difference
between weighted and unweighted. Additionally, weighted and non-weighted mean populations-
served by systems were compared at a 100 percent detection rate, assuming that all 800 small
systems had detections (so all populations-served were served by systems with contaminant
1 This analysis was conducted independent of any particular contaminant. The aim was to determine whether or not
weighting made any difference (related to the mean population exposed) if there is x % of detections in the data. The
analysis was fairly generic and is applicable to any contaminant.
2 A two-sample t-test is conventionally used to test if estimates, usually means, from one sample are statistically
different from mean of the other sample. The test assumes that the two samples being tested are independent of each
other. Because there is no conventional way to test means equality of the same sample with and without weights
(such as in the current consideration), this analysis assumes independence of the sample with and without weights.
If we can take a sample of 3 data points (1 with a weight of x, 2 with a weight of y, and 3 with a weight of z) then
the unweighted sample is 1,2,3, and the weighted sample is replicated as x number of Is, y number of 2s, and z
number of 3s. The unweighted mean, in this case, is 6/3=2, and the weighted mean is (x+2y+3z)/(x+y+z).
F-l
-------
Appendix F. Detailed Description of the Sensitivity Analysis Comparing A djusted/Unadjusted Findings
detections). Again, it was determined that the weights do not significantly change population
means overall. Exhibit F.I illustrates the results.
Exhibit F.1: Comparison of Weighted and Unweighted means for all systems
(ignoring strata information)
Method
Variances
Degrees of
Freedom
t-Value
Pr>|t|
Detection Rate = 1%
Pooled
Satterthwaite
Cochran
Equal
Unequal
Unequal
1598
1581
799
0.34
0.34
0.34
0.7359
0.7359
0.7359
Detection Rate = 2%
Pooled
Satterthwaite
Cochran
Equal
Unequal
Unequal
1598
1075
799
-0.67
-0.67
-0.67
0.4999
0.4999
0.5000
Detection Rate = 3%
Pooled
Satterthwaite
Cochran
Equal
Unequal
Unequal
1598
1167
799
-0.46
-0.46
-0.46
0.6447
0.6447
0.6447
Detection Rate = 4%
Pooled
Satterthwaite
Cochran
Equal
Unequal
Unequal
1598
1232
799
-0.21
-0.21
-0.21
0.8348
0.8349
0.8349
Detection Rate = 5%
Pooled
Satterthwaite
Cochran
Equal
Unequal
Unequal
1598
1270
799
-0.28
-0.28
-0.28
0.7767
0.7768
0.7768
Detection Rate = 6%
Pooled
Satterthwaite
Cochran
Equal
Unequal
Unequal
1598
1303
799
-0.25
-0.25
-0.25
0.7994
0.7994
0.7994
Detection Rate = 7%
Pooled
Satterthwaite
Cochran
Equal
Unequal
Unequal
1598
1326
799
-0.19
-0.19
-0.19
0.8475
0.8475
0.8476
Detection Rate = 8%
Pooled
Satterthwaite
Cochran
Equal
Unequal
Unequal
1598
1348
799
-0.04
-0.04
-0.04
0.9717
0.9717
0.9717
F-2
-------
Appendix F. Detailed Description of the Sensitivity Analysis Comparing A djusted/Unadjusted Findings
Method
Variances
Degrees of
Freedom
t-Value
Pr>|t|
Detection Rate = 9%
Pooled
Satterthwaite
Cochran
Equal
Unequal
Unequal
1598
1358
799
-0.02
-0.02
-0.02
0.9821
0.9821
0.9821
Detection Rate = 10%
Pooled
Satterthwaite
Cochran
Equal
Unequal
Unequal
1598
1344
799
-0.04
-0.04
-0.04
0.9660
0.9660
0.9660
Detection Rate = 50%
Pooled
Satterthwaite
Cochran
Equal
Unequal
Unequal
1598
1113
799
-1.49
-1.49
-1.49
0.1356
0.1357
0.1358
Detection Rate = 100%
Pooled
Satterthwaite
Cochran
Equal
Unequal
Unequal
1598
811
799
-1.34
-1.34
-1.34
0.1815
0.1817
0.1817
Since no significant statistical difference was found between weighted and unweighted
means, an analysis was conducted to look at how weights affect means in different strata, i.e. the
two system types (CWS and NTNCWS) and three system sizes (25-500, 501-3300 and 3301-
10000). For CWS systems (regardless of system size), weights do not appear to affect the mean
(see Exhibit F.2).
Exhibit F.2: Comparison of Weighted and Unweighted Means for
CWS systems by system size
Method
Variances
Degrees of
Freedom
t-Value
Pr>|t|
System Size = 25 - 500
Pooled
Satterthwaite
Cochran
Equal
Unequal
Unequal
244
130
122
0.85
0.85
0.85
0.3987
0.3994
0.3995
System Size = 501 - 3,300
Pooled
Satterthwaite
Cochran
Equal
Unequal
Unequal
504
261
252
1.35
1.35
1.35
0.1766
0.1772
0.1772
System Size = 3,301 - 10,000
Pooled
Satterthwaite
Cochran
Equal
Unequal
Unequal
666
334
333
-1.37
-1.37
-1.37
0.1697
0.1702
0.1702
F-3
-------
Appendix F. Detailed Description of the Sensitivity Analysis Comparing A djusted/Unadjusted Findings
For NTNCWS systems, there is significant statistical difference between weighted and
unweighted means (see Exhibit F.3).3 Note that due to the small number of observations (only
9), no analysis was conducted for NTNCWS system size of 3,301-10,000. For the other 2
systems sizes (25-500 and 501-3300), the equality of means was tested at 5%, 10% and 15%
detection rates due to smaller sample size. This analysis indicated that weights do not play
significant role at small detection rates (5% and 10%) yet weighted means are significantly
different from non-weighted means for higher detection rates (15%).
Exhibit F.3: Comparison of Weighted and Unweighted Means for
NTNCWS systems by system size
Method
Variances
Degrees of
Freedom
t-Value
Pr>|t|
System Size = 25 - 500; Detection Rate = 5%
Pooled
Satterthwaite
Cochran
Equal
Unequal
Unequal
84
42
42
1.15
1.15
1.15
0.2526
0.2559
0.2559
System Size = 501 - 3,300; Detection Rate = 5%
Pooled
Satterthwaite
Cochran
Equal
Unequal
Unequal
74
37
37
1.37
1.37
1.37
0.1764
0.1805
0.1805
System Size = 25 - 500; Detection Rate = 10%
Pooled
Satterthwaite
Cochran
Equal
Unequal
Unequal
84
42
42
1.67
1.67
1.67
0.0992
0.1029
0.1029
System Size = 501 - 3,300; Detection Rate = 10%
Pooled
Satterthwaite
Cochran
Equal
Unequal
Unequal
74
37.2
37
1.67
1.67
1.67
0.1001
0.1042
0.1043
1 In Exhibit B.3., the fractional degrees of freedom are possible because of the use of the Welch-Satterthwaite Approximation
'I
where si and s2 are standard deviations of two samples and Nl and N2 are sample size. The formula is used in t-test when it can
not be assumed that standard deviations from two processes/samples are equivalent.
F-4
-------
Appendix F. Detailed Description of the Sensitivity Analysis Comparing A djusted/Unadjusted Findings
Method
Variances
Degrees of
Freedom
t-Value
Pr>|t|
System Size = 25 - 500; Detection Rate = 15%
Pooled
Satterthwaite
Cochran
Equal
Unequal
Unequal
84
42
42
2.22
2.22
2.22
0.0289
0.0317
0.0317
System Size = 501 - 3,300; Detection Rate = 15%
Pooled
Satterthwaite
Cochran
Equal
Unequal
Unequal
74
37.2
37
2.17
2.17
2.17
0.0330
0.0362
0.0363
System Size = 25 - 500; Detection Rate = 100%
Pooled
Satterthwaite
Cochran
Equal
Unequal
Unequal
84
55.2
42
2.67
2.67
2.67
0.0090
0.0099
0.0107
System Size = 501 - 3,300; Detection Rate = 100%
Pooled
Satterthwaite
Cochran
Equal
Unequal
Unequal
74
71.4
37
5.17
5.17
5.17
<0.0001
<0.0001
<0.0001
System Size = 3,301 - 10,000; Detection Rate = 100%
Pooled
Satterthwaite
Cochran
Equal
Unequal
Unequal
16
8.09
8
-2.69
-2.69
-2.69
0.0162
0.0274
0.0277
F-5
-------
-------
Appendix G. Stage 1 Occurrence Measures for
All CCL 2 Regulatory Determination Contaminants
Monitored Under UCMR 1
Table Gl.a DCPA Degradates - Occurrence Based on Samples, Systems, and Population
Served (UCMR 1 March 2006 Data)
Table Gl .b DCPA Degradates - Statistics for All Detections (UCMR 1 March 2006 Data)
Table Gl.c DCPA Degradates - System Level Occurrence by State and Size Category
(UCMR 1 March 2006 data)
Table Gl .d DCPA Degradates - System Level Occurrence by State and Source Water Type
(UCMR 1 March 2006 data)
Table Gl .e DCPA Degradates - Statistics for All Detections by State (UCMR 1 March 2006
Data)
Table Gl.f DCPA Degradates - Population Served Level Occurrence by State and Size
Category (UCMR 1 March 2006 data)
Table Gl.g DCPA Degradates - Population Served Level Occurrence by State and Source
Water Type (UCMR 1 March 2006 data)
Table G2.a DDE - Occurrence Based on Samples, Systems, and Population Served (UCMR 1
March 2006 Data)
Table G2.b DDE - Number of PWSs by State (UCMR 1 March 2006 Data)
Table G2.c DDE - Total Population-Served by State (UCMR 1 March 2006 Data)
Table G3.a 1,3-Dichloropropene - Occurrence Based on Samples, Systems, and Population
Served (UCMR 1 March 2006 Data) - Small Systems ONLY
Table G3.b 1,3-Dichloropropene - Number of PWSs by State (UCMR 1 March 2006 Data)
Table G3.c 1,3-Dichloropropene - Total Population-Served by State (UCMR 1 March 2006
Data)
Table G4.a 2,4-Dinitrotoluene - Occurrence Based on Samples, Systems, and Population
Served (UCMR 1 March 2006 Data)
Table G4.b 2,4-Dinitrotoluene - Number of PWSs by State (UCMR 1 March 2006 Data)
Table G4.c 2,4-Dinitrotoluene - Total Population-Served by State (UCMR 1 March 2006
Data)
Table G5.a 2,6-Dinitrotoluene - Occurrence Based on Samples, Systems, and Population
Served (UCMR 1 March 2006 Data)
Table G5.b 2,6-Dinitrotoluene - Number of PWSs by State (UCMR 1 March 2006 Data)
Table G5.c 2,6-Dinitrotoluene - Total Population-Served by State (UCMR 1 March 2006
Data)
Table G6.a EPTC - Occurrence Based on Samples, Systems, and Population Served (UCMR
1 March 2006 Data)
Table G6.b EPTC - Number of PWSs by State (UCMR 1 March 2006 Data)
-------
Table G6.c EPIC - Total Population-Served by State (UCMR 1 March 2006 Data)
Table G7.a Fonofos - Occurrence Based on Samples, Systems, and Population Served
(UCMR 1 March 2006 Data)
Table G7.b Fonofos - Number of PWSs by State (UCMR 1 March 2006 Data)
Table G7.c Fonofos - Total Population-Served by State (UCMR 1 March 2006 Data)
Table G8.a MTBE - Occurrence Based on Samples, Systems, and Population Served (UCMR
1 March 2006 Data)
Table G8.b MTBE - Statistics for All Detections (UCMR 1 March 2006 Data)
Table G8.c MTBE - System Level Occurrence by State and Size Category (UCMR 1 March
2006 data)
Table G8.d MTBE - System Level Occurrence by State and Source Water Type (UCMR 1
March 2006 data)
Table G8.e MTBE - Statistics for All Detections by State (UCMR 1 March 2006 Data)
Table G8.f MTBE - Population Served Level Occurrence by State and Size Category (UCMR
1 March 2006 data)
Table G8.g MTBE - Population Served Level Occurrence by State and Source Water Type
(UCMR 1 March 2006 data)
Table G9.a Terbacil - Occurrence Based on Samples, Systems, and Population Served
(UCMR 1 March 2006 Data)
Table G9.b Terbacil - Number of PWSs by State (UCMR 1 March 2006 Data)
Table G9.c Terbacil - Total Population-Served by State (UCMR 1 March 2006 Data)
-------
Appendix G. Stage 1 Occurrence Measures for CCL 2 Contaminants Monitored Under UCMR 1
Table G1.a. ppPA Degradates - Occurrence Based on Samples. Systems. & Population Served (UCMR 1 March 2006 Data)
Water
Type
System Size by
Population
Served
Sample Level
Total # of
Samples
Detections
#
%
System Level
Total # of
Systems
Detections
Systems with
One or More
#
%
Systems with
Two or More
#
%
Population-Served Level
Total Pop.
Served by
Systems
Detections
Pop. Served by
Systems with
One or More
#
%
Pop. Served by
Systems with
Two or More
#
%
Small Systems (Statistical Sample)
GW
SW
25 - 500
501 - 3,300
3,301 -10,000
Total
25 - 500
501 - 3,300
3,301 -10,000
Total
All Small Systems
257
876
1,212
2,345
223
181
523
927
3,272
2
6
29
37
1
1
38
0.78%
0.68%
2.39%
1 .58%
0.55%
0.11%
1.16%
111
245
234
590
52
45
110
207
797
1
3
12
16
1
1
17
0.90%
1 .22%
5.13%
2.71%
2.22%
0.48%
2.13%
1
2
9
12
0
12
0.90%
0.82%
3.85%
2.03%
0.00%
1.51%
27,599
441 ,499
1,470,717
1,939,815
16,662
91,723
712,370
820,755
2,760,570
500
4,692
81,241
86,433
1,500
1,500
87,933
1.81%
1 .06%
5.52%
4.46%
1 .64%
0.18%
3.19%
500
2,997
59,897
63,394
0
63,394
1 .81 %
0.68%
4.07%
3.27%
0.00%
2.30%
Large Systems (Census)
GW
SW
10,001 -50,000
> 50,000
Total
10,001 -50,000
> 50,000
Total
All Large Systems
10,540
5,566
16,106
7,393
7,139
14,532
30,638
273
214
487
164
87
251
738
2.59%
3.84%
3.02%
2.22%
1 .22%
1 .73%
2.41%
1,199
190
1,389
1,183
507
1,690
3,079
87
22
109
34
17
51
160
7.26%
1 1 .58%
7.85%
2.87%
3.35%
3.02%
5.20%
57
17
74
28
13
41
115
4.75%
8.95%
5.33%
2.37%
2.56%
2.43%
3.73%
27,061,195
26,476,158
53,537,353
33,338,950
135,389,905
168,728,855
222,266,208
2,095,370
3,987,609
6,082,979
1,136,909
4,049,548
5,186,457
1 1 ,269,436
7.74%
15.06%
1 1 .36%
3.41 %
2.99%
3.07%
5.07%
1,525,466
3,212,861
4,738,327
958,238
3,310,638
4,268,876
9,007,203
5.64%
12.13%
8.85%
2.87%
2.45%
2.53%
4.05%
All (Small & Large) Systems
Total Water Systems1
33,910
776
2.29%
3,876
177
4.57%
127
3.28%
225,026,778
1 1 ,357,369
5.05%
9,070,597
4.03%
1 The UCMR small water systems (population served < 10,000) are a statistical, representative sample of all national small systems while the UCMR large water systems (population served
> 10,000) represent a census of all large systems. Combined small and large system occurrence summaries accurately present the actual UCMR monitoring results. However, only the
summary findings expressed as percentages accurately reflect national occurrence; combined large and small summaries based on numerical counts of detections at the sample, system,
and population-served levels do not accurately represent national occurrence.
G-1
-------
Appendix G. Stage 1 Occurrence Measures for CCL 2 Contaminants Monitored Under UCMR 1
Table G1.b. DCPA pegradates - Statistics for All Detections (UCMR 1 March 2006 Data)
Water Type
System Size by
Population
Served
Total # of
Detections
Statistics for All Recorded Values Above the Detection Limit (in ug/L)
Minimum | Mean | Median | 99th Percentile | Maximum
Small Systems (Statistical Sample)
GW
SW
25 - 500 1
501 - 3,300
3,301 -10,000
Total
25 - 500
501 - 3,300
3,301 -10,000
Total
All Small Systems
2
6
29
37
0
1
0
1
38
180.00
1.20
1.20
1.20
1.90
1.90
1.20
185.00
1.82
2.49
12.25
1.90
1.90
11.97
185.00
1.60
1.80
1.80
1.90
1.90
1.80
190.00
2.80
7.30
190.00
1.90
1.90
190.00
190.00
2.80
7.30
190.00
1.90
1.90
190.00
Large Systems (Census)
GW
SW
10,001 -50,000
> 50,000
Total
10,001 -50,000
> 50,000
Total
All Large Systems
273
214
487
164
87
251
738
1.00
1.00
1.00
1.00
1.00
1.00
1.00
3.30
2.41
2.91
2.99
3.88
3.30
3.04
2.00
1.85
2.00
2.00
2.30
2.00
2.00
18.00
9.03
15.00
19.00
39.00
24.00
16.00
31.00
11.00
31.00
24.00
39.00
39.00
39.00
All (Small & Large) Systems
Total Water Systems2
776
1.00
3.48
2.00
19.00
190.00
1 Note that there were only two detections of DCPA in this source water type / size category. Thus, the statistics generated for this category are based on only two detections.
2 The UCMR small water systems (population served < 10,000) are a statistical, representative sample of all national small systems while the UCMR large water systems
(population served > 10,000) represent a census of all large systems. Combined small and large system occurrence summaries accurately present the actual UCMR
monitoring results. However, combined large and small summary statistics do not accurately represent national occurrence.
G-2
-------
Appendix G. Stage 1 Occurrence Measures for CCL 2 Contaminants Monitored Under UCMR 1
Table G1.c. DCPA Degradates - System Level Occurrence by State & Size Category (UCMR 1 March 2006 data)
State 1 2
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
Total
Total #
Samples
53
810
226
1,291
8,570
397
370
9
102
1,164
577
268
395
213
249
744
393
245
345
417
1,132
173
91
365
432
450
140
519
124
1,043
41
228
134
1,055
358
72
2,439
550
318
354
1,258
718
103
289
102
546
1,728
469
295
28
40
681
548
151
68
2
2
4
6
16
33,910
Total # PWSs
Total
9
98
47
59
406
56
41
1
8
238
101
5
17
47
21
133
85
41
77
82
132
36
19
71
85
68
3
72
13
115
13
20
21
128
32
11
159
153
52
55
165
85
13
59
17
105
266
52
58
4
10
82
76
35
11
1
1
1
2
3
3,876
Small
4
15
13
12
48
10
6
0
2
31
22
1
3
16
8
28
20
12
9
27
12
8
6
24
16
20
2
30
6
22
4
8
6
16
8
4
29
28
15
11
37
9
2
11
4
14
71
7
16
2
4
17
21
10
3
1
1
1
2
2
797
Large
5
83
34
47
358
46
35
1
6
207
79
4
14
31
13
105
65
29
68
55
120
28
13
47
69
48
1
42
7
93
9
12
15
112
24
7
130
125
37
44
128
76
11
48
13
91
195
45
42
2
6
65
55
25
8
0
0
0
0
1
3,079
# PWSs with Detections
Total
1
9
20
1
2
1
1
1
1
7
5
17
1
9
9
2
8
1
32
21
13
5
1
5
4
177
Small
1
1
1
0
0
0
0
0
1
2
0
2
0
1
0
0
3
0
2
0
1
0
0
0
2
17
Large
0
8
19
1
2
1
1
1
0
5
5
15
1
8
9
2
5
1
30
21
12
5
1
5
2
160
% PWSs with Detections
Total
1 .02%
15.25%
4.93%
2.44%
25.00%
0.42%
20.00%
2.13%
4.76%
5.26%
5.88%
12.88%
2.78%
12.68%
10.59%
1 .74%
40.00%
4.76%
25.00%
13.21%
7.88%
38.46%
0.95%
9.62%
5.26%
4.57%
Small
6.67%
8.33%
2.08%
0.00%
0.00%
0.00%
0.00%
0.00%
12.50%
7.14%
0.00%
16.67%
0.00%
4.17%
0.00%
0.00%
37.50%
0.00%
12.50%
0.00%
2.70%
0.00%
0.00%
0.00%
9.52%
2.13%
Large
0.00%
17.02%
5.31%
2.86%
33.33%
0.48%
25.00%
3.23%
0.00%
4.76%
7.69%
12.50%
3.57%
17.02%
13.04%
2.15%
41 .67%
6.67%
26.79%
16.15%
9.38%
45.45%
1.10%
11.11%
3.64%
5.20%
PWSs w/
Detections
> 1/2 HRL3
#
1
1
2
%
1.41%
0.78%
0.05%
PWSs w/
Detections
>HRL3
#
1
1
%
1.41%
0.03%
The UCMR data are not representative at the state-level.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
3 The HRL used for this analysis was 70 |jg/L.
G-3
-------
Appendix G. Stage 1 Occurrence Measures for CCL 2 Contaminants Monitored Under UCMR 1
Table G1.d. DCPA Degradates - System Level Occurrence by State & Source Water Type (UCMR 1 March 2006 data)
State12
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
Total
Total # PWSs
Total
9
98
47
59
406
56
41
1
8
238
101
5
17
47
21
133
85
41
77
82
132
36
19
71
85
68
3
72
13
115
13
20
21
128
32
11
159
153
52
55
165
85
13
59
17
105
266
52
58
4
10
82
76
35
11
1
1
1
2
3
3,876
GW
4
42
23
45
178
15
11
0
4
220
38
1
15
27
17
84
64
23
8
58
68
18
6
38
75
43
2
70
6
38
6
18
8
88
25
4
71
85
15
20
43
24
6
15
8
19
127
17
14
0
3
55
58
3
2
1
1
0
1
1
1,979
SW
5
56
24
14
228
41
30
1
4
18
63
4
2
20
4
49
21
18
69
24
64
18
13
33
10
25
1
2
7
77
7
2
13
40
7
7
88
68
37
35
122
61
7
44
9
86
139
35
44
4
7
27
18
32
9
0
0
1
1
2
1,897
# PWSs with Detections
Total
1
9
20
1
2
1
1
1
1
7
5
17
1
9
9
2
8
1
32
21
13
5
1
5
4
177
GW
1
9
14
1
0
1
0
1
1
6
3
10
1
8
9
2
8
0
19
19
4
3
0
1
4
125
SW
0
0
6
0
2
0
1
0
0
1
2
7
0
1
0
0
0
1
13
2
9
2
1
4
0
52
% PWSs with Detections
Total
1 .02%
15.25%
4.93%
2.44%
25.00%
0.42%
20.00%
2.13%
4.76%
5.26%
5.88%
12.88%
2.78%
12.68%
10.59%
1 .74%
40.00%
4.76%
25.00%
13.21%
7.88%
38.46%
0.95%
9.62%
5.26%
4.57%
GW
2.38%
20.00%
7.87%
9.09%
0.00%
0.45%
0.00%
3.70%
5.88%
7.14%
4.69%
14.71%
5.56%
21.05%
12.00%
5.26%
44.44%
0.00%
21.59%
26.76%
9.30%
50.00%
0.00%
5.88%
6.90%
6.32%
SW
0.00%
0.00%
2.63%
0.00%
50.00%
0.00%
25.00%
0.00%
0.00%
2.04%
9.52%
10.94%
0.00%
3.03%
0.00%
0.00%
0.00%
7.69%
32.50%
2.27%
7.38%
28.57%
1.16%
11.43%
0.00%
2.74%
# PWSs with
Detections
>1/2HRL3
GW
1
0
1
SW
0
1
1
% PWSs with
Detections
>1/2HRL3
GW
2.63%
0.00%
0.05%
SW
0.00%
2.50%
0.05%
# PWSs with
Detections
>HRL3
GW
1
1
SW
0
0
% PWSs with
Detections
>HRL3
GW
2.63%
0.05%
SW
0.00%
0.00%
The UCMR data are not representative at the state-level.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
3 The HRL used for this analysis was 70 ug/L.
G-4
-------
Appendix G. Stage 1 Occurrence Measures for CCL 2 Contaminants Monitored Under UCMR 1
Table G1.e. DCPA Degradates - Statistics for All Detections by State (UCMR 1 March 2006 Data)
State 1 2
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
Total
Total #
Detections
1
22
102
2
4
1
1
1
2
16
9
38
1
42
20
2
27
4
129
203
111
14
1
10
13
776
Statistics for Detections (in ug/L)
Minimum
2.50
1.00
1.00
3.00
1.00
5.50
1.70
1.50
1.50
1.00
1.30
1.00
1.70
1.00
1.00
1.90
1.20
2.70
1.00
1.00
1.00
1.20
1.90
1.10
1.10
1.00
Median
2.50
2.20
1.85
3.30
1.91
5.50
1.70
1.50
1.65
1.55
2.50
1.95
1.70
1.00
1.75
2.38
1.80
5.80
2.10
1.90
2.10
3.40
1.90
5.15
2.10
2.00
99th
Percentile
2.50
31.00
12.00
3.60
2.80
5.50
1.70
1.50
1.80
8.50
4.90
15.00
1.70
1 90.00
3.00
2.86
11.00
19.00
28.00
11.00
11.00
10.00
1.90
24.00
5.00
19.00
Maximum
2.50
31.00
13.00
3.60
2.80
5.50
1.70
1.50
1.80
8.50
4.90
15.00
1.70
190.00
3.00
2.86
11.00
19.00
39.00
18.00
13.30
10.00
1.90
24.00
5.00
190.00
The UCMR data are not representative at the state-level.
' States are arranged alphabetically based on their 2-digit State abbreviation.
G-5
-------
Appendix G. Stage 1 Occurrence Measures for CCL 2 Contaminants Monitored Under UCMR 1
Table G1.f. DCPA Degradates - Pop. Served Level Occurrence by State & Size Category (UCMR 1 March 2006 data)
State 1'2
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
Total
Total #
PWSs
9
98
47
59
406
56
41
1
8
238
101
5
17
47
21
133
85
41
77
82
132
36
19
71
85
68
3
72
13
115
13
20
21
128
32
11
159
153
52
55
165
85
13
59
17
105
266
52
58
4
10
82
76
35
11
1
1
1
2
3
3,876
Total Population Served by PWSs
Total
239,991
3,966,808
1,396,235
4,246,932
31,914,388
4,085,452
2,390,100
927,055
536,260
15,323,786
6,750,245
105,219
1,110,726
1,686,720
580,914
7,645,947
3,525,721
1,739,325
3,499,097
2,742,078
6,456,374
4,676,636
348,285
5,492,931
3,005,782
3,619,103
68,836
1,273,562
350,315
5,093,736
320,270
965,769
494,401
8,122,662
1,112,569
1,625,791
19,937,535
8,541,989
2,221,224
2,515,862
9,008,128
4,782,110
824,052
2,669,268
353,547
4,269,873
16,706,429
2,011,035
5,137,941
64,400
220,439
4,490,251
2,769,896
781,825
245,695
191
2,300
498
825
31,444
225,026,778
Small
3,454
74,457
54,195
41,298
159,389
37,427
19,834
0
6,800
117,516
61,722
5,504
15,462
26,705
38,297
117,151
112,990
38,626
40,419
88,423
63,293
18,501
8,110
78,697
58,334
51,747
6,140
78,999
15,516
98,839
7,619
23,535
16,250
76,320
7,195
5,856
94,031
123,119
67,039
31,893
92,665
36,651
4,740
50,104
10,156
73,215
251,073
32,702
22,928
400
11,169
41,836
88,774
34,761
1,680
191
2,300
498
825
13,200
2,760,570
Large
236,537
3,892,351
1,342,040
4,205,634
31,754,999
4,048,025
2,370,266
927,055
529,460
15,206,270
6,688,523
99,715
1,095,264
1,660,015
542,617
7,528,796
3,412,731
1,700,699
3,458,678
2,653,655
6,393,081
4,658,135
340,175
5,414,234
2,947,448
3,567,356
62,696
1,194,563
334,799
4,994,897
312,651
942,234
478,151
8,046,342
1,105,374
1,619,935
19,843,504
8,418,870
2,154,185
2,483,969
8,915,463
4,745,459
819,312
2,619,164
343,391
4,196,658
16,455,356
1,978,333
5,115,013
64,000
209,270
4,448,415
2,681,122
747,064
244,015
0
0
0
0
18,244
222,266,208
Population Served by PWSs
with Detections
Total
4,674
197,893
2,149,623
12,825
236,130
11,305
61,750
22,697
9,000
126,235
199,948
432,706
25,000
222,576
307,259
29,846
152,459
25,000
2,565,278
2,723,480
1,191,445
135,079
11,566
424,500
79,095
11,357,369
Small
4,674
3,500
6,870
0
0
0
0
0
9,000
8,604
0
14,200
0
500
0
0
14,330
0
10,430
0
4,954
0
0
0
10,871
87,933
Large
0
194,393
2,142,753
12,825
236,130
11,305
61,750
22,697
0
117,631
199,948
418,506
25,000
222,076
307,259
29,846
138,129
25,000
2,554,848
2,723,480
1,186,491
135,079
11,566
424,500
68,224
11,269,436
% Population Served by
PWSs with Detections
Total
0.12%
4.66%
6.74%
0.54%
44.03%
0.07%
58.69%
1.35%
1.55%
1.65%
5.67%
6.70%
0.53%
4.05%
10.22%
0.59%
15.79%
5.06%
31.58%
13.66%
13.23%
16.39%
0.27%
21.11%
2.86%
5.05%
Small
6.28%
8.47%
4.31%
0.00%
0.00%
0.00%
0.00%
0.00%
23.50%
7.34%
0.00%
22.44%
0.00%
0.64%
0.00%
0.00%
60.89%
0.00%
13.67%
0.00%
5.35%
0.00%
0.00%
0.00%
12.25%
3.19%
Large
0.00%
4.62%
6.75%
0.54%
44.60%
0.07%
61.93%
1.37%
0.00%
1.56%
5.86%
6.55%
0.54%
4.10%
10.42%
0.60%
14.66%
5.23%
31.75%
13.72%
13.31%
16.49%
0.28%
21.46%
2.54%
5.07%
Pop. Served by
PWSs w/
Detections
> 1/2 HRL3
#
500
738,337
738,837
%
0.01%
9.09%
0.33%
Pop. Served by
PWSs w/
Detections
>HRL3
#
500
500
%
0.01%
<0.01%
The UCMR data are not representative at the state-level.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
3 The HRL used for this analysis was 70 |jg/L.
G-6
-------
Appendix G. Stage 1 Occurrence Measures for CCL 2 Contaminants Monitored Under UCMR 1
Table G1.g. DCPA Degradates - Pop. Served Level Occurrence by State & Source Water Type (UCMR 1 March 2006
State 1 2
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
Total
Total Population Served by PWSs
Total
239,991
3,966,808
1 ,396,235
4,246,932
31,914,388
4,085,452
2,390,100
927,055
536,260
15,323,786
6,750,245
105,219
1,110,726
1,686,720
580,914
7,645,947
3,525,721
1,739,325
3,499,097
2,742,078
6,456,374
4,676,636
348,285
5,492,931
3,005,782
3,619,103
68,836
1 ,273,562
350,315
5,093,736
320,270
965,769
494,401
8,122,662
1,112,569
1,625,791
19,937,535
8,541 ,989
2,221,224
2,515,862
9,008,128
4,782,110
824,052
2,669,268
353,547
4,269,873
16,706,429
2,011,035
5,137,941
64,400
220,439
4,490,251
2,769,896
781,825
245,695
191
2,300
498
825
31,444
225,026,778
GW
61 ,692
770,193
369,506
1,601,104
7,097,065
306,580
123,040
0
60,130
12,501,454
744,191
12,500
1 ,025,526
534,972
377,665
1,642,735
1 ,299,570
327,349
187,546
1 ,039,978
1 ,443,348
534,638
29,995
682,593
1,753,601
805,343
65,327
951 ,094
96,096
711,126
74,450
434,460
87,020
2,146,187
954,906
22,393
3,538,426
1,788,032
190,419
402,978
484,457
470,189
98,740
228,191
82,540
1,080,708
3,053,892
367,611
54,564
0
2,149
1 ,554,978
1,111,260
60,546
26,099
191
2,300
0
325
3,200
55,477,168
SW
178,299
3,196,615
1,026,729
2,645,828
24,817,323
3,778,872
2,267,060
927,055
476,130
2,822,332
6,006,054
92,719
85,200
1,151,748
203,249
6,003,212
2,226,151
1,411,976
3,311,551
1,702,100
5,013,026
4,141,998
318,290
4,810,338
1,252,181
2,813,760
3,509
322,468
254,219
4,382,610
245,820
531 ,309
407,381
5,976,475
157,663
1,603,398
16,399,109
6,753,957
2,030,805
2,112,884
8,523,671
4,311,921
725,312
2,441,077
271 ,007
3,189,165
13,652,537
1,643,424
5,083,377
64,400
218,290
2,935,273
1,658,636
721 ,279
219,596
0
0
498
500
28,244
169,549,610
Population Served by PWSs
with Detections
Total
4,674
197,893
2,149,623
12,825
236,130
11,305
61,750
22,697
9,000
126,235
199,948
432,706
25,000
222,576
307,259
29,846
152,459
25,000
2,565,278
2,723,480
1,191,445
135,079
11,566
424,500
79,095
11,357,369
GW
4,674
197,893
1,456,149
12,825
0
11,305
0
22,697
9,000
124,735
161,000
168,267
25,000
184,703
307,259
29,846
152,459
0
645,648
2,445,403
59,454
56,000
0
16,000
79,095
6,169,412
SW
0
0
693,474
0
236,130
0
61,750
0
0
1,500
38,948
264,439
0
37,873
0
0
0
25,000
1,919,630
278,077
1,131,991
79,079
11,566
408,500
0
5,187,957
% Pop. Served by PWSs with
Detections
Total
0.12%
4.66%
6.74%
0.54%
44.03%
0.07%
58.69%
1.35%
1.55%
1.65%
5.67%
6.70%
0.53%
4.05%
10.22%
0.59%
15.79%
5.06%
31.58%
13.66%
13.23%
16.39%
0.27%
0.00%
21.11%
2.86%
5.05%
GW
0.61%
12.36%
20.52%
10.42%
0.00%
0.09%
0.00%
4.24%
2.38%
7.59%
12.39%
11.66%
4.68%
27.06%
17.52%
4.20%
35.09%
0.00%
30.08%
69.11%
12.27%
56.71%
0.00%
0.00%
4.35%
7.12%
11.12%
SW
0.00%
0.00%
2.79%
0.00%
49.59%
0.00%
66.60%
0.00%
0.00%
0.02%
1.75%
5.28%
0.00%
0.79%
0.00%
0.00%
0.00%
6.14%
32.12%
1.70%
13.28%
10.90%
0.36%
0.00%
24.86%
0.00%
3.06%
The UCMR data are not representative at the state-level.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
G-7
-------
Appendix G. Stage 1 Occurrence Measures for CCL 2 Contaminants Monitored Under UCMR 1
Table G2.a. DDE - Occurrence Based on Samples, Systems, and Population Served (UCMR 1 March 2006 Data )
Water Type
System Size by
Population Served
Sample Level
Total Number
of Samples
Detections1
Number
Percent
System Level
Total Number
of Systems
Sampled
Systems with Detections
Number
Percent
Population Served-Level
Total
Population
Served
Pop. Served by
Systems with Detections
Number
Percent
Small Systems (Statistical Sample)
Ground
Water
Surface
Water
25 - 500
501 - 3,300
3,301 -10,000
Total
25 - 500
501 - 3,300
3,301 -10,000
Total
All Small Systems
259
879
1,204
2,342
220
181
508
909
3,251
0
0
0
0.00%
0.00%
0.00%
111
245
234
590
52
45
110
207
797
0
0
0
0.00%
0.00%
0.00%
27,599
441 ,499
1,470,717
1,939,815
16,662
91,723
712,370
820,755
2,760,570
0
0
0
0.00%
0.00%
0.00%
Large Systems (Census)
Ground
Water
Surface
Water
10,001 -50,000
> 50,000
Total
10,001 -50,000
> 50,000
Total
All Large Systems
10,492
5,422
15,914
7,436
7,196
14,632
30,546
1
1
0
1
0.01%
0.01%
0.00%
0.003%
1,191
190
1,381
1,187
509
1,696
3,077
1
1
0
1
0.08%
0.07%
0.00%
0.03%
26,939,587
26,476,158
53,415,745
33,405,163
136,681,205
170,086,368
223,502,113
17,670
17,670
0
17,670
0.07%
0.03%
0.00%
0.01%
All Systems
Total Water Systems2
33,797
1
0.003%
3,874
1
0.03%
226,262,683
17,670
0.01%
1 The single detection of DDE (equal to 3 ug/L) was found in a CWS in Alabama. This detection is greater than the HRL for DDE (HRL=0.2 ug/L).
2 The UCMR small water systems (population served < 10,000) are a statistical, representative sample of all national small systems while the UCMR large water systems (population
served > 10,000) represent a census of all large systems. Combined small and large system occurrence summaries accurately present the actual UCMR monitoring results. However,
only the summary findings expressed as percentages accurately reflect national occurrence; combined large and small summaries based on numerical counts of detections at the
sample, system, and population-served levels do not accurately represent national occurrence.
G-8
-------
Appendix G. Stage 1 Occurrence Measures for CCL 2 Contaminants Monitored Under UCMR 1
Table G2.b. DDE - Number of PWSs by State (UCMR 1 March 2006 Data)
State 1 2
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
Total
Total Number of
Samples
53
809
239
1,322
8,564
396
370
8
103
1,166
542
275
394
213
248
749
401
244
344
318
1,137
175
89
371
434
457
137
527
126
1,043
41
230
135
1,051
362
71
2,332
550
317
351
1,260
717
109
307
103
542
1,750
466
298
28
40
682
552
150
69
2
2
4
6
16
33,797
Total Number of
PWSs
9
98
47
59
407
56
41
1
8
238
101
5
17
47
21
133
86
41
77
77
132
36
19
71
85
68
3
72
13
115
13
20
21
128
32
11
160
153
52
55
165
85
13
59
17
105
266
52
58
4
10
82
76
35
11
1
1
1
2
3
3,874
No. of Small Systems
GW
2
12
9
11
26
3
3
2
31
14
3
12
6
26
19
10
2
23
10
7
4
21
16
17
1
30
4
12
3
8
4
14
6
3
21
24
7
6
21
4
2
5
3
2
61
4
13
3
14
21
1
1
1
1
1
590
SW
2
3
4
1
22
7
3
8
1
4
2
2
1
2
7
4
2
1
2
3
3
1
2
10
1
2
2
2
1
8
4
8
5
16
5
6
1
12
10
3
3
2
1
3
10
2
1
1
1
207
No. of Large Systems
GW
2
30
14
34
152
12
8
2
189
24
1
12
15
11
58
45
13
6
27
58
11
2
17
59
26
1
40
2
26
3
10
4
74
19
1
50
61
8
14
22
20
4
10
5
17
66
13
1
41
37
3
1
1,381
SW
3
53
20
13
207
34
27
1
4
18
55
3
2
16
2
47
21
16
62
23
62
17
11
30
10
22
2
5
67
6
2
11
38
5
6
81
64
29
30
106
56
7
38
8
74
129
32
41
2
6
24
18
22
7
1
1,696
The UCMR data are not representative at the state-level.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
G-9
-------
Appendix G. Stage 1 Occurrence Measures for CCL 2 Contaminants Monitored Under UCMR 1
Table G2.c. DDE - Total Population-Served by State (UCMR 1 March 2006 Data)
State 1 2
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
Total
Total Number of
PWSs
9
98
47
59
407
56
41
1
8
238
101
5
17
47
21
133
86
41
77
77
132
36
19
71
85
68
3
72
13
115
13
20
21
128
32
11
160
153
52
55
165
85
13
59
17
105
266
52
58
4
10
82
76
35
11
1
1
1
2
3
3,874
Total Population
Served
239,991
3,966,808
1,396,235
4,246,932
33,137,788
4,085,452
2,390,100
927,055
536,260
15,323,786
6,750,245
105,219
1,110,726
1 ,686,720
580,914
7,645,947
3,539,721
1,739,325
3,499,097
2,696,031
6,456,374
4,676,636
348,285
5,492,931
3,005,782
3,619,103
68,836
1 ,273,562
350,315
5,093,736
320,270
965,769
494,401
8,122,662
1,112,569
1,625,791
19,956,351
8,541 ,989
2,221,224
2,515,862
9,008,128
4,782,110
824,052
2,669,268
353,547
4,269,873
16,732,165
2,011,035
5,137,941
64,400
220,439
4,490,251
2,769,896
781,825
245,695
191
2,300
498
825
31 ,444
226,262,683
Pop. Served by
Small Systems
GW
3,092
67,068
35,209
39,692
85,318
12,175
1,309
6,800
117,516
28,636
15,462
19,916
35,100
106,661
104,078
27,481
7,622
75,303
50,393
12,301
2,955
57,873
58,334
38,276
2,631
78,999
10,314
47,141
7,416
23,535
10,620
60,020
6,625
5,393
45,407
104,131
23,784
12,378
42,012
24,631
4,740
14,485
9,780
2,533
228,336
16,417
13,849
2,149
38,029
88,774
1,100
191
2,300
325
3,200
1,939,815
SW
362
7,389
18,986
1,606
74,071
25,252
18,525
33,086
5,504
6,789
3,197
10,490
8,912
11,145
32,797
13,120
12,900
6,200
5,155
20,824
13,471
3,509
5,202
51 ,698
203
5,630
16,300
570
463
48,624
18,988
43,255
19,515
50,653
12,020
35,619
376
70,682
22,737
16,285
9,079
400
9,020
3,807
34,761
580
498
500
10,000
820,755
Pop. Served by
Large Systems
GW
58,600
703,125
334,297
1,561,412
7,011,747
294,405
121,731
53,330
12,383,938
715,555
12,500
1,010,064
515,056
342,565
1 ,536,074
1,195,492
299,868
179,924
817,331
1 ,392,955
522,337
27,040
624,720
1 ,695,267
767,067
62,696
872,095
85,782
663,985
67,034
410,925
76,400
2,086,167
948,281
17,000
3,493,019
1 ,683,901
166,635
390,600
442,445
445,558
94,000
213,706
72,760
1,078,175
2,851,292
351,194
40,715
1,516,949
1,022,486
60,546
24,999
53,415,745
SW
177,937
3,189,226
1,007,743
2,644,222
25,966,652
3,753,620
2,248,535
927,055
476,130
2,822,332
5,972,968
87,215
85,200
1,144,959
200,052
5,992,722
2,231,239
1 ,400,831
3,278,754
1,790,277
5,000,126
4,135,798
313,135
4,789,514
1,252,181
2,800,289
322,468
249,017
4,330,912
245,617
531 ,309
401,751
5,960,175
157,093
1,602,935
16,369,301
6,734,969
1 ,987,550
2,093,369
8,473,018
4,299,901
725,312
2,405,458
270,631
3,118,483
13,629,800
1,627,139
5,074,298
64,000
209,270
2,931,466
1 ,658,636
686,518
219,016
18,244
170,086,368
The UCMR data are not representative at the state-level.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
G-10
-------
Appendix G. Stage 1 Occurrence Measures for CCL 2 Contaminants Monitored Under UCMR 1
Table G3.a. 1,3-Dichloropropene - Occurrence Based on Samples, Systems, and Population Served (UCMR 1 March 2006 Data)
Small Systems ONLY
Water Type
System Size by
Population Served
Sample Level
Total Number of
Samples
Detections
Number
Percent
System Level
Total Number
of Systems
Sampled
Systems with Detections
Number
Percent
Population Served-Level
Total
Population
Served
Pop. Served by
Systems with Detections
Number
Percent
Small Systems (Statistical Sample)1
Ground
Water
Surface
Water
25 - 500
501 - 3,300
3,301 - 10,000
Total
25 - 500
501 - 3,300
3,301 - 10,000
Total
All Small Systems
310
941
1,305
2,556
287
251
625
1,163
3,719
0
0
0
0.00%
0.00%
0.00%
111
244
234
589
52
45
110
207
796
0
0
0
0.00%
0.00%
0.00%
27,599
439,01 1
1,470,717
1 ,937,327
16,662
91,723
712,370
820,755
2,758,082
0
0
0
0.00%
0.00%
0.00%
1 1,3-Dichloropropene was not officially monitored under UCMR, but was as added as an extra contaminant for monitoring by the (800) small systems. There are no UCMR data from large
systems on the occurrence of 1,3-dichloropropene.
G-11
-------
Appendix G. Stage 1 Occurrence Measures for CCL 2 Contaminants Monitored Under UCMR 1
Table G3.b. 1,3-Dichloropropene - Number of PWSs by State (UCMR 1 March 2006 Data)
State 1 2
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
Total
Total Number of
Samples
12
87
44
89
283
74
40
10
96
82
4
26
54
57
105
59
65
37
159
82
28
17
90
69
115
20
127
23
146
14
61
29
71
31
22
130
84
67
54
138
38
16
63
14
63
296
34
81
8
17
91
118
50
10
2
2
4
6
5
3,719
Total Number of
PWSs
4
15
13
12
48
10
6
2
31
21
1
3
16
8
28
20
12
9
27
12
8
6
24
16
20
2
30
6
22
4
8
6
16
8
4
29
28
15
11
37
9
2
11
4
14
71
7
16
2
4
17
21
10
3
1
1
1
2
2
796
No. of Small Systems
GW
2
12
9
11
26
3
3
2
31
13
0
3
12
6
26
19
10
2
23
10
7
4
21
16
17
1
30
4
12
3
8
4
14
6
3
21
24
7
6
21
4
2
5
3
2
61
4
13
0
3
14
21
0
1
1
1
0
1
1
589
SW
2
3
4
1
22
7
3
0
0
8
1
0
4
2
2
1
2
7
4
2
1
2
3
0
3
1
0
2
10
1
0
2
2
2
1
8
4
8
5
16
5
0
6
1
12
10
3
3
2
1
3
0
10
2
0
0
1
1
1
207
The UCMR data are not representative at the state-level.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
G-12
-------
Appendix G. Stage 1 Occurrence Measures for CCL 2 Contaminants Monitored Under UCMR 1
Table G3.c. 1,3-Dichloropropene - Total Population-Served by State (UCMR 1 March 2006 Data)
State 1 2
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
Total
Total Number of
PWSs
4
15
13
12
48
10
6
2
31
21
1
3
16
8
28
20
12
9
27
12
8
6
24
16
20
2
30
6
22
4
8
6
16
8
4
29
28
15
11
37
9
2
11
4
14
71
7
16
2
4
17
21
10
3
1
1
1
2
2
796
Total Population
Served
3,454
74,457
54,195
41 ,298
159,389
37,427
19,834
6,800
117,516
59,234
5,504
15,462
26,705
38,297
117,151
112,990
38,626
40,419
88,423
63,293
18,501
8,110
78,697
58,334
51,747
6,140
78,999
15,516
98,839
7,619
23,535
16,250
76,320
7,195
5,856
94,031
123,119
67,039
31 ,893
92,665
36,651
4,740
50,104
10,156
73,215
251,073
32,702
22,928
400
11,169
41 ,836
88,774
34,761
1,680
191
2,300
498
825
13,200
2,758,082
Pop. Served by
Small Systems
GW
3,092
67,068
35,209
39,692
85,318
12,175
1,309
6,800
117,516
26,148
0
15,462
19,916
35,100
106,661
104,078
27,481
7,622
75,303
50,393
12,301
2,955
57,873
58,334
38,276
2,631
78,999
10,314
47,141
7,416
23,535
10,620
60,020
6,625
5,393
45,407
104,131
23,784
12,378
42,012
24,631
4,740
14,485
9,780
2,533
228,336
16,417
13,849
0
2,149
38,029
88,774
0
1,100
191
2,300
0
325
3,200
1,937,327
SW
362
7,389
18,986
1,606
74,071
25,252
18,525
0
0
33,086
5,504
0
6,789
3,197
10,490
8,912
11,145
32,797
13,120
12,900
6,200
5,155
20,824
0
13,471
3,509
0
5,202
51 ,698
203
0
5,630
16,300
570
463
48,624
18,988
43,255
19,515
50,653
12,020
0
35,619
376
70,682
22,737
16,285
9,079
400
9,020
3,807
0
34,761
580
0
0
498
500
10,000
820,755
The UCMR data are not representative at the state-level.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
G-13
-------
Appendix G. Stage 1 Occurrence Measures for CCL 2 Contaminants Monitored Under UCMR 1
Table G4.a. 2,4-Dinitrotoluene - Occurrence Based on Samples, Systems, and Population Served (UCMR 1 March 2006 Data;
Water Type
System Size by
Population Served
Sample Level
Total Number
of Samples
Detections1
Number
Percent
System Level
Total Number
of Systems
Sampled
Systems with Detections
Number
Percent
Population Served-Level
Total
Population
Served
Pop. Served by
Systems with Detections
Number
Percent
Small Systems (Statistical Sample)
Ground
Water
Surface
Water
25 - 500
501 - 3,300
3,301 - 10,000
Total
25 - 500
501 - 3,300
3,301 - 10,000
Total
All Small Systems
259
879
1,204
2,342
220
181
508
909
3,251
0
0
0
0.00%
0.00%
0.00%
111
245
234
590
52
45
110
207
797
0
0
0
0.00%
0.00%
0.00%
27,599
441 ,499
1,470,717
1,939,815
16,662
91,723
712,370
820,755
2,760,570
0
0
0
0.00%
0.00%
0.00%
Large Systems (Census)
Ground
Water
Surface
Water
10,001 -50,000
> 50,000
Total
10,001 -50,000
> 50,000
Total
All Large Systems
10,519
5,425
15,944
7,408
7,161
14,569
30,513
0
1
1
1
0.00%
0.01%
0.01%
0.003%
1,190
190
1,380
1,187
509
1,696
3,076
0
1
1
1
0.00%
0.08%
0.06%
0.03%
26,929,381
26,476,158
53,405,539
33,405,163
136,681,205
170,086,368
223,491,907
0
37,811
37,811
37,811
0.00%
0.11%
0.02%
0.02%
All Systems
Total Water Systems2
33,764
1
0.003%
3,873
1
0.03%
226,252,477
37,811
0.02%
1 The single detection of 2,4-dinitrotoluene (equal to 333 ug/L) was found in a CWS in Tennessee. This detection is greater than the HRL for2,4-dinitrotoluene (HRL=0.05 ug/L).
2 The UCMR small water systems (population served < 10,000) are a statistical, representative sample of all national small systems while the UCMR large water systems (population
served > 10,000) represent a census of all large systems. Combined small and large system occurrence summaries accurately present the actual UCMR monitoring results. However,
only the summary findings expressed as percentages accurately reflect national occurrence; combined large and small summaries based on numerical counts of detections at the
sample, system, and population-served levels do not accurately represent national occurrence.
G-14
-------
Appendix G. Stage 1 Occurrence Measures for CCL 2 Contaminants Monitored Under UCMR 1
Table G4.b. 2,4-Dinitrotoluene - Number of PWSs by State (UCMR 1 March 2006 Data)
State 1 2
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
Total
Total Number of
Samples
53
809
236
1,312
8,538
396
370
8
102
1,166
568
275
394
213
248
749
397
247
344
319
1,137
175
89
371
434
457
137
527
126
1,042
41
230
135
1,051
362
71
2,330
548
317
351
1,259
717
109
292
103
542
1,750
466
298
28
40
682
552
152
69
2
2
4
6
16
33,764
Total Number of
PWSs
9
98
47
59
407
56
41
1
8
238
101
5
17
47
21
133
86
41
77
76
132
36
19
71
85
68
3
72
13
115
13
20
21
128
32
11
160
153
52
55
165
85
13
59
17
105
266
52
58
4
10
82
76
35
11
1
1
1
2
3
3,873
No. of Small Systems
GW
2
12
9
11
26
3
3
2
31
14
3
12
6
26
19
10
2
23
10
7
4
21
16
17
1
30
4
12
3
8
4
14
6
3
21
24
7
6
21
4
2
5
3
2
61
4
13
3
14
21
1
1
1
1
1
590
SW
2
3
4
1
22
7
3
8
1
4
2
2
1
2
7
4
2
1
2
3
3
1
2
10
1
2
2
2
1
8
4
8
5
16
5
6
1
12
10
3
3
2
1
3
10
2
1
1
1
207
No. of Large Systems
GW
2
30
14
34
152
12
8
2
189
24
1
12
15
11
58
45
13
6
26
58
11
2
17
59
26
1
40
2
26
3
10
4
74
19
1
50
61
8
14
22
20
4
10
5
17
66
13
1
41
37
3
1
1,380
SW
3
53
20
13
207
34
27
1
4
18
55
3
2
16
2
47
21
16
62
23
62
17
11
30
10
22
2
5
67
6
2
11
38
5
6
81
64
29
30
106
56
7
38
8
74
129
32
41
2
6
24
18
22
7
1
1,696
The UCMR data are not representative at the state-level.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
G-15
-------
Appendix G. Stage 1 Occurrence Measures for CCL 2 Contaminants Monitored Under UCMR 1
Table G4.c. 2,4-Dinitrotoluene - Total Population-Served by State (UCMR 1 March 2006 Data)
State 1 2
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
Total
Total Number of
PWSs
9
98
47
59
407
56
41
1
8
238
101
5
17
47
21
133
86
41
77
76
132
36
19
71
85
68
3
72
13
115
13
20
21
128
32
11
160
153
52
55
165
85
13
59
17
105
266
52
58
4
10
82
76
35
11
1
1
1
2
3
3,873
Total Population
Served
239,991
3,966,808
1,396,235
4,246,932
33,137,788
4,085,452
2,390,100
927,055
536,260
15,323,786
6,750,245
105,219
1,110,726
1 ,686,720
580,914
7,645,947
3,539,721
1,739,325
3,499,097
2,685,825
6,456,374
4,676,636
348,285
5,492,931
3,005,782
3,619,103
68,836
1 ,273,562
350,315
5,093,736
320,270
965,769
494,401
8,122,662
1,112,569
1,625,791
19,956,351
8,541 ,989
2,221,224
2,515,862
9,008,128
4,782,110
824,052
2,669,268
353,547
4,269,873
16,732,165
2,011,035
5,137,941
64,400
220,439
4,490,251
2,769,896
781,825
245,695
191
2,300
498
825
31 ,444
226,252,477
Pop. Served by
Small Systems
GW
3,092
67,068
35,209
39,692
85,318
12,175
1,309
6,800
117,516
28,636
15,462
19,916
35,100
106,661
104,078
27,481
7,622
75,303
50,393
12,301
2,955
57,873
58,334
38,276
2,631
78,999
10,314
47,141
7,416
23,535
10,620
60,020
6,625
5,393
45,407
104,131
23,784
12,378
42,012
24,631
4,740
14,485
9,780
2,533
228,336
16,417
13,849
2,149
38,029
88,774
1,100
191
2,300
325
3,200
1,939,815
SW
362
7,389
18,986
1,606
74,071
25,252
18,525
33,086
5,504
6,789
3,197
10,490
8,912
11,145
32,797
13,120
12,900
6,200
5,155
20,824
13,471
3,509
5,202
51 ,698
203
5,630
16,300
570
463
48,624
18,988
43,255
19,515
50,653
12,020
35,619
376
70,682
22,737
16,285
9,079
400
9,020
3,807
34,761
580
498
500
10,000
820,755
Pop. Served by
Large Systems
GW
58,600
703,125
334,297
1,561,412
7,011,747
294,405
121,731
53,330
12,383,938
715,555
12,500
1,010,064
515,056
342,565
1 ,536,074
1,195,492
299,868
179,924
807,125
1 ,392,955
522,337
27,040
624,720
1 ,695,267
767,067
62,696
872,095
85,782
663,985
67,034
410,925
76,400
2,086,167
948,281
17,000
3,493,019
1 ,683,901
166,635
390,600
442,445
445,558
94,000
213,706
72,760
1,078,175
2,851,292
351,194
40,715
1,516,949
1,022,486
60,546
24,999
53,405,539
SW
177,937
3,189,226
1,007,743
2,644,222
25,966,652
3,753,620
2,248,535
927,055
476,130
2,822,332
5,972,968
87,215
85,200
1,144,959
200,052
5,992,722
2,231,239
1 ,400,831
3,278,754
1,790,277
5,000,126
4,135,798
313,135
4,789,514
1,252,181
2,800,289
322,468
249,017
4,330,912
245,617
531 ,309
401,751
5,960,175
157,093
1,602,935
16,369,301
6,734,969
1 ,987,550
2,093,369
8,473,018
4,299,901
725,312
2,405,458
270,631
3,118,483
13,629,800
1,627,139
5,074,298
64,000
209,270
2,931,466
1 ,658,636
686,518
219,016
18,244
170,086,368
The UCMR data are not representative at the state-level.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
G-16
-------
Appendix G. Stage 1 Occurrence Measures for CCL 2 Contaminants Monitored Under UCMR 1
Table G5.a. 2,6-Dinitrotoluene - Occurrence Based on Samples, Systems, and Population Served (UCMR 1 March 2006 Data)
Water Type
System Size by
Population Served
Sample Level
Total Number
of Samples
Detections
Number
Percent
System Level
Total Number
of Systems
Sampled
Systems with Detections
Number
Percent
Population Served-Level
Total
Population
Served
Pop. Served by
Systems with Detections
Number
Percent
Small Systems (Statistical Sample)
Ground
Water
Surface
Water
25 - 500
501 - 3,300
3,301 -10,000
Total
25 - 500
501 - 3,300
3,301 -10,000
Total
All Small Systems
259
879
1,204
2,342
220
181
508
909
3,251
0
0
0
0.00%
0.00%
0.00%
111
245
234
590
52
45
110
207
797
0
0
0
0.00%
0.00%
0.00%
27,599
441 ,499
1,470,717
1,939,815
16,662
91 ,723
712,370
820,755
2,760,570
0
0
0
0.00%
0.00%
0.00%
Large Systems (Census)
Ground
Water
Surface
Water
10,001 -50,000
> 50,000
Total
10,001 -50,000
> 50,000
Total
All Large Systems
10,519
5,427
15,946
7,406
7,162
14,568
30,514
0
0
0
0.00%
0.00%
0.00%
1,190
190
1,380
1,187
509
1,696
3,076
0
0
0
0.00%
0.00%
0.00%
26,929,381
26,476,158
53,405,539
33,405,163
136,681,205
170,086,368
223,491,907
0
0
0
0.00%
0.00%
0.00%
All Systems
Total Water Systems1
33,765
0
0.00%
3,873
0
0.00%
226,252,477
0
0.00%
1 The UCMR small water systems (population served < 10,000) are a statistical, representative sample of all national small systems while the UCMR large water systems (population
served > 10,000) represent a census of all large systems. Combined small and large system occurrence summaries accurately present the actual UCMR monitoring results. However,
only the summary findings expressed as percentages accurately reflect national occurrence; combined large and small summaries based on numerical counts of detections at the sample,
system, and population-served levels do not accurately represent national occurrence.
G-17
-------
Appendix G. Stage 1 Occurrence Measures for CCL 2 Contaminants Monitored Under UCMR 1
Table G5.b. 2,6-Dinitrotoluene - Number of PWSs by State (UCMR 1 March 2006 Data)
State 1 2
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
Total
Total Number of
Samples
53
809
236
1,314
8,538
396
370
8
102
1,166
568
275
394
213
248
749
397
247
344
319
1,137
175
89
371
434
457
137
527
126
1,042
41
230
135
1,051
362
71
2,331
548
317
351
1,260
717
109
292
103
542
1,750
462
298
28
40
683
552
152
69
2
2
4
6
16
33,765
Total Number of
PWSs
9
98
47
59
407
56
41
1
8
238
101
5
17
47
21
133
86
41
77
76
132
36
19
71
85
68
3
72
13
115
13
20
21
128
32
11
160
153
52
55
165
85
13
59
17
105
266
52
58
4
10
82
76
35
11
1
1
1
2
3
3,873
No. of Small Systems
GW
2
12
9
11
26
3
3
2
31
14
3
12
6
26
19
10
2
23
10
7
4
21
16
17
1
30
4
12
3
8
4
14
6
3
21
24
7
6
21
4
2
5
3
2
61
4
13
3
14
21
1
1
1
1
1
590
SW
2
3
4
1
22
7
3
8
1
4
2
2
1
2
7
4
2
1
2
3
3
1
2
10
1
2
2
2
1
8
4
8
5
16
5
6
1
12
10
3
3
2
1
3
10
2
1
1
1
207
No. of Large Systems
GW
2
30
14
34
152
12
8
2
189
24
1
12
15
11
58
45
13
6
26
58
11
2
17
59
26
1
40
2
26
3
10
4
74
19
1
50
61
8
14
22
20
4
10
5
17
66
13
1
41
37
3
1
1,380
SW
3
53
20
13
207
34
27
1
4
18
55
3
2
16
2
47
21
16
62
23
62
17
11
30
10
22
2
5
67
6
2
11
38
5
6
81
64
29
30
106
56
7
38
8
74
129
32
41
2
6
24
18
22
7
1
1,696
The UCMR data are not representative at the state-level.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
G-18
-------
Appendix G. Stage 1 Occurrence Measures for CCL 2 Contaminants Monitored Under UCMR 1
Table G5.c. 2,6-Dinitrotoluene - Total Population-Served by State (UCMR 1 March 2006 Data)
State 1 2
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
Total
Total Number of
PWSs
9
98
47
59
407
56
41
1
8
238
101
5
17
47
21
133
86
41
77
76
132
36
19
71
85
68
3
72
13
115
13
20
21
128
32
11
160
153
52
55
165
85
13
59
17
105
266
52
58
4
10
82
76
35
11
1
1
1
2
3
3,873
Total Population
Served
239,991
3,966,808
1,396,235
4,246,932
33,137,788
4,085,452
2,390,100
927,055
536,260
15,323,786
6,750,245
105,219
1,110,726
1 ,686,720
580,914
7,645,947
3,539,721
1,739,325
3,499,097
2,685,825
6,456,374
4,676,636
348,285
5,492,931
3,005,782
3,619,103
68,836
1 ,273,562
350,315
5,093,736
320,270
965,769
494,401
8,122,662
1,112,569
1,625,791
19,956,351
8,541 ,989
2,221,224
2,515,862
9,008,128
4,782,110
824,052
2,669,268
353,547
4,269,873
16,732,165
2,011,035
5,137,941
64,400
220,439
4,490,251
2,769,896
781,825
245,695
191
2,300
498
825
31 ,444
226,252,477
Pop. Served by
Small Systems
GW
3,092
67,068
35,209
39,692
85,318
12,175
1,309
6,800
117,516
28,636
15,462
19,916
35,100
106,661
104,078
27,481
7,622
75,303
50,393
12,301
2,955
57,873
58,334
38,276
2,631
78,999
10,314
47,141
7,416
23,535
10,620
60,020
6,625
5,393
45,407
104,131
23,784
12,378
42,012
24,631
4,740
14,485
9,780
2,533
228,336
16,417
13,849
2,149
38,029
88,774
1,100
191
2,300
325
3,200
1,939,815
SW
362
7,389
18,986
1,606
74,071
25,252
18,525
33,086
5,504
6,789
3,197
10,490
8,912
11,145
32,797
13,120
12,900
6,200
5,155
20,824
13,471
3,509
5,202
51 ,698
203
5,630
16,300
570
463
48,624
18,988
43,255
19,515
50,653
12,020
35,619
376
70,682
22,737
16,285
9,079
400
9,020
3,807
34,761
580
498
500
10,000
820,755
Pop. Served by
Large Systems
GW
58,600
703,125
334,297
1,561,412
7,011,747
294,405
121,731
53,330
12,383,938
715,555
12,500
1,010,064
515,056
342,565
1 ,536,074
1,195,492
299,868
179,924
807,125
1 ,392,955
522,337
27,040
624,720
1 ,695,267
767,067
62,696
872,095
85,782
663,985
67,034
410,925
76,400
2,086,167
948,281
17,000
3,493,019
1 ,683,901
166,635
390,600
442,445
445,558
94,000
213,706
72,760
1,078,175
2,851,292
351,194
40,715
1,516,949
1,022,486
60,546
24,999
53,405,539
SW
177,937
3,189,226
1,007,743
2,644,222
25,966,652
3,753,620
2,248,535
927,055
476,130
2,822,332
5,972,968
87,215
85,200
1,144,959
200,052
5,992,722
2,231,239
1 ,400,831
3,278,754
1,790,277
5,000,126
4,135,798
313,135
4,789,514
1,252,181
2,800,289
322,468
249,017
4,330,912
245,617
531 ,309
401,751
5,960,175
157,093
1,602,935
16,369,301
6,734,969
1 ,987,550
2,093,369
8,473,018
4,299,901
725,312
2,405,458
270,631
3,118,483
13,629,800
1,627,139
5,074,298
64,000
209,270
2,931,466
1 ,658,636
686,518
219,016
18,244
170,086,368
The UCMR data are not representative at the state-level.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
G-19
-------
Appendix G. Stage 1 Occurrence Measures for CCL 2 Contaminants Monitored Under UCMR 1
Table G6.a. EPIC - Occurrence Based on Samples. Systems, and Population Served (UCMR 1 March 2006 Data)
Water Type
System Size by
Population Served
Sample Level
Total Number
of Samples
Detections
Number
Percent
System Level
Total Number
of Systems
Sampled
Systems with Detections
Number
Percent
Population Served-Level
Total
Population
Served
Pop. Served by
Systems with Detections
Number
Percent
Small Systems (Statistical Sample)
Ground
Water
Surface
Water
25 - 500
501 - 3,300
3,301 - 10,000
Total
25 - 500
501 - 3,300
3,301 - 10,000
Total
All Small Systems
259
879
1,204
2,342
220
181
508
909
3,251
0
0
0
0.00%
0.00%
0.00%
111
245
234
590
52
45
110
207
797
0
0
0
0.00%
0.00%
0.00%
27,599
441 ,499
1,470,717
1,939,815
16,662
91,723
712,370
820,755
2,760,570
0
0
0
0.00%
0.00%
0.00%
Large Systems (Census)
Ground
Water
Surface
Water
10,001 -50,000
> 50,000
Total
10,001 -50,000
> 50,000
Total
All Large Systems
10,529
5,418
15,947
7,424
7,176
14,600
30,547
0
0
0
0.00%
0.00%
0.00%
1,190
190
1,380
1,187
509
1,696
3,076
0
0
0
0.00%
0.00%
0.00%
26,929,381
26,476,158
53,405,539
33,405,163
136,681,205
170,086,368
223,491,907
0
0
0
0.00%
0.00%
0.00%
All Systems
Total Water Systems1
33,798
0
0.00%
3,873
0
0.00%
226,252,477
0
0.00%
1 The UCMR small water systems (population served < 10,000) are a statistical, representative sample of all national small systems while the UCMR large water systems (population
served > 10,000) represent a census of all large systems. Combined small and large system occurrence summaries accurately present the actual UCMR monitoring results. However,
only the summary findings expressed as percentages accurately reflect national occurrence; combined large and small summaries based on numerical counts of detections at the sample,
system, and population-served levels do not accurately represent national occurrence.
G-20
-------
Appendix G. Stage 1 Occurrence Measures for CCL 2 Contaminants Monitored Under UCMR 1
Table G6.b. EPIC - Number of PWSs by State (UCMR 1 March 2006 Data)
State 1 2
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
Total
Total Number of
Samples
53
809
239
1,315
8,566
396
370
8
102
1,166
568
275
394
213
248
749
400
247
344
321
1,135
175
89
371
434
457
137
527
126
1,042
41
230
135
1,051
362
71
2,320
548
317
351
1,260
717
109
292
106
542
1,750
466
298
28
40
685
552
152
69
2
2
4
6
16
33,798
Total Number of
PWSs
9
98
47
59
407
56
41
1
8
238
101
5
17
47
21
133
86
41
77
76
132
36
19
71
85
68
3
72
13
115
13
20
21
128
32
11
160
153
52
55
165
85
13
59
17
105
266
52
58
4
10
82
76
35
11
1
1
1
2
3
3,873
No. of Small Systems
GW
2
12
9
11
26
3
3
2
31
14
3
12
6
26
19
10
2
23
10
7
4
21
16
17
1
30
4
12
3
8
4
14
6
3
21
24
7
6
21
4
2
5
3
2
61
4
13
3
14
21
1
1
1
1
1
590
SW
2
3
4
1
22
7
3
8
1
4
2
2
1
2
7
4
2
1
2
3
3
1
2
10
1
2
2
2
1
8
4
8
5
16
5
6
1
12
10
3
3
2
1
3
10
2
1
1
1
207
No. of Large Systems
GW
2
30
14
34
152
12
8
2
189
24
1
12
15
11
58
45
13
6
26
58
11
2
17
59
26
1
40
2
26
3
10
4
74
19
1
50
61
8
14
22
20
4
10
5
17
66
13
1
41
37
3
1
1,380
SW
3
53
20
13
207
34
27
1
4
18
55
3
2
16
2
47
21
16
62
23
62
17
11
30
10
22
2
5
67
6
2
11
38
5
6
81
64
29
30
106
56
7
38
8
74
129
32
41
2
6
24
18
22
7
1
1,696
The UCMR data are not representative at the state-level.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
G-21
-------
Appendix G. Stage 1 Occurrence Measures for CCL 2 Contaminants Monitored Under UCMR 1
Table G6.c. EPIC - Total Population-Served by State (UCMR 1 March 2006 Data)
State 1 2
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
Total
Total Number of
PWSs
9
98
47
59
407
56
41
1
8
238
101
5
17
47
21
133
86
41
77
76
132
36
19
71
85
68
3
72
13
115
13
20
21
128
32
11
160
153
52
55
165
85
13
59
17
105
266
52
58
4
10
82
76
35
11
1
1
1
2
3
3,873
Total Population
Served
239,991
3,966,808
1,396,235
4,246,932
33,137,788
4,085,452
2,390,100
927,055
536,260
15,323,786
6,750,245
105,219
1,110,726
1 ,686,720
580,914
7,645,947
3,539,721
1,739,325
3,499,097
2,685,825
6,456,374
4,676,636
348,285
5,492,931
3,005,782
3,619,103
68,836
1 ,273,562
350,315
5,093,736
320,270
965,769
494,401
8,122,662
1,112,569
1,625,791
19,956,351
8,541 ,989
2,221,224
2,515,862
9,008,128
4,782,110
824,052
2,669,268
353,547
4,269,873
16,732,165
2,011,035
5,137,941
64,400
220,439
4,490,251
2,769,896
781,825
245,695
191
2,300
498
825
31 ,444
226,252,477
Pop. Served by
Small Systems
GW
3,092
67,068
35,209
39,692
85,318
12,175
1,309
6,800
117,516
28,636
15,462
19,916
35,100
106,661
104,078
27,481
7,622
75,303
50,393
12,301
2,955
57,873
58,334
38,276
2,631
78,999
10,314
47,141
7,416
23,535
10,620
60,020
6,625
5,393
45,407
104,131
23,784
12,378
42,012
24,631
4,740
14,485
9,780
2,533
228,336
16,417
13,849
2,149
38,029
88,774
1,100
191
2,300
325
3,200
1,939,815
SW
362
7,389
18,986
1,606
74,071
25,252
18,525
33,086
5,504
6,789
3,197
10,490
8,912
11,145
32,797
13,120
12,900
6,200
5,155
20,824
13,471
3,509
5,202
51 ,698
203
5,630
16,300
570
463
48,624
18,988
43,255
19,515
50,653
12,020
35,619
376
70,682
22,737
16,285
9,079
400
9,020
3,807
34,761
580
498
500
10,000
820,755
Pop. Served by
Large Systems
GW
58,600
703,125
334,297
1,561,412
7,011,747
294,405
121,731
53,330
12,383,938
715,555
12,500
1,010,064
515,056
342,565
1 ,536,074
1,195,492
299,868
179,924
807,125
1 ,392,955
522,337
27,040
624,720
1 ,695,267
767,067
62,696
872,095
85,782
663,985
67,034
410,925
76,400
2,086,167
948,281
17,000
3,493,019
1 ,683,901
166,635
390,600
442,445
445,558
94,000
213,706
72,760
1,078,175
2,851,292
351,194
40,715
1,516,949
1,022,486
60,546
24,999
53,405,539
SW
177,937
3,189,226
1,007,743
2,644,222
25,966,652
3,753,620
2,248,535
927,055
476,130
2,822,332
5,972,968
87,215
85,200
1,144,959
200,052
5,992,722
2,231,239
1 ,400,831
3,278,754
1,790,277
5,000,126
4,135,798
313,135
4,789,514
1,252,181
2,800,289
322,468
249,017
4,330,912
245,617
531 ,309
401,751
5,960,175
157,093
1,602,935
16,369,301
6,734,969
1 ,987,550
2,093,369
8,473,018
4,299,901
725,312
2,405,458
270,631
3,118,483
13,629,800
1,627,139
5,074,298
64,000
209,270
2,931,466
1 ,658,636
686,518
219,016
18,244
170,086,368
The UCMR data are not representative at the state-level.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
G-22
-------
Appendix G. Stage 1 Occurrence Measures for CCL 2 Contaminants Monitored Under UCMR 1
Table G7.a. Fonofos - Sample-, System-, and Population Served-Level Occurrence (UCMR 1 March 2006 Data)
Water Type
System Size by
Population Served
Sample Level
Total Number
of Samples
Detections
Number
Percent
System Level
Total Number
of Systems
Sampled
Systems with Detections
Number
Percent
Population Served-Level
Total
Population
Served
Pop. Served by
Systems with Detections
Number
Percent
Small Systems (Statistical Sample)
Ground
Water
Surface
Water
25 - 500
501 - 3,300
3,301 - 10,000
Total
25 - 500
501 - 3,300
3,301 - 10,000
Total
All Small Systems
95
151
134
380
65
64
134
263
643
0
0
0
0.00%
0.00%
0.00%
43
43
28
114
17
17
30
64
178
0
0
0
0.00%
0.00%
0.00%
10,296
79,739
185,150
275,185
4,744
29,902
198,305
232,951
508,136
0
0
0
0.00%
0.00%
0.00%
Large Systems (Statistical Sample)
Ground
Water
Surface
Water
10,001 -50,000
> 50,000
Total
10,001 -50,000
> 50,000
Total
All Large Systems
272
611
883
199
581
780
1,663
0
0
0
0.00%
0.00%
0.00%
28
22
50
34
33
67
117
0
0
0
0.00%
0.00%
0.00%
792,573
7,207,549
8,000,122
1,291,958
30,967,264
32,259,222
40,259,344
0
0
0
0.00%
0.00%
0.00%
All Systems
Total Water Systems
2,306
0
0.00%
295
0
0.00%
40,767,480
0
0.00%
G-23
-------
Appendix G. Stage 1 Occurrence Measures for CCL 2 Contaminants Monitored Under UCMR 1
Table G7.b. Fonofos - Number of PWSs by State (UCMR 1 March 2006 Data)
State 1 2
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
Total
Total Number of
Samples
2
12
21
35
765
32
21
98
24
2
46
2
2
18
9
33
53
29
6
30
33
34
7
28
16
52
4
18
10
51
78
4
122
20
10
12
76
45
11
13
6
51
217
4
8
12
46
66
8
4
2,306
Total Number of
PWSs
1
3
5
2
39
6
2
15
8
1
7
1
1
5
3
7
9
5
2
8
6
4
2
7
3
9
1
2
2
10
8
1
12
7
3
3
17
6
2
4
2
9
19
1
3
4
6
9
2
1
295
No. of Small Systems
GW
1
2
5
1
6
6
1
4
1
1
3
2
6
2
1
6
3
1
1
6
1
3
1
1
5
3
1
2
3
1
8
1
1
1
1
8
2
2
3
7
114
SW
1
1
2
1
8
3
1
2
1
1
2
1
1
1
1
1
1
4
1
2
1
1
1
2
4
2
2
5
4
1
1
1
2
1
64
No. of Large Systems
GW
1
13
9
2
1
1
1
2
1
1
3
3
4
2
1
1
2
1
1
50
SW
1
1
13
2
1
1
4
1
3
1
1
2
1
2
1
2
5
1
1
1
4
3
2
1
1
2
5
2
1
1
67
The UCMR data are not representative at the state-level.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
G-24
-------
Appendix G. Stage 1 Occurrence Measures for CCL 2 Contaminants Monitored Under UCMR 1
Table G7.c. Fonofos - Total Population-Served by State (UCMR 1 March 2006 Data)
State 1 2
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
Total
Total Number of
PWSs
1
3
5
2
39
6
2
15
8
1
7
1
1
5
3
7
9
5
2
8
6
4
2
7
3
9
1
2
2
10
8
1
12
7
3
3
17
6
2
4
2
9
19
1
3
4
6
9
2
1
295
Total Population
Served
188
50,304
231,182
22,606
9,456,619
1,415,583
48,908
3,085,161
12,586
5,008
118,082
450
970
298,249
12,552
416,408
300,226
176,784
265
62,019
581,274
1,591,818
6,140
48,956
34,328
255,993
203
510,453
28,200
491,189
498,770
1,383
7,327,997
1,752,015
17,740
32,860
185,358
1,691,960
459,312
52,976
28,958
783,081
6,382,552
9,800
5,258
62,749
1,254,766
953,848
2,895
498
40,767,480
Pop. Served by
Small Systems
GW
6,150
8,639
12,314
5,758
13,345
5,180
5,008
8,533
450
970
15,938
3,303
23,544
10,400
185
12,908
13,150
2,118
2,631
8,988
445
3,104
4,033
200
1 1 ,200
3,200
1,383
740
10,086
110
10,957
7,616
2,886
4,300
1,526
15,786
1,258
1,149
10,289
25,405
275,185
SW
188
2,154
6,656
1,606
23,867
10,495
8,500
7,406
2,580
9,249
8,089
4,500
80
9,006
5,200
3,509
4,802
18,365
203
570
8,888
7,000
1,780
6,200
10,601
7,376
9,350
28,669
7,556
9,800
4,000
1,313
2,895
498
232,951
Pop. Served by
Large Systems
GW
21,000
1 ,053,905
3,071,816
106,969
39,000
22,428
62,210
119,440
39,968
28,000
93,489
495,000
644,310
82,783
16,000
654,267
1,374,537
22,000
53,000
8,000,122
SW
42,000
215,887
8,366,533
1 ,399,330
40,408
243,311
385,891
209,972
166,384
40,105
448,684
1 ,584,500
29,081
234,524
506,420
386,500
6,674,059
1,652,146
15,850
26,660
147,800
1 ,676,968
459,312
40,740
24,658
98,619
4,984,673
61 ,600
1,221,164
875,443
32,259,222
The UCMR data are not representative at the state-level.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
G-25
-------
Appendix G. Stage 1 Occurrence Measures for CCL 2 Contaminants Monitored Under UCMR 1
Table G8.a. MTBE - Occurrence Based on Samples, Systems, and Population Served (UCMR 1 March 2006 Data)
Water
Type
System Size by
Population
Served
Sample Level
Total # of
Samples
Detections
#
%
System Level
Total # of
Systems
Detections
Systems with
One or More
#
%
Systems with
Two or More
#
%
Population-Served Level
Total Pop.
Served by
Systems
Detections
Pop. Served by
Systems with
One or More
#
%
Pop. Served by
Systems with
Two or More
#
%
Small Systems (Statistical Sample)
GW
SW
25 - 500
501 - 3,300
3,301 -10,000
Total
25 - 500
501 - 3,300
3,301 -10,000
Total
All Small Systems
259
871
1,211
2,341
224
183
520
927
3,268
3
3
0
3
0.34%
0.13%
0.00%
0.09%
111
244
234
589
52
45
110
207
796
3
3
0
3
1 .2%
0.51%
0.00%
0.38%
0
0
0
0.00%
0.00%
0.00%
27,599
439,01 1
1,470,717
1,937,327
16,662
91,723
712,370
820,755
2,758,082
4,150
4,150
0
4,150
0.95%
0.21 %
0.00%
0.15%
0
0
0
0.00%
0.00%
0.00%
Large Systems (Census)
GW
SW
10,001 -50,000
> 50,000
Total
10,001 -50,000
> 50,000
Total
All Large Systems
10,408
5,516
15,924
7,419
7,157
14,576
30,500
14
3
17
3
3
6
23
0.13%
0.05%
0.11%
0.04%
0.04%
0.04%
0.08%
1,192
189
1,381
1,185
509
1,694
3,075
9
3
12
2
2
4
16
0.76%
1 .59%
0.87%
0.17%
0.39%
0.24%
0.52%
5
5
1
1
2
7
0.42%
0.00%
0.36%
0.08%
0.20%
0.12%
0.23%
26,91 1 ,853
26,361 ,273
53,273,126
33,277,623
136,681,205
169,958,828
223,231 ,954
179,894
241 ,292
421,186
55,388
272,909
328,297
749,483
0.67%
0.92%
0.79%
0.17%
0.20%
0.19%
0.34%
104,596
104,596
22,388
69,199
91,587
196,183
0.39%
0.20%
0.07%
0.05%
0.05%
0.09%
All (Small & Large) Systems
Total Water Systems1
33,768
26
0.08%
3,871
19
0.49%
7
0.18%
225,990,036
753,633
0.33%
196,183
0.09%
1 The UCMR small water systems (population served < 10,000) are a statistical, representative sample of all national small systems while the UCMR large water systems (population served
> 10,000) represent a census of all large systems. Combined small and large system occurrence summaries accurately present the actual UCMR monitoring results. However, only the
summary findings expressed as percentages accurately reflect national occurrence; combined large and small summaries based on numerical counts of detections at the sample, system,
and population-served levels do not accurately represent national occurrence.
G-26
-------
Appendix G. Stage 1 Occurrence Measures for CCL 2 Contaminants Monitored Under UCMR 1
Table G8.b. MTBE - Statistics for All Detections (UCMR 1 March 2006 Data)
Water Type
System Size by
Population
Served
Total # of
Detections
Statistics for All Recorded Values Above the Detection Limit (in ug/L)
Minimum | Mean | Median | 99th Percentile | Maximum
Small Systems (Statistical Sample)
GW
SW
25 - 500 1
501 - 3,300
3,301 - 10,000
Total
25 - 500
501 - 3,300
3,301 - 10,000
Total
All Small Systems
0
3
0
3
0
0
0
0
3
6.00
6.00
6.00
22.57
22.57
22.57
12.70
12.70
12.70
49.00
49.00
49.00
49.00
49.00
49.00
Large Systems (Census)
GW
SW
10,001 -50,000
> 50,000
Total
10,001 -50,000
> 50,000
Total
All Large Systems
14
3
17
3
3
6
23
5.00
5.40
5.00
8.80
8.00
8.00
5.00
14.25
15.83
14.53
18.27
8.87
13.57
14.28
8.20
6.10
7.00
13.00
9.00
9.30
9.00
48.00
36.00
48.00
33.00
9.60
33.00
48.00
48.00
36.00
48.00
33.00
9.60
33.00
48.00
All (Small & Large) Systems
Total Water Systems2
26
5.00
15.24
9.20
49.00
49.00
1 The UCMR small water systems (population served < 10,000) are a statistical, representative sample of all national small systems while the UCMR large water systems
(population served > 10,000) represent a census of all large systems. Combined small and large system occurrence summaries accurately present the actual UCMR
monitoring results. However, combined large and small summary statistics do not accurately represent national occurrence.
G-27
-------
Appendix G. Stage 1 Occurrence Measures for CCL 2 Contaminants Monitored Under UCMR 1
Table G8.c. MTBE - System Level Occurrence by State & Size Category (UCMR 1 March 2006 data)1
State 2 3
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
Total
Total #
Samples
53
809
229
1,286
8,566
397
370
8
102
1,164
564
267
392
213
247
745
410
248
344
488
1,124
172
91
362
431
452
19
525
136
1,046
41
231
134
1,010
353
73
2,369
544
320
355
1,256
720
104
289
101
546
1,724
475
296
26
40
679
553
168
70
2
2
4
6
17
33,768
Total # PWSs
Total
9
98
47
59
407
56
41
1
8
238
99
5
17
47
21
133
86
41
77
84
132
36
19
71
85
68
2
72
13
115
13
20
21
123
32
11
160
153
52
55
165
85
13
59
17
105
264
52
58
4
10
82
76
35
11
1
1
1
2
3
3,871
Small
4
15
13
12
48
10
6
0
2
31
21
1
3
16
8
28
20
12
9
27
12
8
6
24
16
20
2
30
6
22
4
8
6
16
8
4
29
28
15
11
37
9
2
11
4
14
71
7
16
2
4
17
21
10
3
1
1
1
2
2
796
Large
5
83
34
47
359
46
35
1
6
207
78
4
14
31
13
105
66
29
68
57
120
28
13
47
69
48
0
42
7
93
9
12
15
107
24
7
131
125
37
44
128
76
11
48
13
91
193
45
42
2
6
65
55
25
8
0
0
0
0
1
3,075
# PWSs with Detections
Total
2
1
2
1
1
1
2
2
1
2
1
1
1
1
19
Small
0
0
1
0
1
1
0
0
0
0
0
0
0
0
3
Large
2
1
1
1
0
0
2
2
1
2
1
1
1
1
16
% PWSs with Detections
Total
0.49%
2.44%
2.02%
0.75%
0.76%
1 .47%
9.52%
1 .63%
3.13%
1 .25%
0.61%
5.88%
0.95%
2.86%
0.49%
Small
0.00%
0.00%
4.76%
0.00%
8.33%
5.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.38%
Large
0.56%
2.86%
1 .28%
0.95%
0.00%
0.00%
13.33%
1 .87%
4.17%
1 .53%
0.78%
7.69%
1.10%
4.00%
0.52%
1 There is no HRL for this contaminant. Thus, no occurrence analyses relative to the HRL are presented in this table.
2 The UCMR data are not representative at the state-level.
3 States are arranged alphabetically based on their 2-digit State abbreviation.
G-28
-------
Appendix G. Stage 1 Occurrence Measures for CCL 2 Contaminants Monitored Under UCMR 1
Table G8.d. MTBE - System Level Occurrence by State & Source Water Type (UCMR 1 March 2006 data)1
State 2 3
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
Total
Total # PWSs
Total
9
98
47
59
407
56
41
1
8
238
99
5
17
47
21
133
86
41
77
84
132
36
19
71
85
68
2
72
13
115
13
20
21
123
32
11
160
153
52
55
165
85
13
59
17
105
264
52
58
4
10
82
76
35
11
1
1
1
2
3
3,871
GW
4
42
23
45
178
15
11
0
4
220
36
1
15
27
17
84
64
23
8
57
68
18
6
38
75
43
1
70
6
38
6
18
8
84
25
4
71
85
15
20
43
24
6
15
8
19
126
17
14
0
3
55
58
3
2
1
1
0
1
1
1,970
SW
5
56
24
14
229
41
30
1
4
18
63
4
2
20
4
49
22
18
69
27
64
18
13
33
10
25
1
2
7
77
7
2
13
39
7
7
89
68
37
35
122
61
7
44
9
86
138
35
44
4
7
27
18
32
9
0
0
1
1
2
1,901
# PWSs with Detections
Total
2
1
2
1
1
1
2
2
1
2
1
1
1
1
19
GW
1
1
1
1
1
1
1
2
1
2
0
1
1
1
15
SW
1
0
1
0
0
0
1
0
0
0
1
0
0
0
4
% PWSs with Detections
Total
0.49%
2.44%
2.02%
0.75%
0.76%
1 .47%
9.52%
1 .63%
3.13%
1 .25%
0.61%
5.88%
0.95%
2.86%
0.49%
GW
0.56%
9.09%
2.78%
1.19%
1 .47%
2.33%
1 2.50%
2.38%
4.00%
2.82%
0.00%
12.50%
5.26%
33.33%
0.76%
SW
0.44%
0.00%
1 .59%
0.00%
0.00%
0.00%
7.69%
0.00%
0.00%
0.00%
0.82%
0.00%
0.00%
0.00%
0.21%
1 There is no HRL for this contaminant. Thus, no occurrence analyses relative to the HRL are presented in this table.
2 The UCMR data are not representative at the state-level.
3 States are arranged alphabetically based on their 2-digit State abbreviation.
G-29
-------
Appendix G. Stage 1 Occurrence Measures for CCL 2 Contaminants Monitored Under UCMR 1
Table G8.e. MTBE - Statistics for All Detections by State (UCMR 1 March 2006 Data)
State 1 2
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
Total
Total #
Detections
3
2
3
1
1
1
2
3
1
3
2
2
1
1
26
Statistics for Detections (in ug/L)
Minimum
6.00
5.00
8.80
7.00
6.00
49.00
9.40
5.50
16.00
5.40
8.00
5.85
6.10
33.20
5.00
Median
9.60
5.90
12.70
7.00
6.00
49.00
21.20
14.50
16.00
6.10
8.50
11.33
6.10
33.20
9.20
99th
Percentile
19.40
6.80
13.00
7.00
6.00
49.00
33.00
36.00
16.00
48.00
9.00
16.80
6.10
33.20
49.00
Maximum
19.40
6.80
13.00
7.00
6.00
49.00
33.00
36.00
16.00
48.00
9.00
16.80
6.10
33.20
49.00
The UCMR data are not representative at the state-level.
' States are arranged alphabetically based on their 2-digit State abbreviation.
G-30
-------
Appendix G. Stage 1 Occurrence Measures for CCL 2 Contaminants Monitored Under UCMR 1
Table G8.f. MTBE - Population Served Level Occurrence by State & Size Category (UCMR 1 March 2006 data)1
State23
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
Total
Total #
PWSs
9
98
47
59
407
56
41
1
8
238
99
5
17
47
21
133
86
41
77
84
132
36
19
71
85
68
2
72
13
115
13
20
21
123
32
11
160
153
52
55
165
85
13
59
17
105
264
52
58
4
10
82
76
35
11
1
1
1
2
3
3,871
Total Population Served by PWSs
Total
239,991
3,966,808
1 ,396,235
4,246,932
33,137,788
4,085,452
2,390,100
927,055
536,260
15,323,786
6,732,757
105,219
1,110,726
1 ,686,720
580,914
7,645,947
3,539,721
1 ,739,325
3,499,097
2,818,393
6,456,374
4,676,636
348,285
5,492,931
3,005,782
3,619,103
6,140
1 ,273,562
350,315
5,093,736
320,270
965,769
494,401
7,839,337
1,112,569
1 ,625,791
19,956,351
8,541,989
2,221,224
2,515,862
9,008,128
4,782,110
824,052
2,669,268
353,547
4,269,873
16,700,665
2,011,035
5,137,941
64,400
220,439
4,490,251
2,769,896
781,825
245,695
191
2,300
498
825
31 ,444
225,990,036
Small
3,454
74,457
54,195
41,298
159,389
37,427
19,834
0
6,800
117,516
59,234
5,504
15,462
26,705
38,297
117,151
112,990
38,626
40,419
88,423
63,293
18,501
8,110
78,697
58,334
51,747
6,140
78,999
15,516
98,839
7,619
23,535
16,250
76,320
7,195
5,856
94,031
123,119
67,039
31,893
92,665
36,651
4,740
50,104
10,156
73,215
251 ,073
32,702
22,928
400
11,169
41,836
88,774
34,761
1,680
191
2,300
498
825
13,200
2,758,082
Large
236,537
3,892,351
1 ,342,040
4,205,634
32,978,399
4,048,025
2,370,266
927,055
529,460
15,206,270
6,673,523
99,715
1 ,095,264
1,660,015
542,617
7,528,796
3,426,731
1 ,700,699
3,458,678
2,729,970
6,393,081
4,658,135
340,175
5,414,234
2,947,448
3,567,356
1,194,563
334,799
4,994,897
312,651
942,234
478,151
7,763,017
1,105,374
1,619,935
19,862,320
8,418,870
2,154,185
2,483,969
8,915,463
4,745,459
819,312
2,619,164
343,391
4,196,658
16,449,592
1 ,978,333
5,115,013
64,000
209,270
4,448,415
2,681,122
747,064
244,015
18,244
223,231,954
Population Served by PWSs
with Detections
Total
218,710
15,245
23,138
17,700
2,100
1,300
50,000
99,091
28,750
123,760
69,199
13,876
78,916
1 1 ,848
753,633
Small
0
0
750
0
2,100
1,300
0
0
0
0
0
0
0
0
4,150
Large
218,710
15,245
22,388
17,700
0
0
50,000
99,091
28,750
123,760
69,199
13,876
78,916
1 1 ,848
749,483
% Population Served by
PWSs with Detections
Total
0.66%
0.64%
0.34%
0.23%
0.03%
0.04%
10.11%
1 .26%
2.58%
0.62%
0.77%
3.92%
1 .85%
1 .52%
0.33%
Small
0.00%
0.00%
1 .27%
0.00%
3.32%
2.51%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.15%
Large
0.66%
0.64%
0.34%
0.24%
0.00%
0.00%
10.46%
1 .28%
2.60%
0.62%
0.78%
4.04%
1 .88%
1 .59%
0.34%
There is no HRL for this contaminant. Thus, no occurrence analyses relative to the HRL are presented in this table.
2 The UCMR data are not representative at the state-level.
3 States are arranged alphabetically based on their 2-digit State abbreviation.
G-31
-------
Appendix G. Stage 1 Occurrence Measures for CCL 2 Contaminants Monitored Under UCMR 1
Table G8.g. MTBE - Population Served Level Occurrence by State & Source Water Type (UCMR 1 March 2006 data)
State 1 2
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
Total
Total Population Served by PWSs
Total
239,991
3,966,808
1 ,396,235
4,246,932
33,137,788
4,085,452
2,390,100
927,055
536,260
15,323,786
6,732,757
105,219
1,110,726
1 ,686,720
580,914
7,645,947
3,539,721
1 ,739,325
3,499,097
2,818,393
6,456,374
4,676,636
348,285
5,492,931
3,005,782
3,619,103
6,140
1 ,273,562
350,315
5,093,736
320,270
965,769
494,401
7,839,337
1,112,569
1 ,625,791
19,956,351
8,541 ,989
2,221 ,224
2,515,862
9,008,128
4,782,110
824,052
2,669,268
353,547
4,269,873
16,700,665
2,011,035
5,137,941
64,400
220,439
4,490,251
2,769,896
781 ,825
245,695
191
2,300
498
825
31 ,444
225,990,036
GW
61 ,692
770,193
369,506
1,601,104
7,097,065
306,580
123,040
0
60,130
12,501,454
726,703
12,500
1 ,025,526
534,972
377,665
1 ,642,735
1 ,299,570
327,349
187,546
1,014,996
1 ,443,348
534,638
29,995
682,593
1 ,753,601
805,343
2,631
951 ,094
96,096
711,126
74,450
434,460
87,020
1 ,970,402
954,906
22,393
3,538,426
1 ,788,032
190,419
402,978
484,457
470,189
98,740
228,191
82,540
1 ,080,708
3,068,128
367,61 1
54,564
0
2,149
1 ,554,978
1,111,260
60,546
26,099
191
2,300
0
325
3,200
55,210,453
SW
1 78,299
3,196,615
1 ,026,729
2,645,828
26,040,723
3,778,872
2,267,060
927,055
476,130
2,822,332
6,006,054
92,719
85,200
1,151,748
203,249
6,003,212
2,240,151
1 ,41 1 ,976
3,311,551
1 ,803,397
5,013,026
4,141,998
318,290
4,810,338
1,252,181
2,813,760
3,509
322,468
254,219
4,382,610
245,820
531 ,309
407,381
5,868,935
1 57,663
1 ,603,398
16,417,925
6,753,957
2,030,805
2,112,884
8,523,671
4,311,921
725,312
2,441 ,077
271 ,007
3,189,165
13,632,537
1 ,643,424
5,083,377
64,400
218,290
2,935,273
1 ,658,636
721 ,279
219,596
0
0
498
500
28,244
170,779,583
Population Served by PWSs
with Detections
Total
218,710
15,245
23,138
17,700
2,100
1,300
50,000
99,091
28,750
123,760
69,199
13,876
78,916
1 1 ,848
753,633
GW
1 5,000
15,245
750
1 7,700
2,100
1,300
17,000
99,091
28,750
123,760
0
1 3,876
78,916
1 1 ,848
425,336
SW
203,710
0
22,388
0
0
0
33,000
0
0
0
69,199
0
0
0
328,297
% Pop. Served by PWSs with
Detections
Total
0.66%
0.64%
0.34%
0.23%
0.03%
0.04%
10.11%
1 .27%
2.61 %
0.62%
0.77%
3.92%
1 .85%
1 .52%
0.33%
GW
0.21 %
12.39%
0.10%
1 .08%
0.15%
0.16%
19.54%
5.08%
3.05%
3.50%
0.00%
16.81%
7.30%
19.57%
0.77%
SW
0.78%
0.00%
0.37%
0.00%
0.00%
0.00%
8.10%
0.00%
0.00%
0.00%
0.81 %
0.00%
0.00%
0.00%
0.19%
1 The UCMR data are not representative at the state-level.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
G-32
-------
Appendix G. Stage 1 Occurrence Measures for CCL 2 Contaminants Monitored Under UCMR 1
Table G9.a. Terbacil - Occurrence Based on Samples, Systems, and Population Served (UCMR 1 March 2006 Data)
Water Type
System Size by
Population Served
Sample Level
Total Number
of Samples
Detections
Number
Percent
System Level
Total Number
of Systems
Sampled
Systems with Detections
Number
Percent
Population Served-Level
Total
Population
Served
Pop. Served by
Systems with Detections
Number
Percent
Small Systems (Statistical Sample)
Ground
Water
Surface
Water
25 - 500
501 - 3,300
3,301 - 10,000
Total
25 - 500
501 - 3,300
3,301 - 10,000
Total
All Small Systems
259
879
1,204
2,342
220
181
508
909
3,251
0
0
0
0.00%
0.00%
0.00%
111
245
234
590
52
45
110
207
797
0
0
0
0.00%
0.00%
0.00%
27,599
441 ,499
1,470,717
1,939,815
16,662
91,723
712,370
820,755
2,760,570
0
0
0
0.00%
0.00%
0.00%
Large Systems (Census)
Ground
Water
Surface
Water
10,001 -50,000
> 50,000
Total
10,001 -50,000
> 50,000
Total
All Large Systems
10,516
5,418
15,934
7,430
7,185
14,615
30,549
0
0
0
0.00%
0.00%
0.00%
1,190
190
1,380
1,187
509
1,696
3,076
0
0
0
0.00%
0.00%
0.00%
26,929,381
26,476,158
53,405,539
33,405,163
136,681,205
170,086,368
223,491,907
0
0
0
0.00%
0.00%
0.00%
All Systems
Total Water Systems1
33,800
0
0.00%
3,873
0
0.00%
226,252,477
0
0.00%
1 The UCMR small water systems (population served < 10,000) are a statistical, representative sample of all national small systems while the UCMR large water systems (population
served > 10,000) represent a census of all large systems. Combined small and large system occurrence summaries accurately present the actual UCMR monitoring results. However,
only the summary findings expressed as percentages accurately reflect national occurrence; combined large and small summaries based on numerical counts of detections at the sample,
system, and population-served levels do not accurately represent national occurrence.
G-33
-------
Appendix G. Stage 1 Occurrence Measures for CCL 2 Contaminants Monitored Under UCMR 1
Table G9.b. Terbacil - Number of PWSs by State (UCMR 1 March 2006 Data)
State12
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
Total
Total Number of
Samples
53
809
239
1,315
8,565
396
370
8
102
1,168
568
275
394
213
248
749
400
247
344
324
1,135
175
87
371
434
457
137
527
126
1,042
41
230
135
1,051
362
71
2,325
548
317
350
1,260
717
109
292
103
542
1,750
466
298
28
40
684
552
152
69
2
2
4
6
16
33,800
Total Number of
PWSs
9
98
47
59
407
56
41
1
8
238
101
5
17
47
21
133
86
41
77
76
132
36
19
71
85
68
3
72
13
115
13
20
21
128
32
11
160
153
52
55
165
85
13
59
17
105
266
52
58
4
10
82
76
35
11
1
1
1
2
3
3,873
No. of Small Systems
GW
2
12
9
11
26
3
3
2
31
14
3
12
6
26
19
10
2
23
10
7
4
21
16
17
1
30
4
12
3
8
4
14
6
3
21
24
7
6
21
4
2
5
3
2
61
4
13
3
14
21
1
1
1
1
1
590
SW
2
3
4
1
22
7
3
8
1
4
2
2
1
2
7
4
2
1
2
3
3
1
2
10
1
2
2
2
1
8
4
8
5
16
5
6
1
12
10
3
3
2
1
3
10
2
1
1
1
207
No. of Large Systems
GW
2
30
14
34
152
12
8
2
189
24
1
12
15
11
58
45
13
6
26
58
11
2
17
59
26
1
40
2
26
3
10
4
74
19
1
50
61
8
14
22
20
4
10
5
17
66
13
1
41
37
3
1
1,380
SW
3
53
20
13
207
34
27
1
4
18
55
3
2
16
2
47
21
16
62
23
62
17
11
30
10
22
2
5
67
6
2
11
38
5
6
81
64
29
30
106
56
7
38
8
74
129
32
41
2
6
24
18
22
7
1
1,696
The UCMR data are not representative at the state-level.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
G-34
-------
Appendix G. Stage 1 Occurrence Measures for CCL 2 Contaminants Monitored Under UCMR 1
Table G9.c. Terbacil - Total Population-Served by State (UCMR 1 March 2006 Data)
State12
Alaska
Alabama
Arkansas
Arizona
California
Colorado
Connecticut
D.C.
Delaware
Florida
Georgia
Guam
Hawaii
Iowa
Idaho
Illinois
Indiana
Kansas
Kentucky
Louisiana
Massachusetts
Maryland
Maine
Michigan
Minnesota
Missouri
N. Mariana Is.
Mississippi
Montana
North Carolina
North Dakota
Nebraska
New Hampshire
New Jersey
New Mexico
Nevada
New York
Ohio
Oklahoma
Oregon
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Virginia
Virgin Islands
Vermont
Washington
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
Total
Total Number of
PWSs
9
98
47
59
407
56
41
1
8
238
101
5
17
47
21
133
86
41
77
76
132
36
19
71
85
68
3
72
13
115
13
20
21
128
32
11
160
153
52
55
165
85
13
59
17
105
266
52
58
4
10
82
76
35
11
1
1
1
2
3
3,873
Total Population
Served
239,991
3,966,808
1,396,235
4,246,932
33,137,788
4,085,452
2,390,100
927,055
536,260
15,323,786
6,750,245
105,219
1,110,726
1,686,720
580,914
7,645,947
3,539,721
1,739,325
3,499,097
2,685,825
6,456,374
4,676,636
348,285
5,492,931
3,005,782
3,619,103
68,836
1,273,562
350,315
5,093,736
320,270
965,769
494,401
8,122,662
1,112,569
1,625,791
19,956,351
8,541 ,989
2,221,224
2,515,862
9,008,128
4,782,110
824,052
2,669,268
353,547
4,269,873
16,732,165
2,011,035
5,137,941
64,400
220,439
4,490,251
2,769,896
781 ,825
245,695
191
2,300
498
825
31,444
226,252,477
Pop. Served by
Small Systems
GW
3,092
67,068
35,209
39,692
85,318
12,175
1,309
6,800
117,516
28,636
15,462
19,916
35,100
106,661
104,078
27,481
7,622
75,303
50,393
12,301
2,955
57,873
58,334
38,276
2,631
78,999
10,314
47,141
7,416
23,535
10,620
60,020
6,625
5,393
45,407
104,131
23,784
12,378
42,012
24,631
4,740
14,485
9,780
2,533
228,336
16,417
13,849
2,149
38,029
88,774
1,100
191
2,300
325
3,200
1,939,815
SW
362
7,389
18,986
1,606
74,071
25,252
18,525
33,086
5,504
6,789
3,197
10,490
8,912
11,145
32,797
13,120
12,900
6,200
5,155
20,824
13,471
3,509
5,202
51,698
203
5,630
16,300
570
463
48,624
18,988
43,255
19,515
50,653
12,020
35,619
376
70,682
22,737
16,285
9,079
400
9,020
3,807
34,761
580
498
500
10,000
820,755
Pop. Served by
Large Systems
GW
58,600
703,125
334,297
1,561,412
7,011,747
294,405
121,731
53,330
12,383,938
715,555
12,500
1,010,064
515,056
342,565
1,536,074
1,195,492
299,868
179,924
807,125
1,392,955
522,337
27,040
624,720
1,695,267
767,067
62,696
872,095
85,782
663,985
67,034
410,925
76,400
2,086,167
948,281
17,000
3,493,019
1,683,901
166,635
390,600
442,445
445,558
94,000
213,706
72,760
1,078,175
2,851 ,292
351,194
40,715
1,516,949
1,022,486
60,546
24,999
53,405,539
SW
177,937
3,189,226
1,007,743
2,644,222
25,966,652
3,753,620
2,248,535
927,055
476,130
2,822,332
5,972,968
87,215
85,200
1,144,959
200,052
5,992,722
2,231,239
1 ,400,831
3,278,754
1,790,277
5,000,126
4,135,798
313,135
4,789,514
1,252,181
2,800,289
322,468
249,017
4,330,912
245,617
531 ,309
401,751
5,960,175
157,093
1 ,602,935
16,369,301
6,734,969
1 ,987,550
2,093,369
8,473,018
4,299,901
725,312
2,405,458
270,631
3,118,483
13,629,800
1,627,139
5,074,298
64,000
209,270
2,931,466
1 ,658,636
686,518
219,016
18,244
170,086,368
The UCMR data are not representative at the state-level.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
G-35
-------
-------
Appendix H. Sample-Point Level Occurrence Measures
Table HI .a DCPA Degradates - Sample Point Level Analysis - Summary of all threshold
evaluations (UCMR 1 March 2006 data)
Table HI .b DCPA Degradates - Sample Point Level Analysis - Detections greater than HRL
of70|ig/L
Table HI .c DCPA Degradates - Sample Point Level Analysis - Detections greater than 1A
HRL of 35 |ig/L
Table HI .d DCPA Degradates - Sample Point Level Analysis - Detections (> MRL of 1 |ig/L)
Table H2.a MTBE - Sample Point Level Analysis - Summary of all threshold evaluations
(UCMR 1 March 2006 data)
Table H2.b MTBE - Sample Point Level Analysis - detections (> MRL of 5 |ig/L)
-------
-------
Appendix H. Sample-Point-Level Occurrence Measures
Table H1.a. DCPA Degradates - Sample-Point-Level Analysis - Summary of all threshold evaluations (UCMR 1 March 2006 data)
The UCMR small water systems (population served < 10,000) are a statistical, representative sample of all national small systems while the UCMR large water
systems (population served > 10,000) represent a census of all large systems. The numbers presented below are the sum of the small system national extrapolation
estimates and the actual large system census results.
Threshold
HRL
(70 ug/L)
1/2 HRL
(35 ug/L)
MRL
(1 ug/L)
Standard Stage 1 Analysis1
Number
Sys
373
374
849
Pop
113,000
851 ,337
12,387,436
Percentage
Sys
0.03%
0.05%
4.57%
Pop
0.0002%
0.33%
5.05%
At least 2 Detects at 1 SP2
Number
Sys
373
373
660
Pop
113,000
113,000
8,738,401
Percentage
Sys
0.03%
0.03%
2.92%
Pop
0.0002%
0.0002%
3.58%
At least 1 Detect at 2 SPs3
Number
Sys
0
0
174
Pop
0
0
7,698,891
Percentage
Sys
0%
0%
2.22%
Pop
0%
0%
3.28%
Populations Proportional to
% SP detects4
Number
SPs
439
446
1,314
Pop
113,000
400,131
3,646,916
Percentage
SPs
0.01%
0.05%
3.00%
Pop
0.0002%
0.13%
1 .37%
1 Occurrence findings based on systems and population-served by systems, with at least one analytical detection of DCPA mono/di-acid degradates> MRL, > 1/2 HRL, or > HRL. For aggregate population-
served values, for each system that had a detect the full population-served value of that system was added to the aggregate (in contrast to proportional populations in 4 below).
2 Occurrence findings based on systems, and population-served by systems, with at least two detections t MRL) or two detections above a threshold (>1/2 HRL or HRL) at a single sample point (SP). For
aggregate population-served values, for each system that had a detect the full population-served value of that system was added to the aggregate (in contrast to proportional populations in 4 below).
Occurrence findings based on systems, and population-served by systems, with at least one detection t MRL) or one detection above a threshold (> 1/2 HRL or HRL) at each of two or more SPs in the
system. For aggregate population-served values, for each system that had a detect the full population-served value of that system was added to the aggregate (in contrast to proportional populations in 4
below).
4 The extrapolated number of small system sample points with a contaminant detection was estimated by multiplying the percentage of UCMR 1 small system sample points with a contaminant detection by the
total number of sample points nationally. The national number of small system sample points was estimated by multiplying the average number of sample points for a system water type category by the total
number of systems nationally in that category. The large system sample point numbers presented in this table are direct counts of the UCMR 1 large system data (no extrapolations are necessary). Population-
served values for each system were adjusted based on the distribution of detections among SPs of a system. For each system, the gross population-served was multiplied by the proportion of total SPs with
detects. These adjusted sums were then aggregated to create the summary statistics presented above. One simplifying assumption is that a system's entire population-served is uniformly distributed across all
the system's SPs.
H-1
-------
Appendix H. Sample-Point-Level Occurrence Measures
Table H1.b. DCPA Degradates - Sample-Point-Level Analysis -
Detections greater than HRL of 70 |jg/L
Water Type
System Size by
Population Served
Total Number
UCMR
Systems | Population
National Inventory
Systems | Population
Small Systems (Statstical sample)
Ground Water
Surface Water
<500
501 - 3,300
3,301 -10,000
Total
<500
501 - 3,300
3,301 -10,000
Total
All Small Systems
111
245
234
590
52
45
110
207
797
27,599
441,499
1,470,717
1,939,815
16,662
91,723
712,370
820,755
2,760,570
41,415
12,128
2,529
56,072
1,639
1,659
1,044
4,342
60,414
6,231,348
15,602,332
14,390,656
36,224,336
306,256
2,674,107
6,209,891
9,190,254
45,414,590
Large Systems (Census)
Ground Water
Surface Water
10,001 -50,000
> 50,000
Total
10,001 -50,000
> 50,000
Total
All Large Systems
Total Water Systems1
1,199
190
1,389
1,183
507
1,690
3,079
3,876
27,061,195
26,476,158
53,537,353
33,338,950
135,389,905
168,728,855
222,266,208
225,026,778
63,493
267,680,798
Standard Stage 1 Analysis
UCMR
Systems | Population
Percentage
Systems | Population
National Extrapolation
Systems | Population
1
1
0
1
500
500
0
500
0.90%
0.17%
0.00%
0.13%
1.81%
0.03%
0.00%
0.02%
373
373
0
373
113,000
113,000
0
113,000
0
0
0
1
0
0
0
500
0.00%
0.00%
0.00%
0.03%
0.00%
0.00%
0.00%
0.0002%
373
113,000
Analyses based on UCMR 1 data as of March 2006, and represent recent adjustments to the
population-served values for large systems that minimize population double-counting in consecutive systems.
Note that small water systems (population served £ 10,000) conducting UCMR monitoring represent a
statistically representative sub-sample of all small systems, while the UCMR large water systems (population
served > 10,000) represent a census of all large systems. Comparing and totaling raw data between small and
large systems may not accurately represent national occurrence.
Occurrence findings based on systems and population-served by systems, with at least one
analytical detection of DCPA mono/di-acid degradates greater than the threshold (> 70 ug/L).
For aggregate population-served values, for each system that had a detect the full population-
served value of that system was added to the aggregate (in contrast to proportional
populations).
H-2
-------
Appendix H. Sample-Point-Level Occurrence Measures
Table H1.b. DCPA Degradates - Sample-Point-Level Analysis -
Detections greater than HRL of 70 |jg/L
Water Type
System Size by
Population Served
Total Number
UCMR
Systems | Population
National Inventory
Systems | Population
Small Systems (Statistical sample)
Ground Water
Surface Water
<500
501 - 3,300
3,301 -10,000
Total
<500
501 - 3,300
3,301 -10,000
Total
All Small Systems
111
245
234
590
52
45
110
207
797
27,599
441,499
1,470,717
1,939,815
16,662
91,723
712,370
820,755
2,760,570
41,415
12,128
2,529
56,072
1,639
1,659
1,044
4,342
60,414
6,231,348
15,602,332
14,390,656
36,224,336
306,256
2,674,107
6,209,891
9,190,254
45,414,590
Large Systems (Census)
Ground Water
Surface Water
10,001 -50,000
> 50,000
Total
10,001 -50,000
> 50,000
Total
All Large Systems
Total Water Systems1
1,199
190
1,389
1,183
507
1,690
3,079
3,876
27,061,195
26,476,158
53,537,353
33,338,950
135,389,905
168,728,855
222,266,208
225,026,778
63,493
267,680,798
At least 2 Detects at 1 SP
UCMR
Systems | Population
Percentage
Systems | Population
National Extrapolation
Systems | Population
1
1
0
1
500
500
0
500
0.90%
0.17%
0.00%
0.13%
1.81%
0.03%
0.00%
0.02%
373
373
0
373
113,000
113,000
0
113,000
0
0
0
1
0
0
0
500
0.00%
0.00%
0.00%
0.03%
0.00%
0.00%
0.00%
0.0002%
373
113,000
Analyses based on UCMR 1 data as of March 2006, and represent recent adjustments to the
population-served values for large systems that minimize population double-counting in consecutive systems.
Note that small water systems (population served £ 10,000) conducting UCMR monitoring represent a
statistically representative sub-sample of all small systems, while the UCMR large water systems (population
served > 10,000) represent a census of all large systems. Comparing and totaling raw data between small and
large systems may not accurately represent national occurrence.
Occurrence findings based on systems, and population-served by systems, with at least two
detections above the threshold at a single sample point (SP). For aggregate population-
served values, for each system that had a detect the full population-served value of that
system was added to the aggregate (in contrast to proportional populations).
H-3
-------
Appendix H. Sample-Point-Level Occurrence Measures
Table H1.b. DCPA Degradates - Sample-Point-Level Analysis -
Detections greater than HRL of 70 |jg/L
Water Type
System Size by
Population Served
Total Number
UCMR
Systems | Population
National Inventory
Systems | Population
Small Systems (Statistical sample)
Ground Water
Surface Water
<500
501 - 3,300
3,301 -10,000
Total
<500
501 - 3,300
3,301 -10,000
Total
All Small Systems
111
245
234
590
52
45
110
207
797
27,599
441,499
1,470,717
1,939,815
16,662
91,723
712,370
820,755
2,760,570
41,415
12,128
2,529
56,072
1,639
1,659
1,044
4,342
60,414
6,231,348
15,602,332
14,390,656
36,224,336
306,256
2,674,107
6,209,891
9,190,254
45,414,590
Large Systems (Census)
Ground Water
Surface Water
10,001 -50,000
> 50,000
Total
10,001 -50,000
> 50,000
Total
All Large Systems
Total Water Systems1
1,199
190
1,389
1,183
507
1,690
3,079
3,876
27,061,195
26,476,158
53,537,353
33,338,950
135,389,905
168,728,855
222,266,208
225,026,778
63,493
267,680,798
At least 1 Detect at 2 SPs
UCMR
Systems | Population
Percentage
Systems | Population
National Extrapolation
Systems | Population
0
0
0
0
0
0
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0
0
Analyses based on UCMR 1 data as of March 2006, and represent recent adjustments to the
population-served values for large systems that minimize population double-counting in consecutive systems.
Note that small water systems (population served £ 10,000) conducting UCMR monitoring represent a
statistically representative sub-sample of all small systems, while the UCMR large water systems (population
served > 10,000) represent a census of all large systems. Comparing and totaling raw data between small and
large systems may not accurately represent national occurrence.
Occurrence findings based on systems, and population-served by systems, with at least one
detection above the threshold at each of two or more SPs in the system. For aggregate
population-served values, for each system that had a detect the full population-served value
of that system was added to the aggregate (in contrast to proportional populations).
H-4
-------
Appendix H. Sample-Point-Level Occurrence Measures
Table H1.b. DCPA Degradates - Sample-Point-Level Analysis -
Detections greater than HRL of 70 |jg/L
Water Type
System Size by
Population Served
Total Number
UCMR
Systems | Population
National Inventory
Systems | Population
Small Systems (Statstical sample)
Ground Water
Surface Water
<500
501 - 3,300
3,301 -10,000
Total
<500
501 - 3,300
3,301 -10,000
Total
All Small Systems
111
245
234
590
52
45
110
207
797
27,599
441,499
1,470,717
1,939,815
16,662
91,723
712,370
820,755
2,760,570
41,415
12,128
2,529
56,072
1,639
1,659
1,044
4,342
60,414
6,231,348
15,602,332
14,390,656
36,224,336
306,256
2,674,107
6,209,891
9,190,254
45,414,590
Large Systems (Census)
Ground Water
Surface Water
10,001 -50,000
> 50,000
Total
10,001 -50,000
> 50,000
Total
All Large Systems
Total Water Systems1
1,199
190
1,389
1,183
507
1,690
3,079
3,876
27,061,195
26,476,158
53,537,353
33,338,950
135,389,905
168,728,855
222,266,208
225,026,778
63,493
267,680,798
Populations Proportional to % SP detects
UCMR
SPs | Population
Percentage
SPs | Population
National Extrapolation
SPs | Population
1
1
0
1
500
500
0
500
0.76%
0.08%
0.00%
0.07%
1.81%
0.03%
0.00%
0.02%
439
439
0
439
113,000
113,000
0
113,000
0
0
0
1
0
0
0
500
0.00%
0.00%
0.00%
0.01%
0.00%
0.00%
0.00%
0.00%
439
113,000
Analyses based on UCMR 1 data as of March 2006, and represent recent adjustments to the
population-served values for large systems that minimize population double-counting in consecutive systems.
Note that small water systems (population served £ 10,000) conducting UCMR monitoring represent a
statistically representative sub-sample of all small systems, while the UCMR large water systems (population
served > 10,000) represent a census of all large systems. Comparing and totaling raw data between small and
large systems may not accurately represent national occurrence.
The extrapolated number of small system sample points with a contaminant detection was estimated by
multiplying the percentage of UCMR 1 small system sample points with a contaminant detection by the total
number of sample points nationally. The national number of small system sample points was estimated by
multiplying the average number of sample points for a system water type category by the total number of
systems nationally in that category. The large system sample point numbers presented in this table are direct
counts of the UCMR 1 large system data (no extrapolations are necessary).
Population-served values for each system were adjusted based on the distribution of detections among SPs of a
system. For each system, the gross population-served was multiplied by the proportion of total SPs with
detects. These adjusted sums were then aggregated to create the summary statistics presented above. One
simplifying assumption is that a system's entire population-served is uniformly distributed across all the system's
SPs.
H-5
-------
Appendix H. Sample-Point-Level Occurrence Measures
Table H1.c. DCPA Degradates - Sample-Point-Level Analysis -
Detections greater than 1/2 HRL of 35 ug/L
Water Type
System Size by
Population Served
Total Number
UCMR
Systems | Population
National Inventory
Systems | Population
Small Systems (Statstical sample)
Ground Water
Surface Water
<500
501 - 3,300
3,301 -10,000
Total
<500
501 - 3,300
3,301 -10,000
Total
All Small Systems
111
245
234
590
52
45
110
207
797
27,599
441,499
1,470,717
1,939,815
16,662
91,723
712,370
820,755
2,760,570
41,415
12,128
2,529
56,072
1,639
1,659
1,044
4,342
60,414
6,231,348
15,602,332
14,390,656
36,224,336
306,256
2,674,107
6,209,891
9,190,254
45,414,590
Large Systems (Census)
Ground Water
Surface Water
10,001 -50,000
> 50,000
Total
10,001 -50,000
> 50,000
Total
All Large Systems
Total Water Systems1
1,199
190
1,389
1,183
507
1,690
3,079
3,876
27,061,195
26,476,158
53,537,353
33,338,950
135,389,905
168,728,855
222,266,208
225,026,778
63,493
267,680,798
Standard Stage 1 Analysis
UCMR
Systems | Population
Percentage
Systems | Population
National Extrapolation
Systems | Population
1
1
0
1
500
500
0
500
0.90%
0.17%
0.00%
0.13%
1.81%
0.03%
0.00%
0.02%
373
373
0
373
113,000
113,000
0
113,000
0
1
1
1
2
0
738,337
738,337
738,337
738,837
0.00%
0.20%
0.06%
0.03%
0.05%
0.00%
0.55%
0.44%
0.33%
0.33%
374
851,337
Analyses based on UCMR 1 data as of March 2006, and represent recent adjustments to the
population-served values for large systems that minimize population double-counting in consecutive systems.
Note that small water systems (population served < 10,001) conducting UCMR monitoring represent a
statistically representative sub-sample of all small systems, while the UCMR large water systems (population
served > 10,000) represent a census of all large systems. Comparing and totaling raw data between small and
large systems may not accurately represent national occurrence.
Occurrence findings based on systems and population-served by systems, with at least one
analytical detection of DCPA mono/di-acid degradates greater than the threshold (> 35 ug/L).
For aggregate population-served values, for each system that had a detect the full population-
served value of that system was added to the aggregate (in contrast to proportional
populations).
H-6
-------
Appendix H. Sample-Point-Level Occurrence Measures
Table H1.c. DCPA Degradates - Sample-Point-Level Analysis -
Detections greater than 1/2 HRL of 35 ug/L
Water Type
System Size by
Population Served
Total Number
UCMR
Systems | Population
National Inventory
Systems | Population
Small Systems (Statistical sample)
Ground Water
Surface Water
<500
501 - 3,300
3,301 -10,000
Total
<500
501 - 3,300
3,301 -10,000
Total
All Small Systems
111
245
234
590
52
45
110
207
797
27,599
441,499
1,470,717
1,939,815
16,662
91,723
712,370
820,755
2,760,570
41,415
12,128
2,529
56,072
1,639
1,659
1,044
4,342
60,414
6,231,348
15,602,332
14,390,656
36,224,336
306,256
2,674,107
6,209,891
9,190,254
45,414,590
Large Systems (Census)
Ground Water
Surface Water
10,001 -50,000
> 50,000
Total
10,001 -50,000
> 50,000
Total
All Large Systems
Total Water Systems1
1,199
190
1,389
1,183
507
1,690
3,079
3,876
27,061,195
26,476,158
53,537,353
33,338,950
135,389,905
168,728,855
222,266,208
225,026,778
63,493
267,680,798
At least 2 Detects at 1 SP
UCMR
Systems | Population
Percentage
Systems | Population
National Extrapolation
Systems | Population
1
1
0
1
500
500
0
500
0.90%
0.17%
0.00%
0.13%
1.81%
0.03%
0.00%
0.02%
373
373
0
373
113,000
113,000
0
113,000
0
0
0
1
0
0
0
500
0.00%
0.00%
0.00%
0.03%
0.00%
0.00%
0.00%
0.00022%
373
113,000
Analyses based on UCMR 1 data as of March 2006, and represent recent adjustments to the
population-served values for large systems that minimize population double-counting in consecutive systems.
Note that small water systems (population served < 10,001) conducting UCMR monitoring represent a
statistically representative sub-sample of all small systems, while the UCMR large water systems (population
served > 10,000) represent a census of all large systems. Comparing and totaling raw data between small and
large systems may not accurately represent national occurrence.
Occurrence findings based on systems, and population-served by systems, with at least two
detections above the threshold at a single sample point (SP). For aggregate population-
served values, for each system that had a detect the full population-served value of that
system was added to the aggregate (in contrast to proportional populations).
H-7
-------
Appendix H. Sample-Point-Level Occurrence Measures
Table H1.c. DCPA Degradates - Sample-Point-Level Analysis -
Detections greater than 1/2 HRL of 35 ug/L
Water Type
System Size by
Population Served
Total Number
UCMR
Systems | Population
National Inventory
Systems | Population
Small Systems (Statistical sample)
Ground Water
Surface Water
<500
501 - 3,300
3,301 -10,000
Total
<500
501 - 3,300
3,301 -10,000
Total
All Small Systems
111
245
234
590
52
45
110
207
797
27,599
441,499
1,470,717
1,939,815
16,662
91,723
712,370
820,755
2,760,570
41,415
12,128
2,529
56,072
1,639
1,659
1,044
4,342
60,414
6,231,348
15,602,332
14,390,656
36,224,336
306,256
2,674,107
6,209,891
9,190,254
45,414,590
Large Systems (Census)
Ground Water
Surface Water
10,001 -50,000
> 50,000
Total
10,001 -50,000
> 50,000
Total
All Large Systems
Total Water Systems1
1,199
190
1,389
1,183
507
1,690
3,079
3,876
27,061,195
26,476,158
53,537,353
33,338,950
135,389,905
168,728,855
222,266,208
225,026,778
63,493
267,680,798
At least 1 Detect at 2 SPs
UCMR
Systems | Population
Percentage
Systems | Population
National Extrapolation
Systems | Population
0
0
0
0
0
0
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0
0
Analyses based on UCMR 1 data as of March 2006, and represent recent adjustments to the
population-served values for large systems that minimize population double-counting in consecutive systems.
Note that small water systems (population served < 10,001) conducting UCMR monitoring represent a
statistically representative sub-sample of all small systems, while the UCMR large water systems (population
served > 10,000) represent a census of all large systems. Comparing and totaling raw data between small and
large systems may not accurately represent national occurrence.
Occurrence findings based on systems, and population-served by systems, with at least one
detection above the threshold at each of two or more SPs in the system. For aggregate
population-served values, for each system that had a detect the full population-served value
of that system was added to the aggregate (in contrast to proportional populations).
-------
Appendix H. Sample-Point-Level Occurrence Measures
Table H1.c. DCPA Degradates - Sample-Point-Level Analysis -
Detections greater than 1/2 HRL of 35 ug/L
Water Type
System Size by
Population Served
Total Number
UCMR
Systems | Population
National Inventory
Systems | Population
Small Systems (Statstical sample)
Ground Water
Surface Water
<500
501 - 3,300
3,301 -10,000
Total
<500
501 - 3,300
3,301 -10,000
Total
All Small Systems
111
245
234
590
52
45
110
207
797
27,599
441,499
1,470,717
1,939,815
16,662
91,723
712,370
820,755
2,760,570
41,415
12,128
2,529
56,072
1,639
1,659
1,044
4,342
60,414
6,231,348
15,602,332
14,390,656
36,224,336
306,256
2,674,107
6,209,891
9,190,254
45,414,590
Large Systems (Census)
Ground Water
Surface Water
10,001 -50,000
> 50,000
Total
10,001 -50,000
> 50,000
Total
All Large Systems
Total Water Systems1
1,199
190
1,389
1,183
507
1,690
3,079
3,876
27,061,195
26,476,158
53,537,353
33,338,950
135,389,905
168,728,855
222,266,208
225,026,778
63,493
267,680,798
Populations Proportional to % SP detects
UCMR
SPs | Population
Percentage
SPs | Population
National Extrapolation
SPs | Population
1
1
0
1
500
500
0
500
0.76%
0.08%
0.00%
0.07%
1.81%
0.03%
0.00%
0.02%
439
439
0
439
113,000
113,000
0
113,000
0
7
7
7
8
0
287,131
287,131
287,131
287,631
0%
0.25%
0.13%
0.05%
0.05%
0%
0.21%
0.17%
0.13%
0.13%
446
400,131
Analyses based on UCMR 1 data as of March 2006, and represent recent adjustments to the
population-served values for large systems that minimize population double-counting in consecutive systems.
Note that small water systems (population served < 10,001) conducting UCMR monitoring represent a
statistically representative sub-sample of all small systems, while the UCMR large water systems (population
served > 10,000) represent a census of all large systems. Comparing and totaling raw data between small and
large systems may not accurately represent national occurrence.
The extrapolated number of small system sample points with a contaminant detection was estimated by
multiplying the percentage of UCMR 1 small system sample points with a contaminant detection by the total
number of sample points nationally. The national number of small system sample points was estimated by
multiplying the average number of sample points for a system water type category by the total number of
systems nationally in that category. The large system sample point numbers presented in this table are direct
counts of the UCMR 1 large system data (no extrapolations are necessary).
Population-served values for each system were adjusted based on the distribution of detections among SPs of a
system. For each system, the gross population-served was multiplied by the proportion of total SPs with
detects. These adjusted sums were then aggregated to create the summary statistics presented above. One
simplifying assumption is that a system's entire population-served is uniformly distributed across all the system's
SPs.
H-9
-------
Appendix H. Sample-Point-Level Occurrence Measures
Table H1.d. DCPA Degradates - Sample-Point-Level Analysis -
Detections (> MRL of 1 ug/L)
Water Type
System Size by
Population Served
Total Number
UCMR
Systems I Population
National Inventory
Systems I Population
Small Systems (Statstical sample)
Ground Water
Surface Water
<500
501 - 3,300
3,301 -10,000
Total
<500
501 - 3,300
3,301 -10,000
Total
All Small Systems
111
245
234
590
52
45
110
207
797
27,599
441,499
1,470,717
1,939,815
16,662
91,723
712,370
820,755
2,760,570
41,415
12,128
2,529
56,072
1,639
1,659
1,044
4,342
60,414
6,231,348
15,602,332
14,390,656
36,224,336
306,256
2,674,107
6,209,891
9,190,254
45,414,590
Large Systems (Census)
Ground Water
Surface Water
10,001 -50,000
> 50,000
Total
10,001 -50,000
> 50,000
Total
All Large Systems
Total Water Systems1
1,199
190
1,389
1,183
507
1,690
3,079
3,876
27,061,195
26,476,158
53,537,353
33,338,950
135,389,905
168,728,855
222,266,208
225,026,778
63,493
267,680,798
Standard Stage 1 Analysis
UCMR
Systems I Population
Percentage
Systems I Population
National Extrapolation
Systems I Population
1
3
12
16
1
1
17
500
4,692
81,241
86,433
1,500
1,500
87,933
0.90%
1 .22%
5.13%
2.71%
2.22%
0.48%
2.13%
1.81%
1.06%
5.52%
4.46%
1 .64%
0.18%
3.19%
373
149
130
652
37
37
689
113,000
166,000
795,000
1,074,000
44,000
44,000
1,118,000
87
22
109
34
17
51
160
177
2,095,370
3,987,609
6,082,979
1,136,909
4,049,548
5,186,457
11,269,436
11,357,369
7.26%
11.58%
7.85%
2.87%
3.35%
3.02%
5.20%
4.57%
7.74%
15.06%
11.36%
3.41%
2.99%
3.07%
5.07%
5.05%
849
12,387,436
Analyses based on UCMR 1 data as of March 2006, and represent recent adjustments to the
population-served values for large systems that minimize population double-counting in consecutive systems.
Note that small water systems (population served < 10,001) conducting UCMR monitoring represent a
statistically representative sub-sample of all small systems, while the UCMR large water systems (population
served > 10,000) represent a census of all large systems. Comparing and totaling raw data between small and
large systems may not accurately represent national occurrence.
Occurrence findings based on systems and population-served by systems, with at least one
analytical detection of DCPA mono/di-acid degradates. For aggregate population-served
values, for each system that had a detect the full population-served value of that system was
added to the aggregate (in contrast to proportional populations).
H-10
-------
Appendix H. Sample-Point-Level Occurrence Measures
Table H1.d. DCPA Degradates - Sample-Point-Level Analysis -
Detections (> MRL of 1 ug/L)
Water Type
System Size by
Population Served
Total Number
UCMR
Systems I Population
National Inventory
Systems I Population
Small Systems (Statistical sample)
Ground Water
Surface Water
<500
501 - 3,300
3,301 -10,000
Total
<500
501 - 3,300
3,301 -10,000
Total
All Small Systems
111
245
234
590
52
45
110
207
797
27,599
441,499
1,470,717
1,939,815
16,662
91,723
712,370
820,755
2,760,570
41,415
12,128
2,529
56,072
1,639
1,659
1,044
4,342
60,414
6,231,348
15,602,332
14,390,656
36,224,336
306,256
2,674,107
6,209,891
9,190,254
45,414,590
Large Systems (Census)
Ground Water
Surface Water
10,001 -50,000
> 50,000
Total
10,001 -50,000
> 50,000
Total
All Large Systems
Total Water Systems1
1,199
190
1,389
1,183
507
1,690
3,079
3,876
27,061,195
26,476,158
53,537,353
33,338,950
135,389,905
168,728,855
222,266,208
225,026,778
63,493
267,680,798
At least 2 Detects at 1 SP
UCMR
Systems I Population
Percentage
Systems I Population
National Extrapolation
Systems I Population
1
2
8
11
0
11
500
2,997
51,897
55,394
0
55,394
0.90%
0.82%
3.42%
1 .86%
0.00%
1 .38%
1.81%
0.68%
3.53%
2.86%
0.00%
2.01%
373
99
86
558
0
558
113,000
106,000
508,000
727,000
0
727,000
51
15
66
25
11
36
102
113
1,420,280
2,942,386
4,362,666
850,097
2,798,638
3,648,735
8,011,401
8,066,795
4.25%
7.89%
4.75%
2.11%
2.17%
2.13%
3.31%
2.92%
5.25%
11.11%
8.15%
2.55%
2.07%
2.16%
3.60%
3.58%
660
8,738,401
Analyses based on UCMR 1 data as of March 2006, and represent recent adjustments to the
population-served values for large systems that minimize population double-counting in consecutive systems.
Note that small water systems (population served < 10,001) conducting UCMR monitoring represent a
statistically representative sub-sample of all small systems, while the UCMR large water systems (population
served > 10,000) represent a census of all large systems. Comparing and totaling raw data between small and
large systems may not accurately represent national occurrence.
Occurrence findings based on systems, and population-served by systems, with at least two
detections at a single sample point (SP). For aggregate population-served values, for each
system that had a detect the full population-served value of that system was added to the
aggregate (in contrast to proportional populations).
H-11
-------
Appendix H. Sample-Point-Level Occurrence Measures
Table H1.d. DCPA Degradates - Sample-Point-Level Analysis -
Detections (> MRL of 1 ug/L)
Water Type
System Size by
Population Served
Total Number
UCMR
Systems I Population
National Inventory
Systems I Population
Small Systems (Statistical sample)
Ground Water
Surface Water
<500
501 - 3,300
3,301 -10,000
Total
<500
501 - 3,300
3,301 -10,000
Total
All Small Systems
111
245
234
590
52
45
110
207
797
27,599
441,499
1,470,717
1,939,815
16,662
91,723
712,370
820,755
2,760,570
41,415
12,128
2,529
56,072
1,639
1,659
1,044
4,342
60,414
6,231,348
15,602,332
14,390,656
36,224,336
306,256
2,674,107
6,209,891
9,190,254
45,414,590
Large Systems (Census)
Ground Water
Surface Water
10,001 -50,000
> 50,000
Total
10,001 -50,000
> 50,000
Total
All Large Systems
Total Water Systems1
1,199
190
1,389
1,183
507
1,690
3,079
3,876
27,061,195
26,476,158
53,537,353
33,338,950
135,389,905
168,728,855
222,266,208
225,026,778
63,493
267,680,798
At least 1 Detect at 2 SPs
UCMR
Systems I Population
Percentage
Systems I Population
National Extrapolation
Systems I Population
1
4
5
0
5
2,297
27,084
29,381
0
29,381
0.41%
1.71%
0.85%
0.00%
0.63%
0.52%
1.84%
1.51%
0.00%
1.06%
50
43
93
0
93
81,000
265,000
346,000
0
346,000
42
14
56
15
10
25
81
86
1,162,085
2,768,576
3,930,661
566,515
2,855,715
3,422,230
7,352,891
7,382,272
3.50%
7.37%
4.03%
1.27%
1.97%
1.48%
2.63%
2.22%
4.29%
10.46%
7.34%
1.70%
2.11%
2.03%
3.31%
3.28%
174
7,698,891
Analyses based on UCMR 1 data as of March 2006, and represent recent adjustments to the
population-served values for large systems that minimize population double-counting in consecutive systems.
Note that small water systems (population served < 10,001) conducting UCMR monitoring represent a
statistically representative sub-sample of all small systems, while the UCMR large water systems (population
served > 10,000) represent a census of all large systems. Comparing and totaling raw data between small and
large systems may not accurately represent national occurrence.
Occurrence findings based on systems, and population-served by systems, with at least one
detection at each of two or more SPs in the system. For aggregate population-served
values, for each system that had a detect the full population-served value of that system was
added to the aggregate (in contrast to proportional populations).
H-12
-------
Appendix H. Sample-Point-Level Occurrence Measures
Table H1.d. DCPA Degradates - Sample-Point-Level Analysis -
Detections (> MRL of 1 ug/L)
Water Type
System Size by
Population Served
Total Number
UCMR
Systems I Population
National Inventory
Systems I Population
Small Systems (Statstical sample)
Ground Water
Surface Water
<500
501 - 3,300
3,301 -10,000
Total
<500
501 - 3,300
3,301 -10,000
Total
All Small Systems
111
245
234
590
52
45
110
207
797
27,599
441,499
1,470,717
1,939,815
16,662
91,723
712,370
820,755
2,760,570
41,415
12,128
2,529
56,072
1,639
1,659
1,044
4,342
60,414
6,231,348
15,602,332
14,390,656
36,224,336
306,256
2,674,107
6,209,891
9,190,254
45,414,590
Large Systems (Census)
Ground Water
Surface Water
10,001 -50,000
> 50,000
Total
10,001 -50,000
> 50,000
Total
All Large Systems
Total Water Systems1
1,199
190
1,389
1,183
507
1,690
3,079
3,876
27,061,195
26,476,158
53,537,353
33,338,950
135,389,905
168,728,855
222,266,208
225,026,778
63,493
267,680,798
Populations Proportional to % SP detects
UCMR
SPs I Population
Percentage
SPs I Population
National Extrapolation
SPs I Population
1
4
18
23
1
1
24
500
3,314
33,108
36,922
1,500
1,500
38,422
0.76%
0.89%
2.86%
1.90%
2.13%
0.41%
1.65%
1.81%
0.75%
2.25%
1.90%
1.64%
0.18%
1.39%
439
194
210
843
46
46
889
113,000
117,000
324,000
554,000
44,000
44,000
598,000
172
128
300
80
45
125
425
449
892,141
572,747
1,464,888
661,586
922,442
1,584,028
3,048,916
3,087,338
3.16%
4.57%
3.64%
3.20%
1 .62%
2.37%
3.14%
3.00%
3.30%
2.16%
2.74%
1 .98%
0.68%
0.94%
1 .37%
1 .37%
1,314
3,646,916
Analyses based on UCMR 1 data as of March 2006, and represent recent adjustments to the
population-served values for large systems that minimize population double-counting in consecutive systems.
Note that small water systems (population served < 10,001) conducting UCMR monitoring represent a
statistically representative sub-sample of all small systems, while the UCMR large water systems (population
served > 10,000) represent a census of all large systems. Comparing and totaling raw data between small and
large systems may not accurately represent national occurrence.
The extrapolated number of small system sample points with a contaminant detection was estimated by
multiplying the percentage of UCMR 1 small system sample points with a contaminant detection by the total
number of sample points nationally. The national number of small system sample points was estimated by
multiplying the average number of sample points for a system water type category by the total number of
systems nationally in that category. The large system sample point numbers presented in this table are direct
counts of the UCMR 1 large system data (no extrapolations are necessary).
Population-served values for each system were adjusted based on the distribution of detections among SPs of a
system. For each system, the gross population-served was multiplied by the proportion of total SPs with
detects. These adjusted sums were then aggregated to create the summary statistics presented above. One
simplifying assumption is that a system's entire population-served is uniformly distributed across all the system's
SPs.
H-13
-------
Appendix H. Sample-Point-Level Occurrence Measures
Table H2.a. MTBE - Sample-Point-Level Analysis - Summary of all threshold evaluations (UCMR 1 March 2006 data)
The UCMR small water systems (population served < 10,000) are a statistical, representative sample of all national small systems while the UCMR large water
systems (population served > 10,000) represent a census of all large systems. The numbers presented below are the sum of the small system national extrapolation
estimates and the actual large system census results.
Threshold
MRL
(5 ug/L)
Standard Stage 1 Analysis1
Number
Sys
165
Pop
896,483
Percentage
Sys
0.49%
Pop
0.33%
At least 2 Detects at 1 SP2
Number
Sys
4
Pop
96,739
Percentage
Sys
0.10%
Pop
0.04%
At least 1 Detect at 2 SPs3
Number
Sys
3
Pop
99,444
Percentage
Sys
0.08%
Pop
0.04%
Populations Proportional to
% SP detects4
Number
SPs
166
Pop
198,640
Percentage
SPs
0.15%
Pop
0.05%
1 Occurrence findings based on systems and population-served by systems, with at least one analytical detection of MTBE. For aggregate population-served values, for each system that had a detect the
full population-served value of that system was added to the aggregate (in contrast to proportional populations in 4 below).
2 Occurrence findings based on systems, and population-served by systems, with at least two detections at a single sample point (SP). For aggregate population-served values, for each system that had
a detect the full population-served value of that system was added to the aggregate (in contrast to proportional populations in 4 below).
3 Occurrence findings based on systems, and population-served by systems, with at least one detection at each of two or more SPs in the system. For aggregate population-served values, for each
system that had a detect the full population-served value of that system was added to the aggregate (in contrast to proportional populations in 4 below).
4 The extrapolated number of small system sample points with a contaminant detection was estimated by multiplying the percentage of UCMR 1 small system sample points with a contaminant detection
by the total number of sample points nationally. The national number of small system sample points was estimated by multiplying the average number of sample points for a system water type category by
the total number of systems nationally in that category. The large system sample point numbers presented in this table are direct counts of the UCMR 1 large system data (no extrapolations are
necessary). Population-served values for each system were adjusted based on the distribution of detections among SPs of a system. For each system, the gross population-served was multiplied by the
proportion of total SPs with detects. These adjusted sums were then aggregated to create the summary statistics presented above. One simplifying assumption is that a system's entire population-served
is uniformly distributed across all the system's SPs.
H-14
-------
Appendix H. Sample-Point-Level Occurrence Measures
Table H2.b. MTBE - Sample-Point -Level Analysis -
detections (> MRL of 5 ug/L)
Water Type
System Size by
Population Served
Total Number
UCMR
Systems Population
National Inventory
Systems Population
Small Systems (Statistical sample)
Ground Water
Surface Water
<500
501 - 3,300
3,301-10,000
Total
<500
501 - 3,300
3,301-10,000
Total
All Small Systems
111
244
234
589
52
45
110
207
796
27,599
439,011
1,470,717
1,937,327
16,662
91,723
712,370
820,755
2,758,082
41,415
12,128
2,529
56,072
1,639
1,659
1,044
4,342
60,414
6,231,348
15,602,332
14,390,656
36,224,336
306,256
2,674,107
6,209,891
9,190,254
45,414,590
Large Systems (Census)
Ground Water
Surface Water
10,001 -50,000
> 50,000
Total
10,001 -50,000
> 50,000
Total
All Large Systems
Total Water Systems1
1,192
189
1,381
1,185
509
1,694
3,075
3,871
26,911,853
26,361,273
53,273,126
33,277,623
136,681,205
169,958,828
223,231,954
225,990,036
63,489
268,646,544
Standard Stage 1 Analysis
UCMR
Systems
Population
Percentage
Systems Population
National Extrapolation
Systems
Population
3
3
0
3
4,150
4,150
0
4,150
1.23%
0.51%
0.00%
0.38%
0.95%
0.21%
0.00%
0.15%
149
149
0
149
147,000
147,000
0
147,000
9
3
12
2
2
4
16
19
179,894
241,292
421,186
55,388
272,909
328,297
749,483
753,633
0.76%
1.59%
0.87%
0.17%
0.39%
0.24%
0.52%
0.49%
0.67%
0.92%
0.79%
0.17%
0.20%
0.19%
0.34%
0.33%
165
896,483
Analyses based on UCMR 1 data as of March 2006, and represent recent adjustments to the
population-served values for large systems that minimize population double-counting in consecutive systems.
Note that small water systems (population served < 10,001) conducting UCMR monitoring represent a
statistically representative sub-sample of all small systems, while the UCMR large water systems (population
served > 10,000) represent a census of all large systems. Comparing and totaling raw data between small and
large systems may not accurately represent national occurrence.
Occurrence findings based on systems and population-served by systems, with at least one
analytical detection of MTBE. For aggregate population-served values, for each system that
had a detect the full population-served value of that system was added to the aggregate (in
contrast to proportional populations).
-------
Appendix H. Sample-Point-Level Occurrence Measures
Table H2.b. MTBE - Sample-Point -Level Analysis -
detections (> MRL of 5 ug/L)
Water Type
System Size by
Population Served
Total Number
UCMR
Systems Population
National Inventory
Systems Population
Small Systems (Statistical sample)
Ground Water
Surface Water
<500
501 - 3,300
3,301-10,000
Total
<500
501 - 3,300
3,301-10,000
Total
All Small Systems
111
244
234
589
52
45
110
207
796
27,599
439,011
1,470,717
1,937,327
16,662
91,723
712,370
820,755
2,758,082
41,415
12,128
2,529
56,072
1,639
1,659
1,044
4,342
60,414
6,231,348
15,602,332
14,390,656
36,224,336
306,256
2,674,107
6,209,891
9,190,254
45,414,590
Large Systems (Census)
Ground Water
Surface Water
10,001 -50,000
> 50,000
Total
10,001 -50,000
> 50,000
Total
All Large Systems
Total Water Systems1
1,192
189
1,381
1,185
509
1,694
3,075
3,871
26,911,853
26,361,273
53,273,126
33,277,623
136,681,205
169,958,828
223,231,954
225,990,036
63,489
268,646,544
At least 2 Detects at 1 SP
UCMR
Systems
Population
Percentage
Systems Population
National Extrapolation
Systems
Population
0
0
0
0
0
0
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0
0
0
0
0
0
3
3
1
1
4
4
74,351
74,351
22,388
22,388
96,739
96,739
0.25%
0.22%
0.08%
0.06%
0.13%
0.10%
0.28%
0.14%
0.07%
0.01%
0.04%
0.04%
4
96,739
Analyses based on UCMR 1 data as of March 2006, and represent recent adjustments to the
population-served values for large systems that minimize population double-counting in consecutive systems.
Note that small water systems (population served < 10,001) conducting UCMR monitoring represent a
statistically representative sub-sample of all small systems, while the UCMR large water systems (population
served > 10,000) represent a census of all large systems. Comparing and totaling raw data between small and
large systems may not accurately represent national occurrence.
Occurrence findings based on systems, and population-served by systems, with at least two
detections at a single sample point to the distribution system (SP). For aggregate
population-served values, for each system that had a detect the full population-served value
of that system was added to the aggregate (in contrast to proportional populations).
-------
Appendix H. Sample-Point-Level Occurrence Measures
Table H2.b. MTBE - Sample-Point -Level Analysis -
detections (> MRL of 5 ug/L)
Water Type
System Size by
Population Served
Total Number
UCMR
Systems
Population
National Inventory
Systems Population
Small Systems (Statistical sample)
Ground Water
Surface Water
<500
501 - 3,300
3,301-10,000
Total
<500
501 - 3,300
3,301-10,000
Total
All Small Systems
111
244
234
589
52
45
110
207
796
27,599
439,011
1,470,717
1,937,327
16,662
91,723
712,370
820,755
2,758,082
41,415
12,128
2,529
56,072
1,639
1,659
1,044
4,342
60,414
6,231,348
15,602,332
14,390,656
36,224,336
306,256
2,674,107
6,209,891
9,190,254
45,414,590
Large Systems (Census)
Ground Water
Surface Water
10,001 -50,000
> 50,000
Total
10,001 -50,000
> 50, 000
Total
All Large Systems
Total Water Systems1
1,192
189
1,381
1,185
509
1,694
3,075
3,871
26,911,853
26,361,273
53,273,126
33,277,623
136,681,205
169,958,828
223,231,954
225,990,036
63,489
268,646,544
At least 1 Detect at 2 SPs
UCMR
Systems Population
Percentage
Systems Population
National Extrapolation
Systems Population
0
0
0
0
0
0
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0
0
0
0
0
0
2
2
1
1
3
3
30,245
30,245
69,199
69,199
99,444
99,444
0.17%
0.14%
0.20%
0.06%
0.10%
0.08%
0.11%
0.06%
0.05%
0.04%
0.04%
0.04%
3
99,444
Analyses based on UCMR 1 data as of March 2006, and represent recent adjustments to the
population-served values for large systems that minimize population double-counting in consecutive systems.
Note that small water systems (population served < 10,001) conducting UCMR monitoring represent a
statistically representative sub-sample of all small systems, while the UCMR large water systems (population
served > 10,000) represent a census of all large systems. Comparing and totaling raw data between small and
large systems may not accurately represent national occurrence.
Occurrence findings based on systems, and population-served by systems, with at least
one detection at each of two or more SPs in the system. For aggregate population-served
values, for each system that had a detect the full population-served value of that system
was added to the aggregate (in contrast to proportional populations).
-------
Appendix H. Sample-Point-Level Occurrence Measures
Table H2.b. MTBE - Sample-Point -Level Analysis -
detections (> MRL of 5 ug/L)
Water Type
System Size by
Population Served
Total Number
UCMR
Systems
Population
National Inventory
Systems Population
Small Systems (Statistical sample)
Ground Water
Surface Water
<500
501 - 3,300
3,301-10,000
Total
<500
501 - 3,300
3,301-10,000
Total
All Small Systems
111
244
234
589
52
45
110
207
796
27,599
439,011
1,470,717
1,937,327
16,662
91,723
712,370
820,755
2,758,082
41,415
12,128
2,529
56,072
1,639
1,659
1,044
4,342
60,414
6,231,348
15,602,332
14,390,656
36,224,336
306,256
2,674,107
6,209,891
9,190,254
45,414,590
Large Systems (Census)
Ground Water
Surface Water
10,001 -50,000
> 50,000
Total
10,001 -50,000
> 50, 000
Total
All Large Systems
Total Water Systems1
1,192
189
1,381
1,185
509
1,694
3,075
3,871
26,911,853
26,361,273
53,273,126
33,277,623
136,681,205
169,958,828
223,231,954
225,990,036
63,489
268,646,544
Populations Proportional to % SP detects
UCMR
SPs | Population
Percentage
SPs | Population
National Extrapolation
SPs | Population
3
3
0
3
2,450
2,450
0
2,450
0.67%
0.25%
0.00%
0.21%
0.56%
0.13%
0.00%
0.09%
147
147
0
147
87,000
87,000
0
87,000
11
3
14
2
3
5
19
22
28,746
48,390
77,136
27,102
7,402
34,504
111,640
114,090
0.20%
0.11%
0.17%
0.08%
0.11%
0.09%
0.14%
0.15%
0.11%
0.18%
0.14%
0.08%
0.01%
0.02%
0.05%
0.05%
166
198,640
Analyses based on UCMR 1 data as of March 2006, and represent recent adjustments to the
population-served values for large systems that minimize population double-counting in consecutive systems.
Note that small water systems (population served < 10,001) conducting UCMR monitoring represent a
statistically representative sub-sample of all small systems, while the UCMR large water systems (population
served > 10,000) represent a census of all large systems. Comparing and totaling raw data between small and
large systems may not accurately represent national occurrence.
The extrapolated number of small system sample points with a contaminant detection was estimated by
multiplying the percentage of UCMR 1 small system sample points with a contaminant detection by the total
number of sample points nationally. The national number of small system sample points was estimated by
multiplying the average number of sample points for a system water type category by the total number of
systems nationally in that category. The large system sample point numbers presented in this table are direct
counts of the UCMR 1 large system data (no extrapolations are necessary).
Population-served values for each system were adjusted based on the distribution of detections among SPs of
a system. For each system, the gross population-served was multiplied by the proportion of total SPs with
detects. These adjusted sums were then aggregated to create the summary statistics presented above. One
simplifying assumption is that a system's entire population-served is uniformly distributed across all the
system's SPs.
H-18
------- |