vvEPA
United States
Environmental Protection
Agency
Perchlorate Occurrence
and Monitoring Report
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Office of Water
EPA 816-R-19-003
May 2019
http://water.epa.gov/drink
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Executive Summary
On February 11, 2011 (76 FR 7762; USEPA, 201 la), the United States Environmental
Protection Agency (EPA) announced its decision to regulate perchlorate under the Safe Drinking
Water Act (SDWA) based on its finding that perchlorate meets the SDWA's three criteria for
regulating a contaminant: 1) the contaminant may have an adverse effect on the health of
persons, 2) the contaminant is known to occur or there is a substantial likelihood that the
contaminant will occur in public water systems (PWSs) with a frequency and at levels of public
health concern, and 3) in the sole judgment of the Administrator, regulation of such contaminant
presents a meaningful opportunity for health risk reduction for persons served by PWSs.
The EPA is proposing a Maximum Contaminant Level Goal (MCLG) and a National
Primary Drinking Water Regulation (NPDWR) for perchlorate in PWSs. In accordance with
Section 1412(b)(3)(c) of SDWA, the EPA must prepare a Health Risk Reduction and Cost
Analysis (HRRCA) of the proposed Maximum Contaminant Level (MCL) and alternative MCLs.
The HRRCA must assess the quantifiable and non-quantifiable costs that are likely to occur as a
result of compliance with the MCL. These costs could be for new treatment processes as well as
incremental monitoring and administrative costs. The EPA must also provide an estimate of the
health risk reduction benefits likely to occur as a result of the treatment to comply with each
perchlorate concentration level assessed.
The EPA evaluated the available peer-reviewed science and supporting studies, as well as
data collected by accepted methods on the national occurrence of perchlorate in drinking water.
The EPA determined that the data from the Unregulated Contaminant Monitoring Rule 1
(UCMR 1) are the best available nationally representative data for characterizing the frequency
and levels of perchlorate occurrence in public drinking water systems. The UCMR 1 perchlorate
monitoring of drinking water - a census of large PWSs (serving more than 10,000 people) and a
nationally representative statistical sample of small systems (serving 10,000 people or fewer) -
represents the most extensive, nationally representative monitoring program for perchlorate in
public drinking water systems. PWSs conducted UCMR 1 monitoring for perchlorate in drinking
water between 2001 and 2005. The EPA used UCMR 1 data to estimate the national occurrence
of perchlorate in public drinking water systems. To support this analysis, the EPA also reviewed
state-sponsored studies (including Arizona, California, Iowa, Maryland, Massachusetts, Nevada,
New Jersey and Texas) and other drinking water occurrence data (including American Water
Works Association Research Foundation, American Water System Survey, Consumer
Confidence Reports and the Environmental Working Group).
Occurrence analyses based on this updated UCMR 1 Perchlorate Data set identify
analytical detections in PWSs located in 26 states and 2 territories. Analytical detections of
perchlorate at or above 4 |ig/L were identified in 1.58% (540) of the 34,132 UCMR 1 perchlorate
samples. An estimated 4.60% of large PWSs (141 large systems) serving approximately 16.2
million people reported at least one detection of perchlorate at or above 4 |ig/L and 1.0% of
small PWSs (8 small systems) serving approximately 13,000 people reported perchlorate
detections at or above 4 |ig/L. The percentage of ground water and surface water PWSs reporting
perchlorate detections is about the same. While perchlorate analytical detections are fairly
numerous and widespread geographically, the UCMR 1 findings indicate that perchlorate occurs
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at relatively low levels. Fifteen systems had detections of perchlorate greater than 18 |ig/L, two
systems had detections greater than 56 |ig/L, and one system had a detection greater than 90
Hg/L.
Exhibit ES-1. Systems and Populations with at least One Detection Relative to
Select Thresholds Based on the Updated UCMR 1 Perchlorate Data set
Total
Systems with at least one detection > threshold
System Type
Number
of
Systems
in
UCMR 1
Total Pop.
Served by
Systems in
UCMR 1
£ 4 |jg/L
>18 |jg/L
> 56 |jg/L
> 90 jjg/L
Number
of
Systems
Pop.
Served by
Systems
Number
of
Systems
Pop.
Served
by
Systems
Number
of
Systems
Pop.
Served
by
Systems
Number
of
Systems
Pop.
Served
by
Systems
Small
Systems
(serving
<10,000)
797
2,760,570
8
13,483
1
4,309
0
0
0
0
Large
Systems
(serving
>10,000)
3,068
222,853,101
141
16,159,082
14
696,871
2
64,733
1
25,972
All Systems
3,865
225,613,671
149
16,172,565
15
701,180
2
64,733
1
25,972
1 The UCMR 1 minimum reporting level (MRL) for perchlorate was equal to 4 |jg/L. Thus, assessments relative to the threshold of
greater than or equal to 4 |jg/L served to identify all perchlorate sample detections in UCMR 1.
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Contents
Executive Summary i
Contents iii
Exhibits v
Appendices vii
Abbreviations viii
1 Introduction 1
1.1 SDWA Statutory Requirements and Rulemaking Process for Perchlorate in Drinking
Water 2
1.2 State Standards and Guidelines for Perchlorate in Drinking Water 3
2 Perchlorate Background 6
2.1 Chemical and Physical Properties 6
2.2 Sources of Perchlorate 7
2.2.1 Natural Sources 8
2.2.2 Production and Use 8
2.3 Environmental Fate and Transport of the Perchlorate Ion 10
3 Perchlorate Occurrence Data in Unregulated Contaminant Monitoring Rule 1 12
3.1 UCMR 1 Program Overview 12
3.2 Monitoring Frequency and Location 13
3.3 Completeness of UCMR 1 Perchlorate Data set 16
3.4 Summary of UCMR 1 Perchlorate Monitoring Data and QA/QC Review 17
3.4.1 QA/QC Review - Phase 1 17
3.4.2 QA/QC Review - Phase 2 18
3.4.3 UCMR 1 Perchlorate Data Subsequent to Phase 1 and 2 QA/QC Review 20
3.5 UCMR 1 Analytical Method 314.0 21
4 Analysis of the UCMR 1 Perchlorate Data set 22
4.1 Analytical Approach and Resulting Occurrence Estimates 22
4.2 System-Level Analyses 23
4.3 Sample Point-Level Analyses 28
4.4 Spatial and Graphical Assessments 33
5 Laboratory Analytical Methods 37
5.1 EPA Methods 37
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5.2 Methods Used by States 40
5.3 Laboratory Analysis Cost Estimates 41
6 References 42
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Exhibits
Exhibit ES-1. Systems and Populations with at least One Detection Relative to Select
Thresholds Based on the Updated UCMR 1 Perchlorate Data set ii
Exhibit 1: Summary of State Standards and Guidance Levels for Perchlorate in Drinking Water .. 4
Exhibit 2: Summary of State Guidance Levels for Perchlorate in Ground Water 5
Exhibit 3: Chemical Structure of Perchlorate 6
Exhibit 4: Physical and Chemical Properties 6
Exhibit 5: Number of PWSs Collecting UCMR 1 Ground Water (GW) and Surface Water (SW)
Samples for Perchlorate Analysis by Month During the Sampling Period (Top: GW
Systems; Bottom: SW Systems) 15
Exhibit 6: PWSs with UCMR 1 Monitoring Results 16
Exhibit 7: Counts of the Number of Records Removed from the UCMR 1 Perchlorate Data set
from Phase 1 and Phase 2 of QA/QC Review 20
Exhibit 8: Perchlorate Detection Rates and Summary of Detected Concentrations Based on the
Updated UCMR 1 Perchlorate Data set 23
Exhibit 9: Systems and Populations with a SINGLE Detection Relative to Various Thresholds
Based on the Updated UCMR 1 Perchlorate Data set 25
Exhibit 10: Systems and Populations with TWO ORMOREDetections Relative to Various
Thresholds Based on the Updated UCMR 1 Perchlorate Data set 26
Exhibit 11: Systems and Populations with At Least One Detection At Two or More Sample
Points Based on the Updated UCMR 1 Perchlorate Data set 27
Exhibit 12: Sample Points With at Least One Detection and Their Proportional Populations
Based on the Updated UCMR 1 Perchlorate Data set 30
Exhibit 13: Sample Points With at Least Two Detections and Their Proportional Populations
Based on the Updated UCMR 1 Perchlorate Data set 31
Exhibit 14: Portion of Systems with Perchlorate Detections in Various Percentages of System
Sampling Points (Among Systems with at Least One Detection) Based on the
Updated UCMR 1 Perchlorate Data set 32
Exhibit 15: Number of UCMR 1 Systems and Sample Points Exceeding Various Concentration
Thresholds Based on the Updated UCMR 1 Perchlorate Data set 33
Exhibit 16: Geographic Distribution of Perchlorate - States with At Least One Detection Equal to
or Above the MRL (> 4 |ig/L) Based on the Updated UCMR 1 Perchlorate Data set. 34
Exhibit 17: Geographic Distribution of Perchlorate - State Percentage of PWSs with At Least
One Detection Equal to or Above the MRL (> 4 |ig/L) Based on the Updated UCMR
1 Perchlorate Data set 35
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Exhibit 18: System-level Geographic Distribution of Perchlorate -Systems With Detections
Greater than 18 ng/L, 56 ng/L, and 90 ng/L Based on the Updated UCMR 1
Perchlorate Data set 36
Exhibit 19: Comparison of EPA Analytical Methods for the Analysis of Perchlorate in
Drinking Water 39
Exhibit 20: Cost Estimates of Laboratory Analytical Methods for Perchlorate 41
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Appendices
Appendix A: Occurrence in Ambient Water and in Drinking Water (from Sources Other than
UCMR 1)
Appendix B: Data Quality Considerations from the Chamber of Commerce
Appendix C: UCMR 1 Perchlorate Detections with Source Water Detection Categories
Identified
Appendix D: Updated UCMR 1 State-Level Occurrence Measures
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Abbreviations
ADEQ
Arizona Department of Environmental Quality
AMS
Alfred Merritt Smith Treatment Plant
ASTSWMO
Association of State and Territorial Solid Waste Management Officials
ATSDR
Agency for Toxic Substances and Disease Registry
AWS
American Water System
AWWA
American Water Works Association
AwwaRF
American Water Works Association Research Foundation
BBDR
Biologically Based Dose Response
CAEPA
California Environmental Protection Agency
CA OEHHA
California's Office of Environmental Health Hazard Assessment
CA UCRM
California's Unregulated Chemicals Requiring Monitoring
CAP
Central Arizona Project
CASRN
Chemical Abstract Services Registry Number
CCL
Contaminant Candidate List
CCR
Consumer Confidence Report
CDHS
California Department of Health Services
CDPH
California Department of Public Health
CWS
Community Water System
DL
Detection Limit
DQO
Data Quality Objective
DWP
Drinking Water Program
EP
Entry Point
EPA
Environmental Protection Agency
EPA STORET
EPA Storage and Retrieval (Data Warehouse)
EWG
Environmental Working Group
HRRCA
Health Risk Reduction and Cost Analysis
IASWRL
Iowa Statewide Rural Well Water Survey
IC
Ion Chromatography
LC
Liquid Chromatography
LCMRL
Lowest Concentration Minimum Reporting Level
LIWC
Long Island Water Conference
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MassDEP
Massachusetts Department of Environmental Protection
MCL
Maximum Contaminant Level
MCLG
Maximum Contaminant Level Goal
MDL
Method Detection Limit
MEG
Maximum Exposure Guidelines
MRL
Minimum Reporting Level
MS
Mass Spectrometry
MWD
Metropolitan Water District
NAWQA
National Water-Quality Assessment
NDEP
Nevada Division of Environmental Protection
NHANES
National Health and Nutrition Examination Survey
NJDEP
New Jersey Department of Environmental Protection
NJDWQI
New Jersey Drinking Water Quality Institute
NMED
New Mexico Environment Department
NPDWR
National Primary Drinking Water Regulation
NRC
National Research Council
NTNCWS
Non-Transient Non-Community Water System
NWIS
National Water Information System
OGWDW
Office of Ground Water and Drinking Water
PHG
Public Health Goal
PPM
Parts Per Million
PSV
Preliminary Screening Values
PWS
Public Water System
PWSID
Public Water System Identification Number
QA
Quality Assurance
QAPP
Quality Assurance Project Plan
QC
Quality Control
RL
Reporting Level
RM
River Mountains Treatment Plant
RSD
Relative Standard Deviation
SCDHS
Suffolk County Department of Health Service
SCWA
Suffolk County Water Authority
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SDWA
Safe Drinking Water Act
SIM
Selective Ion Monitoring
SNWS
Southern Nevada Water System
SR
Source Water
TCEQ
Texas Commission on Environmental Quality
TDS
Total Dissolved Solids
TNCWS
Transient Non-Community Water System
TRI
Toxics Release Inventory
UC MR 1
Unregulated Contaminant Monitoring Rule 1
USGAO
United States Government Accountability Office
USGS
United States Geological Survey
WaterRF
Water Research Foundation
WSSC
Washington Suburban Sanitary Commission
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1 Introduction
This occurrence and monitoring report describes the data and analyses used by the U.S.
Environmental Protection Agency (EPA) to develop national estimates of perchlorate occurrence
in public drinking water systems. Additional supplemental perchlorate occurrence background
information and data were also reviewed. The information, data, and analyses described in this
report are organized into six chapters and five appendices with a brief description of each chapter
and appendix presented below.
• Chapter 1: The Introduction provides the regulatory history of perchlorate in the
context of public drinking water and a summary of state drinking water standards and
guidance levels.
• Chapter 2: Perchlorate Background provides information on perchlorate chemical and
physical properties, sources of perchlorate, environmental fate, and laboratory analytical
methods.
• Chapter 3: Perchlorate Occurrence Data from the Unregulated Contaminant
Monitoring Rule 1 (UCMR 1) presents background information on the UCMR 1
Perchlorate Data set, as well as the quality assurance / quality control (QA/QC) review of
those data.
• Chapter 4: Analysis of the UCMR 1 Occurrence Data discusses the non-parametric
approach for analyzing the occurrence data and presents results based on that analysis.
• Chapter 5: Laboratory Analytical Methods discusses the analytical methods used in
the identification and quantification of perchlorate in drinking water.
• Chapter 6: References is a list of the cited and supporting scientific literature used in
development of the document.
• Appendix A presents occurrence data compiled by states and other organizations for
perchlorate from a variety of ambient water and non-UCMR 1 drinking water sources.
• Appendix B provides a summary of considerations for additional data quality measures
related to comments from the Chamber of Commerce, as well as a comparison of current
perchlorate data from the State of California with California UCMR 1 perchlorate data.
• Appendix C presents the public water system inventory and other background details
regarding UCMR 1 perchlorate detections from source water samples and samples from
entry points to the distribution systems as discussed in Section 3.4.2.
• Appendix D provides a summary of monitoring results and occurrence analyses by state
based on the Updated UCMR 1 Perchlorate Data set.
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1.1 SDWA Statutory Requirements and Rulemaking Process for Perchlorate in
Drinking Water
The Safe Drinking Water Act (SDWA) Sections 1412(b)( 1 )-(6) and (15) describe
requirements for regulating drinking water contaminants. The United States Environmental
Protection Agency (EPA) included perchlorate on the first, second, and third Contaminant
Candidate Lists (CCLs) that were published in the Federal Register on March 2, 1998, February
24, 2005, and October 8, 2009, respectively (USEPA, 1998; USEPA, 2005a; USEPA, 2009a).
On May 1, 2007, the EPA published an update on the agency's evaluation of perchlorate as part
of the preliminary regulatory determination for 11 other CCL 2 contaminants (72 FR 24016;
USEPA, 2007a). The agency did not made a preliminary determination for perchlorate at that
time. However, the agency requested public comment on the information included in the notice
and on the options that the agency was evaluating, it also requested information that could assist
the agency in its decision-making process.
On October 10, 2008, the EPA published a preliminary regulatory determination for
perchlorate (73 FR 60262; USEPA, 2008a), requesting public comment on its determination that
development of a National Primary Drinking Water Regulation (NPDWR) for perchlorate would
not present a meaningful opportunity for health risk reduction for persons served by public water
systems (PWSs). The October 2008 notice describes in detail the EPA's basis for its preliminary
regulatory determination.
On January 8, 2009, the EPA (USEPA, 2009b) announced that it was seeking advice
from the National Academy of Sciences (NAS) before making a final determination on whether
to issue a national regulation for perchlorate in drinking water. In conjunction with that
announcement, the EPA also issued an interim health advisory of 15 parts per billion (ppb or
|ig/L) to assist state and local officials in addressing local contamination of perchlorate in
drinking water and making a corresponding change to the factors considered in cleaning up
Superfund sites.
On August 19, 2009 (74 FR 41883; USEPA, 2009c), the EPA published the Perchlorate
Supplemental Request for Comments and stated that it was not, at that time, planning to request
additional National Research Council (NRC) review of issues related to perchlorate. Instead, the
EPA requested comment on additional approaches to analyzing data related to the EPA's
perchlorate regulatory determination. These additional comments were sought in an effort to
ensure consideration of all potential options for evaluating whether there is a meaningful
opportunity for human health risk reduction of perchlorate through an NPDWR. The EPA stated
that the alternative analyses (e.g., alternative health reference levels based on body weight and
water consumption of 12 life stages ranging from birth to less than 21 years old) presented in the
notice could lead the agency to make a determination to regulate perchlorate.
On February 11, 2011 (76 FR 7762; USEPA, 201 la), the EPA announced its decision to
regulate perchlorate under the SDWA based on its finding that perchlorate meets the SDWA's
three criteria for regulating a contaminant: 1) the contaminant may have an adverse effect on the
health of persons, 2) the contaminant is known to occur or there is a substantial likelihood that
the contaminant will occur in PWSs with a frequency and at levels of public health concern, and
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3) in the sole judgment of the Administrator, regulation of such contaminant presents a
meaningful opportunity for health risk reduction for persons served by PWSs.
On May 29, 2013, the EPA Science Advisory Board (SAB) recommended that the EPA,
as part of its development of a regulation for perchlorate, derive a perchlorate Maximum
Contaminant Level Goal (MCLG) through the use of a physiologically-based pharmacokinetic/
pharmacodynamic model based upon perchlorate's mode of action regarding human health. The
findings of this modeling are to be applied toward the development of a Maximum Contaminant
Level (MCL). The EPA collaborated with the Food and Drug Administration to implement the
SAB recommendations and conduct the modeling.
To address the SAB recommendations, the EPA created Biologically Based Dose
Response (BBDR) models that predicts changes in thyroid hormone levels as a result of
nutritional iodine intake and perchlorate exposure in women prior to pregnancy and early
gestation. These models were peer reviewed in January 2017.4 Reviewers stressed the
importance of developing an early pregnancy model when considering adverse
neurodevelopmental impacts. The EPA responded to this peer review by developing an early
pregnancy model and updated key parameters for that model.
The EPA carried out a subsequent peer review January 2018 to evaluate updates to the
BBDR model and presented the alternative approaches that link the revised perchlorate BBDR
model predictions to neurodevelopmental effects. The January 2018 peer review was largely
supportive of the efforts described in the EPA's report titled "Proposed Approaches to Inform the
Derivation of a Maximum Contaminant Level Goal for Perchlorate in Drinking Water."
When proposing an MCL, the EPA must publish, and seek comment on, the Health Risk
Reduction and Cost Analysis (HRRCA) of each alternative MCL considered (SDWA Section
1412(b)(3)(C)(i)). This includes the quantifiable and non-quantifiable benefits from reductions in
health risk, including those from removing co-occurring contaminants (not counting the benefits
resulting from compliance with other proposed or final regulations); costs of compliance (not
counting costs resulting from other regulations); any increased health risks (including those from
co-occurring contaminants) that may result from compliance; and incremental costs and benefits
of each alternative MCL considered.
1.2 State Standards and Guidelines for Perchlorate in Drinking Water
There also have been state actions on perchlorate standards, guidelines, and advisories. In
2006, Massachusetts adopted a drinking water standard for perchlorate of 2 |ig/L, and in 2007,
4 Biologically Based Dose Response Models for the Effect of Perchlorate on Thyroid Hormones in the Infant, Breast
Feeding Mother, Pregnant Mother, and Fetus: Model Development, Revision, and Preliminary Dose-Response
Analysis. The report is available through the docket at http://www.regulations.gov (Docket ID No. EPA-HQ-OW-
2016-0439).
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California promulgated a drinking water standard of 6 |ig/L.5 Other states have established non-
enforceable guidance levels, action or advisory levels.
Exhibit 1 presents a summary of the state standards and guidance levels for perchlorate in
drinking water and Exhibit 2 presents a summary of the state guidance levels for perchlorate in
ground water. Depending on the state, a particular level may require a PWS to notify the public,
serve as a screening tool for further action, or guide clean-up actions.
Exhibit 1: Summary of State Standards and Guidance Levels for Perchlorate in
Drinking Water
State
Level
(ng/L)
Description
State Drinking Water Standards
California
6
Existing MCL
Massachusetts
2
Existing MCL
State Drinking Water Guidance, Action or Advisory Levels12 3
Arizona
14
Health-based guidance level (USEPA Region 9, 2016)
Hawaii
15
Action level for drinking water (HI DOH, 2017)
Maine
0.8
Maximum Exposure Guidelines (MEG) for Drinking Water (ME DHHS, 2016)
Maryland
1
Advisory Level (ASTSWMO, 2011; Harford County Government, 2007)
Nevada
18
Provisional action level based upon EPA guidance (NDEP, 2012)
New Jersey
5
Interim Ground Water Quality Criteria (NJ DEP, 2016)
New Mexico
1
Drinking Water Guidance Level (ASTSWMO, 2011)
13.8
Tap water screening level (NMED, 2014)
New York
5
Drinking Water Planning Level (ASTSWMO, 2011)
18
State Guidance Level (NY DOH, 2010)
Oregon
4
Recommended Action Level (OR DHS, 2004)
Vermont
4
Interim enforcement standard (ASTSWMO, 2011)
Adapted from the United States Government Accountability Office (USGAO) (2010) and Association of State and
Territorial Solid Waste Management Officials (ASTSWMO) (2011).
1 A "Preliminary Screening Value" (PSV) of 24.5 ng/L in Alabama had been cited in ASTSWMO (2011). However, that
value can no longer be verified.
2 A "drinking water threshold level" and "interim action level" of 4 ng/L in Kansas and Texas, respectively, had been
cited in USGAO (2010). However, these values can no longer be verified.
3 In a self-published, non-peer-reviewed study by Integral Consulting (2016), additional and/or updated state
advisories for perchlorate were noted, including: Iowa, with an advisory level of 4.9 ng/L; New Hampshire, with a
public health goal of 1 ng/L and; Vermont, with an advisory level of 2.2 ng/L. These advisories are not included on the
drinking water-related websites of these three states.
5 In January 2011, the State of California proposed a Public Health Goal (PHG) of 1 |ig/L for perchlorate. The
existing California MCL is based on an earlier California 2004 PHG of 6 |ig/L (CA EPA, 2011). In February 2015,
CA's Office of Environmental Health Hazard Assessment (CA OEHHA) released final technical support document
for the 1 |ig/L PHG for perchlorate (CA EPA, 2015).
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Exhibit 2: Summary of State Guidance Levels for Perchlorate in Ground Water
State
Level
(ng/L)
Description
State Guidance, Action or Advisory Levels for Perchlorate in Ground Water1
Alaska
14
Groundwater clean-up level for perchlorate (AK DEC, 2019)
Florida
4
Clean-up target level for potable water (This level, established in regulation, is not a
standard but serves as a default level for contaminated site clean-ups. Alternative levels
may be used where there is sufficient site-specific information.) (FL Department of the
State, 2005)
40
Clean-up target level for ground water of low yield or poor quality (This level, established
in regulation, is not a standard but serves as a default level for contaminated site clean-
ups. Alternative levels may be used where there is sufficient site-specific information.)
(FL Department of the State, 2005)
Hawaii
26
Action levels for ground water that could be a source of drinking water (HI DOH, 2017)
600
Action levels for ground water not used as a source of drinking water (HI DOH, 2017)
Iowa
15
Statewide Standards for a Protected Groundwater Source (IA DNR, 2019)
75
Statewide Standards for an Unprotected Groundwater Source (IA DNR, 2019)
Kansas
10.9
Default risk-based clean-up level for residential or drinking water pathway (KDHE, 2015)
70.9
Default risk-based clean-up level for nonresidential pathway (KDHE, 2015)
Maryland
15
Groundwater clean-up standards for Type I and II Aquifers (MDE, 2018)
Missouri
10.9
Groundwater Target Concentrations at Point of Exposure (MO DNR, 2006)
Nebraska
15
Voluntary Clean-up Program Remediation Goals (NDEQ, 2018)
Nevada
18
Provisional action level used as default clean-up level for all ground water (NDEP, 2012)
New Mexico
4-18
Ground water clean-up level (NMED, 2004)
Texas
17
Protective clean-up level for residential land use (TCEQ, 2018)
51
Protective clean-up level for industrial/commercial land use (TCEQ, 2018)
Vermont
2
Interim preventive action level (VT DEC, 2015)
4
Interim enforcement standard; interim groundwater quality standard. (This level is
considered guidance, despite its being termed a "standard.") (VT DEC, 2015)
Wisconsin
0.1
Public health ground water quality standard — preventive action limit (Wl Administrative
Code, 2017)
1
Public health ground water quality standard — enforcement standard (Wl Administrative
Code, 2017)
Adapted from USGAO (2010) and ASTSWMO (2011).
1 A "Preliminary Screening Value" (PSV) of 24.5 ng/L in Alabama had been cited in ASTSWMO (2011). However, that
value can no longer be verified.
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2 Perchlorate Background
This section summarizes background on perchlorate including its chemical and physical
properties; sources; environmental fate and transport of the perchlorate ion; and laboratory
analytical methods.
2.1 Chemical and Physical Properties
Perchlorate is an inorganic chemical containing one chlorine atom bound to four oxygen
atoms in a tetrahedral configuration (see Exhibit 3). As such, perchlorates (ClO/f) are a group of
anions that form salts with most cations.
Exhibit 3: Chemical Structure of Perchlorate
0
0= CI — 0-
0
Figure based on information from the Hazardous Substances Data Bank (HSDB), 2012.
Commonly used perchlorate salts include ammonium perchlorate and potassium
perchlorate. Perchlorate is also used as a component of sodium perchlorate, aluminum
perchlorate, hydrazine perchlorate, hydrogen perchlorate, hydroxylammonium perchlorate,
lithium perchlorate, magnesium perchlorate, nitronium perchlorate, and as perchloric acid. As an
anion, there is no single Chemical Abstracts Service Registry Number (CASRN) for perchlorate,
as each salt has its own properties. Registry numbers for the most common forms of perchlorate
and their chemical and physical properties are presented in Exhibit 4.
Exhibit 4: Physical and Chemical Properties
Property
Data
Perchlorate
Ammonium
perchlorate
Potassium
perchlorate
Sodium perchlorate
CASRN
14797-73-0
7790-98-9
7778-74-7
7601-89-0
Chemical Formula
CI04"
NH4CIO4
KCIO4
NaCICM
Molecular Weight
99.45 g/mol
(ChemlDPIus, 2011)
117.49 g/mol (Merck,
1983)
138.55 g/mol (Merck,
1983)
122.44 g/mol (Merck,
1983)
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Property
Data
Perchlorate
Ammonium
perchlorate
Potassium
perchlorate
Sodium perchlorate
Color/ Physical State
-
Colorless or white
orthorhombic crystals
(Hazardous Substances
Data Bank [HSDB],
2011)
Colorless
orthorhombic crystals
or white crystalline
powder (HSDB, 2011;
Agency for Toxic
Substances and
Disease Registry
[ATSDR], 2008;
Merck, 1983)
White orthorhombic,
deliquescent crystals
(HSDB, 2011; CRC
Press, 1981; Merck,
1983)
Boiling Point
-
-
400 deg C dec. (CRC
Press, 1981)
-
Melting Point
-
130 deg C (ATSDR,
2008)
400 deg C dec.
(ATSDR, 2008); 525
deg C (HSDB, 2011)
471 deg C dec.
(ATSDR, 2008) 482
deg C dec (CRC
Press 1981); 480
deg C dec. (HSDB,
2011)
Density
-
1.95 g/mL (CRC Press,
1981; Merck, 1983)
2.52 g/mL at 10 deg C
(CRC Press, 1981;
Merck, 1983)
2.52 g/cm3 (HSDB,
2011); 2.02 g/mL
(Merck, 1983;
ATSDR, 2008)
Vapor Pressure
-
Very low (ATSDR,
2008)
Very low (ATSDR,
2008)
Very low (ATSDR,
2008)
Solubility in Water
-
200 g/L at 25 deg C
(HSDB, 2011); 249 g/L
at 25 deg C (ATSDR,
2008)
20.6 g/L at 25 deg C
(ATSDR, 2008); 15 g/L
at 25 deg C (HSDB,
2011)
2100 g/L at 25 deg C
(HSDB, 2011;
ATSDR, 2008)
Other Solvents
-
Acetic acid, slightly
soluble alcohol (CRC
Press, 1981); methanol,
slightly soluble ethanol
and acetone, very
slightly soluble ethyl
acetate and ether
(HSDB, 2011)
Very slightly soluble
alcohol (CRC Press,
1981); insoluble in
alcohol and ether
(HSDB, 2011)
Alcohol (CRC Press,
1981)
g/mol = grams per mole;" indicates that no information was found; deg C = degrees Celsius; dec. = decomposes;
g/mL = grams per milliliter; g/cm3 = grams per cubic centimeter; g/L = grams per liter
2.2 Sources of Perchlorate
Perchlorate is both a naturally occurring and man-made chemical. The following section
presents information on perchlorate's natural sources; its production and anthropogenic sources;
and environmental fate and transport when naturally occurring or man-made perchlorate is
present in soil and/or water.
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2.2.1 Natural Sources
Caliche ores, found in Chile, rich in sodium nitrate (NaNCb), are a natural source of
perchlorate (USEPA, 2001a). This sodium nitrate (known as Chilean saltpeter) has been mined
and refined to produce commercial fertilizers used in the United States. Perchlorate has also been
found in other geologic materials. Orris et al. (2003) measured perchlorate at levels exceeding
1,000 parts per million (ppm or mg/kg) in several samples of natural minerals, including potash
ore from New Mexico and Saskatchewan, Canada; playa crust from Bolivia; and hanksite from
California.
Rao et al. (2007) found widespread, naturally-occurring perchlorate in diverse
unsaturated zones (just below the root zone) in arid and semi-arid regions of Nevada, New
Mexico, Texas and Utah. It was postulated that the amount of naturally-occurring perchlorate in
aggregate is sufficiently large to affect groundwater when recharge percolates through these
unsaturated zones. The perchlorates and other salts (e.g., chlorides) in this region are present due
to atmospheric deposition and concentration through evaporation over thousands of years.
Walvoord et al. (2003) as cited in Trumpolt et al. (2005) presents the theory that chlorides from
land and sea are blown into the atmosphere where they react photochemically with ozone to
produce perchlorate in a process similar to that which produces nitrate. Plummer et al. (2005) as
cited in Rao et al. (2007) cite meteoric events as potential natural sources of perchlorate.
Dasgupta et al. (2005) detected perchlorate in many rain and snow samples and
demonstrated that perchlorate is formed by a variety of simulated atmospheric processes
suggesting that natural, atmospherically derived perchlorate exists in the environment. Barron et
al. (2006) developed a method for the rapid determination of perchlorate in rainwater samples,
with a detection limit (DL) between 70 and 80 ng/L. Of 10 rainwater samples collected in Ireland
in 2005, perchlorate was detected in 4 samples at concentrations between 0.075 [j,g/L and 0.113
[j,g/L, and in 1 other sample at 2.8 |ig/L, Kang et al. (2006) conducted seven-day experiments to
determine if it was possible to produce perchlorate by exposing various chlorine intermediates to
UV radiation in the form of high intensity UV lamps and/or ambient solar radiation. Perchlorate
formation was demonstrated in aqueous salt solutions with initial concentrations of hypochlorite,
chlorite, or chlorate between 100 and 10,000 mg/L.
2.2.2 Production and Use
While perchlorate has a wide variety of industrial uses, it is primarily used in the form of
ammonium perchlorate as an oxidizer in solid fuels used to power rockets, missiles, and
fireworks. Perchlorate can also be present in road flares, lubricating oils, matches, aluminum
refining, rubber manufacturing, paint and enamel manufacturing, leather tanning, and as a dye
mordant.
As noted above, Chilean saltpeter has been mined and refined to produce commercial
fertilizers. Before 2001, these accounted for about 0.14% of fertilizer application in the United
States (USEPA, 2001a). USEPA (2001a) conducted a broad survey of fertilizers and other raw
materials and found that all products surveyed were devoid of perchlorate except for those
known to contain or to be derived from mined Chilean saltpeter.
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Historically, American Pacific Corporation and Kerr-McGee were the major producers of
ammonium perchlorate. Their perchlorate production took place at facilities in Nevada and Utah.
Smaller manufacturers located in New York, Oregon, Mississippi, and California ceased
production between 1948 and 1975. Kerr-McGee ceased ammonium perchlorate production in
July 1998 (Nevada Division of Environmental Protection [NDEP], 2011).
No production data on this contaminant are available from the EPA's Inventory Update
Reporting program, and no industrial release data are available from the EPA's Toxics Release
Inventory (TRI). The list of chemicals for which TRI reporting is required has never included
perchlorate (USEPA, 2011b).
The Agency for Toxic Substances and Disease Registry (ATSDR) (2008) reports that
recent production data for ammonium perchlorate as well as the other forms of perchlorate listed
in Exhibit 4 are lacking. In 1994, U.S. production of ammonium perchlorate was estimated at 22
million pounds (Mendiratta etal., 1996).
Sodium hypochlorite (NaOCl) is effectively used for water disinfection. However,
perchlorate has been detected in hypochlorite solutions. A study by the American Water Works
Association and Water Research Foundation (AWWA/WaterRF, 2009) found that perchlorate
can be present in hypochlorite solutions and can continue to form with the rate of formation
depending on storage conditions. The study found that to minimize perchlorate formation sodium
hypochlorite should be stored in dark and cool conditions, diluted if possible, and used within a
few weeks of manufacture.
In an earlier limited study, the Massachusetts Department of Environmental Protection
(MassDEP) found that perchlorate may be present in sodium hypochlorite solutions used in
water and wastewater treatment plants, and that the level of perchlorate occurrence depends upon
storage conditions and the initial purity of the stock solution (MassDEP, 2006a). The Town of
Tewksbury, Massachusetts conducted a small study to evaluate the impact of storage conditions
(temperature and light) on a new shipment of sodium hypochlorite stock solution. Perchlorate
concentrations in the new stock solution were found to increase from 0.2 [j,g/L to levels ranging
from 995 [j,g/L to 6,750 (J,g/L, depending on the storage conditions. Accounting for the large
dilution factor (e.g., 20,000 to 1 ratio) used in chlorination processes at drinking water treatment
plants, MassDEP (2006a) concluded that "absent additional efforts to minimize breakdown of
hypochlorite solutions, it would appear that low levels of the perchlorate ion (0.2 [j.g/L to 0.4
(j,g/L) detected in a drinking water supply disinfected with sodium hypochlorite solutions could
be attributable to the chlorination process."
It is not clear at this time what proportion of perchlorate found in public water supplies or
entering the food chain comes from these various natural and anthropogenic sources. The
significance of different sources likely varies regionally. A study by Dasgupta etal. (2006)
analyzes the three principal sources of perchlorate and their relative contributions to the food
chain. These include use as an oxidizer including rocket propellants, Chilean saltpeter used
principally as fertilizer, and perchlorate produced by natural atmospheric processes. Dasgupta et
al. (2006) concluded that while there may be some localized exceptions, fertilizer with Chilean
saltpeter likely has an equal or greater contribution to the food chain than oxidizer contributions
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(not including fireworks). Contributions of perchlorate by natural processes are generally even
less.
2.3 Environmental Fate and Transport of the Perchlorate Ion
Perchlorate salts are highly soluble in water, and because perchlorate sorbs poorly to
mineral surfaces and organic material, perchlorate is mobile in soil and aqueous environments
(ATSDR, 2008; USEPA, 2002).
Most perchlorate salts exposed to water will readily dissolve and dissociate into the
cation and perchlorate anion (Gullick et al., 2001). The perchlorate ion is unlikely to form
insoluble metal complexes in water or be removed from water in this manner (Cotton and
Wilkinson, 1980). The perchlorate ion is very stable and inert to reduction despite the high
oxidation state of chlorine (Urbansky, 2000). Ionized salts will not undergo hydrolysis and
perchlorates are not expected to undergo direct photolysis or to volatilize in water (ATSDR,
2008; HSDB, 2011). Therefore, the ion may persist for decades under normal environmental
conditions in ground water and surface water (Gullick et al., 2001).
Biological removal and uptake of perchlorate has been observed in aquatic conditions.
Anaerobic microbial biodegradation of perchlorate occurs in anoxic ground water and sediments
(ATSDR, 2008). In the absence of nitrate and with influent perchlorate concentrations of up to
32 mg/L, wetlands have been shown to reduce perchlorate concentrations to less than 4 |ig/L
(Tan et al., 2004). In a study of willow trees in sand bioreactors designed to remove perchlorate
from contaminated water, 11% of the original perchlorate concentration measured throughout the
whole tree was lost to degradation (to chloride) in the leaves (Nzengung et al., 1999). Aquatic
organisms have also demonstrated uptake of perchlorate. One lake study found an indication of
food transfer of perchlorate from ingestion of contaminated periphyton, detritus, or invertebrates
(Theodorakis et al., 2006). However, another study found that, in aquatic organisms,
bioconcentration of perchlorates is low (Dean et al., 2004). For a detailed discussion on the
biological treatment of perchlorate, see the EPA's report entitled, "Technologies and Costs for
Treating Perchlorate-Contaminated Waters."
The perchlorate ion is unlikely to adsorb to soil since studies show that in solutions of
moderate ionic strength, the perchlorate ion is only weakly adsorbed to mineral surfaces (Logan,
2001; Urbansky and Brown, 2003; Urbansky and Collette, 2001). Therefore, perchlorate will be
highly mobile in soil, traveling over the soil with surface water runoff or migrating through the
soil to ground water systems (ATSDR, 2008; Gullick et al., 2001). This has been corroborated
by studies that have measured perchlorate in surface water and ground water far from release
sites (ATSDR, 2008). While perchlorate is not subject to volatilization (partitioning to the
gaseous or vapor phase) to any significant extent, it may be transported to the atmosphere by
mechanical means: e.g., wind-borne erosion of perchlorate aerosols (fine particles in the solid
phase) and perchlorate-contaminated soil particles (ATSDR, 2008).
Removal of perchlorate from the soil by living organisms has been shown to occur
through microbial degradation as well as plant uptake and degradation (ATSDR, 2008; Tipton et
al., 2003). Anaerobic microbial degradation in soil has been seen in both laboratory and in situ
studies; however, soil type and the presence of nitrate will influence the rate of degradation
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(Herman and Frankenberger, 1998; Logan, 1998; Tan et al., 2004). In one experimental study,
perchlorate in Yolo loam fully degraded in 30 days while no degradation occurred in Columbia
loam (Tipton et al., 2003). Both soil samples were three years old. The authors inferred that
carbon-rich Yolo loam had preserved colonies of perchlorate-digesting bacteria better than the
carbon-poor Columbia loam, and viewed their results as confirming the importance of
biodegradation (and the relative unimportance of adsorption) as a fate process for perchlorate in
soil. A study of sediment and soil from two Texas sites contaminated by perchlorate showed that
degradation in the soil and sediments did not readily occur until most of the nitrate had degraded
(Tan et al., 2004). A study of perchlorate uptake by tobacco showed that through a wide range of
soil perchlorate concentrations, uptake and accumulation occurred but there were not enough
data available to show whether or not the plant degraded the perchlorate (Ellington et al., 2001).
Perchlorate uptake in plants has also been observed in salt cedar, cucumber, lettuce, and soybean,
though nutrients such as nitrate may hinder the uptake of perchlorate (Urbansky et al., 2000; Yu
et al., 2004).
Perchlorate salts released to the atmosphere are expected to exist adsorbed to particulate
matter or as solid aerosols (ATSDR, 2008). Removal is likely to occur through deposition not
degradation since reaction with gas-phase oxidants and photolysis is unlikely (ATSDR, 2008). A
study investigating perchloric acid photolysis in the atmosphere found photolysis to be negligible
(Jaegle etal., 1996).
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3 Perchlorate Occurrence Data in Unregulated Contaminant Monitoring
Rule 1
This section describes the UCMR 1 perchlorate occurrence data set used by the EPA to
generate national estimates of perchlorate occurrence in drinking water. The agency determined
that the best available source of perchlorate occurrence data in drinking water is the EPA
administered UCMR 1. UCMR 1 is the only nationally representative drinking water monitoring
program that has sampled for perchlorate. This section provides an overview of the UCMR
program and the first UCMR monitoring cycle, UCMR 1. Details are provided to characterize
the UCMR 1 data including sampling schedule, frequency, locations, system source water types
and size, and the perchlorate laboratory analytical method used. See Section 4 for a more
detailed discussion of the perchlorate occurrence analysis conducted using the UCMR 1 data.
In addition to the UCMR 1 data, the EPA evaluated numerous national-scale studies and
surveys, and state-sponsored studies of perchlorate occurrence in drinking water and ambient
water, Appendix A presents a summary of these data sets. System compliance data from the
State of California is described in detail in Appendix B.
3.1 UCMR 1 Program Overview
In 1999, the EPA developed the UCMR program in coordination with the Contaminant
Candidate List (CCL) and the National Drinking Water Contaminant Occurrence Database to
provide national occurrence information on unregulated contaminants (64 FR 50556, USEPA,
1999d; 65 FR 11372, USEPA, 2000; and 66 FR 2273, USEPA, 2001b). UCMR 1 established a
three-tiered approach for monitoring contaminants based on the availability of analytical
methods and information on contaminant properties. The first tier and highest priority of the
three-tier ranking system, designated as List 1, included perchlorate and other unregulated
contaminants for which suitable laboratory methods are available; these were scheduled to
undergo full "Assessment Monitoring."
The UCMR operates on a five-year cycle, with the first cycle extending from 2001
through 2005, although most monitoring was conducted from 2001 to 2003. For UCMR 1, the
EPA required all PWSs serving more than 10,000 people ("large" systems), plus a statistically
representative national sample of 800 PWSs serving 10,000 people or fewer ("small" systems),
to conduct Assessment Monitoring of List 1 contaminants (USEPA, 2001c). Approximately one-
third of the participating small systems were scheduled to monitor List 1 contaminants during
each calendar year from 2001 through 2003. Large systems could conduct one year of
monitoring for List 1 contaminants anytime during the 2001-2003 UCMR 1 period.
The UCMR 1 program design, including system selection and overall monitoring
approach, was peer reviewed (USEPA, 1999e). The program was designed expressly to provide
nationally representative occurrence data for unregulated contaminants in public drinking water
systems..6 There is no nationally representative alternative to the UCMR 1 data. The EPA
6 See USEPA (2005e), USEPA (2007b), and USEPA (2008b) for more information on all aspects of UCMR 1,
including study design, completeness, and quality assurance/quality control procedures.
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selected PWSs to conduct monitoring for the UCMR 1 program based on the number of people
they serve, the source of their water, and whether they serve the same customers year-round. All
large community water systems (CWSs) and non-transient non-community water systems
(NTNCWSs), as well as a national sample of 800 small CWSs and NTNCWSs were required to
conduct monitoring under the UCMR 1. Two categories of PWSs were exempt from UCMR 1
monitoring: PWSs that purchase their entire water supply from another PWS and transient non-
community water systems (TNCWSs). For more details on the classification of public drinking
water systems, go to: http://water.epa.gov/infrastructure/drinkingwater/pws/factoids.cfm.
The objective of the UCMR 1 sampling approach for small systems was to collect
contaminant occurrence data from a statistically selected, nationally representative sample of
systems. Small system sampling was stratified and population-weighted, and included some
sampling adjustments such as selection of at least two systems from each state. As previously
stated, with contaminant monitoring data from all large PWSs and a nationally representative
sample of small PWSs, the UCMR 1, List 1 Assessment Monitoring program is nationally
representative of contaminant occurrence in public drinking water systems and therefore is
suitable for national estimates of perchlorate occurrence in public drinking water systems.
Perchlorate occurrence is known to have decreased in some important source waters
(such as the Lower Colorado River) and in the two states (Massachusetts and California) that
now regulate perchlorate in drinking water. (These important cases are discussed in Appendix A
and Appendix B of this report.) However, because perchlorate remains unregulated and largely
unmonitored across most of the United States, other locations, areas and regions have no newer
comparable data (and across these other regions perchlorate occurrence could have stayed about
the same, increased or decreased). Therefore, to conduct a consistent and statistically sound
assessment of national perchlorate occurrence in public drinking water systems, the EPA is using
a modified UCMR 1 data set in this report.
3.2 Monitoring Frequency and Location
UCMR 1 required surface water systems to sample four times at each entry point to the
distribution system (or entry point) over a one-year period, while ground water systems were
required to sample twice per entry point over a one-year period. One of the quarterly (surface
water systems) or semi-annual (ground water systems) sampling events had to occur in the
defined vulnerable.7 period of May through July, or an alternate vulnerable period designated by
the state, to ensure monitoring of potentially higher contaminant concentrations. Surface water
systems had to select either the first, second, or third month of a quarter and then take the
remaining samples at three-month intervals for the following three quarters of the monitoring
year. Ground water systems were required to designate a sample collection during one of the
most vulnerable months, and then schedule another sample collection within five to seven
months.
7 For UCMR 1, a vulnerable period is 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.
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PWSs sampled at entry points after treatment. These entry points were meant to be
representative of each principal non-emergency source of water in use over the 12-month
monitoring period. UCMR 1 explicitly allowed source water monitoring, under certain
conditions. As the EPA stated in the Federal Register on September 17, 1999, "In response to
public comment, the EPA modified the rule [from the proposal] to allow alternative sampling
points to be used: sampling points identified by the State for compliance monitoring under 40
CFR 141.24(f)(1), (2), and (3), and/or source (raw) water sampling points, if the State uses
source water monitoring as a more stringent monitoring requirement" (64 FR 50570; USEPA,
1999d). The EPA also stated that "If monitoring at source (raw) water sampling points indicates
detection of any of the contaminants on the monitoring list, then the system in most cases will be
required to shift its unregulated contaminant monitoring to the entry point to the distribution
system. These flexibilities in the sampling location should enable systems and States to
coordinate compliance and unregulated contaminant monitoring more extensively."
The EPA designed the UCMR 1 program with geographic, geologic, and temporal
variability in mind. A census of all large systems and a primarily population-weighted statistical
sample of small systems ensured monitoring across the varied geography and geology of the
country. An additional program requirement was the selection for monitoring of at least two
small systems in each state. The study design addressed temporal variability in contaminant
occurrence by defining a vulnerable period and requiring at least one UCMR 1 sample at each
system during that period. In this way, the national UCMR 1 results reflect multiple seasons and
multiple years across the country and therefore are not biased by weather conditions of a single
season, year, or geographic region.
Exhibit 5 illustrates the monthly distribution of ground water and surface water
perchlorate sampling events. Ground water sampling events, which were conducted biennially,
were concentrated 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.
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Exhibit 5: Number of PWSs Collecting UCMR 1 Ground Water (GW) and Surface
Water (SW) Samples for Perchlorate Analysis by Month During the Sampling
Period (Top: GW Systems; Bottom: SW Systems)
300
E
o
¦*-<
>.
CO
250
200
150
100
50
Groundwater Systems
0
Jan-00
Jan-01 Jan-02 Jan-03 Jan-04
Sampling Period
Jan-05
Surface Water Systems
o 300
nilnniinii
Jan-00 Jan-01 Jan-02 Jan-03
Sampling Period
Jan-04
Jan-05
Exhibit 6 is a map of all large and small systems that submitted UCMR 1 data to the
EPA. 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.
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Exhibit 6: PWSs with UCMR 1 Monitoring Results
Small
systems
systems
3.3 Completeness of UCMR 1 Perchlorate Data set
To ensure that occurrence estimates based on UCMR 1 data dependably reflect national
conditions, the EPA assessed the completeness and representativeness of the UCMR 1
contaminant sample data. Background discussions of data quality issues can be found in the
UCMR 1 statistical design (USEPA, 200Id) and the quality assurance project plan (QAPP)
(USEPA, 2003). 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 final UCMR 1 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. These and other quality
assessments suggest the large system contaminant occurrence data are dependable for national
contaminant occurrence analyses.
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Nearly all PWSs (99.2%) reported the results of their perchlorate assessment results to
the EPA (3,865 large and small PWSs responded out of a total of 3,897 PWSs). Of the 800
representative small systems required to collect samples, the EPA received monitoring results
from 797 systems (99.6%). Of the 3,097 large systems identified for inclusion in the census, the
EPA received monitoring results from 3,068 systems (99.1%). About two-thirds of the non-
responsive systems were served by ground water (note that perchlorate detections were more
frequent in surface water systems).
Texas had 37.5% (12 of the 32) of the non-responsive large PWSs. Of the 184 large
PWSs in Texas that did report perchlorate results, about 2.2% had perchlorate detections.
(Nationally, an estimated 4.6% of large PWSs reported at least one detection of perchlorate).
These 32 non-responsive large systems serve approximately 0.7% of the total population. If any
of these non-responsive systems had detectable levels of perchlorate, then the UCMR 1 results
would underestimate actual occurrence.
3.4 Summary of UCMR 1 Perchlorate Monitoring Data and QA/QC Review
This section provides a description of the two phases of QA/QC review of the UCMR 1
Perchlorate Data set. Section 3.4.1 describes the EPA's initial quality review and data check of
the UCMR 1 data. Section 3.4.2 describes the EPA's consideration of the "Information Quality
Guidelines (IQG) Request for Correction" received from the Chamber of Commerce in
September 2012 and the resulting QA/QC review of the UCMR 1 perchlorate data. Section 3.4.3
summarizes the final version of the UCMR 1 perchlorate data set (post-QA/QC reviews) that was
used as the basis of the occurrence analyses presented in this report.
3.4.1 QA/QC Review - Phase 1
UCMR 1 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. A total of 34,728 perchlorate samples were collected with 647 detections
reported. Samples were collected between May 1, 2000 and October 25, 2005, with almost 94%
of samples collected between January 2001 and December 2003. The EPA reviewed the 34,728
perchlorate samples and identified 397 sample records (10 of which were detections) that did not
meet quality approval requirements for the following reasons:
(1) records from non-approved perchlorate labs;
(2) records identified as duplicates (i.e., having the same PWSID, Facility ID, Sample Point
ID, and sample collection date)
a. if there were duplicate detections, the lesser of the two analytical results was
deleted;
b. if there was a mix of non-detect and detect duplicates, the non-detect record was
deleted;
c. if there were duplicate non-detections, all but one of the duplicate records was
deleted;
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(3) records from CA4810015 were deleted because it was determined the system uses the
same water source as CA4810003, and including data from both systems would provide
duplicate results; and
(4) records from four systems were excluded (MA4261024, PR0005226, PR0005246, and
PR0005617) because the size of the populations they served had changed and they were
no longer officially considered large systems.
In all, 397 samples and 10 detections were identified from the QA/QC review described above;
see USEPA (2008b) for more information on the QA/QC review. Excluding those 397 samples
and 10 detections resulted in a UCMR 1 perchlorate data set with 34,331 samples from 3,865
PWSs with a reported 637 detections. A second phase of data quality checks, described below in
Section 3.4.2, resulted in additional revisions to the data set.
3.4.2 QA/QC Review - Phase 2
In September of 2012, the EPA received a "Request for Correction" letter from the
United States Chamber of Commerce regarding information and data (regarding the occurrence
of perchlorate in drinking water) used by the EPA in its determination to regulate perchlorate.
This letter stated that the EPA relied upon data that did not comply with data quality guidelines.
In response to the letter, the EPA reassessed some components of the UCMR 1 data and some
more recent studies that considered local perchlorate occurrence. A summary of the EPA's
consideration of the Chamber of Commerce comments is included below. Additional details
regarding these considerations are included in Appendix B of this report.
UCMR 1 Perchlorate Source Water Sampling Data Review
The Chamber of Commerce letter stated that some UCMR 1 raw source water sample
analytical detections of perchlorate did "not comply with data quality guidelines because it was
not collected by accepted methods." Of the 34,331 total samples in the UCMR 1 Perchlorate
Data set, 69% (23,731) were collected at the entry points to the distribution system while the
remaining 31% (10,600) were collected from untreated (but UCMR 1 eligible) source water
sample locations. Of the 637 samples that detected perchlorate, 56% (355) were collected at the
entry points to the distribution system while the remaining 44% (282) were collected from source
water sample locations. All source water samples with perchlorate detections were collected
from PWSs serving more than 10,000 people.
In a response to the Chamber of Commerce in February of 2013,8 the EPA explained that
UCMR 1 allowed source water sampling points in a particular State if that State uses source
water monitoring as a more stringent compliance monitoring requirement. The EPA did,
however, conduct a more detailed assessment of the source water sample detections; a detailed
description of this evaluation is presented in Appendix B. Ultimately, the EPA determined that,
as is consistent with State compliance monitoring programs that enable source water sampling, it
was most appropriate to exclude the source water sample detections from the UCMR 1
8 https://www.epa.gov/sites/production/files/2015-06/documents/12004-response.pdf
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Perchlorate Data set when those samples had appropriate follow-up entry point samples that
were included in the UCMR 1 Perchlorate Data set. In contrast, any source water sample
perchlorate detections for which no follow-up entry point sampling was conducted by PWSs
were retained in the UCMR 1 Perchlorate Data set. Following this convention, the resulting
UCMR 1 data set contains 34,132 perchlorate samples from 3,865 systems with a total of 540
detections9 (1.58% of all samples) from 149 PWSs (3.86% of all PWSs).
Follow-up Information Relevant to UCMR 1 Perchlorate Data
The Chamber of Commerce letter also stated that some UCMR 1 data did "not comply
with data quality guidelines because it is not representative of current conditions." The Chamber
of Commerce provided information on follow-up sampling, as well as additional research into
some of the UCMR 1 perchlorate sampling and detections that indicated some of the detections
included in the UCMR 1 data set did not fully reflect conditions at some PWSs at the time of the
UCMR 1 sampling. Information such as state drinking water annual compliance reports, and
studies by Brandhuber et al. (2009) and AWWA (2008) were noted by the Chamber and were
reviewed and considered by the EPA.
In response to the Chamber's request, the EPA evaluated publicly available compliance
data from the States of California and Massachusetts. The UCMR 1 data set was designed to be
nationally representative of perchlorate occurrence at the time of sampling (2001 through 2005).
The EPA acknowledges that conditions may have changed regarding perchlorate occurrence
after the time of UCMR 1 sampling. The EPA believes that it is important to consider the effect
that the State mandated regulations for perchlorate in drinking water has had on the contaminant
occurrence in public water systems.
To update the occurrence data for systems sampled during UCMR 1 from the States of
California and Massachusetts, the EPA identified all systems and corresponding entry points
which had reported perchlorate detections in UCMR 1. Once the systems and entry points with
detections were appropriately identified, the EPA then used a combination of available data from
Consumer Confidence Reports (CCRs) and perchlorate compliance monitoring data from
California (https://sdwis.waterboards.ca.gov/PDWW/) and Massachusetts
(https://www.mass.gov/service-details/public-water-supplier-document-search) to match current
compliance monitoring data (where available) to the corresponding water systems and entry
points sampled during UCMR 1.
Out of the 540 detections resulting from the previous QA/QC step, the EPA updated data
for 321 detections (320 from California systems and 1 from a Massachusetts system10). The
convention used by the EPA to accomplish the substitution of data was to match entry points
with compliance data for active entry points based on most recently reported compliance
monitoring data, if more than one data point was reported for an entry point, the assigned value
9 The 540 detections are the result of the original 637 detections in the UCMR 1 minus 97 source water detections.
10 Data from the State of Massachusetts indicates that system MA2064000 is in compliance with the state MCL for
Perchlorate of 2 ppb. Compliance records for system MA2064000 are available in the Perchlorate docket (EPA-HQ-
OW-2018-0780).
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is an average of the annual monitoring results at the entry point. In cases were the EPA could not
find updated entry point data, then the original data from UCMR 1 for such entry point was kept.
In addition, the EPA used CCRs information for its data update effort. The process for
data substitution using CCR information was accomplished by assigning a default value of 6
|ig/L to all entry points in a given system if perchlorate was reported in the CCR as detected and
within compliance of the California MCL. For other systems, if perchlorate was reported as not
detected in the CCR then a default value of 4 |ig/L (equal to the MRL) was assigned to all entry
points in a given system. Appendix B presents information regarding the State compliance
records utilized by the EPA for the data substitution effort.
3.4.3 UCMR 1 Perchlorate Data Subsequent to Phase 1 and 2 QA/QC Review
Subsequent to the two phases of QA/QC review of the UCMR 1 perchlorate data, a total
of 34,132 samples from 3,865 systems remained, including a total of 540 detections. This data
set, referred to as the "Updated UCMR 1 Perchlorate Data set," serves as the basis for all
occurrence analyses, graphs, and maps presented in Section 4 of this report. Exhibit 7
summarizes the count of records removed from the two phases of QA/QC review.
Exhibit 7: Counts of the Number of Records Removed from the UCMR 1
Perchlorate Data set from Phase 1 and Phase 2 of QA/QC Review
Step
UCMR 1
Perchlorate Data
Included
Excluded
Original Records
34,728
Phase 1: Removal of duplicates, data from non-approved perchlorate labs,
and data from systems no longer considered large systems. See Section 3.4.1
for details.
34,331
397
Phase 2: Removal of source water detections that had follow-up entry point
samples that were included in the UCMR 1 Perchlorate Data set. See Section
3.4.2 Appendix B and Appendix C for details.
34,132
199
Final Records
34,132
Percent Included
98.3%
Note that Appendix C presents all 637 perchlorate detections from UCMR 1 sampling
included in the data set prior to the Phase 2 QA/QC review (i.e., removal of source water
detections with follow-up entry point sample). Specifically, the table in Appendix C presents (for
each of the 637 original UCMR 1 individual detections) the state, public water system
identification number (PWSID), Facility ID, sample point ID, sample point type (EP = entry
point; SR = source water), the system's source water type, system size, the sample date, the
result value (in |ig/L), and the source water sample category (if the detection was from source
water).
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3.5 UCMR 1 Analytical Method 314.0
The EPA developed Method 314.0, revision 1.0 for the analysis of perchlorate under the
UCMR 1. The Minimum Reporting Level (MRL) was 4 |ig/L and was based on the EPA's
experience and detailed assessments during method development. The ability to reliably quantify
a concentration less than 4 |ig/L was not evaluated at the time because this MRL was adequate
given the general levels of health concern during development of the UCMR 1 in the late 1990s.
This analytical method was the only method used to analyze UCMR 1 water samples for
perchlorate analysis. All perchlorate laboratory analytical results generated under UCMR 1 have
undergone QA/QC review according to the UCMR 1 program. For a detailed discussion of
laboratory analytical methods for perchlorate see Section 5.
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4 Analysis of the UCMR 1 Perchlorate Data set
The EPA has evaluated the available peer-reviewed science, perchlorate occurrence
studies, and data collected by accepted methods on the national occurrence of perchlorate in
drinking water. The EPA has determined that UCMR 1 is the best available nationally
representative data on the frequency and degree (concentration) of perchlorate in drinking water.
As previously discussed, the UCMR 1 perchlorate monitoring of drinking water - conducted by
a census of large PWSs (serving more than 10,000 people) and a nationally representative
statistical sample of small systems (serving 10,000 people or fewer) - represents the most
extensive, nationally representative monitoring program for perchlorate in public drinking water
systems.
Section 4.1 describes the analytical approach used and provides the resulting tabulated
and graphical findings that characterize the national occurrence of perchlorate in drinking water,
based on the UCMR 1 data. The perchlorate occurrence findings are presented relative to a range
of concentration thresholds to enable a characterization of the frequency and degree of
perchlorate occurrence. The results of the analysis are presented in Sections 4.2, 4.3, and 4.4.
4.1 Analytical Approach and Resulting Occurrence Estimates
The EPA analyzed the updated UCMR 1 perchlorate occurrence data described in Section
3.4.3 above (34,132 samples with 540 detections from 149 systems) to estimate the frequency
and degree of perchlorate in public drinking water systems and to estimate the population-served
by those systems. To estimate analytical monitoring results, the EPA used a non-parametric
approach which includes the number and percent of UCMR 1 samples with an analytical
detection (a measured sample concentration of perchlorate) that exceeds a concentration
threshold of interest. These counts are done at the system level and sample point level to
characterize national perchlorate occurrence. Perchlorate occurrence was assessed relative to a
range of concentration thresholds including 4 |ig/L, 18 |ig/L, 56 |ig/L, and 90 |ig/L. Additionally,
assessments relative to the threshold of greater than or equal to 4 |ig/L served to identify all
perchlorate sample detections. The results of the analyses are presented in terms of number or
percent of PWSs and/or samples with perchlorate concentrations greater than a particular
threshold. Additionally, the number and percent of the population served by systems or by
sample points with detections is also presented to provide an estimate of the population
consuming public drinking water with various frequencies and degrees of perchlorate
occurrence.
A limitation of the non-parametric approach is that it can only be used for threshold
concentrations that are at or above the UCMR 1 MRL of 4 |ig/L for perchlorate. There are also
no measures of uncertainty or estimates of error. The national estimates of perchlorate
occurrence based on the non-parametric analyses of the UCMR 1 data are found in Sections
4.2.1 and 4.2.2 with additional state-level details presented in Appendix D. Exhibit 8 presents
some summary statistics of the UCMR 1 data used for all national occurrence analyses in this
section.
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Exhibit 8: Perchlorate Detection Rates and Summary of Detected Concentrations
Based on the Updated UCMR 1 Perchlorate Data set
Source water
Type
Total
Number of
Samples
Samples
with
Detections
Concentration Value of
Detections (|jg/L)
Minimum
Median
Maximum
Small Systems (serving < 10,000 people)
Ground Water
2,355
6
4.3
5.3
19.6
Surface Water
940
9
4.0
5.8
6.8
All Small
Systems
3,295
15
4.0
5.8
19.6
Large Systems (serving > 10,000 people)
Ground Water
16,121
166
4.0
6.0
70.0
Surface Water
14,716
359
4.0
4.0
420.0
All Large
Systems
30,837
525
4.0
4.6
420.0
All Systems
All Systems
34,132
540
4.0
4.7
420.0
4.2 System-Level Analyses
The EPA analyzed the updated UCMR 1 Perchlorate Data set to determine system-level
occurrence for the number of systems (and population served by those systems) with one or more
analytical detections, and the number of systems with two or more analytical detections. The
EPA also evaluated the number of systems that had at least one detection at two of its sample
points. This measure addresses the distribution of perchlorates occurrence throughout a system.
For analyses relative to a particular concentration threshold, if a system is identified with two or
more detections at a sample point, the EPA used the maximum detected concentration in the
analysis to estimate potential exposure for the population served by that system.
Perchlorate system-level occurrence analyses are presented in Exhibit 9 through Exhibit
11. These analyses characterize the frequency and degree of perchlorate occurrence at
concentrations (or thresholds) of 4, 18, 56 and 90 |ig/L.
Exhibit 9 presents the number of PWSs and associated populations that had at least one
analytical detection of perchlorate relative to the various thresholds. A total of 149 systems
serving approximately 16.2 million people were served water from PWSs that had at least one
detection of perchlorate. As the detection threshold increases, the number of affected systems
and associated populations decrease. At 18 |ig/L, the number of systems reporting perchlorate
detections drops to 15 systems serving approximately 700,000 people. Two systems serving
approximately 65,000 people had detections greater than 56 |ig/L, and one system serving
approximately 26,000 people had a detection above 90 |ig/L.
Exhibit 10 presents the number of PWSs and associated populations that had two or more
analytical detections of perchlorate relative to the various thresholds. This estimate provides an
assessment of perchlorate persistent or recurring occurrence. A total of 73 systems serving
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approximately 12 million people had two or more detections of perchlorate. As the detection
threshold increases, the number of affected systems and associated populations decrease. At 18
|ig/L, the number of systems reporting two or more perchlorate detections drops to 1 system
serving approximately 40,000 people.
Exhibit 11 presents the number of systems and associated populations that had at least
one analytical detection at two or more sample points above the various thresholds. This
assessment attempts to address the distribution of perchlorate occurrence throughout a system.
Note that roughly half of all UCMR 1 systems sampled only at one sample point and, therefore,
were not included in this analysis. A total of 52 systems (all large systems) serving about 10.8
million people had at least one detection of perchlorate at two or more sampling points. As the
thresholds increase, the number of systems and associated proportional populations decrease.
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Exhibit 9: Systems and Populations with a SINGLE Detection Relative to Various Thresholds Based on the Updated
UCMR 1 Perchlorate Data set
Concentration Thresholds
System Type
Source
Water Type
Total
Number of
Systems in
UCMR 1
Total Pop.
Served by
Systems in
UCMR 1
> 4 |jg/L
>18 |jg/L
> 56 |jg/L
> 90 jjg/L
Number of
Systems
Pop.
Served
Number of
Systems
Pop.
Served
Number of
Systems
Pop.
Served
Numberof
Systems
Pop.
Served
Ground
Water
590
1,939,815
5
7,360
1
4,309
0
0
0
0
Small Systems
(serving
<10,000)
Surface
Water
207
820,755
3
6,123
0
0
0
0
0
0
All Systems
797
2,760,570
8
13,483
1
4,309
0
0
0
0
Ground
Water
1,379
53,765,152
62
4,474,125
6
173,480
1
38,761
0
0
Large Systems
(serving
>10,000)
Surface
Water
1,689
169,087,949
79
11,684,957
8
523,391
1
25,972
1
25,972
All Systems
3,068
222,853,101
141
16,159,082
14
696,871
2
64,733
1
25,972
Ground
Water
1,969
55,704,967
67
4,481,485
7
177,789
1
38,761
0
0
All Systems
Surface
Water
1,896
169,908,704
82
11,691,080
8
523,391
1
25,972
1
25,972
All Systems
3,865
225,613,671
149
16,172,565
15
701,180
2
64,733
1
25,972
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Exhibit 10: Systems and Populations with TWO OR MORE Detections Relative to Various Thresholds Based on the
Updated UCMR 1 Perchlorate Data set
Concentration Thresholds
System Type
Source
Water Type
Total
Number of
Systems in
UCMR 1
Total Pop.
Served by
Systems in
UCMR 1
> 4 |jg/L
>18 |jg/L
> 56 |jg/L
> 90 jjg/L
Number of
Systems
Pop.
Served
Number of
Systems
Pop.
Served
Number of
Systems
Pop.
Served
Numberof
Systems
Pop.
Served
Ground
Water
590
1,939,815
1
56
0
0
0
0
0
0
Small Systems
(serving
<10,000)
Surface
Water
207
820,755
3
6,123
0
0
0
0
0
0
All Systems
797
2,760,570
4
6,179
0
0
0
0
0
0
Ground
Water
1,379
53,765,152
32
3,105,652
1
38,761
0
0
0
0
Large Systems
(serving
>10,000)
Surface
Water
1,689
169,087,949
37
9,044,290
0
0
0
0
0
0
All Systems
3,068
222,853,101
69
12,149,942
1
38,761
0
0
0
0
Ground
Water
1,969
55,704,967
33
3,105,708
1
38,761
0
0
0
0
All Systems
Surface
Water
1,896
169,908,704
40
9,050,413
0
0
0
0
0
0
All Systems
3,865
225,613,671
73
12,156,121
1
38,761
0
0
0
0
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Exhibit 11: Systems and Populations with At Least One Detection At Two or More Sample Points Based on the
Updated UCMR 1 Perchlorate Data set
Concentration Thresholds
System Type
Source
Water Type
Total
Number of
Systems in
UCMR 1
Total Pop.
Served by
Systems in
UCMR 1
> 4 |jg/L
>18 |jg/L
> 56 |jg/L
> 90 jjg/L
Number of
Systems
Pop.
Served
Number of
Systems
Pop.
Served
Number of
Systems
Pop.
Served
Numberof
Systems
Pop.
Served
Ground
Water
590
1,939,815
0
0
0
0
0
0
0
0
Small Systems
(serving
<10,000)
Surface
Water
207
820,755
0
0
0
0
0
0
0
0
All Systems
797
2,760,570
0
0
0
0
0
0
0
0
Ground
Water
1,379
53,765,152
24
2,890,719
1
38,761
0
0
0
0
Large Systems
(serving
>10,000)
Surface
Water
1,689
169,087,949
28
7,951,355
0
0
0
0
0
0
All Systems
3,068
222,853,101
52
10,842,074
1
38,761
0
0
0
0
Ground
Water
1,969
55,704,967
24
2,890,719
1
38,761
0
0
0
0
All Systems
Surface
Water
1,896
169,908,704
28
7,951,355
0
0
0
0
0
0
All Systems
3,865
225,613,671
52
10,842,074
1
38,761
0
0
0
0
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4.3 Sample Point-Level Analyses
The system-level analysis in Section 4.2.1, while valuable for illustrative purposes,
reflects the conservative assumption that if a perchlorate detection is found in a single entry (or
sampling) point in a system, even in a system with multiple entry/sampling points, then the entire
population served by the system is potentially served water containing perchlorate. However,
there are 2,004 UCMR 1 PWSs that have more than 1 sample point and some 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, the EPA conducted analyses at the sample point level to provide additional
details of contaminant occurrence by sample point. These occurrence measures include a sample
point "proportional population" occurrence assessment that estimates potential exposure
(population served with water containing perchlorate) based on perchlorate occurrence at the
sample point (instead of the entire PWS) level. These sample point level analyses were
conducted for sample points with at least one perchlorate analytical detection, as well as sample
points with two or more perchlorate analytical detections.
Sample Point "Proportional Populations"
The sample point proportional population occurrence measure is a less conservative
estimate of the population served by a system with a perchlorate detection. The actual population
served by the different distribution systems within a PWS with multiple distribution systems is
not known; these data are not required for reporting. Therefore, to derive this sample point-level
measure, the EPA assumed that all distribution systems at PWSs with multiple distribution
systems evenly serve the system's population. For example, if a PWS has two distribution
systems, serves a population of 30,000, and has an analytical detection of perchlorate in one of
its two sample locations, then a population of 15,000 (one half of 30,000) would be estimated to
be potentially exposed to perchlorate. How well this assumption reflects actual populations
exposed to perchlorate occurrence depends on the distribution system and service population
configurations of individual systems.
Two Detections at One Sample Point
The "two detections at one sample point" occurrence measure identifies which PWSs
have at least two or more 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 perchlorate occurrence over time at the particular sampling
point location within the system. For analyses relative to a particular concentration threshold, if a
system is identified with two or more detections at a sample point, the EPA used the maximum
detected concentration in the analysis to estimate potential exposure for the population served by
that system.
These occurrence analyses are also presented relative to perchlorate concentrations
thresholds of 4, 18, 56 and 90 |ig/L. At all thresholds, detection rates were higher in large
systems than in small systems.
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Exhibit 12 presents the number of sample points in UCMR 1 that had at least one
perchlorate detection. A total of 336 sample points serving about 4.1 million people had at least
one perchlorate detection. As the perchlorate concentration thresholds increase, the number of
sample points and associated proportional populations decrease, ending at the 90 |ig/L threshold
with 1 sample point, serving about 26,000 people.
Exhibit 13 presents the number of sample points in UCMR 1 that had at least two
perchlorate detections above the perchlorate concentration thresholds. As described earlier, this
analysis provides an indication of persistent, or recurring, perchlorate occurrence overtime at the
particular sampling location within the system. A total of 126 sample points serving about 1.2
million people had at least two detections of perchlorate). No sample points had two or more
detections of perchlorate greater than 18 |ig/L, 56 |ig/L, or 90 |ig/L.
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Exhibit 12: Sample Points With at Least One Detection and Their Proportional Populations Based on the Updated
UCMR 1 Perchlorate Data set
Concentration Thresholds
System Type
Source
Water Type
Total UCMR
1 Sample
Points
Total UCMR 1
Population
> 4 |jg/L
>18 |jg/L
> 56 |jg/L
> 90 jjg/L
Number of
Sample
Points
Proportional
Population
Number of
Sample
Points
Proportional
Population
Number
of
Sample
Points
Proportional
Population
Number
of
Sample
Points
Proportional
Population
Ground
Water
1,211
1,939,815
5
3,361
1
2,155
0
0
0
0
Small Systems
(serving
<10,000)
Surface
Water
243
820,755
3
6,123
0
0
0
0
0
0
All Systems
1,454
2,760,570
8
9,484
1
2,155
0
0
0
0
Ground
Water
8,212
53,765,152
123
628,539
8
117,926
1
6,460
0
0
Large Systems
(serving
>10,000)
Surface
Water
5,270
169,087,949
205
3,434,702
8
500,480
1
25,972
1
25,972
All Systems
13,482
222,853,101
328
4,063,241
16
618,406
2
32,432
1
25,972
Ground
Water
9,423
55,704,967
128
631,900
9
120,081
1
6,460
0
0
All Systems
Surface
Water
5,513
169,908,704
208
3,440,825
8
500,480
1
25,972
1
25,972
All Systems
14,936
225,613,671
336
4,072,725
17
620,561
2
32,432
1
25,972
Note: Due to trailing decimal places (not shown in the table) for the population served by ground water and surface water sample points, the counts of total population served may appear to be
slightly off.
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Exhibit 13: Sample Points With at Least Two Detections and Their Proportional Populations Based on the Updated
UCMR 1 Perchlorate Data set
System Type
Source
Water Type
Total UCMR
1 Sample
Points
Total UCMR 1
Population
Concentration Thresholds
> 4 |jg/L
>18 |jg/L
> 56 |jg/L
> 90 jjg/L
Number of
Sample
Points
Proportional
Population
Number of
Sample
Points
Proportional
Population
Number
of
Sample
Points
Proportional
Population
Number
of
Sample
Points
Proportional
Population
Small Systems
(serving
<10,000)
Ground
Water
1,211
1,939,815
1
56
0
0
0
0
0
0
Surface
Water
243
820,755
3
6,123
0
0
0
0
0
0
All Systems
1,454
2,760,570
4
6,179
0
0
0
0
0
0
Large Systems
(serving
>10,000)
Ground
Water
8,212
53,765,152
31
114,287
0
0
0
0
0
0
Surface
Water
5,270
169,087,949
91
1,123,105
0
0
0
0
0
0
All Systems
13,482
222,853,101
122
1,237,392
0
0
0
0
0
0
All Systems
Ground
Water
9,423
55,704,967
32
114,343
0
0
0
0
0
0
Surface
Water
5,513
169,908,704
94
1,129,228
0
0
0
0
0
0
All Systems
14,936
225,613,671
126
1,243,571
0
0
0
0
0
0
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Exhibit 14 shows the proportion of systems detecting perchlorate in various percentages
of their sample points. Of the 149 PWSs with at least one detection of perchlorate, nearly half
(48%) of the systems had detections in 25% or fewer of their sample points. A little more than
half of the systems (52%) had detections in more than one-quarter of their sample points and
29% had detections in more than half of their sample points. (About 20% of all UCMR 1 systems
with detections of perchlorate had only 1 sample point.)
Exhibit 14: Portion of Systems with Perchlorate Detections in Various
Percentages of System Sampling Points (Among Systems with at Least One
Detection) Based on the Updated UCMR 1 Perchlorate Data set
01
*-»
01
Q
01
60%
50%
40%
30%
20%
£ 10%
< 25%
> 25% to 50%
> 50% to 75%
> 75% to 100%
Percent of SPs with Detections within Systems
Exhibit 15 displays the number of PWSs and sample points with at least one detection
that exceeded the perchlorate concentration thresholds of 4, 18, 56 |ig/L, and 90 |ig/L. A total of
336 sample points at 149 systems had at least one detection greater than or equal to 4 |ig/L.
Seventeen sample points at 15 systems had at least one detection greater than 18 |ig/L. Two
sample points at two systems had at least one detection greater than 56 |ig/L and one sample
points at one system had a detection greater than 90 |ig/L. Note that systems and sample points
with exceedances of the higher thresholds are counted multiple times in Exhibit 15 (i.e., systems
counted as exceeding 56 |ig/L are also counted as exceeding 4 and 18 |ig/L).
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Exhibit 15: Number of UCMR 1 Systems and Sample Points Exceeding Various
Concentration Thresholds Based on the Updated UCMR 1 Perchlorate Data set
350
300
= 4 ng/L
> 18 Hg/L > 56 Hg/L
Perchlorate Concentration
> 90 ng/L
4.4 Spatial and Graphical Assessments
Spatial and graphical assessments of the updated UCMR 1 perchlorate monitoring data
are provided in this section. Perchlorate was detected at PWSs in 26 states, Puerto Rico, and the
Commonwealth of the Northern Mariana Islands (see Exhibit 16). The EPA identified
perchlorate analytical detections in PWSs across states in the southern portion of the country,
several states in the Northeast, Washington, Nebraska, Minnesota, Illinois, and Ohio. States with
the highest percentage of systems with perchlorate analytical detections were California,
Arizona, Nevada, and Oklahoma. The Northern Mariana Islands also had a high proportion of
systems with analytical detections (33%), but since only three systems were sampled, this
distinction is based on a relatively small sample size. Breakdowns of sampling efforts by state
can be found in Appendix D, including state-level (non-parametric) counts of systems and
population served by systems; systems (and population served by systems) with detections; and
summaries of detected concentrations.
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Exhibit 16: Geographic Distribution of Perchlorate - States with At Least One
Detection Equal to or Above the MRL (> 4 pg/L) Based on the Updated UCMR 1
Perchlorate Data set
| | Entities with No Detections
m Entities with Detections (5 4 ug/L)
~ Guam ~ Mariana Is.
~ Virgin Is. ~ Puerto Rico
~ Tribes
This map depicts UCMR 1 results from both small systems and large systems, (Note: Small and large system data
were collected in all states.) As discussed in this report, 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.
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Exhibit 17: Geographic Distribution of Perchlorate - State Percentage of PWSs
with At Least One Detection Equal to or Above the MRL (> 4 pg/L) Based on the
Updated UCMR 1 Perchlorate Data set
This map depicts UCMR 1 results from both small systems and large systems. (Note: Small and large system data
were collected in all states.) As discussed in this report, 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.
Exhibit 18 provides a map of the locations and concentrations of perchlorate detections
greater than 18 ng/L and 56 |ig/L in PWSs across the United States based on data in the updated
UCMR 1 data set. The map shows widespread detections of perchlorate across large portions of
the United States. Systems with the highest perchlorate concentrations (i.e., greater than 56 |ig/L)
were located in Florida and Puerto Rico.
| | Entities with No Detections
| | Entities with No Detections
| | Entities with Detections at 0.01 - 3.00 % of PWSs
| j Entities with Detections at 3.01 - 10.00 % of PWSs
[~~| Entities with Detections at 10.01 - 34.00 % of PWSs
~ Guam § Mariana Is.
~ Virgin Is. ~ Puerto Rico
~ Tribes
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Exhibit 18: System-level Geographic Distribution of Perchlorate -Systems With
Detections Greater than 18 ng/L, 56 ng/L, and 90 ng/L Based on the Updated
UCMR 1 Perchlorate Data set
Legend
>90 ppb
>56 ppb
~ X
>18 ppb
• x
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5 Laboratory Analytical Methods
5.1 EPA Methods
The EPA has developed five analytical methods for the identification and quantification
of perchlorate in drinking water. These methods - 314.0, 314.1, 314.2, 331.0, and 332.0 - have
different characteristics, performance, and costs. A description of these methods is presented
below.
The EPA Method 314.0, "Determination of Perchlorate in Drinking Water Using Ion
Chromatography" (Revision 1.0, USEPA, 1999a) reports a method detection limit (MDL) of
0.53 |ig/L. Single-laboratory mean percent recoveries in various aqueous matrices range from
86% to 113% with relative standard deviations (RSDs) of 1.0% to 12.8%. A minimum reporting
level (MRL) is not specified in the method; however, a range of 3.0 to 5.0 |ig/L is cited as a
benchmark range for quality assurance/quality control (QA/QC) procedures. The MRL is
typically established as either a concentration that is greater than three times the laboratory MDL
or at a concentration that yields a response greater than a signal to noise ratio of five. In either
case, the MRL must not be below the lowest instrument calibration standard (USEPA, 1999a).
Method 314.0 was widely adopted as the standard perchlorate method.
Method 314.0 has the potential for interferences in the determination of perchlorate. The
EPA developed options for minimizing interferences to mitigate the potential perchlorate
misidentification. The EPA has identified three types of potential interferences:
• direct chromatographic coelution - an analyte response is observed at very nearly the
same retention time (i.e., the "time window" when an analyte emerges from the ion
chromatography (IC) column and is "seen" by the detector) as perchlorate;
• concentration dependent coelution - observed when the response of higher than typical
concentrations of a neighboring peak (i.e., another compound in the sample) overlap into
the retention time window of perchlorate; and
• ionic character displacement - retention times may significantly shift due to the influence
of high ionic strength matrices (high mineral content or hardness) overloading the
exchange sites in the ion chromatography column and significantly shortening the
retention time of perchlorate.
The possibility of interferences and perchlorate misidentification may become greater if
reporting levels (RLs) are reduced from the EPA's original MRL of 4 |ig/L associated with the
use of EPA Method 314.0 for perchlorate monitoring under UCMR 1, to 1 |ig/L. Sensitivity can
be improved by either increasing the sample injection volume or incorporating a smaller
diameter analytical column. In both cases, however, column capacity will limit the volume of
sample that can be injected on-column without degradation of chromatographic resolution. The
EPA understood the potential for reduced resolution when setting the UCMR 1 perchlorate MRL
at 4 |ig/L rather than at a lower concentration.
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Massachusetts Department of Environmental Protection reduced the reporting level to 1
|ig/L by using lower concentration spiking solutions and standards for laboratory QC (MassDEP,
2004a) along with a series of initial and ongoing quality control requirements and limits
(MassDEP, 2006a). The physical modifications made by MassDEP constitute such a significant
modification that the modified method can no longer be considered EPA Method 314.0. An
increase in sample injection volume and a smaller-bore chromatographic column would reduce
the chromatographic resolution of EPA Method 314.0. As a result, the interferences that are
identified in EPA Method 314.0 can be exacerbated for higher ionic strength samples with
elevated total dissolved solids (TDS) and are more likely to have retention times that can result
in falsely assigning these interferences as detections of perchlorate.
The EPA believes that the injection and chromatographic conditions specified in the
EPA's original publication of EPA Method 314.0, along with mitigative steps that are included
to reduce interferences, are critical to proper resolution and identification of perchlorate.
Therefore, the EPA has confidence in the analytical results and the detections found in UCMR 1
monitoring that resulted from the use of EPA Method 314.0 as originally published.
After the EPA published Method 314.0, the agency adopted additional method
development goals for the analysis of perchlorate in drinking water including: 1) reducing MRL
to less than 1 |ig/L through the application of sample concentration techniques, microbore
analytical columns, and advanced detection systems (i.e., mass spectrometry), 2) further
increasing the tolerance for high ionic strength matrices, and 3) enhancing measurement
selectivity.
EPA Method 314.1, "Determination of Perchlorate in Drinking Water Using Inline
Column Concentration/Matrix Elimination Ion Chromatography with Suppressed Conductivity
Detection" (Revision 1.0, USEPA, 2005b) documents an EPA single-laboratory lowest
concentration minimum reporting levels (LCMRLs) of less than 0.2 |ig/L (detection limit [DL] =
0.03 |ig/L) using online sample pre-concentration. The method uses matrix diversion to handle
high ionic strength matrices (up to 1,000 mg/L total dissolved solids [TDS]) and added
confirmation analysis using a second analytical column (USEPA, 2005b).
EPA Method 314.2, "Determination of Perchlorate in Drinking Water Using Two-
Dimensional Ion Chromatography with Suppressed Conductivity Detection" (USEPA, 2008c)
documents an EPA single-laboratory LCMRLs of less than 0.1 |ig/L (DLs < 0.02 |ig/L) using
large volume injection. The method uses 2-D chromatography to handle high ionic strength
matrices (up to 1,000 mg/L TDS) by isolating perchlorate in the first dimension and measuring it
in the second dimension (USEPA, 2008c).
EPA Method 331.0, "Determination of Perchlorate in Drinking Water by Liquid
Chromatography Electrospray Ionization Mass Spectrometry" (Revision 1.0, USEPA, 2005c)
documents an EPA single-laboratory LCMRLs of less than 0.1 |ig/L (DLs < 0.01 |ig/L), applied
multiple analytical advancements to a liquid chromatography (LC) analysis including a
perchlorate selective LC column (IonPak AS-21), mass spectrometry (MS) or tandem mass
spectrometry (MS/MS) detection for selectivity and sensitivity, and a custom 0-18 isotopically
labeled internal standard (Cl1804~) (USEPA, 2005c).
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EPA Method 332.0, "Determination of Perchlorate in Drinking Water by Ion
Chromatography with Suppressed Conductivity and Electrospray Ionization Mass Spectrometry"
(USEPA, Revision 1.0, 2005d) documents an EPA single-laboratory LCMRL of 0.1 |ig/L (DL =
0.02 |ig/L), applied multiple analytical advancements in an IC analysis including suppressed
conductivity IC, MS or MS/MS detection for selectivity and sensitivity, and a custom 0-18
isotopically labeled internal standard (Cl180/f) (USEPA, 2005d).
In May 2012, the California Department of Public Health's Drinking Water and
Radiation Laboratory published recommendations regarding the potential for perchlorate
degradation in water samples. According to the guidance/recommendation, EPA Methods 314.1,
314.2, 331.0 and 332.0 require that water samples be filtered in the field and kept cold during
shipment to the laboratory. EPA Method 314.0 does not include this sample preservation
requirement. Since microbial degradation of perchlorate requires anaerobic conditions, field
filtration is not necessary when using EPA Method 314.0 provided aerobic conditions are
maintained for the samples until analysis. Aerobic conditions can be effected by half-filling
sample bottles in the field, agitating them to dissolve air in the samples and then chilling them on
ice for delivery to the laboratory (CA EPA, 2016).
It is anticipated that most drinking water samples will be aerobic in nature and will not
become anaerobic prior to analysis within the 28-day holding time specified in EPA Method
314.0. Any air in the headspace of a sample to be analyzed by EPA Method 314.0 will support
aeration of the sample due to agitation during shipping. EPA Method 314.0 indicates that
perchlorate has been shown to be stable for at least 28 days.
Exhibit 19 compares the five EPA analytical methods for the analysis of perchlorate in
drinking water.
Exhibit 19: Comparison of EPA Analytical Methods for the Analysis of Perchlorate
in Drinking Water
Method
LCMRL or MRL1
(H9/L)
MDL/DL
(H9/L)
Perchlorate
Retention
Time
(minutes)
Demonstrates
Acceptable
Performance in
1,000 mg/L
TDS
Confirmation
Complexity
314.0
4.0 (MRL)
0.53
11
No.11
Matrix Spike
Assessment
Moderate
314.1
0.13-0.14
0.03
30-35
Yes
Second Column
Analysis
Moderate
314.2
0.038 -0.06
0.012-0.018
37
Yes
2-D
High
331.0
0.022
(MS/MS)
0.056
(Selected Ion
Monitoring [SIM])
0.005
(MS/MS)
0.008
(SIM)
9
Yes
MS/MS or MS
Moderate
11 EPA Method 314.0 was demonstrated to provide acceptable performance for samples up to 600 - 700 TDS using the AG16/AS16
analytical column
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Method
LCMRL or MRL1
(M9/L)
MDL/DL
(M9/L)
Perchlorate
Retention
Time
(minutes)
Demonstrates
Acceptable
Performance in
1,000 mg/L
TDS
Confirmation
Complexity
332.0
0.10 (SIM)
0.02
8
Yes
MS
Moderate
1 Value for EPA Method 314.0 is a "national" MRL for perchlorate monitoring conducted under UCMR 1. Remaining values are for
the EPA's single-laboratory LCMRLs generated during method development. MRLs have not been established for EPA Methods
314.1, 314.2, 331.0, and 332.0.
5.2 Methods Used by States
EPA Methods 314.0, 314.1, 314.2, 331.0, and 332.0 underwent the EPA's analytical
method development and validation processes. The validation process includes a protocol for
modifications to any existing EPA-approved analytical methods and a protocol for new
determinative techniques. Both validation protocols are rigorous and consider many technical
aspects of analytical method performance, (USEPA, 1999b; USEPA, 1999c) including:
• Detection limits;
• Instrument calibration;
• Precision and analyte recovery;
• Analyte retention times;
• Contamination in blanks;
• Development of Quality Control Acceptance Criteria;
• Analysis of field samples; and
• Other technical aspects of sample analysis and data reporting.
UCMR 1 required PWSs to conduct assessment monitoring for perchlorate using method
3 14.0. In 2004, MassDEP began to evaluate laboratory performance for the analysis of
perchlorate in drinking water (MassDEP, 2004a; 2004b). MassDEP indicated use of a modified
EPA Method 314.0 to achieve a reporting level of 1.0 |ig/L (MassDEP wanted reliable
laboratory performance to extend below what was to become their drinking water standard of 2.0
|ig/L in 2006). The modifications include the use of lower spiking, lower concentration standard
solutions, and an initial and on-going quality control protocol (MassDEP, 2004a; 2006a). In
2006, MassDEP published a data set of confirmed perchlorate detections above 1.0 |ig/L
(MassDEP, 2006b). These data were generated in 2004, 2005 and early 2006. Although the
analytical method is not specified in MassDEP (2006b), presumably a modified version of EPA
Method 314.0 was used.
By 2007, MassDEP had included EPA Methods 314.1, 331.0 and 332.0 as acceptable
methods for the analysis of perchlorate in DW (MassDEP, 2007), indicating that these methods
could achieve reliable quantitation at or below 1.0 |ig/L. The single-laboratory LCMRLs for
these three methods are listed in Exhibit 19.
Note that EPA Method 314.2 was not published until 2008. The single-laboratory
LCMRLs for EPA Method 314.2 are 0.038-0.060 |ig/L. These LCMRLs are specific to the
EPA's method development laboratory. In consideration of natural variability in laboratory
performance nationwide, MRLs for EPA Methods 314.1, 314.2, 331.0 and 332.0 would possibly
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be less than 1.0 |ig/L. MRLs have not been determined for these methods because these methods
have not been selected for use in a national regulatory program. Thus, reliable quantitation in the
sub-|ig/L range should be attainable using EPA Methods 314.1, 314.2, 331.0, and/or 332.0 while
reliable quantitation using EPA Method 314.0 is possible only at or above approximately 4 |ig/L
to minimize the potential for false positives.
A review of available state data for perchlorate (i.e., California, Illinois, Massachusetts
and Ohio) indicates the predominant use of EPA Method 314.0, although limited use of 314.1
and 331.0 is indicated by the State of Massachusetts. California perchlorate monitoring data
indicates the use of methods "314" and "331 "
5.3 Laboratory Analysis Cost Estimates
The EPA compiled cost estimates for perchlorate analytical methods by asking
laboratories to provide a low-to-high price range that they might charge for running perchlorate
methods. In April of 2018, three laboratories were contacted. The estimates, summarized in
Exhibit 20, vary depending on the quantity of samples submitted for analysis, target reporting
levels and other analytical complexities or contractual factors.
Exhibit 20: Cost Estimates of Laboratory Analytical Methods for Perchlorate
EPA Perchlorate
Method
Low
Estimate Per
Analysis
High
Estimate Per
Analysis
Notes *
EPA METHOD 314.0
$55
$65
Range is based on information from two of the three
laboratories contacted.
EPA METHOD 314.1
-
-
None of the labs contacted run this method.
EPA METHOD 314.2
-
-
None of the labs contacted run this method.
EPA METHOD 331.0
$90
$175
Range is based on information from two of the three
laboratories contacted.
EPA METHOD 332.0
$175
$175
Estimate is based on information from one of the three
laboratories contacted.
* Sample analysis cost may depend on the number of samples submitted and the turnaround time requested.
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45
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May 2019
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46
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May 2019
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48
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May 2019
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Chromatography, Revision 1.0, November 1999.
USEPA. 1999b. Protocol for EPA Approval of Alternate Test Procedures for Organic and
Inorganic Analytes in Wastewater and Drinking Water. EPA 821-B-98-002. Office of
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USEPA. 1999c. Protocol for EPA Approval of New Methods for Organic and Inorganic
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March 1999. 56 pp.
USEPA. 1999d. Revisions to the Unregulated Contaminant Monitoring Regulation for Public
Water Systems; Final Rule. Federal Register. Vol. 64, No. 180, p. 50556-50620, September
17, 1999.
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Vol. 65, No. 42, p. 11372-11385, March 2, 2000.
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Report. EPA 600-R-01-047. May 2001.
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Analytical Methods for List 2 Contaminants; Clarifications to the Unregulated Contaminant
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815-R-01-023. Office of Water, USEPA. 65 pp.
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Monitoring Regulation (1999). EPA Report 815-R-01-004. Office of Water, USEPA. 36 pp.
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Characterization. External Review Draft. NCEA-1-0503. Washington, DC: National Center
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Contaminant Monitoring Regulation. Draft EPA Report, Office of Water.
49
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May 2019
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Vol. 70, No. 36, p. 9071-9077, February 24, 2005.
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Inline Column Concentration/Matrix Elimination Ion Chromatography with Suppressed
Conductivity Detection, Revision 1.0, EPA 815-R-05-009, May 2005.
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007, January 2005.
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Spectrometry, Revision 1.0, EPA/600/R-05/049, March 2005.
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Two-Dimensional Ion Chromatography with Suppressed Conductivity Detection, Version
1.0, EPA 815-B-08-001, May 2008.
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No. 194, p. 51850-51862, October 8, 2009.
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53800644ble.html. Accessed March 8, 2017.
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No. 159, p. 41883-41893, August 19, 2009.
50
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USEPA. 201 la. Drinking Water: Regulatory Determination on Perchlorate. Federal Register.
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on a Method for the Determination of Perchlorate in Fertilizers. Journal of Environmental
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Urbansky, E.T. and S.K. Brown. 2003. Perchlorate Retention and Mobility in Soils. Journal of
Environmental Monitoring. 5:455-462.
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Vermont Department of Environmental Conservation (VT DEC). 2015. Interim Groundwater
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and R.G. Striegl. 2003. A reservoir of nitrate beneath desert soils. Science. 302(5647): 1021-
1024. As cited in Trumpolt, et al., 2005.
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in Terrestrial Plants. Ecotoxicology and Environmental Safety. 58(l):44-49.
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Appendix A:
Occurrence in Ambient Water and in
Drinking Water (from Sources Other
than UCMR 1)
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Appendix A: Occurrence in Ambient Water and in Drinking Water
(from Sources Other than UCMR 1)
May 2019
Appendix A: Occurrence in Ambient Water and in Drinking Water (from
Sources Other than UCMR 1)
Occurrence data for perchlorate are available from a variety of sources in addition to
UCMR 1, as noted in Section 3. Summaries of perchlorate occurrence in ambient water are
available from the United States Geological Survey (USGS) National Water-Quality Assessment
(NAWQA) program, USGS National Water Information System (NWIS) Database, the EPA's
Storage and Retrieval (EPA STORET) Data Warehouse, three regional studies with limited
sampling, and monitoring along the Lower Colorado River. The EPA also reviewed drinking
water data from state-sponsored studies (including Arizona, California, Iowa, Maryland,
Massachusetts, Nevada, New Jersey, and Texas, the American Water Works Association
Research Foundation (AwwaRF), American Water System (AWS) Survey, Consumer
Confidence Reports (CCRs), and the Environmental Working Group (EWG).
A.l Occurrence in Ambient Water
Lakes, rivers, and aquifers are the sources of most drinking water. Contaminant
occurrence in ambient water provides information on the potential for contaminants to adversely
affect drinking water supplies. Occurrence data and information from ambient water, including
ambient water serving as source water for public drinking water systems, is supplemental to data
and information from finished drinking water. Data that characterize contaminant occurrence in
public drinking water systems at entry points to the distribution systems (as compared to data for
ambient or source water) much more closely reflect the quality of water delivered to and
consumed by the populations served by PWSs. As with all occurrence data, those from ambient
water sources also must be considered in terms of their scope and how representative they are of
a particular geographic area and, specifically in this report, what information they can provide
when characterizing the national occurrence of perchlorate in public drinking water systems.
Occurrence data for perchlorate in ambient water are available from the USGS NAWQA
program, non-NAWQANWIS data, and from the EPA's STORET Data Warehouse. In addition,
summaries of three regional studies with limited sampling and from monitoring along the Lower
Colorado River are presented below. The Lower Colorado River monitoring results are important
since the Lower Colorado River is a key source of drinking water for a large number of PWSs in
southern California and several large systems in Nevada and Arizona.
United States Geological Survey (USGS) National Water-Quality Assessment (NAWQA)
Ambient Water Analyses
USGS instituted the NAWQA program in 1991 to examine ambient water quality status
and trends in the United States. The NAWQA program generates high quality contaminant
occurrence and other water quality parameter data for significant watersheds and aquifers across
the nation. The program collects data on surface and groundwater chemistry, hydrology, land
use, stream habitat, and aquatic life in parts or all of nearly all 50 States. The program is
designed to apply nationally consistent methods to provide a uniform basis for contaminant
occurrence comparisons and assessments among study basins across the country and over time.
A-l
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Appendix A: Occurrence in Ambient Water and in Drinking Water
(from Sources Other than UCMR 1)
May 2019
The occurrence assessments can also serve to facilitate interpretation of natural and
anthropogenic factors affecting national water quality. For more detailed information on
NAWQA program design and implementation, refer to Leahy and Thompson (1994) and
Hamilton et al. (2004).
The process of sampling, analysis, and data synthesis is divided into cycles of
approximately ten years: Cycle 1 covered 1991-2001, Cycle 2 covered 2002-2012, and Cycle 3 is
on-going and covers 2013-2023. Study units are sampled and analyzed on a staggered schedule
within each cycle. Each NAWQA cycle begins with a two-year startup phase for planning and
retroactive analysis, followed by a three-year intensive data-collection phase, and finally a five-
year phase analyzing the data, developing reports, and continuing a low level of monitoring
(NRC, 2012).
During Cycle 1 (1991-2001), 51 study units were sampled. A total of 6,307 wells from
272 ground water networks or clusters were monitored in Cycle 1. Surface water sampling points
(6,400 sampling points from 505 sites) were located on rivers and streams; lakes, reservoirs, and
coastal waters were excluded from the monitoring program.
In Cycle 2 (2002-2012), the number of study units was reduced from 51 in Cycle 1 to 42
(NRC, 2012). Long-term monitoring was established at 113 streams representing 8 major river
basins. Long-term ground water monitoring was established at sites representing 20 principal
aquifers with more than 10 to 15 years of consistent monitoring data available (Rowe et al.,
2013).
Cycle 3 sampling is currently underway (2013-2023). Surface water monitoring will be
conducted at 313 surface water sites, increased from 113 sites in Cycle 2 (Rowe et al., 2013).
Ground water assessments in Cycle 3 will be designed to evaluate status and trends at the
principal aquifer (PA) and national scales. Assessments are planned in 24 PAs that account for
the majority of current and future national ground water use for drinking water will be selected.
Note that data through 2016 are presented in this report. For more details on the Cycle 3
sampling design, refer to Rowe et al., 2010 and 2013).
The EPA performed a summary analysis of Cycle 2 and available Cycle 3 NAWQA data
(through 2016) for perchlorate. (No Cycle 1 data were available for perchlorate.) The EPA's
analysis of the NAWQA data is a simple, non-parametric occurrence analysis that provides
summary statistics to characterize contaminant occurrence. The EPA calculated detection
frequencies as the percentage of samples and the percentage of sites with at least one detection,
without any censoring or weighting. (A detection is an analytical result equal to or greater than
the reporting level.) The EPA calculated other descriptive statistics as well, including the
minimum, median, 90th percentile, 99th percentile, and maximum concentrations (based only on
samples with detections). Reporting levels varied over time during the NAWQA program.
Therefore, in some cases the minimum concentration reported as a detection could be lower than
the highest reporting level.
A-2
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Appendix A: Occurrence in Ambient Water and in Drinking Water
(from Sources Other than UCMR 1)
May 2019
The results of the NAWQA perchlorate analysis are presented in Exhibit A-l and Exhibit
A-2. These data were downloaded from the Water Quality Portal in September 2018 (WQP,
2018). In Cycle 2, perchlorate was detected in approximately 48% of 154 samples and at slightly
more than 48% of 139 sites. The median concentration based on detections was equal to 1.3
|ig/L. In Cycle 3 (data through 2016), perchlorate was detected in nearly 68% of 112 samples
and at 64% of 100 sites. The median concentration based on detections in Cycle 3 was equal to
0.59 |ig/L.
Exhibit A-1: Perchlorate NAWQA Data - Summary of Detected Concentrations
Source Water
Type
Concentration Value of Detections (|jg/L)
Minimum
Median
90th Percentile
99th Percentile
Maximum
Cycle 2 (2002 -2012)
Ground Water
0.11
1.3
7.25
9.99
10.1
Surface Water
0.25
0.25
0.25
0.25
0.25
All Sites
0.11
1.3
6.85
9.99
10.1
Cycle 3 (2013-2016)
Ground Water
0.1
0.59
2.63
8.04
13.8
Surface Water
NA
NA
NA
NA
NA
All Sites
0.1
0.59
2.63
8.04
13.8
Source: WQP, 2018
Exhibit A-2: Perchlorate NAWQA Data - Summary of Samples and Sites
Source Water Type
Total
Number of
Samples
Samples with
Detections
Total
Number of
Sites
Sites with Detections
Number
Percent
Number
Percent
Cycle 2 (2002 -2012)
Ground Water
153
73
47.71%
138
66
47.83%
Surface Water
1
1
100.00%
1
1
100.00%
All Sites
154
74
48.05%
139
67
48.20%
Cycle 3 (2013-2016)
Ground Water
112
76
67.86%
100
64
64.00%
Surface Water
NA
NA
NA
NA
NA
NA
All Sites
112
76
67.86%
100
64
64.00%
Source: WQP, 2018
A-3
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Non-NA WQA National Water Information System (NWIS) Data
The National Water Information System (NWIS) is the Nation's principal repository of
water resources data USGS collects from over 1.5 million sites (USGS, 2016). NWIS-Web is the
general online interface to the USGS NWIS database. Discrete water-sample and time-series data
are available from sites in all 50 States, including 5 million water samples with 90 million water-
quality results. All USGS water quality and flow data are stored in NWIS, including site
characteristics, streamflow, ground water level, precipitation, and chemical analyses of water,
sediment, and biological media, though not all parameters are available for every site. NWIS
houses the NAWQA data and includes other USGS data from unspecified projects. NWIS
contains many more samples at many more sites than the NAWQA Program. Although NWIS is
comprised of primarily ambient water data, some finished drinking water data are included as
well. This section presents analyses of non-NAWQA data in NWIS, downloaded from the Water
Quality Portal in December 2017 (WQP, 2017). Note that within NWIS there are some data
identified as perchlorate "finished water" data. These data do not overlap with the results
presented in Exhibit A-l and Exhibit A-2.
The results of the non-NAWQA NWIS perchlorate analysis are presented in Exhibit A-3
and Exhibit A-4. Perchlorate was detected in approximately 56% of 4,626 samples and at
approximately 45% of 2,837 sites. The median concentration based on detections was equal to
1.465 |ig/L. (Note that the NWIS data are presented as downloaded; potential outliers were not
evaluated or excluded from the analysis.)
Exhibit A-3: Perchlorate NWIS Data - Summary of Detected Concentrations
Source Water
Type
Concentration Value of Detections (|jg/L)
Minimum1
Median
90th Percentile
99th Percentile
Maximum
Ground Water
0
1.5
12,000
18,000,000
33,000,000
Surface Water
0.016
0.248
37
7,050.8
9,200
Finished Water
0.16
16
28.7
42.92
45
All Sites
0
1.465
10,000
17,160,000
33,000,000
Source: WQP, 2017
1A minimum value of zero may represent a detection that was entered into the database as a non-numerical value
(e.g., "Present").
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May 2019
Exhibit A-4: Perchlorate NWIS Data - Summary of Samples and Sites
Source Water
Type
Total
Number
of
Samples
Samples with
Detections
Total
Number of
Sites
Sites with Detections
Number
Percent
Number
Percent
Ground Water
4,479
2,451
54.72%
2,782
1,236
44.43%
Surface Water
129
120
93.02%
53
50
94.34%
Finished Water
18
13
72.22%
12
7
58.33%
All Sites
4,626
2,584
55.86%
2,837
1,285
45.29%
Source: WQP, 2017
Storage and Retrieval Data Warehouse, 1996 - 2016
Until June 2018, the EPA's STORET Data Warehouse was a collaborative database
containing raw biological, chemical, and physical data from surface and ground water sampling
conducted by federal, state and local agencies, Indian tribes, volunteer groups, academics, and
others. A wide variety of data relating to water quality from all 50 states as well as multiple
territories and jurisdictions of the United States were represented in this data system. The
database is comprised of primarily ambient water data, but in some cases finished drinking water
data are included, as well. Users began populating the STORET Data Warehouse in 1999. The
STORET Data Warehouse was decommissioned in June of 2018. Currently, the Water Quality
Exchange (WQX) is available for data partners to submit their monitoring data; the Water
Quality Portal (WQP) is available for users to retrieve water monitoring data.
STORET's data quality limitations include variations in the extent of national coverage
and data completeness from parameter to parameter. Data may have been collected as part of
targeted, rather than randomized, monitoring. Furthermore, there are no restrictions on
submission of data based on analytical methods or quality assurance (QA) practices. For more
general information on STORET and WQX data, please refer to:
https://www.epa.gov/waterdata/water-quality-data-wqx.
This section presents analyses of STORET data, downloaded from the WQP in December
2017 (WQP, 2017). The EPA reviewed STORET ground water data from wells and surface
water data from lakes, rivers/streams, and reservoirs (WQP, 2017). The perchlorate occurrence
data in STORET comprise 8,883 samples collected at 751 sites in 7 states. The results of the
STORET analysis are presented in Exhibit A-5 through Exhibit A-7. Minimum detected
concentrations are reported in Exhibit A-5; these minimum values may be indicative of reporting
levels used. (A minimum value of zero, on the other hand, likely represents a non-detection that
was entered into the database as a numerical value.) Note that results cannot be considered
representative of the states or source water types sampled.
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(from Sources Other than UCMR 1)
May 2019
Exhibit A-5: Perchlorate STORET Data - Summary of Detected Concentrations
Source Water
Type
Concentration Value of Detections (|jg/L)
Minimum1
Median
90th Percentile
99th Percentile
Maximum
Ground Water
0
3
17
250
230,000
Surface Water
0
0.96
13.84
130,048
210,000
All Sites
0
2.9
16.99
408.9
230,000
Source: WQP, 2017
1A minimum value of zero may represent a detection that was entered into the database as a non-numerical value
(e.g., "Present").
Exhibit A-6: Perchlorate STORET Data - Summary of Samples and Sites
Source Water
Type
Total
Number
of
Samples
Samples with
Detections
Total
Number of
Sites
Sites with Detections
Number
Percent
Number
Percent
Ground Water
8,383
7,503
89.50%
575
430
74.78%
Surface Water
500
308
61.60%
176
110
62.50%
All Sites
8,883
7,811
87.93%
751
540
71.90%
Source: WQP, 2017
Exhibit A-7: Perchlorate STORET Data - Summary of States
Source Water
Type
Total
Number of
States
States with
Detections
Number
Percent
Ground Water
5
4
80%
Surface Water
6
6
100%
Total
7
6
86%
Source: WQP, 2017
The number of states with ground water data plus the number of
states with surface water data is not equal to the "Total" number
of states providing data because some states provided both
ground water and surface water data.
Multi-state Sampling
A USGS study by Kalkhoff et al. (2010) was designed to determine the occurrence of
perchlorate in agricultural areas in the Midwestern and North-Central United States, as well as
arid parts of the Central and Western United States. During the summer and early fall of 2004,
samples were collected from 171 sites on rivers and streams (located in 19 states) and 146 sites
from wells (located in 5 states). Sample locations were chosen based on the availability of wells
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(from Sources Other than UCMR 1)
May 2019
and streams being sampled as part of other USGS programs. Perchlorate was detected in samples
collected in 15 states and was detected in 18.7% (34 of 182) samples from rivers and streams and
in 43.2% (64 of 148) ground water samples at concentrations greater than or equal to 0.4 |ig/L.
Perchlorate concentrations in surface water samples were greater than or equal to 1 |ig/L in 7
states. Perchlorate concentrations in ground water samples were greater than or equal to 1 |ig/L
in 4 states. Only one surface water and one ground water sample had concentrations greater than
5 |ig/L.
As part of a USGS project in cooperation with the National Park Service, Hooggestraat
and Rowe (2016) studied perchlorate occurrence related to fireworks displays in Mount
Rushmore National Memorial occurring from 1998 through 2009. The study analyzed 106 water
samples from 6 groundwater and 14 surface water sites within and bordering the park between
May and August of 2011 through 2014, December 2014 and February 2015. Sampling sites
represented all three major drainage basins in Mount Rushmore National Memorial as well as
two drainage basins outside the park for comparison. Perchlorate was detected above the MRL
(ranging from 0.0088 to 0.28 (ig/L) in 88.6% (39 of 44) of groundwater samples and 90.3% (56
of 62) of surface water samples. The detected concentrations ranged from 0.057 to 38 [ig/L in
groundwater and 0.049 to 54 [ig/L in surface water with median detected concentrations of 19
[ig/L and 12 [ig/L respectively. Twenty-five ground water detections and 24 surface water
detections were greater than 15 [ig/L.
In an effort to evaluate overall perchlorate occurrence and investigate regional trends in
"natural" perchlorate occurrence, Parker et al. (2008) collected and analyzed 326 groundwater
samples from all 48 contiguous states. Samples came primarily from domestic, single-family
wells with the remainder from small public water supplies and active springs. Sites were selected
based on proximity to known perchlorate use and release sites and population density. No
samples were taken within a 25 km radius of a perchlorate use or release site, which were
identified using the EPA and the U.S. General Accountability Office (USGAO) databases. Wells
recently disinfected using hypochlorite and wells with in-line chlorination systems were also
avoided. Approximately 70% of sample sites came from counties with densities less than the
U.S. average population density, and 29% of the sample sites came from extremely rural
counties with four or fewer people per square kilometer. Perchlorate was detected at
concentrations above the MRL of 0.120 [ig/L in all states except those located in New England,
as well as Illinois and West Virginia. Of the 326 samples, 137 (42%) were detected above the
MRL, while 42 (13%) were between the MDL (0.040 (ig/L) and the MRL. The median detection
concentration was 3.80 [ig/L, and the maximum detected concentration was 10.4 [ig/L. There
were 28 (9%) samples with detected concentrations greater than 1.0 [ig/L. Sample concentrations
greater than 1.0 [ig/L were most common in the Southeast, the Desert Southwest (Arizona, New
Mexico, and Texas), and the Great Plains regions. Based on the results of this study, strong
regional trends in perchlorate occurrence were not apparent; however, when the results were
summarized by geographical area, some patterns emerged. Perchlorate detections were relatively
rare in the Northeast, the Midwest, and the Pacific Coast states. Measurable levels of perchlorate
were seemingly more prevalent in the Southeast, the Great Plains, the Intermountain West, and
the Desert Southwest. Parker et al. (2008) stated that the results of their survey could be used to
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Appendix A: Occurrence in Ambient Water and in Drinking Water
(from Sources Other than UCMR 1)
May 2019
support the notion that formation and persistence are somewhat more prevalent in semiarid
regions.
Lower Colorado River
The primary source of perchlorate in the Lower Colorado River comes from
manufacturing facilities near Henderson, Nevada at a facility once owned by Kerr McGee
Corporation, now owned by Tronox, Inc. Contaminated ground water seeps into the Las Vegas
Wash which drains into Lake Mead and ultimately into the Colorado River as it flows through
the Hoover Dam. Detectable concentrations of perchlorate have been found along the river from
Lake Mead to the international boundary near Yuma. Since the discovery of perchlorate in the
Colorado River in 1997, several studies have assessed the extent of perchlorate contamination.
Occurrence information related to perchlorate monitoring in the Lower Colorado River
was provided by the Nevada Division of Environmental Protection (NDEP) and the Southern
Nevada Water Authority. The Lower Colorado River importantly serves as a primary source of
water for the Metropolitan Water District (MWD) of Southern California and as a source of
water for several PWSs in Arizona. Over the last decade, there has been a significant decrease in
perchlorate concentrations in the Lower Colorado River following successful perchlorate point-
source remediation efforts at two industrial sites located in the southeastern portion of the Las
Vegas Valley in Nevada. (The NDEP has extensively studied and documented the treatment
efficacy related to perchlorate point-source remediation efforts at these sites and the resulting
achievements in decreased perchlorate concentrations downstream in the Lower Colorado
River.) Full remediation activities were underway at the two sites between 2002 and 2006.
NDEP compiled perchlorate results from sampling locations along the Colorado River at
Lake Mead, Nevada (near downstream location from the remediation sites), Willow Beach,
Arizona (slightly more than 10 miles downstream from the Lake Mead sampling point), and
Whitsett, California (more than 100 miles further downstream) (NDEP, 2011). The NDEP
information indicated that perchlorate concentrations at the Lake Mead sampling point ranged
from 6 to 25 |ig/L prior to 2004. Since 2010, all sample results have ranged between a
perchlorate concentration of 1 and 5 |ig/L, with most results less than 2 |ig/L. At the Willow
Beach sampling location the results were similar: prior to 2003, perchlorate concentrations
ranged from 4 to 10 |ig/L and after 2008 concentrations ranged from 1 to 2 |ig/L (NDEP, 2011).
The Whitsett sampling location is at the MWD source water intake point along Lake
Havasu on the Lower Colorado River. (The Central Arizona Project intake is also located along
Lake Havasu on the Lower Colorado River less than five miles downstream from the Whitsett
intake.) A decrease is observed over the past 14 years in perchlorate concentrations in samples
collected at the Whitsett intake. Perchlorate concentrations initially ranged between 4 |ig/L and 9
|ig/L from 1997 until October 2002. The perchlorate concentration range decreased to between 2
|ig/L and 5 |ig/L from October 2002 to October 2005. After late 2005, perchlorate concentrations
from the Lower Colorado River water samples collected at the Whitsett intake have been at or
below 2 |j,g/L (NDEP, 2011). The Whitsett intake monitoring results from the more than 120
samples collected between 1997 to 2011 are shown in Exhibit A-8 below. The perchlorate
A-8
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Appendix A: Occurrence in Ambient Water and in Drinking Water
(from Sources Other than UCKIR 1)
May 2019
analytical methods (and their respective detection limits) changed over the sampling period;
nonetheless, a consistent decreasing trend in perchlorate concentrations is shown, especially after
point-source remediation efforts began in 2002. Data from Willow Beach and the USGS
sampling station below the Hoover Dam (roughly 140 and 150 miles upstream, respectively,
from the Whitsett intake) are also plotted on the same graph. These time series data show a
similar general decreasing trend in perchlorate concentrations as are shown in the Whitsett intake
results. However, that general decreasing trend appears not to continue between 2013 and 2016
at the USGS station.
Exhibit A-8: Perchlorate Raw Water Sample Results from the Whitsett Intake,
USGS Station Below the Hoover Dam, and Willow Beach Sampling Points, 1997-
2016
00
o
o
T—
CNJ
CO
LO
CD
00
CD
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T—
CNJ
CO
LO
CD
CJ)
CD
CD
o
o
O
O
o
O
O
o
o
O
CJ)
CD
CD
o
o
O
O
o
O
O
o
o
O
O
o
O
O
o
O
O
o
T—
CNJ
CNJ
CNJ
CNJ
CNJ
CNJ
CNJ
CNJ
CNJ
CNJ
CNJ
CNJ
CNJ
CNJ
CNJ
CNJ
CNJ
CNJ
Year
Willow Beach
USGS Station Below Hoover Dam
Whitsett Intake
Figure adapted from NDEP (2011)
A-9
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Appendix A: Occurrence in Ambient Water and in Drinking Water
(from Sources Other than UCMR 1)
May 2019
The EPA conducted a correlation analysis using times series data (reflecting changes in
perchlorate concentrations over time) to compare perchlorate sample concentrations at the
Whitsett intake (raw water) with perchlorate concentrations in samples collected from California
public water systems (finished water). These public water systems are known to purchase some
amount of Lower Colorado River water via MWD (or a MWD member agency). The statistical
analyses identified no correlation over time between perchlorate concentrations in Lower
Colorado River raw water samples and in California public water system finished water samples.
The lack of correlation likely reflects the effects on perchlorate occurrence due to PWS blending
of source waters (e.g., mixing of MWD-sourced water with locally sourced or self-sourced water
including ground water from local wells).
A.2 Occurrence in Drinking Water from Data Sources Other than UCMR 1
In addition to UCMR 1 perchlorate occurrence data, the EPA also reviewed state-
sponsored studies. These other data sources, described below, represent different levels of
geographic coverage. None of these data sources are nationally representative. Some survey data
covered multiple states (e.g., the AwwaRF and AWS studies). There may be overlap between
UCMR 1 data and other sources as the data were collected and compiled for different purposes.
For example, the EWG data presented below may report some of the same detections as the State
of Massachusetts, also presented below.
Whenever possible, state-level UCMR 1 findings were compared to state-level data from
sources described below. Since UCMR 1 monitoring data represents a census of large systems,
the UCMR 1 perchlorate occurrence findings for large systems are representative of occurrence
at the state level. Note, however, that UCMR 1 sampling of small systems was designed to be
statistically valid at the national level, but the selected small systems are not necessarily
representative of all small systems in each state. State percentages of UCMR 1 systems with
detections of perchlorate include results from the statistical sample of small systems and the
census of large systems. Therefore, UCMR 1 state-level findings should only be considered an
approximation of contaminant occurrence in a particular state. Exhibit A-9 summarizes the
drinking water data sources reviewed in more detail in Sections A.2.1 and A.2.2. Section A.2.3
includes a summary of perchlorate data from the California Department of Public Health.
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Appendix A: Occurrence in Ambient Water and in Drinking Water
(from Sources Other than UCMR 1)
May 2019
Exhibit A-9: Summary of Drinking Water Occurrence Studies Discussed in
Sections A.2.1 and A.2.2
Data Set
Geographic
Coverage
Date
Range
Type of
Water
Tested
Detection
Limit
Number of Systems and/or
Samples
National-Scale Studies or Surveys of Drinking Water Occurrence
American Water Works
Association Research
Foundation
Targeted
Sampling -
29 states;
Non-Targeted
Sampling -
31 states
1998-
2000
Drinking
Water &
Non-
Drinking
Water
4 pg/L
Targeted Sampling: 160
drinking water samples (130
SW and 30 GW samples);
79 PWSs; 12 non-drinking
water samples (7 SW and 5
GW)
Non-Targeted Sampling: 138
drinking water samples (79 SW
and 59 GW)
American Water System
Survey
SW sites -
11 states;
GW sites -
17 states
1997-
1998
Untreated
Source
Water
4 pg/L
42 samples from 40 SW sites;
522 samples from 367 GW sites
Environmental Working
Group
4 states
2010-
2015
Drinking
Water
unknown
unknown
National Health and
Nutrition Examination
Survey
30 counties
2005-
2006
Drinking
Water
0.1 pg/L
3,262 samples from tap
Individual and Small Multi-State Studies
Arizona Department of
Environmental Quality
Arizona
2004
Drinking
Water &
Non-
Drinking
Water
4 pg/L;
2 pg/L
74 samples at 67 sites
Consumer Confidence
Reports
5 states
2010-
2016
Drinking
Water
unknown
5 systems
Iowa Statewide Rural Well
Water Survey
Iowa
2006-
2008
Drinking
Water
4 pg/L;
8 pg/L
437 samples analyzed with
MDL of 4 pg/L;
34 samples analyzed with MDL
of 8 pg/L
Maryland Department of
Environment
Maryland
2008
Drinking
Water
unknown
972 samples;
8 Systems
Massachusetts
Department of
Environmental Protection
Massachusetts
2000-
2019
Drinking
Water
unknown
15,974 samples;
911 systems
New Jersey Drinking
Water Quality Institute
New Jersey
2003-
2005
Drinking
Water
1 pg/L
114 samples;
67 systems
Nevada Division of
Environmental Protection
Nevada
1999-
2011
Drinking
Water
unknown
2 treatment plants
Potomac River Study
Maryland
2007-
2008
Drinking
Water
unknown
8 drinking water utilities
A-l 1
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Appendix A: Occurrence in Ambient Water and in Drinking Water
(from Sources Other than UCMR 1)
May 2019
Data Set
Geographic
Coverage
Date
Range
Type of
Water
Tested
Detection
Limit
Number of Systems and/or
Samples
Texas Commission of
Environmental Quality
Texas & New
Mexico
2001-
2004
Drinking
Water
4 ug/L;
1 hq/l
152 samples;
52 systems
A.2.1 National-Scale Studies or Surveys of Drinking Water Occurrence
American Water Works Association Research Foundation Survey
AwwaRF sponsored a nationwide survey of perchlorate occurrence from 1998 to 2000
(Wang et al., 2002).4 Wang et al. (2002) compared the results of targeted sampling performed
from 1999 to 2000 to the results of non-targeted sampling (PWS-initiated sampling or other data
collection efforts) performed in 1998.
The targeted sampling analyzed 160 drinking water samples (130 surface water and 30
ground water samples) from 79 PWSs in 29 states, plus an additional 12 non-drinking water
samples (7 surface water and 5 ground water) from 2 states. AwwaRF selected "high risk"
perchl orate sampling sites that were geographically diverse. Some California PWSs whose data
were already available from regulatory agencies were not included in the study.
Of the 160 targeted drinking water samples, 7 (2 surface water and 5 ground water) had
detections of perchl orate. Four of the five PWSs with ground water detections were in Maryland,
Arizona, and New York. (The identity and location of the fifth was withheld in the published
study to preserve the anonymity of the PWS.) Both of the PWSs with surface water detections
were in Arizona. Five of the 12 targeted non-drinking water samples (4 surface water and 1
ground water) had detections of perchl orate. These samples were collected from PWSs in the
States of Texas and New Mexico. All detections could be correlated with known or likely nearby
sources of perchlorate contamination.
In the non-targeted sampling, AwwaRF collected 138 drinking water samples (79 surface
water and 59 ground water) from large PWSs in 31 states. Of the four apparent detections, three
samples were false positives.5 The remaining detection was legitimate; the source water (the
Colorado River) was known to be contaminated at the time of sampling.
The AwwaRF study concluded that drinking water perchlorate contamination tends to be
localized near sources of perchlorate release. Ground water contamination tends to be limited to
within a 4-mile radius of point sources, and surface water contamination tends to be limited to
within 15 miles downstream of point sources.
4 The American Water Works Association Research Foundation is now known as the Water Research Foundation
(WaterRF).
5 The false positives cited in Wang et al., 2002 were not a result of the use of EPA Method 314.0. These samples
were analyzed using an IC-based analytical method that was developed by the California Department of Health
Services prior to the EPA's publication of EPA Method 314.0.
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(from Sources Other than UCMR 1)
May 2019
American Water System Survey
AWS manages PWSs nationwide. In 1997 and 1998, AWS conducted a survey of
perchlorate occurrence in (mostly untreated) source waters. AWS collected 42 samples from 40
surface water sites in 11 states, and 522 samples from 367 ground water sites in 17 states. The
reporting level was 4 |ig/L (Gullick et al., 2001).
Perchlorate was not detected in any of the surface water samples. Initial results from
ground water indicated perchlorate detections in 29 samples from 18 sites in California, Indiana,
Iowa, New Mexico, and Pennsylvania, with a maximum concentration of 7.1 |ig/L (a higher
concentration of 20 |ig/L appeared to be due to laboratory error). Follow-up sampling and
analysis suggested that the perchlorate detections in Indiana, Iowa, and Pennsylvania were false
positives. Multiple samples confirmed the presence of perchlorate in at least five of six
California sites and four of seven New Mexico sites. In California, military and research
facilities near the affected wells were known sources of perchlorate contamination. In New
Mexico, the exact origins of the contamination was not identified, but nearby potential sources
include military bases, explosive mining activity, research laboratories, a landfill, and an
industrial Superfund site (Gullick et al., 2001).
Environmental Working Group
In July 2017, EWG released their "National Drinking Water Database" which includes
drinking water occurrence data for both regulated and unregulated drinking water contaminants.
Samples were collected between 2010 and 2015 from all 50 states and the District of Columbia
(EWG, 2018). EWG states that the 2017 database includes results on 502 contaminants.
EWG reviewed the data for inconsistencies and invited AWWA and the Association of
Metropolitan Water Agencies to review their data and/or have the data verified by the PWSs
included in the study. The updated data were downloaded on April 26, 2019 for use in this
occurrence report.
The EWG data include the number of detections, population served, and the number of
exceedances of contaminant-specific thresholds. EWG compared the results with state health-
based standards and guidelines. EWG provides rankings of the highest average level of a given
contaminant and presents data (average and range of detected concentrations) for the top ten
water systems with the highest average level of that contaminant. Hence, the data are
summarized, but the results are not detailed enough to estimate the magnitude of occurrence.
Data collected between 2010 and 2015 identified perchlorate in 199 PWSs serving more
than 7 million people in 4 states plus Washington, D.C. (Exhibit A-10; EWG, 2019). EWG found
that 37 systems in 3 states reported a maximum concentration of perchlorate above an EWG-
suggested health-based limit of 1 |ig/L. EWG selected the value by surveying health-based and
legal limits established by state and federal agencies and selecting the most conservative one (in
the case of perchlorate, the California public health goal of 1 |ig/L).
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(from Sources Other than UCMR 1)
May 2019
Exhibit A-10: Summary of EWG Perchlorate Data, 2010-2015
State
PWSs with Detections of Perchlorate1
PWSs with Detections of Perchlorate
Above EWG-defined Health-Based Limit
of 1 |jg/L
Number of PWSs
Population served
Number of PWSs
Population served
California
45
2,473,118
22
410,838
Massachusetts
129
2,037,267
2
4,617
Virginia
2
1,269,000
0
0
New York
20
669,215
13
435,810
Washington, D.C.
3
644,822
0
0
Total
199
7,093,422
37
851,265
Source: EWG, 2019
1 The laboratory analytical method detection levels (the minimum concentration thresholds that define a detection)
were not specified in the study and could potentially differ within and between states.
National Health and Nutrition Examination Survey
The National Health and Nutrition Examination Survey (NHANES) is an ongoing series
of surveys conducted by the National Center for Health Statistics of the Centers for Disease
Control and Prevention. NHANES is a population-based survey designed to collect data on the
health and nutritional status of the United States population. For the 2005 and 2006 survey, tap
water samples were collected from the residences of one-half of the survey participants age 12
and older. A total of 3,262 tap water samples were collected from survey participants residing in
30 NHANES 'primary sampling units' (counties or groups of contiguous counties) (Blount et al.,
2010). Perchlorate was included as a tap water analyte in this survey. The laboratory analytical
method used to quantify perchlorate in the tap water samples was an ion chromatography tandem
mass spectrometry method with a detection limit of 0.1 «g/L (Blount et al., 2010; Valentin-
Blasini et al., 2007).6
The 3,262 tap water samples, collected by the NHANES in 30 counties (or groups of
contiguous counties), represent neither a census nor a statistical sample of finished drinking
water from public water systems nationally. The sample locations were determined by the health
data objectives of the NHANES which do not account for the geographic variability of
perchlorate in the environment or in tap water (Blount et al., 2010). Additionally, due to the
confidentiality of the NHANES health data, the sources of the tap water sampled are an unknown
mix of system sizes and source water types, and could include some private wells. Therefore, the
NHANES perchlorate occurrence data are distinctly different from, and cannot be directly
compared to the UCMR 1 perchlorate data.
6 Additional information regarding the NHANES 2005-2006 study design and the laboratory analytical method for
tap water samples can be found at http://www.cdc. gov/nchs/nhanes/nhanes2005-2006/nhanes05 06.htm.
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May 2019
The summary statistics of perchlorate occurrence from the NHANES tap water sampling
are presented in Exhibit A-l 1. (The Blount et al., 2010 results presented in Exhibit A-l 1 are
based on all samples, not just sample detections.) With a method reporting limit much lower in
this study (0.1 (J,g/L) compared to the UCMR 1 (4 (J,g/L), perchlorate was detected in a much
higher percentage of water samples (83%) compared with UCMR 1 (1.86%). Greater than 95
percent of NHANES perchlorate sample detections were at concentrations lower than 4 (J,g/L.
Noting that chlorine used for disinfection is known to contain perchlorate as a by-product
and that liquid hypochlorite (also used in disinfection) can break down to form perchlorate
depending on storage conditions, Blount et al. (2010) states that trace levels of perchlorate in
(treated) tap water may result from the disinfection process (see discussion in section 2.2.2 of the
main body of the report).
Exhibit A-11: Summary of 2005-2006 NHANES Tap Water Perchlorate Occurrence
Data
Number of
Samples
Percentage
of
Detections
Geometric
Mean
(in pg/L)
95%
confidence
interval
(in pg/L)
Percentile (in |jg/L)
25th
50th
75th
90th
95th
3,262
83%
0.71
(0.511-
0.998)
0.620
1.16
1.39
1.64
1.89
From Blount et al. (2010)
A.2.2 Individual and Small Multi-State Studies
Arizona Department of Environmental Quality
In 1999 the Arizona Department of Environmental Quality (ADEQ) conducted a
perchlorate occurrence study of Arizona water resources. ADEQ collected source water samples
from the Colorado River, Central Arizona Project (CAP) Canal, and various ground water
sources throughout the Phoenix metropolitan area. These samples showed perchlorate
concentrations ranging from 480 |ig/L in Lake Mead (part of the Colorado River system) to
between 11 |ig/L and non-detection (at that time defined as less than 4 |ig/L) along the Colorado
River main stem and the Central Arizona Project.
About 95% of potable water for the City of Phoenix is derived from surface water
sources, including the Colorado River. In 2000 and 2001, the City conducted a second round of
perchlorate monitoring at the same sample locations used in the 1999 ADEQ study.
Monitoring results showed perchlorate along the River and in the CAP Canal, however, at
decreased levels (ADEQ, 2004).
In 2004, the City collected 392 finished water distribution samples and found 39
perchlorate detections at, or above, the MDL of 4 |ig/L. Also in 2004, ADEQ collected 74
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May 2019
samples from 67 sites that included Colorado River water, man-made recreational
impoundments, canals, wells, agricultural areas and ground water recharge projects. Samples
were analyzed using a modified EPA Method 314.1 with a reporting limit of 2 |ig/L. Perchlorate
was detected in 24 samples from 24 different sites. Perchlorate concentrations ranged from non-
detection to 7.4 |ig/L. For more detailed occurrence measures from the ADEQ database, refer to
ADEQ (2004) or AWWA (2005).
The ADEQ perchlorate occurrence data could not be directly compared with the UCMR
1 perchlorate data because ADEQ sampled both drinking water and non-drinking water sources
and did not distinguish between the two. Also, ADEQ sampled sites that were susceptible to
perchlorate contamination and were isolated from activities or land use practices commonly
associated with perchlorate. (The UCMR 1 results from Arizona are included in Appendix D.)
Consumer Confidence Reports
CCRs are annual water quality reports that CWSs are required to provide to their
customers. These reports summarize information on water sources, detected contaminants, and
system compliance with EPA drinking water standards; they may also include general
educational material. Under the CCR Rule (40 CFR Subpart O) CWSs with 15 or more
connections or serving at least 25 year-round residents must prepare and distribute a CCR to all
billing units or service connections every year. Systems serving 100,000 or more residents are
also required to post their current CCRs on a publicly accessible Internet site. The EPA reviewed
CCRs published by the 22 systems that serve over 1 million customers, as identified in the third
Unregulated Contaminant Monitoring Regulation (UCMR 3) database, for unregulated
contaminant occurrence information. Data on perchlorate were available from CCRs prepared by
5 CWSs: one system in CA (City of Los Angeles), one system in MA (Massachusetts Water
Resources Authority), one system in MO (St. Louis County), one system in New York (Suffolk
County), and one system in Ohio (City of Columbus).
The City of Los Angeles included data on perchlorate in its 2015 CCR. The number of
samples collected was not reported. Perchlorate was monitored for but not detected during 2015.
The Massachusetts Water Resources Authority included data on perchlorate in its 2010
CCR. Water from the MWRA comes from the Quabbin Reservoir and the Wachusett Reservoir.
The specific location of sampling, as well as the number of samples collected, was not reported.
Detection concentrations ranged from 0.05 to 0.07 ng/L, with an average detection level of 0.06
M-g/L.
St. Louis County, Missouri included data on perchlorate in its 2015 and 2016 CCRs.
Samples were collected from the county's surface water sources, the Missouri River and the
Meramec River. The number of samples collected was not reported. Perchlorate was tested for
but not detected in water leaving the treatment facility.
Suffolk County, New York, included data on perchlorate in its past five CCRs (2012
through 2016). Suffolk County is served by groundwater from four major aquifers beneath Long
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May 2019
Island. For all five years of data, neither the number nor percent of samples with detects was
reported. A total of about 300 to 400 finished water samples were collected each year with
sample analytical concentrations ranging from non-detection (ND) to a high of 6.14 |ig/L in
2013.
The City of Columbus, Ohio included data on perchlorate in its CCRs for 2010 through
2015. Columbus is served by both surface water from the Scioto River and Big Walnut Creek, as
well as ground water sources. All six years of CCRs from Columbus reported that perchlorate
was not detected in the drinking water. The number of samples collected at each location was not
reported.
Iowa Statewide Rural Well Water Survey
The Iowa Department of Natural Resources, the Geological Survey Bureau, and the
University of Iowa Center for Health Effects of Environmental Contamination conducted a
survey of rural well water (IA SWRL 1) to provide statistically valid estimates, statewide and
within regions, of water quality in private wells. The survey was conducted in 2 phases - phase 1
from 1988 through 1989 and the phase 2 from 2006 to 2008. Ground water was sampled from
473 private drinking water wells, of which 471 samples were tested for perchlorate. A total of
437 samples were analyzed with the MDL of 4 |ig/L and 34 samples were analyzed with the
MDL of 8 |ig/L (University of Iowa, 2009). Perchlorate was detected once at a concentration of
20 |ig/L. University of Iowa (2009) did not specify if this detection was from the group of
samples with an MDL of 4 |ig/L or 8 |ig/L.
Long Island, New York
The Long Island Water Conference (LIWC) submitted comments to the EPA on the
preliminary determination on perchlorate issued by the EPA in October 2008. In their comment,
LIWC presented findings from perchlorate occurrence studies from the Long Island aquifer. The
information presented below was extracted from the LIWC public comment to the EPA, sent on
November 26, 2008 (LIWC, 2008).
Long Island was one of the first designated Sole Source Aquifer systems in the United
States and, with a total population of nearly three million, it is considered to be one of the most
intensively used and critical aquifer systems in the country.
Perchlorate monitoring of public water supplies on Long Island began in the spring of
1998. Initially in response to perchlorate detection reports elsewhere in the United States, the
Suffolk County Water Authority (SCWA) collected samples from wells at five wellfields. Of the
initial sample results, one well indicated a concentration of perchlorate of 30 |ig/L. The SCWA
removed this well from service. At the end of 1998, the NY State Department of Health provided
an Action Level of 18 |ig/L. This well later showed concentrations as high as 127 |ig/L in
samples collected during subsequent test pumping.
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Between 1998 and 2000, a total of 18 profile wells were installed by the Suffolk County
Department of Health Service (SCDHS) Bureau of Groundwater Resources in locations
upgradient and downgradient of a fireworks disposal pit which was located in the northwest
corner of the site. Perchlorate was detected in 9 test wells downgradient of the pit in
concentrations as high as 3,370 |ig/L.
Maryland Department of Environment
Perchlorate is present at significant levels in ground water and surface water at three
Department of Defense facilities. At Aberdeen Proving Ground in Harford County, Maryland,
perchlorate was detected in ground water at seven different locations at levels as high as 350
|ig/L. Perchlorate has been detected in the water supply of the City of Aberdeen; the state set an
advisory level of 1 |ig/L for the city's drinking water.
Although no public drinking water supply wells have been impacted, perchlorate levels in
ground water at the Naval Support Facility at Indian Head have been detected at levels as high as
2,900 |ig/L. At a number of other sites in Cecil County, Maryland, perchlorate contamination
was detected in ground water monitoring wells at levels as high as 230,000 |ig/L in the late
1990's. In the one case where perchlorate contamination impacted the drinking water supply, the
Department provided bottled water to affected residents and required installation of a treatment
system to address contamination. Perchlorate contamination has also been detected in the
Potomac River, the source of drinking water for millions of Maryland, Virginia, West Virginia
and District of Columbia residents.
The State of Maryland provided the EPA with a file containing all perchlorate monitoring
results that are currently in Maryland's database. Most of the water samples (98% or 952 of 970)
were collected from the City of Aberdeen's PWS (see Exhibit A-12). In addition, the data file
sent by the state included raw water sample results from the EPA Potomac River Study in 2008.
This study is described below (separately) under "Potomac River Study."
Exhibit A-12: Perchlorate Occurrence Data from the State of Maryland, May 2002 -
October 2010
PWS ID
System Name
Date Range
Number
of
Samples
Number
of Detects
Range of Detected
Concentrations
MD0120001
City of Aberdeen1
May '02 - Dec. '08
952
540
1 pg/L - 5.6 pg/L
MD0150005
Washington Suburban Sanitary
Commission
Oct '07
2
2
0.95- 1.04 pg/L
MD0210010
City of Hagerstown
Sept. '05 - Apr. '08
2
1
0.62 pg/L
MD0120003
Maryland American Water
Company
Mar. '10
2
0
ND
MD0120016
Harford County D.P.W.
Nov. '09-Oct. '10
10
0
ND
MD0010019
Luke / Newpage Luke Mill
Dec. '07 - Jan. '08
2
2
0.0809-0.0833
pg/L
MD0100011
Fort Detrick
Apr. '09
1
0
ND
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May 2019
PWS ID
System Name
Date Range
Number
of
Samples
Number
of Detects
Range of Detected
Concentrations
MD1120016
Harford Center Inc.
Nov. '09
1
0
ND
1 Recent Drinking Water Quality Reports for Abderdeen from the year 2014 and 2015 (available online at:
http://www.aberdeenmd.gov/sites/aberdeenmd/files/file/file/final ccr 2014- coa.pdf and
http://www.mde.state.md.us/programs/WaterAA/ater Supplv/ConsumerConfidenceReports/Documents/CCR2016/Harford/Citv of A
berdeen.pdf) indicate that perchlorate was not detected.
Massachusetts Department of Environmental Protection
In 2006, MassDEP set a state-wide MCL for perchlorate of 2 |ig/L. As of January 1,
2007, all CWSs andNTNCWSs were required to complete initial monitoring as follows:7 ground
water systems sampled twice at the entry points to the distribution system, once during the month
of April and once during the month of September; surface water systems sampled once in four
consecutive quarters at entry points. If, after completing these initial monitoring requirements, no
perchlorate was detected, a PWS could reduce sampling to once per year. If a PWS detected
perchlorate above 1 |ig/L, the system conducted quarterly monitoring for at least one year. With
the Department's approval, a system could reduce reduced the frequency to annual sampling if
the monitoring results were consistently below the MCL.
The Massachusetts Executive Office of Energy and Environmental Affairs hosts an
online data portal to allow public access to drinking water monitoring results. The EPA
downloaded all available perchlorate sampling data from finished water through 2019. (Data
were downloaded on April 26, 2019.) Perchlorate monitoring data were available from June
2000 through April 2019. A total of 15,974 finished water results were available from 911 public
water systems. Detection limits ranged from 0.00086 ng/L to 1 ng/L. Water samples were
analyzed with Methods 314.0, 314.1, 331.0, and 332.0. Exhibit A-13, Exhibit A-14, and Exhibit
A-15 summarize the available perchlorate monitoring data from Massachusetts, including the
number of samples, systems and numbers of detections. (Detections were counted as any result
greater than zero.)
7 Historical data gathered after January 1, 2004, meeting the initial monitoring requirements, may be used to meet
the initial monitoring requirements.
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(from Sources Other than UCMR 1)
Exhibit A-13: Perchlorate Finished Water Occurrence Data from the MA EEA Data
Portal June 2000 - April 20191 - Summary of Samples
System Size
Samples
Total
Number
Number of
Detections
Percent of
Detections
Number of
Detections
£ 1 |Jg/L
Percent of
Detections
£ 1 |Jg/L
Number of
Detections
£ 4 |jg/L
Percent of
Detections
£ 4 |jg/L
Small Systems
(Population < 10,000)
9,954
2,562
25.7%
341
3.4%
77
0.8%
Large Systems
(Population > 10,000)
6,020
2,273
37.8%
91
1.5%
3
0.0%
1 The data set included only a handful of records collected prior to 2004.
Exhibit A-14: Perchlorate Finished Water Occurrence Data from the MA EEA Data
Portal June 2000 - April 20191 - Summary of Systems
System Size
Systems
Total
Number
Number
with
Detections
Percent
with
Detections
Number
with
Detections
£ 1 |Jg/L
Percent
with
Detections
£ 1 |Jg/L
Number
with
Detections
£ 4 |jg/L
Percent
with
Detections
£ 4 |jg/L
Small Systems
(Population < 10,000)
779
382
49.0%
40
5.1%
11
1.4%
Large Systems
(Population > 10,000)
132
119
90.2%
20
15.2%
3
2.3%
1 The data set included only nine records collected prior to 2004.
Exhibit A-15: Perchlorate Finished Water Occurrence Data from the MA EEA Data
Portal June 2000 - April 20191 - Summary of Detected Concentrations
System Size
Detected Concentration (|jg/L)
Minimum
Detection
Median
Detection
90th
Percentile
Maximum
Detection
Small Systems
(Population < 10,000)
0.026
0.17
1.39
1,300
Large Systems
(Population > 10,000)
0.026
0.15
0.47
9.9
1 The data set included only nine records collected prior to 2004.
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The EPA's UCMR 1 data are only representative at the state level for large systems.
UCMR 1 sampling at 132 Massachusetts PWSs did not detect perchlorate in any small PWSs
and detected perchlorate in only one large PWS (at a concentration of 6 |ig/L).
New Mexico Environment Department
The New Mexico Environment Department (NMED) submitted comments to the EPA on
the preliminary determination on perchlorate issued by the EPA in October 2008. In their
comment, NMED presented findings from perchlorate occurrence studies in their state. The
information presented below was extracted from the NMED public comment to the EPA, sent on
November 26, 2008 (NMED, 2008).
At Cannon Air Force Base, near Clovis, New Mexico, NMED received data in 1999
showing perchlorate concentrations of 46 |ig/L in production well PW-2 and 21 |ig/L in
production well PW-7. These wells are both active drinking water production wells that serve
users on the base. Data from NMED gathered in 2001 from Cannon showed perchlorate
contamination of 23.5 |ig/L in PW-12, another drinking water production well (NMED, 2001a;
as cited in NMED, 2008).
At the Melrose Bombing Range, also near Clovis, NMED received data in 1999 showing
perchlorate contamination in production well PW-11, an active drinking water production well
for the facility, at 25 |ig/L. NMED obtained data in 2001 from Melrose that showed perchlorate
concentrations of 30.3 |ig/L and 40.7 |ig/L in PW-11, and a perchlorate concentration of 5.52
|ig/L in PW-13, another on-site facility drinking water supply well (NMED, 2001b; as cited in
NMED, 2008).
New Jersey Drinking Water Quality Institute
The New Jersey Department of Environmental Protection (NJDEP) requested that the
New Jersey Drinking Water Quality Institute (NJDWQI) investigate the need to establish a
regulatory limit for perchlorate in New Jersey's drinking water. NJDEP conducted perchlorate
sampling between 2003 and early 2005. NJDEP selected PWSs (both CWSs and NTNCWSs)
based on their potential vulnerability to perchlorate contamination (including proximity to
military installations and unexploded ordnance, and proximity to sites that showed perchlorate
detections in the UCMR 1 data set). In a few circumstances, NJDEP sampled PWSs that had
tested positive for perchlorate in UCMR 1 sampling. Most of the samples were collected before
treatment, although a small number of samples were collected at entry points to distribution
systems. The samples were analyzed using EPA Method 314.0, with an MRL of 1 |ig/L.
NJDEP collected 114 samples from 67 PWSs. Most, but not all, of these samples were
taken before treatment. Perchlorate was detected in 21 (18%) samples from 11 (16%) systems.
The maximum concentration of perchlorate that was detected was 23 |ig/L with an MRL of 1
|ig/L. For more details on the NJDEP study, refer to NJDWQI (2005). UCMR 1 sampling at 128
PWSs in New Jersey did not detect perchlorate in any small PWSs and detected perchlorate in 6
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(from Sources Other than UCMR 1)
May 2019
(5.4%) large PWSs with a maximum concentration of 13 |ig/L. (The EPA's UCMR 1 data are
only representative at the state level for large systems.)
Nevada Division of Environmental Protection
NDEP provided the EPA with data for perchlorate occurrence in drinking water from two
treatment plants (Alfred Merritt Smith [AMS] Water Treatment Facility and River Mountains
[RM] Water Treatment Facility) that are part of the Southern Nevada Water System (SNWS)
(NDEP, 2011). The SNWS sources water from the Lower Colorado River and is a wholesale
system that sells water to the Las Vegas Valley Water District and other water purveyors in the
Las Vegas Valley.
Exhibit A-16 presents perchlorate occurrence data for raw (untreated) water and finished
(treated) water from the AMS and RM Treatment Plants from 1999 to 2011. (No perchlorate
treatment was conducted at these PWSs during the period of this sampling.) Although laboratory
analytical methods changed over the period of sampling, perchlorate occurrence in both raw and
finished water decreased in a relatively consistent and overall significant amount over the 13-
year sampling period. The decreased perchlorate concentrations indicated here mirror the time
period and range of similar decreases identified in the Lower Colorado River sampling presented
separately at the end of Section A. 1.
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May 2019
Exhibit A-16: Perchlorate Raw and Finished Water Data from Alfred Merritt Smith
(AMS) and River Mountains (RM) Treatment Plants
Figure adapted from NDEP (2011)
Potomac River Study
Eight drinking water utilities between western Maryland and Washington, D.C.
participated in the EPA Survey on the Temporal and Spatial Distributi on of Perchlorate in the
Potomac River (Impellitteri el al., 2011). The utilities sampled paired raw and finished water
once a month for one year from October 2007 to September 2008. The samples were analyzed
using EPA Method 332.0 and perchlorate was detected in nearly every sample. Perchlorate levels
tended to be lowest (generally < 1 |ig/'L) during the December 2007 - May 2008 period and
slightly higher in the October - November 2007 and June - September 2008 samples. Raw water
concentrations ranged from 0.03 |ig/L to 7.63 |ig/L, while treated water sample concentrations
ranged from 0.02 ug I. to 5.86 |ig/L.
Texas Commission of Environmental Quality
In response to UCMR 1 monitoring that identified the presence of perchlorate in several
locations in drinking water well fields serving Midland, TX, the Texas Commission on
Environmental Quality (TCEQ) contracted the Texas Tech University Water Resources Center to
conduct a preliminary survey of ground water in nine counties, most of which overlie the Texas
High Plains Aquifer System (Jackson et al.. 2005). In samples collected between July and
26
AMS Finish
RM Finish
24
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May 2019
December 2002, perchlorate was detected above 0.5 [j,g/L in 179 out of 254 PWSs and private
wells in 9 counties in the Texas Southern High Plains (Jackson et al., 2005). Perchlorate
concentrations exceeded 4 [j,g/L in 88 wells. The maximum concentrations were 58.8 [j,g/L for
private wells and 45.6 [j,g/L for public water system wells (Jackson et al., 2005).
The initial 9 county study was expanded to 54 counties in Texas and 3 counties in eastern
New Mexico. The purpose of the study was to examine the source of perchlorate. Sampling was
completed in the summer of 2004. Single samples were collected from each well and analyzed
using EPA Method 314.0 with a detection limit of 1 |ig/L. Jackson et al. (2005) found 1)
ubiquitous distribution of perchlorate, 2) perchlorate was found in a well types (i.e., public,
domestic, irrigation and monitoring wells) and 3) perchlorate was found in all major aquifers.
The authors believe that the evidence did not support any single anthropogenic source or
atmospheric generation. Rather, perchlorate occurrence is likely related to a complex
combination of transport and evaporative concentration.
Additional system-level analysis was performed by the EPA using a data set received
from the Texas researchers in November 2005. In all, 152 finished water samples were collected
from 52 public water systems. Samples were collected between 2001 and 2004. Twenty-three
PWSs (44%) detected perchlorate at levels greater than 4 |ig/L.
In the UCMR 1 data set, samples were collected from 255 PWSs in Texas. Perchlorate
was not detected in any small PWSs in Texas but was detected in 4 (2.2%) large PWSs. The
maximum concentration of perchlorate that was detected in Texas was 32 |ig/L. Since the
UCMR 1 data for large systems are not representative at the state level because Texas did not
provide data for 12 large systems, the UCMR 1 findings listed above should only be considered
an approximation of perchlorate occurrence in Texas.
A.2.3 California Department of Public Health
Since 1997, California Department of Public Health (CDPH) Drinking Water Program
(DWP) (formerly part of the California Department of Health Services (CDHS)) has conducted
extensive sampling for perchlorate, sampling thousands of drinking water systems and drinking
water wells throughout the state. Perchlorate was first found in drinking water wells in eastern
Sacramento County where ammonium perchlorate was used as a solid rocket propellant. As a
result of the detection, CDHS sampled additional drinking water wells in southern California
where similar potential sources of contamination existed. From this sampling effort, perchlorate
was detected in numerous wells that were considered vulnerable in Riverside and San
Bernardino Counties. In addition, perchlorate was also detected at low levels (5-9 |ig/L) in
Colorado River water, an important source of drinking and agricultural irrigation water in
southern California. (The sources of perchlorate in the Colorado River, releases from ammonium
perchlorate manufacturing facilities in southern Nevada, have undergone extensive remediation
starting in the early 2000s.) More information on perchlorate sampling in California is available
on the following California Environmental Protection Agency (CalEPA) web page:
http://www.waterboards.ca.gov/drinking_water/certlic/drinkingwater/Perchlorate.shtml.
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May 2019
CDHS established a drinking water action level for perchlorate of 18 |ig/L in 1997. Two
years later, in 1999, CDHS adopted a regulation that added perchl orate to the list of unregulated
chemicals for which monitoring is required under the State of California's Unregulated
Chemicals Requiring Monitoring (CA UCRM) program. Of the approximately 4,400 community
systems and non-transient non-community systems (with their approximately 12,000 drinking
water sources), those that were considered vulnerable to perchl orate contamination were subject
to UCRM monitoring. Systems with fewer than 150 service connections could be exempted. The
UCRM monitoring was to have been completed by December 31, 2003. In 2002, CDHS reduced
the drinking water action level to 4 |ig/L and in March of 2004 the California Office of
Environmental Health Hazard Assessment established a public health goal for perchlorate of 6
|ig/L. Use of a notification level ended when California adopted an MCL of 6 |ig/L in 2007. In
February of 2015, California established a new public health goal for perchlorate of 1 |ig/L.
In January of 2019, water quality data from California were downloaded from the web at:
http://www.waterboards.ca.gov/drinking water/certlic/drinkingwater/EDTlibrary.shtml. For the
period of 1997 through 2018, 250,450 perchlorate sample records were available. From 2001 to
2018, the number of samples reported ranged from about 6,000 to 21,000 annually and the
number of PWSs sampling for perchlorate each year ranged from 241 to 3,434. Between 1997
and 2006, about 6 percent of small systems and almost 26 percent of large systems detected
perchlorate at or above the 4 |ig/L. Between 2007 and 2018, about 2.9 percent of small systems
and almost 23 percent of large systems detected perchlorate at or above 4 |ig/L. The largest
number of samples and number of systems sampling was in 2008, the first year following the
adoption of the perchlorate MCL, when approximately 3,400 systems collected and reported the
results for nearly 21,000 samples.
The California perchlorate data set includes perchlorate detections in finished water as
well as raw source water monitored by California PWSs. With data from 1997 to 2018, there are
perchlorate occurrence data that pre-date the 2007 perchlorate rule. There are two other
important caveats regarding the California perchlorate data as presented in this report; one
regarding compliance monitoring sample locations and the other regarding what the results
represent.
Not all sample results in the data set represent compliance monitoring sample locations.
The data set does not contain parameters or metadata that serve to distinguish compliance
monitoring locations from monitoring locations that are not formal compliance monitoring
points. Raw water sample locations (such as well head/ground water sources) can serve as a
compliance sampling location if that water source is not treated or not blended prior to
distribution to customers. However, if that same groundwater source is treated and/or blended,
then the source is not considered a treated water compliance monitoring point (though sample
results from that sample point could nonetheless be included in the California perchlorate data
set). 8 The determination of whether a raw ground water sample is or is not a compliance
o
Personal communication with M. Barston, November 11, 2011. Staff at the California Department of Public
Health, Division of Drinking Water and Environmental Management.
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May 2019
monitoring point requires system-specific information beyond the current scope of research
conducted for the analyses presented below. The California perchlorate occurrence summary,
therefore, reflects portions of data from sample points that are not formal compliance monitoring
points.
Through communication with staff from the California Department of Public Health,9 it
was confirmed that most, and perhaps all, of these high sample results are likely from sample
points that are not final compliance monitoring sample points (the water represented by these
samples is either subsequently treated and/or mixed with other water sources). Nonetheless, these
sample locations with high perchlorate concentrations could serve as PWS source water that is
blended and/or treated so are included here to fully characterize perchlorate detections in water
monitored at California PWSs. The occurrence findings in this appendix reflect all the
perchlorate data downloaded from California's website for the years 1997 through 2018 with the
exception of data associated with water source or well type records identified as "WW"
(wastewater) "MW" (monitoring well), "AG" (agriculture/irrigation well), and null (no status
specified).
For comparison and context, the perchlorate data set from the State of California is
compared to the California perchlorate sampling results found in the UCMR 1 monitoring. This
comparison and the state-level data analysis presented in Appendix D were conducted using the
Updated UCMR 1 Data set (see Section 4.1 of the report for more details regarding the updated
data set). Exhibit A-17 presents the total number of samples and the number and percent of
samples with detections of perchlorate included in the California Updated UCMR 1 Data set and
the California monitoring data set. Exhibit A-18 presents a summary of the detected
concentrations of perchlorate in both data sets.
Exhibit A-19 presents the total number of systems sampled and the number and percent
of systems with detections of perchlorate for both the UCMR 1 and the California monitoring
data sets. Similar to the sample-level results presented in Exhibit A-17, the California UCMR 1
small and large system data and the California monitoring small and large system data show a
larger proportion of surface water systems compared to ground water systems with detections of
perchlorate greater than or equal to 4 |ig/L. Also, a larger proportion of large systems compared
to small systems (in both data sets) have detections of perchlorate greater than or equal to 4
Hg/L-
9 Personal communication with D. Mazzera, November 11, 2011. Research Scientist at the California Department of
Public Health, Division of Drinking Water and Environmental Management.
A-26
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EPA - OGWDW
Appendix A: Occurrence in Ambient Water and in Drinking Water
(from Sources Other than UCMR 1)
May 2019
Exhibit A-17: Comparison of the California Perchlorate Data in the Updated UCMR
1 Data set to the California Monitoring Data Set - Summary of Sample Level
Results
Source Water Type /
System Size 1
Total
Number of
Samples
Number of
Detections
(> 4 ng/L)
Percent of
Detections
(> 4 ng/L)
Number of
Detections
> 6 |jg/L
Percent of
Detections
> 6 |jg/L
Data from California in Updated UCMR 1 Dataset (2001-2005)
Small Ground Water Systems
130
0
0.0%
0
0.0%
Small Surface Water Systems
113
2
1.8%
0
0.0%
All Small Systems
243
2
0.8%
0
0.0%
Large Ground Water Systems
4,188
38
0.9%
2
0.05%
Large Surface Water Systems
4,441
280
6.3%
5
0.11%
Large Systems
8,629
318
3.7%
7
0.08%
Data from the California Monitoring Data Set (1997-2006)
Small Ground Water Systems
6,272
1,259
20.1%
805
12.8%
Small Surface Water Systems
4,717
957
20.3%
482
10.2%
All Small Systems
10,989
2,216
20.2%
1,287
11.7%
Large Ground Water Systems
10,204
825
8.1%
456
4.5%
Large Surface Water Systems
36,270
8,608
23.7%
5,576
15.4%
Large Systems
46,474
9,433
20.3%
6,032
13.0%
Data from the California Monitoring Data Set (2007-2018)
Small Ground Water Systems
38,261
3,061
8.0%
1,820
4.8%
Small Surface Water Systems
23,680
3,384
14.3%
2,238
9.5%
All Small Systems
61,941
6,445
10.4%
4,058
6.6%
Large Ground Water Systems
32,981
4,355
13.2%
3,342
10.1%
Large Surface Water Systems
98,065
18,708
19.1%
11,604
11.8%
Large Systems
131,046
23,063
17.6%
14,946
11.4%
1 Small systems serve 10,000 people or fewer. Large systems serve more than 10,000 people.
Exhibit A-18: Comparison of the California Perchlorate Data in the Updated UCMR
1 Data set to the California Monitoring Data Set - Summary of Detected
Concentrations
Source Water Type /
System Size 1
Detected Concentrations > 4 (jg/L (in |jg/L)
Minimum
Median
90th
Percentile
99th
Percentile
Maximum
Data from California in Updated UCMR 1 Data set (2001-2005)
Small Ground Water Systems
-
-
-
-
-
Small Surface Water Systems
4.0
4.0
4.0
4.0
4.0
All Small Systems
4.0
4.0
4.0
4.0
4.0
A-27
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EPA - OGWDW
Appendix A: Occurrence in Ambient Water and in Drinking Water
(from Sources Other than UCMR 1)
May 2019
Source Water Type /
System Size 1
Detected Concentrations > 4 (jg/L (in |jg/L)
Minimum
Median
90th
Percentile
99th
Percentile
Maximum
Large Ground Water Systems
4.0
4.0
6.0
8.9
9.7
Large Surface Water Systems
4.0
4.0
6.0
7.0
7.0
Large Systems
4.0
4.0
6.0
7.0
9.7
Data from the California Monitoring Data Set (1997-2006)
Small Ground Water Systems
4.0
8.3
51.0
86.7
159.0
Small Surface Water Systems
4.0
6.1
8.1
28.4
33.0
All Small Systems
4.0
6.5
44.0
71.9
159.0
Large Ground Water Systems
4.0
7.9
36.0
79.3
95.9
Large Surface Water Systems
4.0
7.6
20.0
250.0
820.0
Large Systems
4.0
7.6
22.0
240.0
820.0
Data from the California Monitoring Data Set (2007-2018)
Small Ground Water Systems
4.0
7.3
17.0
62.0
270.0
Small Surface Water Systems
4.0
13.0
26.0
47.3
91.0
All Small Systems
4.0
8.1
24.0
59.0
270.0
Large Ground Water Systems
4.0
11.0
43.0
65.0
120.0
Large Surface Water Systems
4.0
7.2
19.0
67.0
460.0
Large Systems
4.0
7.6
26.0
66.0
460.0
1 Small systems serve 10,000 people or fewer. Large systems serve more than 10,000 people.
Exhibit A-19: Comparison of California Perchlorate Data in the Updated UCMR 1
Data set to the California Monitoring Data Set - Summary of Systems
Source Water Type /
System Size 1
Total
Number of
Systems
Systems
with
Detections
(> 4 ng/L)
Percent of
Systems
with
Detections
(> 4 ng/L)
Systems
with
Detections
> 6 |jg/L
Percent of
Systems
with
Detections
> 6 |jg/L
Data from California in Updated UCMR 1 Data set (2001-2005)
Small Ground Water Systems
26
0
0.0%
0
0.0%
Small Surface Water Systems
22
1
4.5%
0
0.0%
All Small Systems
48
1
2.1%
0
0.0%
Large Ground Water Systems
151
12
7.9%
2
1.3%
Large Surface Water Systems
206
37
18.0%
1
0.5%
Large Systems
357
49
13.7%
3
0.8%
Data from the California Monitoring Data Set (1997-2006)
Small Ground Water Systems
797
46
5.8%
29
3.6%
Small Surface Water Systems
203
18
8.9%
8
3.9%
All Small Systems
1,000
64
6.4%
37
3.7%
A-28
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EPA - OGWDW
Appendix A: Occurrence in Ambient Water and in Drinking Water
(from Sources Other than UCMR 1)
May 2019
Source Water Type /
System Size 1
Total
Number of
Systems
Systems
with
Detections
(> 4 ng/L)
Percent of
Systems
with
Detections
(> 4 ng/L)
Systems
with
Detections
> 6 |jg/L
Percent of
Systems
with
Detections
> 6 |jg/L
Large Ground Water Systems
109
17
15.6%
11
10.1%
Large Surface Water Systems
260
78
30.0%
57
21.9%
Large Systems
369
95
25.7%
68
18.4%
Data from the California Monitoring Data Set (2007-2018)
Small Ground Water Systems
3,813
105
2.8%
57
1.5%
Small Surface Water Systems
699
26
3.7%
16
2.3%
All Small Systems
4,512
131
2.9%
73
1.6%
Large Ground Water Systems
125
18
14.4%
13
10.4%
Large Surface Water Systems
272
72
26.5%
46
16.9%
Large Systems
397
90
22.7%
59
14.9%
1 Small systems serve 10,000 people or fewer. Large systems serve more than 10,000 people.
A-29
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Appendix B
Considerations for Additional Data
Quality Measures
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EPA - OGWDW Appendix B. Considerations for Additional Data Quality Measures
May 2019
Appendix B. Considerations for Additional Data Quality Measures
The EPA received an "Information Quality Guidelines (IQG) Request for Correction"
letter from the United States Chamber of Commerce (the "Chamber") in September of 2012.
This letter stated that, in the EPA's determination to regulate perchlorate, the Agency relied upon
data that did not comply with various data quality guidelines. In response to the letter, the EPA
considered some components of the UCMR 1 data and reviewed some recent studies regarding
local perchlorate occurrence. These considerations led to some additional data quality measures
being applied to the UCMR 1 Perchlorate Data set prior to analysis. This appendix presents the
EPA's considerations of information in the September 2012 Chamber letter, a description of the
additional data quality measures conducted, and a comparison of current California perchlorate
occurrence results to the updated UCMR 1 California data.
B.l UCMR 1 Perchlorate Source Water Sampling Data Review
The EPA used the UCMR 1 Perchlorate Data set to characterize the frequency and levels
of perchlorate occurrence in public drinking water systems for the five perchlorate
announcements discussed in Section 1.1 of this report (USEPA, 2007a; USEPA, 2008a; USEPA,
2009c; USEPA, 2009d; and USEPA, 201 la). The data set used in support of those actions
contained 34,331 samples from 3,865 systems including a total of 637 detections (1.9% of all
samples) from 160 PWSs (4.1% of all UCMR 1 systems).
The September 2012 Chamber letter to the EPA stated that some UCMR 1 raw source
water sample analytical detections of perchlorate did "not comply with data quality guidelines
because it was not collected by accepted methods." Of the 34,331 total samples in the UCMR 1
Perchlorate Data set, 69% (23,731) were collected at the entry points to the distribution system
while the remaining 31% (10,600) were collected from untreated (but UCMR 1 eligible) source
water sample locations. Of the 637 samples that detected perchlorate, 56% (355) were collected
at the entry points to the distribution system while the remaining 44% (282) were collected from
source water sample locations. All source water samples with perchlorate detections were
collected from PWSs serving more than 10,000 people.
Considering this data quality comment in the Chamber letter, the Agency conducted a
more detailed evaluation of the source water sample detections. At the time of the UCMR 1
perchlorate monitoring, every system that reported a perchlorate detection in a source water
sample was notified by the EPA of the UCMR 1 requirement that for each source water sample
detection, the system must conduct follow-up sampling at the entry point to the distribution
system that is associated with the source water sample detection. After the UCMR 1 monitoring
period ended, the EPA evaluated system-level monitoring records to determine if the system met
UCMR 1 follow-up sampling requirements. The agency found a mix of results and sorted the
sample findings into the following four categories:
1. Systems that collected source water and entry point samples at the same time;
2. Systems with a perchlorate source water sample detection that collected follow-up entry
point samples;
3. Systems that did not collect follow-up entry point samples because the well was removed
from service; and
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EPA - OGWDW Appendix B. Considerations for Additional Data Quality Measures
May 2019
4. Systems with a perchlorate source water sample detection that did not collect follow-up
entry point samples.
Below is a description of each category along with the number of perchlorate sampling
records assigned to the category.
Category 1 - Systems that collected source water and entry point samples at the same time
This category contains perchlorate monitoring data that PWSs collected concurrently (on
the same day) at both source water sample locations (wells) and entry points to the distribution
systems. There are 33 source water perchlorate detections and 32 source water samples that did
not detect perchlorate in this category.
Category 2 - Systems with a perchlorate source water sample detection that collected follow-up
entry point samples
The EPA evaluated PWS follow-up sampling documentation to identify when PWSs
conducted follow-up sampling as required by the UCMR 1. This evaluation was based on data
supplied by the PWS, including the source water sample date, the sample date of an entry point
result, the names assigned to sample points and any comments provided by the PWS. The EPA's
evaluation resulted in identification and inclusion of 64 source water sample perchlorate
detections and 70 non-detections in this category.
Category 3 - Systems that did not collect follow-up entry point samples because the well was
removedfrom service
This category contains perchlorate monitoring data that PWSs collected from source
water sample locations (wells) that were subsequently removed from service. Inclusion of a
source water sample in this category was based on information provided by, or obtained from,
PWSs. A total of 52 source water perchlorate detections and 16 non-detections are included in
this category.
Category 4 - Systems with a perchlorate source water sample detection that did not collect
follow-up entry point samples
As was the case for evaluating Category 2, inclusion of source water samples in this
category required review of monitoring records to decide whether PWSs had conducted follow-
up sampling as required. Some samples were included in this category based on the absence of
entry point samples (e.g., if there was no record of entry point samples at a system subsequent to
a source water detection sample date, it was concluded that the system did not conduct follow-up
sampling). Included in this category are 133 source water perchlorate detections and 33 non-
detections.
Source Water Breakdown Summary
As a result of the evaluation of perchlorate system-level monitoring records to determine
if PWSs met UCMR 1 follow-up sampling requirements, the EPA found 433 source water
B-2
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EPA - OGWDW Appendix B. Considerations for Additional Data Quality Measures
May 2019
records of which 65% (282) of the samples had perchlorate detections and 35% (151) did not.
See Exhibit B-l for a breakdown of the four categories.
Exhibit B-1: Categories of UCMR 1 Source Water Samples Analyzed for
Perchlorate and the Number of Perchlorate Detection and Non-Detections per
Category
Category
Description of Category
Detects
Non-
Detects
Total
Records
1
Systems that collected source water and entry point
samples at the same time
33
32
65
2
Systems with a perchlorate source water sample detection
that collected follow-up entry point samples
64
70
134
3
Systems that did not collect follow-up entry point samples
because the well was removed from service
52
16
68
4
Systems with a perchlorate source water sample detection
that did not collect follow-up entry point samples
133
33
166
Total
All Four Categories
282
151
433
The EPA excluded Category 1 and 2 source water samples from the UCMR 1 Perchlorate
Data set used in this report because these samples were replaced by entry point samples collected
for and included in the UCMR 1 Perchlorate Data set. In contrast, no follow-up sampling was
conducted by PWSs for the source water sample perchlorate detections in Categories 3 or 4 so
the EPA retained those sample records in the UCMR 1 Perchlorate Data set. The resulting data
set contains 34,132 samples from 3,865 systems including a total of 540 detections.1 (1.58% of
all samples) from 149 PWSs (3.86% of all PWSs). This compares to the complete UCMR 1
(March 2006) data set that included 34,331 samples with 637 detections (1.86% of all samples)
from 160 PWSs (4.14% of all PWSs).
Appendix C presents all 637 perchlorate detections from UCMR 1 sampling, conducted
between 2001 and 2005. Specifically, the table presents (for each of the 637 original UCMR 1
individual detections) the state, public water system identification number (PWSID), Facility ID,
sample point ID, sample point type (EP = entry point; SR = source water), the system's source
water type, system size, the sample date, the result value (in |ig/L), and the source water sample
category (if the detection was from source water). As described above, the agency found a mix of
source water detection results and sorted the sample findings into four categories. The EPA
excluded Category 1 and 2 source water detections (as well as non-detection records from the
1 The 540 detections are the result of the original 637 detections in the UCMR 1 data set minus 33 detections (from
Category 1) and 64 detections (from Category 2).
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EPA - OGWDW Appendix B. Considerations for Additional Data Quality Measures
May 2019
same sample points) from the updated UCMR 1 Perchlorate Data set that serves as the basis for
all occurrence analyses, graphs, and maps presented in Section 4.2 of this report.
B.2 Follow-up Information Relevant to UCMR 1 Perchlorate Data
The September 2012 Chamber letter also stated that some UCMR 1 data did "not comply
with data quality guidelines because it is not representative of current conditions." The Chamber
presented additional and later sampling (some subsequent to the UCMR 1 monitoring period),
noting that some of the detections included in the UCMR 1 data set did not fully reflect
conditions at some PWSs at the time of the UCMR 1 sampling. Additional information, as
presented in the Chamber 2012 letter, included studies by Brandhuber et al. (2009) and AWWA
(2008), as well as state drinking water annual compliance reports.
Brandhuber et al. (2009) conducted a review of perchlorate occurrence in public water
systems, utilizing the UCMR 1 data in the analysis. As a follow-up to the UCMR 1 sampling,
Brandhuber et al. attempted to contact all 160 public water systems the UCMR 1 data set with
detections of perchlorate. Seventy of the 160 systems responded to the survey; these systems
indicated that 192 sources testing positive for perchlorate were still on-line. Of these, 63 sources
required treatment to meet applicable state regulations. Some utilities indicated that the
perchlorate concentrations had dropped in some sources since the time of the original UCMR 1
sampling; thus, those sources continued to operate. In contrast, 32 sources from a total of 13
systems had been taken off-line because of the level of perchlorate contamination in the original
UCMR 1 monitoring. Eight systems indicated they would be replacing sources that had been
taken off-line and 12 systems reported that their drinking water did not contain perchlorate.
Brandhuber et al. (2009) did not indicate which systems fell into which categories described
above. Without identification of specific systems, it is not possible to use this information to
somehow modify or augment the UCMR 1 perchlorate data set. A total of 90 water systems
(more than half) with UCMR 1 perchlorate detections did not respond to the Brandhuber et al.
(2009) follow-up survey so additional information on those systems' perchlorate levels is not
known.
The 2012 Chamber letter recommended that the EPA's occurrence analyses exclude all
UCMR 1 perchlorate detections from California that were greater than 6 |ig/L (the State's
Maximum Contaminant Level (MCL) for perchlorate as of 2007) and instead replace those
results with data from the CDPH (2009) Annual Compliance Report. According to the Chamber,
the CDPH (2009) report identifies 9 small PWSs with a total population served of 776 that have
at least one perchlorate detection greater than 6 |ig/L.2 The Chamber's letter states that based on
UCMR 1 data for California, using the high-end estimate, that an estimated 4.2 million people
are served by PWSs with at least one perchlorate detection greater than 6 |ig/L. If these data
were removed from the analysis, the national estimate of total population served by PWSs with
at least one detection greater than 6 |ig/L would decrease by an estimated 4.2 million. The EPA
closely evaluated the data and related estimates in the Chamber letter and was not been able to
2 The 2009 CDPH Annual Compliance Report actually lists only two systems with perchlorate MCL violations and
nine systems with perchlorate monitoring and reporting violations (i.e., the systems failed to monitor). Note also that
the nine systems serve a total of 766 people according to the report. The report is available on the internet at:
http://www.swrcb.ca.gov/drinking water/certlic/drinkingwater/Publications.shtml.
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May 2019
reproduce the 4.2 million estimated decrease. (The EPA's review of the UCMR 1 data identifies
that the total population served by PWSs in California with at least one detection greater than 6
|ig/L is 6.7 million. The UCMR 1 data indicate that 11.8 million people are served by PWSs
nationally with at least one detection greater than 6 |ig/L. Excluding the population served by
California PWSs with at least one detection greater than 6 |ig/L (6.7 million) from the total
UCMR 1 population served by PWSs with at least one detection greater than 6 |ig/L (11.8
million) would result in an estimated 5.1 million people potentially exposed to perchlorate
greater than 6 |ig/L.)
Additional follow-up information subsequent to the UCMR 1 monitoring was included in
AWWA (2008). In that study was a description of a follow-up study to contact several PWSs
inquiring about the validity of the estimated perchlorate concentrations from UCMR 1 sampling.
The Chamber's 2012 letter describes post-UCMR 1 perchlorate information for four water
systems:
• Henderson, Nevada (PWSID = NV0000076; population served = 220,000)
• High Point, North Carolina (PWSID = NC0241020; population served = 88,420)
• Manatee County, Florida (PWSID = FL6411132; population served = 198,500)
• Midland, Texas (PWSID = TX1650001; population served = 98,045)
UCMR 1 sampling included four detections of perchlorate from the City of Henderson,
Nevada. The maximum detection was equal to 23 |ig/L. However, a 2009 water quality report
from this water system indicated that perchlorate detections did not exceed 5.9 |ig/L. AWWA
(2008) stated that the more current perchlorate measurements were expected to be more
representative of current (2009) levels in the City of Henderson source water intake than the
measurements collected in the early 2000s for the UCMR sampling effort. The Chamber
recommended that this system not be counted in any UCMR 1 estimates for perchlorate
occurrence above 6 |ig/L and that 246,000 people be removed from any exposure estimates of
perchlorate occurrence above 6 |ig/L. (Note that the population served by this system as it
appears in the UCMR 1 data set is equal to 220,000.)
The City of High Point, North Carolina included a perchlorate detection of 13.8 |ig/L in
the UCMR 1 data set. AWWA (2008) stated that this detection was later confirmed by the
contract laboratory as a false positive. A lab supervisor at the City of High Point, North Carolina
indicated that subsequent source water sampling conducted by the U.S. Geological Survey and
the City also confirmed the absence of perchlorate in their source water. The Chamber
recommended that this system not be counted in any UCMR 1 estimates for perchlorate
occurrence and that 104,000 people be removed from any exposure estimates. (Note that the
population served by this system as it appears in the UCMR 1 data set is equal to 88,420.)
UCMR 1 sampling included a perchlorate detection of 30 |ig/L from a Manatee County,3
Florida water system. According to AWWA (2008), a worker at the Manatee County Public
Works Department believes that the positive hit was attributable to analytical errors. Perchlorate
3 The 2012 Chamber letter indicated that this system reported a detection of 21 |ig/L. That detected concentration
could not be found in the UCMR 1 data set. The perchlorate detection from this system was equal to 30 |ig/L.
B-5
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EPA - OGWDW Appendix B. Considerations for Additional Data Quality Measures
May 2019
was not detected in any other UCMR sampling from their system. The Chamber recommended
that this system not be counted in any UCMR 1 estimates for perchlorate occurrence and that
447,000 people be removed from any exposure estimates. (Note that the population served by
this system as it appears in the UCMR 1 data set is equal to 198,500.)
The City of Midland, Texas included a perchlorate detection of 7.92 |ig/L in the UCMR 1
data set. AWWA (2008) stated that the well field with high perchlorate concentrations was
abandoned after the perchlorate contamination was discovered. The Chamber recommended that
this system not be counted in any UCMR 1 estimates for perchlorate occurrence and that 111,000
people be removed from any exposure estimates. (Note that the population served by this system
as it appears in the UCMR 1 data set is equal to 98,045.)
The 2012 Chamber letter indicated that these four drinking water systems, described
above, serving approximately 900,000 people, should not be included in any occurrence
estimates above 6 ng/L. (As stated above, the combined population served by these four water
systems as of the time of UCMR 1 sampling was actually equal to 600,000.) Although the EPA
acknowledges that conditions may have changed in regard to perchlorate occurrence after the
time of UCMR 1 sampling, it is important to include all of the sampling data (as subject to
quality checks and reviews) to maintain the representativeness of the UCMR 1 data set as a
whole. The information provided in Brandhuber et al. (2009) and AWWA (2008) was for a small
subset of all the public water systems represented in the UCMR 1 data set. With a select and very
incomplete update, it is not possible to know more current conditions for perchlorate occurrence
nationally as represented in all UCMR 1 systems. Therefore, it is not appropriate to update some
systems' data and not others given the need for high data quality, consistency, and national
representativeness that is provided by the UCMR 1 perchlorate data.
The EPA also notes that the AWWA (2008) report found a significant number of
California PWSs with perchlorate source water detections that were not in the UCMR 1
perchlorate data set. (This information was not noted in the 2012 Chamber letter.) AWWA
(2008) reported that in a separate state-wide sampling effort, perchlorate detections were found
in approximately twice as many of the source waters than were reported in UCMR 1 California
data set. Several factors were listed as potential reasons for the discrepancies between the
statewide California sampling and the UCMR 1 data set: (1) some (or all) of the contaminated
sources in the California data set that were not in the UCMR 1 data set may have been small
PWSs that were not included in the UCMR 1 sampling effort; (2) the California data set includes
some samples that reported perchlorate concentrations below 4 ng/L (these perchlorate
detections would not have appeared in the UCMR data set) and; (3) the California data set (1997
- 2003) includes samples collected prior to the UCMR 1 sampling effort (2001 - 2003).
Although unlikely, it is possible that source waters sampled prior to the UCMR sampling effort
were remediated, reducing concentrations below 4 ng/L before samples were collected for
analysis under UCMR. It is also possible that some wells were taken out of service. These types
of findings underscore the importance of using the UCMR 1 perchlorate data set (given the data
quality and representativeness), and not modifying it with select, ad hoc, or incomplete data.
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EPA - OGWDW Appendix B. Considerations for Additional Data Quality Measures
May 2019
B.3 Additional Comparison of UCMR 1 Perchlorate Data from California to
Recent California Perchlorate Results
To further investigate how occurrence levels may have changed in California since the
time of UCMR 1 monitoring, the EPA compared perchlorate occurrence results from UCMR 1 to
current perchlorate occurrence results for each California water system with measurable
detections in UCMR 1. The EPA identified all systems and corresponding entry points in
California which had reported perchlorate detections in UCMR 1. The EPA used a combination
of available data from current Consumer Confidence Reports (CCRs) and perchlorate
compliance monitoring data from California (https://sdwis.waterboards.ca.gov/PDWW/) to
match current compliance monitoring data (where available) to the corresponding water systems
and entry points sampled during UCMR 1.
As described in Section 3.4.2, the EPA updated the UCMR 1 data for 320 detections from
California based on current information. The EPA's convention for these updates was to
substitute data from the UCMR 1 entry points with the most recently reported compliance
monitoring data from the same (active) entry point. If more than one data point was reported for
an entry point, the assigned value was an average of the annual monitoring results at the entry
point.
In addition, when updated entry point data were not available, the EPA used information
from current CCRs for its data update effort. The EPA used CCR information for the updates by
assigning a default value of 6 |ig/L to all entry points in a given system if perchlorate was
reported in the CCR as detected but within compliance of the California MCL. For systems
where perchlorate was reported as not having been detected in the CCR then a default value of 4
|ig/L (equal to the MRL) was assigned to all entry points in a given system. In cases were the
EPA could not find updated entry point data or CCR information, then the original data from
UCMR 1 for the entry point was retained.
Exhibit B-2 presents information for the 50 systems in California that reported
perchlorate detections in UCMR 1. This exhibit provides a comparison of the UCMR 1 results to
the updated occurrence data compiled by the EPA based on the substitution process explained
above. Copies of the documents (i.e., CCRs and Compliance Data) used by the EPA to complete
its data substitution for systems in California are publicly available in the perchlorate docket
under the document titled "Perchlorate Compliance Records - California Systems."
Exhibit B-2: Comparison of UCMR 1 Results and Updated Occurrence Data for 50
Systems from California with UCMR 1 Perchlorate Detections
PWS ID
PWS Name
UCMR 1 Results
Max.
Detection
from Updated
Occurrence
Data
#
Samples
#
Detections
Max.
Detection
CA1300549
Imperial Valley College
4
2
6.2
4
CA1310001
City of Brawley
4
2
5.2
4
CA1510031
City of Bakersfield
106
1
7.6
7.6
B-7
-------
EPA - OGWDW Appendix B. Considerations for Additional Data Quality Measures
May 2019
PWS ID
PWS Name
UCMR 1 Results
Max.
Detection
from Updated
Occurrence
Data
#
Samples
#
Detections
Max.
Detection
CA1910007
Azusa Light & Water
14
2
11
6
CA1910017
Santa Clarita Water Company
22
1
4.2
6
CA1910033
Dominguez Water Corp.
55
1
9.2
4
CA1910036
CA Water Service Company - Ela
26
4
7.7
4
CA1910062
City of La Verne
6
5
20
7
CA1910063
Lincoln Avenue Water Company
11
2
15
6
CA1910087
Metropolitan Water District of S. CA
40
2
4.6
4
CA1910124
City of Pasadena Water Department
24
18
35
6
CA1910126
City of Pomona Water Department
48
26
12
6
CA1910143
City of San Fernando Water Department
9
1
8.9
4
CA1910144
San Gabriel CWD
10
1
4.2
4
CA1910154
City of South Pasadena Water Department
2
1
4.5
6
CA1910167
City of Vernon Water Department
18
2
5.4
4
CA1910205
Suburban Water Systems - San Jose
3
1
7.2
6
CA2710010
CA Water Service Company - Salinas
76
2
22.3
4
CA3010001
City of Anaheim
72
7
5.3
4.3
CA3010022
Southern CA Water Company - West Orange
45
7
6.2
6
CA3010038
City of Santa Ana
48
1
4.4
6
CA3010062
City of Garden Grove
39
2
4.4
6
CA3010092
Irvine Ranch Water District
63
1
6
4
CA3010094
Trabuco Canyon Water District
9
1
5
4
CA3310001
Coachella VWD - Cove Community
162
1
5.9
5.9
CA3310005
Desert Water Agency
105
14
6.6
5.8
CA3310009
Eastern Municipal Water District
31
2
7.5
4
CA3310016
City of He met
21
2
7.2
6
CA3310021
Jurupa Community Services District
32
1
4.6
6
CA3310031
City of Riverside
82
37
42
4
CA3310037
City of Corona
73
41
13
4
CA3310044
Rubidoux Community San. District
8
6
10.3
6
CA3410004
Carmichael Water District
34
1
4.1
4.1
CA3610004
West San Bernardino CWD
44
8
7.5
4
CA3610012
City of Chino
26
4
6.8
4
CA3610013
City of Loma Linda
6
1
5
5
CA3610034
City of Ontario
51
15
12
4
CA3610036
City of Chino Hills
18
1
4.4
4
CA3610037
Redlands City MUD
163
48
67
4
CA3610038
City of Rialto
30
5
33
4
CA3610041
San Gabriel Valley Water Co. - Fontana
82
10
15
6
CA3610043
Southern CA Water Company - Barstow
39
1
4.7
4
B-8
-------
EPA - OGWDW Appendix B. Considerations for Additional Data Quality Measures
May 2019
PWS ID
PWS Name
UCMR 1 Results
Max.
Detection
from Updated
Occurrence
Data
#
Samples
#
Detections
Max.
Detection
CA3610064
East Valley Water District
94
22
16
4
CA3610705
Fort Irwin
17
1
9.7
9.7
CA3710006
City of Escondido
12
1
4.3
4
CA3910001
California Water Service - Stockton
73
1
4.8
4
CA3910011
City of Tracy
26
1
21
4
CA3910012
City of Stockton
67
1
6
6
CA4310001
CA Water Service Company - Los Altos
58
1
4.7
4
CA4310022
Great Oaks Water Company, Inc.
31
1
4.4
4
The State of California provides copies of their drinking water annual compliance
reports online..4 The reports were consulted for the years 2008 through 2017 and are summarized
in Exhibit B-3. Violations of the State of California MCL of 6 |ig/L are listed in the table below.
According to the annual compliance reports, there have been very few violations of the
perchlorate MCL since the adoption of the MCL in 2007. No systems had violations between
2012 and 2015. Three systems in 2017 had MCL violations.
Exhibit B-3: Summary of MCL Violations from California Annual Compliance
Reports for Public Water Systems
Year
Number of MCL
Violations
Number of Systems
with MCL Violations
2008
4
3
2009
2
2
2010
1
1
2011
2
1
2012
0
0
2013
0
0
2014
0
0
2015
0
0
2016
0
0
2017
9
3
Exhibit B-4 presents the updated data set for the 540 perchlorate detections retained from
UCMR 1 after data quality measures were completed. The table presents updated data set that
serves as the basis for all UCMR 1 perchlorate occurrence analyses, graphs, and maps presented
in Section 4 of this report.
4 Source: http://www.swrcb.ca.gov/drinking water/certlic/drinkingwater/Publications.shtml
B-9
-------
EPA-OGWDW AppendixB. Considerations for Additional Data Quality Measures May 2019
Exhibit B-4. Updated Dataset for Perchlorate Detections
State
PWSID
Facility ID
Source Water
Type
Size
Category
Updated Result
(Mfl/L)1
1
AL
AL0000029
00007T
GW
Large
7.2
2
AL
AL0000553
00016
GW
Large
8.9
3
AL
AL0000553
00016
GW
Large
8.4
4
AL
AL0001002
00003T
GW
Large
5.5
5
AL
AL0001070
00051
GW
Large
8.5
6
AL
AL0001070
0000IT
SW
Large
11.0
7
AR
AR0000209
00001
SW
Large
4.5
8
AR
AR0000209
00002
SW
Large
6.6
9
AR
AR0000459
00001
GW
Large
5.5
10
AZ
AZ0407017
01822
SW
Large
5.7
11
AZ
AZ0407017
01823
SW
Large
5.6
12
AZ
AZ0407025
01811
SW
Large
5.1
13
AZ
AZ0407025
01812
SW
Large
5.2
14
AZ
AZ0407093
00155
GW
Large
4.6
15
AZ
AZ0407093
00158
GW
Large
4.9
16
AZ
AZ0407093
01833
SW
Large
6.0
17
AZ
AZ0407093
01833
SW
Large
4.1
18
AZ
AZ0407093
01834
SW
Large
4.6
19
AZ
AZ0407095
01872
SW
Large
6.9
20
AZ
AZ0407095
01872
SW
Large
5.1
21
AZ
AZ0407095
01872
SW
Large
4.5
22
AZ
AZ0407098
00191
GW
Large
4.1
23
AZ
AZ0407098
01836
SW
Large
6.9
24
AZ
AZ0407098
01836
SW
Large
5.3
25
AZ
AZ0410112
00165
GW
Large
11.9
26
AZ
AZ0410112
00351
GW
Large
4.8
27
AZ
AZ0414004
00407
SW
Large
4.0
28
AZ
AZ0414024
01813
SW
Large
6.1
29
AZ
AZ0414024
01813
SW
Large
4.7
30
AZ
AZ0414024
01813
SW
Large
4.2
31
AZ
AZ0414024
01816
SW
Large
6.4
32
AZ
AZ0414024
01816
SW
Large
4.7
33
AZ
AZ0414024
01816
SW
Large
4.1
34
AZ
AZ0415010
00831
SW
Small
6.0
35
AZ
AZ0415010
00831
SW
Small
5.9
36
AZ
AZ0415010
00831
SW
Small
5.8
37
CA
CA1300549
00001T
SW
Small
4.0
38
CA
CA1300549
00001T
SW
Small
4.0
39
CA
CA1310001
00950
SW
Large
4.0
40
CA
CA1310001
00950
SW
Large
4.0
41
CA
CA1510031
00026
GW
Large
7.6
42
CA
CA1910007
00500
GW
Large
6.0
43
CA
CA1910007
00500
GW
Large
6.0
44
CA
CA1910017
00020
GW
Large
6.0
B-10
-------
EPA-OGWDW AppendixB. Considerations for Additional Data Quality Measures May 2019
Exhibit B-4. Updated Dataset for Perchlorate Detections
State
PWSID
Facility ID
Source Water
Type
Size
Category
Updated Result
(Mfl/L)1
45
CA
CA1910033
00024
GW
Large
4.0
46
CA
CA1910036
00004
GW
Large
4.0
47
CA
CA1910036
00004
GW
Large
4.0
48
CA
CA1910036
00004
GW
Large
4.0
49
CA
CA1910036
00004
GW
Large
4.0
50
CA
CA1910062
00010
GW
Large
7.0
51
CA
CA1910062
00012
GW
Large
7.0
52
CA
CA1910062
00016
GW
Large
7.0
53
CA
CA1910062
00018
GW
Large
7.0
54
CA
CA1910062
00032
GW
Large
7.0
55
CA
CA1910063
17
GW
Large
6.0
56
CA
CA1910063
17
GW
Large
6.0
57
CA
CA1910087
00023
SW
Large
4.0
58
CA
CA1910087
00003T
SW
Large
4.0
59
CA
CA1910124
00006
GW
Large
6.0
60
CA
CA1910124
00006
GW
Large
6.0
61
CA
CA1910124
00007
GW
Large
6.0
62
CA
CA1910124
00010
GW
Large
6.0
63
CA
CA1910124
00014
GW
Large
6.0
64
CA
CA1910124
00014
GW
Large
6.0
65
CA
CA1910124
00018
GW
Large
6.0
66
CA
CA1910124
00018
GW
Large
6.0
67
CA
CA1910124
00019
GW
Large
6.0
68
CA
CA1910124
00019
GW
Large
6.0
69
CA
CA1910124
00020
GW
Large
6.0
70
CA
CA1910124
00020
GW
Large
6.0
71
CA
CA1910124
00021
GW
Large
6.0
72
CA
CA1910124
00021
GW
Large
6.0
73
CA
CA1910124
00022
GW
Large
6.0
74
CA
CA1910124
00022
GW
Large
6.0
75
CA
CA1910124
00028
GW
Large
6.0
76
CA
CA1910124
00028
GW
Large
6.0
77
CA
CA1910126
00002
GW
Large
6.0
78
CA
CA1910126
00002
GW
Large
6.0
79
CA
CA1910126
00002
GW
Large
6.0
80
CA
CA1910126
00003
GW
Large
6.0
81
CA
CA1910126
00007
GW
Large
6.0
82
CA
CA1910126
00010
GW
Large
6.0
83
CA
CA1910126
00010
GW
Large
6.0
84
CA
CA1910126
00010
GW
Large
6.0
85
CA
CA1910126
00013
GW
Large
6.0
86
CA
CA1910126
00021
GW
Large
6.0
87
CA
CA1910126
00021
GW
Large
6.0
88
CA
CA1910126
00023
GW
Large
6.0
B-ll
-------
EPA-OGWDW AppendixB. Considerations for Additional Data Quality Measures May 2019
Exhibit B-4. Updated Dataset for Perchlorate Detections
State
PWSID
Facility ID
Source Water
Type
Size
Category
Updated Result
(Mfl/L)1
89
CA
CA1910126
00023
GW
Large
6.0
90
CA
CA1910126
00023
GW
Large
6.0
91
CA
CA1910126
00025
GW
Large
6.0
92
CA
CA1910126
00025
GW
Large
6.0
93
CA
CA1910126
00025
GW
Large
6.0
94
CA
CA1910126
00026
GW
Large
6.0
95
CA
CA1910126
00026
GW
Large
6.0
96
CA
CA1910126
00030
GW
Large
6.0
97
CA
CA1910126
00049
GW
Large
6.0
98
CA
CA1910126
00049
GW
Large
6.0
99
CA
CA1910126
00049
GW
Large
6.0
100
CA
CA1910126
00050
GW
Large
6.0
101
CA
CA1910126
00051
GW
Large
6.0
102
CA
CA1910126
00051
GW
Large
6.0
103
CA
CA1910143
00002
GW
Large
4.0
104
CA
CA1910144
00016
GW
Large
4.0
105
CA
CA1910154
00950
GW
Large
6.0
106
CA
CA1910167
00012
GW
Large
4.0
107
CA
CA1910167
00012
GW
Large
4.0
108
CA
CA1910205
00034
GW
Large
6.0
109
CA
CA2710010
00029
GW
Large
4.0
110
CA
CA2710010
00046
GW
Large
4.0
111
CA
CA3010001
00032
GW
Large
4.3
112
CA
CA3010001
00032
GW
Large
4.3
113
CA
CA3010001
00032
GW
Large
4.3
114
CA
CA3010001
00033
GW
Large
4.0
115
CA
CA3010001
00055
SW
Large
4.0
116
CA
CA3010001
00055
SW
Large
4.0
117
CA
CA3010001
00055
SW
Large
4.0
118
CA
CA3010022
00020
GW
Large
6.0
119
CA
CA3010022
00020
GW
Large
6.0
120
CA
CA3010022
00022
GW
Large
6.0
121
CA
CA3010022
00022
GW
Large
6.0
122
CA
CA3010022
00022
GW
Large
6.0
123
CA
CA3010022
00024
GW
Large
6.0
124
CA
CA3010022
00025
GW
Large
6.0
125
CA
CA3010038
00019
GW
Large
6.0
126
CA
CA3010062
00019
GW
Large
6.0
127
CA
CA3010062
00019
GW
Large
6.0
128
CA
CA3010092
00015
GW
Large
4.0
129
CA
CA3010094
00001
GW
Large
4.0
130
CA
CA3310001
00147
GW
Large
5.9
131
CA
CA3310005
00013
GW
Large
5.8
132
CA
CA3310005
00013
GW
Large
5.8
B-12
-------
EPA-OGWDW AppendixB. Considerations for Additional Data Quality Measures May 2019
Exhibit B-4. Updated Dataset for Perchlorate Detections
State
PWSID
Facility ID
Source Water
Type
Size
Category
Updated Result
(Mfl/L)1
133
CA
CA3310005
00019
GW
Large
4.0
134
CA
CA3310005
00023
GW
Large
4.0
135
CA
CA3310005
00023
GW
Large
4.0
136
CA
CA3310005
00023
GW
Large
4.0
137
CA
CA3310005
00024
GW
Large
4.0
138
CA
CA3310005
00024
GW
Large
4.0
139
CA
CA3310005
00029
GW
Large
4.0
140
CA
CA3310005
00032
GW
Large
4.0
141
CA
CA3310005
00032
GW
Large
4.0
142
CA
CA3310005
00039
GW
Large
4.0
143
CA
CA3310005
00039
GW
Large
4.0
144
CA
CA3310005
00039
GW
Large
4.0
145
CA
CA3310009
00042
GW
Large
4.0
146
CA
CA3310009
00047
GW
Large
4.0
147
CA
CA3310016
00003
GW
Large
6.0
148
CA
CA3310016
00003
GW
Large
6.0
149
CA
CA3310021
00003
GW
Large
6.0
150
CA
CA3310031
00015
GW
Large
4.0
151
CA
CA3310031
00027
GW
Large
4.0
152
CA
CA3310031
00027
GW
Large
4.0
153
CA
CA3310031
00027
GW
Large
4.0
154
CA
CA3310031
00028
GW
Large
4.0
155
CA
CA3310031
00028
GW
Large
4.0
156
CA
CA3310031
00028
GW
Large
4.0
157
CA
CA3310031
00029
GW
Large
4.0
158
CA
CA3310031
00030
GW
Large
4.0
159
CA
CA3310031
00031
GW
Large
4.0
160
CA
CA3310031
00031
GW
Large
4.0
161
CA
CA3310031
00031
GW
Large
4.0
162
CA
CA3310031
00032
GW
Large
4.0
163
CA
CA3310031
00034
GW
Large
4.0
164
CA
CA3310031
00035
GW
Large
4.0
165
CA
CA3310031
00036
GW
Large
4.0
166
CA
CA3310031
00036
GW
Large
4.0
167
CA
CA3310031
00036
GW
Large
4.0
168
CA
CA3310031
00038
GW
Large
4.0
169
CA
CA3310031
00038
GW
Large
4.0
170
CA
CA3310031
00041
GW
Large
4.0
171
CA
CA3310031
00043
GW
Large
4.0
172
CA
CA3310031
00043
GW
Large
4.0
173
CA
CA3310031
00051
GW
Large
4.0
174
CA
CA3310031
00052
GW
Large
4.0
175
CA
CA3310031
00053
GW
Large
4.0
176
CA
CA3310031
00078
GW
Large
4.0
B-13
-------
EPA-OGWDW AppendixB. Considerations for Additional Data Quality Measures May 2019
Exhibit B-4. Updated Dataset for Perchlorate Detections
State
PWSID
Facility ID
Source Water
Type
Size
Category
Updated Result
(Mfl/L)1
177
CA
CA3310031
00080
GW
Large
4.0
178
CA
CA3310031
00083
GW
Large
4.0
179
CA
CA3310031
00085
GW
Large
4.0
180
CA
CA3310031
00085
GW
Large
4.0
181
CA
CA3310031
00100
GW
Large
4.0
182
CA
CA3310031
00111
GW
Large
4.0
183
CA
CA3310031
00111
GW
Large
4.0
184
CA
CA3310031
00111
GW
Large
4.0
185
CA
CA3310031
00120
GW
Large
4.0
186
CA
CA3310031
00120
GW
Large
4.0
187
CA
CA3310037
00006
GW
Large
4.0
188
CA
CA3310037
00007
GW
Large
4.0
189
CA
CA3310037
00008
GW
Large
4.0
190
CA
CA3310037
00008
GW
Large
4.0
191
CA
CA3310037
00009
GW
Large
4.0
192
CA
CA3310037
00011
GW
Large
4.0
193
CA
CA3310037
00011
GW
Large
4.0
194
CA
CA3310037
00011
GW
Large
4.0
195
CA
CA3310037
00012
GW
Large
4.0
196
CA
CA3310037
00012
GW
Large
4.0
197
CA
CA3310037
00012
GW
Large
4.0
198
CA
CA3310037
00013
GW
Large
4.0
199
CA
CA3310037
00013
GW
Large
4.0
200
CA
CA3310037
00014
GW
Large
4.0
201
CA
CA3310037
00014
GW
Large
4.0
202
CA
CA3310037
00014
GW
Large
4.0
203
CA
CA3310037
00015
GW
Large
4.0
204
CA
CA3310037
00015
GW
Large
4.0
205
CA
CA3310037
00019
SW
Large
4.0
206
CA
CA3310037
00021
GW
Large
4.0
207
CA
CA3310037
00021
GW
Large
4.0
208
CA
CA3310037
00021
GW
Large
4.0
209
CA
CA3310037
00024
GW
Large
4.0
210
CA
CA3310037
00024
GW
Large
4.0
211
CA
CA3310037
00024
GW
Large
4.0
212
CA
CA3310037
00025
GW
Large
4.0
213
CA
CA3310037
00027
GW
Large
4.0
214
CA
CA3310037
00027
GW
Large
4.0
215
CA
CA3310037
00027
GW
Large
4.0
216
CA
CA3310037
00030
GW
Large
4.0
217
CA
CA3310037
00030
GW
Large
4.0
218
CA
CA3310037
00030
GW
Large
4.0
219
CA
CA3310037
00031
GW
Large
4.0
220
CA
CA3310037
00031
GW
Large
4.0
B-14
-------
EPA-OGWDW AppendixB. Considerations for Additional Data Quality Measures May 2019
Exhibit B-4. Updated Dataset for Perchlorate Detections
State
PWSID
Facility ID
Source Water
Type
Size
Category
Updated Result
(Mfl/L)1
221
CA
CA3310037
00031
GW
Large
4.0
222
CA
CA3310037
00032
GW
Large
4.0
223
CA
CA3310037
00032
GW
Large
4.0
224
CA
CA3310037
00033
GW
Large
4.0
225
CA
CA3310037
00033
GW
Large
4.0
226
CA
CA3310037
00043
SW
Large
4.0
227
CA
CA3310037
00043
SW
Large
4.0
228
CA
CA3310044
00002
GW
Large
6.0
229
CA
CA3310044
00002
GW
Large
6.0
230
CA
CA3310044
00004
GW
Large
6.0
231
CA
CA3310044
00004
GW
Large
6.0
232
CA
CA3310044
00006
GW
Large
6.0
233
CA
CA3310044
00006
GW
Large
6.0
234
CA
CA3410004
00001
GW
Large
4.1
235
CA
CA3610004
00028
GW
Large
4.0
236
CA
CA3610004
00028
GW
Large
4.0
237
CA
CA3610004
00028
GW
Large
4.0
238
CA
CA3610004
00028
GW
Large
4.0
239
CA
CA3610004
00031
GW
Large
4.0
240
CA
CA3610004
00031
GW
Large
4.0
241
CA
CA3610004
00031
GW
Large
4.0
242
CA
CA3610004
00031
GW
Large
4.0
243
CA
CA3610012
00005
GW
Large
4.0
244
CA
CA3610012
00005
GW
Large
4.0
245
CA
CA3610012
00015
GS
Large
4.0
246
CA
CA3610012
00016
GS
Large
4.0
247
CA
CA3610013
00009
GW
Large
5.0
248
CA
CA3610034
00003
GW
Large
4.0
249
CA
CA3610034
00003
GW
Large
4.0
250
CA
CA3610034
00003
GW
Large
4.0
251
CA
CA3610034
00008
GW
Large
4.0
252
CA
CA3610034
00008
GW
Large
4.0
253
CA
CA3610034
00008
GW
Large
4.0
254
CA
CA3610034
00008
GW
Large
4.0
255
CA
CA3610034
00008
GW
Large
4.0
256
CA
CA3610034
00012
GW
Large
4.0
257
CA
CA3610034
00012
GW
Large
4.0
258
CA
CA3610034
00012
GW
Large
4.0
259
CA
CA3610034
00012
GW
Large
4.0
260
CA
CA3610034
00015
GW
Large
4.0
261
CA
CA3610034
00016
GW
Large
4.0
262
CA
CA3610034
00032
GW
Large
4.0
263
CA
CA3610036
00010
GW
Large
4.0
264
CA
CA3610037
00004
GW
Large
4.0
B-15
-------
EPA-OGWDW AppendixB. Considerations for Additional Data Quality Measures May 2019
Exhibit B-4. Updated Dataset for Perchlorate Detections
State
PWSID
Facility ID
Source Water
Type
Size
Category
Updated Result
(Mfl/L)1
265
CA
CA3610037
00004
GW
Large
4.0
266
CA
CA3610037
00004
GW
Large
4.0
267
CA
CA3610037
00004
GW
Large
4.0
268
CA
CA3610037
00016
GW
Large
4.0
269
CA
CA3610037
00028
GW
Large
4.0
270
CA
CA3610037
00028
GW
Large
4.0
271
CA
CA3610037
00028
GW
Large
4.0
272
CA
CA3610037
00028
GW
Large
4.0
273
CA
CA3610037
00028
GW
Large
4.0
274
CA
CA3610037
00031
GW
Large
4.0
275
CA
CA3610037
00031
GW
Large
4.0
276
CA
CA3610037
00037
GW
Large
4.0
277
CA
CA3610037
00037
GW
Large
4.0
278
CA
CA3610037
00037
GW
Large
4.0
279
CA
CA3610037
00038
GW
Large
4.0
280
CA
CA3610037
00038
GW
Large
4.0
281
CA
CA3610037
00038
GW
Large
4.0
282
CA
CA3610037
00038
GW
Large
4.0
283
CA
CA3610037
00038
GW
Large
4.0
284
CA
CA3610037
00039
GW
Large
4.0
285
CA
CA3610037
00039
GW
Large
4.0
286
CA
CA3610037
00039
GW
Large
4.0
287
CA
CA3610037
00041
GW
Large
4.0
288
CA
CA3610037
00041
GW
Large
4.0
289
CA
CA3610037
00041
GW
Large
4.0
290
CA
CA3610037
00044
GW
Large
4.0
291
CA
CA3610037
00044
GW
Large
4.0
292
CA
CA3610037
00044
GW
Large
4.0
293
CA
CA3610037
00044
GW
Large
4.0
294
CA
CA3610037
00044
GW
Large
4.0
295
CA
CA3610037
00045
GW
Large
4.0
296
CA
CA3610037
00045
GW
Large
4.0
297
CA
CA3610037
00045
GW
Large
4.0
298
CA
CA3610037
00045
GW
Large
4.0
299
CA
CA3610037
00047
GW
Large
4.0
300
CA
CA3610037
00047
GW
Large
4.0
301
CA
CA3610037
00047
GW
Large
4.0
302
CA
CA3610037
00047
GW
Large
4.0
303
CA
CA3610037
00049
GW
Large
4.0
304
CA
CA3610037
00051
GW
Large
4.0
305
CA
CA3610037
00051
GW
Large
4.0
306
CA
CA3610037
00052
GW
Large
4.0
307
CA
CA3610037
00052
GW
Large
4.0
308
CA
CA3610037
00052
GW
Large
4.0
B-16
-------
EPA-OGWDW AppendixB. Considerations for Additional Data Quality Measures May 2019
Exhibit B-4. Updated Dataset for Perchlorate Detections
State
PWSID
Facility ID
Source Water
Type
Size
Category
Updated Result
(Mfl/L)1
309
CA
CA3610037
00054
GW
Large
4.0
310
CA
CA3610037
00054
GW
Large
4.0
311
CA
CA3610037
00102
GW
Large
4.0
312
CA
CA3610038
00010
GW
Large
4.0
313
CA
CA3610038
00014
GW
Large
4.0
314
CA
CA3610038
00015
GW
Large
4.0
315
CA
CA3610038
00015
GW
Large
4.0
316
CA
CA3610038
00017
GW
Large
4.0
317
CA
CA3610041
00010
GW
Large
6.0
318
CA
CA3610041
00026
GW
Large
6.0
319
CA
CA3610041
00029
GW
Large
6.0
320
CA
CA3610041
00029
GW
Large
6.0
321
CA
CA3610041
00033
GW
Large
6.0
322
CA
CA3610041
00033
GW
Large
6.0
323
CA
CA3610041
00036
GW
Large
6.0
324
CA
CA3610041
00036
GW
Large
6.0
325
CA
CA3610041
00042
GW
Large
6.0
326
CA
CA3610041
00042
GW
Large
6.0
327
CA
CA3610043
00025
GW
Large
4.0
328
CA
CA3610064
00017
GW
Large
4.0
329
CA
CA3610064
00018
GW
Large
4.0
330
CA
CA3610064
00018
GW
Large
4.0
331
CA
CA3610064
00018
GW
Large
4.0
332
CA
CA3610064
00018
GW
Large
4.0
333
CA
CA3610064
00020
GW
Large
4.0
334
CA
CA3610064
00020
GW
Large
4.0
335
CA
CA3610064
00021
GW
Large
4.0
336
CA
CA3610064
00021
GW
Large
4.0
337
CA
CA3610064
00022
GW
Large
4.0
338
CA
CA3610064
00022
GW
Large
4.0
339
CA
CA3610064
00022
GW
Large
4.0
340
CA
CA3610064
00022
GW
Large
4.0
341
CA
CA3610064
00023
GW
Large
4.0
342
CA
CA3610064
00023
GW
Large
4.0
343
CA
CA3610064
00023
GW
Large
4.0
344
CA
CA3610064
00026
GW
Large
4.0
345
CA
CA3610064
00026
GW
Large
4.0
346
CA
CA3610064
00028
GW
Large
4.0
347
CA
CA3610064
00028
GW
Large
4.0
348
CA
CA3610064
00028
GW
Large
4.0
349
CA
CA3610064
00028
GW
Large
4.0
350
CA
CA3610705
00014
GW
Large
9.7
351
CA
CA3710006
00018
SW
Large
4.0
352
CA
CA3910001
00013
GW
Large
4.0
B-17
-------
EPA-OGWDW AppendixB. Considerations for Additional Data Quality Measures May 2019
Exhibit B-4. Updated Dataset for Perchlorate Detections
State
PWSID
Facility ID
Source Water
Type
Size
Category
Updated Result
(Mfl/L)1
353
CA
CA3910011
00008
SW
Large
4.0
354
CA
CA3910012
00030
GW
Large
6.0
355
CA
CA4310001
00020
GW
Large
4.0
356
CA
CA4310022
00007
GW
Large
4.0
357
FL
FL3490751
08004
GW
Large
4.7
358
FL
FL4501242
08001
GW
Large
17.0
359
FL
FL6280049
08001
GW
Large
16.0
360
FL
FL6280049
08002
GW
Large
14.0
361
FL
FL6280250
08001
GW
Large
38.0
362
FL
FL6280250
08002
GW
Large
46.0
363
FL
FL6280250
08004
GW
Large
70.0
364
FL
FL6411132
08001
SW
Large
30.0
365
FL
FL6531812
08001
GW
Small
4.7
366
GA
GA1130001
03775
GW
Large
5.2
367
GA
GA1530021
03905
GW
Large
5.2
368
GA
GA2190000
15152
GW
Large
38.0
369
IL
IL1610650
17079
SW
Large
8.3
370
IL
IL1970450
33066
GW
Large
4.0
371
LA
LA1089001
0000IT
SW
Large
24.0
372
MA
MA2064000
00011
SW
Large
2.0
373
MD
MD0120001
00001
GW
Large
19.2
374
MD
MD0120002
00001
SW
Large
19.9
375
MD
MD0210010
00001
SW
Large
4.0
376
MN
MN1620009
00017
GW
Large
4.5
377
MN
MN1660010
00006
GW
Large
6.0
378
MP
MP0000001
90009
GW
Large
8.0
379
MP
MP0000001
90009
GW
Large
4.7
380
MP
MP0000001
90049
GW
Large
14.0
381
MP
MP0000001
90049
GW
Large
12.0
382
MS
MS0750005
00004T
GW
Small
19.6
383
NC
NC0241020
00005
SW
Large
13.8
384
NC
NC0326332
00035
GW
Large
5.6
385
NC
NC0326332
00035
GW
Large
4.3
386
NC
NC0326332
00069
GW
Large
6.2
387
NC
NC0326332
00069
GW
Large
5.7
388
NC
NC0326332
00070
GW
Large
4.0
389
NC
NC0326332
00074
GW
Large
8.6
390
NC
NC0326332
00074
GW
Large
6.2
391
NC
NC0326332
00076
GW
Large
7.3
392
NC
NC0326332
00076
GW
Large
6.0
393
NC
NC0326332
00077
GW
Large
8.0
394
NC
NC0326332
00077
GW
Large
6.6
395
NC
NC0326332
00104
GW
Large
5.5
396
NC
NC0326332
00104
GW
Large
4.2
B-18
-------
EPA-OGWDW AppendixB. Considerations for Additional Data Quality Measures May 2019
Exhibit B-4. Updated Dataset for Perchlorate Detections
State
PWSID
Facility ID
Source Water
Type
Size
Category
Updated Result
(Mfl/L)1
397
NC
NC0347025
00023
GW
Large
4.1
398
NC
NC0347025
00048
GW
Large
10.4
399
NC
NC0454010
00048
GW
Large
4.2
400
NC
NC0464126
00001
GW
Small
6.2
401
NC
NC0464126
00001
GW
Small
5.8
402
NC
NC0465232
00026
GW
Large
5.9
403
NC
NC0465232
00058
GW
Large
7.1
404
NE
NE3111106
03581
GW
Large
7.2
405
NE
NE3111106
03581
GW
Large
4.9
406
NJ
NJ0113001
00003
GW
Large
4.0
407
NJ
NJ0247001
00036
GW
Large
13.0
408
NJ
NJ0247001
00036
GW
Large
5.1
409
NJ
NJ0614003
00012
GW
Large
6.0
410
NJ
NJ0614003
00012
GW
Large
6.0
411
NJ
NJ0713001
00003
GW
Large
5.3
412
NJ
NJ1225001
00025
GW
Large
5.2
413
NJ
NJ1225001
00027
GW
Large
7.1
414
NJ
NJ1225001
00027
GW
Large
4.8
415
NJ
NJ1514001
00013
GW
Large
5.2
416
NM
NM3527305
00036
GW
Large
5.8
417
NM
NM3527305
00036
GW
Large
5.1
418
NM
NM3528616
00003
GW
Large
20.0
419
NM
NM3528616
00003
GW
Large
16.0
420
NM
NM3528616
00003
GW
Large
15.0
421
NV
NV0000076
00206
SW
Large
23.0
422
NV
NV0000076
00206
SW
Large
13.0
423
NV
NV0000076
00206
SW
Large
9.5
424
NV
NV0000076
00206
SW
Large
5.9
425
NV
NV0000289
00224
SW
Large
17.2
426
NV
NV0000289
00224
SW
Large
11.0
427
NV
NV0000289
00224
SW
Large
10.0
428
NV
NV0000289
00224
SW
Large
5.7
429
NV
NV0000289
00225
SW
Large
14.0
430
NV
NV0000289
00225
SW
Large
7.2
431
NV
NV0000289
00225
SW
Large
5.9
432
NV
NV0000289
00225
SW
Large
5.4
433
NV
NV0001048
00238
SW
Small
6.8
434
NV
NV0001048
00238
SW
Small
6.4
435
NV
NV0001048
00238
SW
Small
5.4
436
NV
NV0001048
00238
SW
Small
5.0
437
NY
NY2 900000
33969
GW
Large
8.9
438
NY
NY2 900000
33969
GW
Large
5.3
439
NY
NY2 900000
33969
GW
Large
5.0
440
NY
NY2 900000
33979
GW
Large
4.2
B-19
-------
EPA-OGWDW AppendixB. Considerations for Additional Data Quality Measures May 2019
Exhibit B-4. Updated Dataset for Perchlorate Detections
State
PWSID
Facility ID
Source Water
Type
Size
Category
Updated Result
(Mfl/L)1
441
NY
NY2902817
34010
GW
Large
5.0
442
NY
NY2902817
34014
GW
Large
4.2
443
NY
NY2902817
34015
GW
Large
4.4
444
NY
NY2902826
34074
GW
Large
4.0
445
NY
NY2902829
22570
GW
Large
6.4
446
NY
NY2902829
22571
GW
Large
7.7
447
NY
NY2902829
25282
GW
Large
5.6
448
NY
NY2902829
34093
GW
Large
5.5
449
NY
NY2902829
34099
GW
Large
6.3
450
NY
NY2902829
34106
GW
Large
4.5
451
NY
NY2902830
34122
GW
Large
4.7
452
NY
NY2902830
34132
GW
Large
5.6
453
NY
NY2902845
34290
GW
Large
4.3
454
NY
NY2902845
34291
GW
Large
4.7
455
NY
NY2902845
34292
GW
Large
11.0
456
NY
NY2902845
34292
GW
Large
7.5
457
NY
NY2902845
34292
GW
Large
6.5
458
NY
NY2902845
34294
GW
Large
7.5
459
NY
NY2902845
34294
GW
Large
7.5
460
NY
NY2902845
34294
GW
Large
7.3
461
NY
NY2902856
34351
GW
Large
6.7
462
NY
NY2902856
68556
GW
Large
14.0
463
NY
NY2902856
68557
GW
Large
11.0
464
NY
NY5103263
40721
GW
Large
5.4
465
NY
NY5103263
40730
GW
Large
4.8
466
NY
NY5103271
40759
GW
Large
5.6
467
NY
NY5103271
40759
GW
Large
4.6
468
NY
NY5110526
41077
GW
Large
6.8
469
NY
NY5110526
41077
GW
Large
5.7
470
NY
NY5110526
41078
GW
Large
6.7
471
NY
NY5110526
41078
GW
Large
5.9
472
NY
NY5110526
41094
GW
Large
6.1
473
NY
NY5110526
41094
GW
Large
4.6
474
NY
NY5110526
41220
GW
Large
12.1
475
NY
NY5110526
41220
GW
Large
12.0
476
NY
NY5110526
41220
GW
Large
11.7
477
NY
NY5110526
41220
GW
Large
10.5
478
NY
NY5110526
41220
GW
Large
7.1
479
NY
NY5110526
68636
GW
Large
5.4
480
NY
NY5110526
68741
GW
Large
4.9
481
NY
NY5110526
82078
GW
Large
4.6
482
NY
NY5110526
82733
GW
Large
7.6
483
NY
NY5110526
82733
GW
Large
7.0
484
NY
NY5110526
82733
GW
Large
6.8
B-20
-------
EPA-OGWDW AppendixB. Considerations for Additional Data Quality Measures May 2019
Exhibit B-4. Updated Dataset for Perchlorate Detections
State
PWSID
Facility ID
Source Water
Type
Size
Category
Updated Result
(Mfl/L)1
485
NY
NY5110526
82733
GW
Large
5.8
486
OH
OH0900715
00008
GW
Large
27.1
487
OH
OH0900715
00008
GW
Large
5.9
488
OH
OH1300812
00003
GW
Large
7.1
489
OH
OH1800111
00002
SW
Large
4.9
490
OH
OH2000111
00002
SW
Large
5.7
491
OH
OH2903312
00014
GW
Large
17.2
492
OH
OH4301611
00002
SW
Large
9.2
493
OH
OH4401612
00006
GW
Large
32.3
494
OH
OH6703211
00002
SW
Large
5.3
495
OK
OK1020406
10880
SW
Large
11.0
496
OK
OK1020419
10204
SW
Large
17.0
497
OK
OK2001412
12292
GW
Large
9.7
498
OK
OK2001412
12300
GW
Large
8.6
499
OK
OK2001412
12305
GW
Large
9.7
500
OK
OK2001412
20619
GW
Large
13.0
501
OK
OK2002412
11032
GW
Large
30.0
502
OK
OK2002445
11038
GW
Large
10.3
503
OK
OK2007701
18386
GW
Large
12.0
504
OK
OK2007701
18387
GW
Large
13.0
505
PA
PA1090082
00101
GW
Large
4.7
506
PA
PA1090082
00102
GW
Large
4.4
507
PA
PA1460020
00103
GW
Large
10.0
508
PA
PA1460020
00108
GW
Large
8.0
509
PA
PA3060038
00105
GW
Large
4.0
510
PA
PA4310012
00101
SW
Large
6.7
511
PA
PA6200036
00100
GW
Large
32.7
512
PA
PA6250028
00102
SW
Large
4.5
513
PA
PA7360123
00101
SW
Large
12.1
514
PR
PR0002702
00004
SW
Large
420.0
515
SC
SC0220005
00101T
GW
Small
4.3
516
SC
SC1620001
00402
GW
Large
7.4
517
SC
SC2820005
00107T
GW
Large
4.5
518
TN
TN0000150
00002T
SW
Large
9.0
519
TX
TX1070190
04001
SW
Large
8.1
520
TX
TX1100002
04003
GW
Large
32.0
521
TX
TX1370001
04005
GW
Large
4.5
522
TX
TX1370001
04006
GW
Large
4.0
523
TX
TX1650001
04002
GW
Large
7.9
524
VA
VA3001700
20368
GW
Small
4.3
525
WA
WA5325200
00003
GW
Large
6.0
526
WA
WA5325200
00013
GW
Large
5.0
527
WA
WA5325200
00014
GW
Large
4.0
528
WA
WA5325200
00017
GW
Large
6.0
B-21
-------
EPA-OGWDW AppendixB. Considerations for Additional Data Quality Measures May 2019
Exhibit B-4. Updated Dataset for Perchlorate Detections
State
PWSID
Facility ID
Source Water
Type
Size
Category
Updated Result
(Mfl/L)1
529
WA
WA5343500
00010
GW
Large
7.0
530
WA
WA5343500
00023
GW
Large
9.0
531
WA
WA5345550
00003
GW
Large
4.0
532
WA
WA5345550
00007
GW
Large
6.0
533
WA
WA5345550
00021
GW
Large
5.0
534
WA
WA5345550
00016T
GW
Large
5.0
535
WA
WA5345550
00019T
GW
Large
6.0
536
WA
WA5370050
00001
GW
Large
4.0
537
WA
WA5370050
00001
GW
Large
4.0
538
WA
WA5370050
00005
GW
Large
5.0
539
WA
WA5370050
00008
GW
Large
8.0
540
WA
WA5382844
00007T
GW
Large
4.0
1 The EPA updated UCMR 1 data for systems located in the States of Califonia and Massachussets using current
compliance records as described in Section 3.4.2 and Apendix B.3. The Updated Dataset serves as the basis for all
occurrence analyses, graphs, and maps presented in Section 4 of this report.
B-22
-------
Appendix C:
UCMR 1 Perchlorate Detections with
Source Water Detection Categories
Identified
-------
EPA - OGWDW
Appendix C. UCMR 1 Perchlorate Detections
May 2019
Appendix C. UCMR 1 Perchlorate Detections with Source Water Detection
Categories Identified
Exhibit C-l presents all 637 perchlorate detections from UCMR 1 sampling, conducted
between 2001 and 2005. Specifically, the table presents (for each of the 637 original UCMR 1
individual detections) the state, public water system identification number (PWSID), Facility ID,
sample point ID, sample point type (EP = entry point; SR = source water), the system's source
water type, system size, the sample date, the result value (in |ig/L), and the source water sample
category (if the detection was from source water). As described in Section 4.1 and Appendix B
of this report, the agency found a mix of source water detection results and sorted the sample
findings into four categories. The EPA excluded Category 1 and 2 source water detections (a
total of 97) as well as non-detection records from the same sample points (a total of 102 non-
detections) from the Updated UCMR 1 Perchlorate Data set. This updated version of the data set
serves as the basis for all UCMR 1 perchlorate occurrence analyses, graphs, and maps presented
in Section 4 of this report.
Appendix C Page i/ Introduction
-------
EPA-OGWDW Appendix C. UCMR 1 Perchlorate Detections May 2019
Exhibit C-1. Perchlorate Detections in the UCMR 1 Dataset with Source Water Detection Categories Identified
State
PWSID
Facility ID
Sample Point ID
Sample
Point Type
Source
Water
Type
Size
Category
Sample Date
Result
Value
(Mfl/L)
Category1
1
AL
AL0000029
00007T
0029005
EP
GW
L
12/11/2002
7.2
2
AL
AL0000553
00016
0553006
EP
GW
L
1/10/2002
8.4
3
AL
AL0000553
00016
0553006
EP
GW
L
6/13/2002
8.9
4
AL
AL0001002
00003T
1002003
EP
GW
L
12/6/2002
5.5
5
AL
AL0001070
00051
1070003
EP
SW
VL
7/16/2001
8.5
6
AL
AL0001070
00001T
1070001
EP
SW
VL
9/19/2001
11
7
AR
AR0000209
00001
0209001
EP
SW
VL
11/5/2002
4.5
8
AR
AR0000209
00002
0209002
EP
SW
VL
11/5/2002
6.6
9
AR
AR0000459
00001
0459001
EP
GW
L
1/13/2003
5.5
10
AZ
AZ0407017
01822
005
EP
SW
L
4/22/2003
5.7
11
AZ
AZ0407017
01823
001
EP
SW
L
4/22/2003
5.6
12
AZ
AZ0407025
01811
405
EP
SW
VL
4/11/2002
5.1
13
AZ
AZ0407025
01812
406
EP
SW
VL
4/11/2002
5.2
14
AZ
AZ0407093
01833
001
EP
SW
VL
2/6/2002
4.07
15
AZ
AZ0407093
00158
043
EP
SW
VL
3/13/2002
4.93
16
AZ
AZ0407093
01834
002
EP
SW
VL
3/13/2002
4.56
17
AZ
AZ0407093
00155
040
EP
SW
VL
3/27/2002
4.56
18
AZ
AZ0407093
01833
001
EP
SW
VL
5/6/2002
6.04
19
AZ
AZ0407095
01872
001
EP
SW
VL
3/20/2002
6.9
20
AZ
AZ0407095
01872
001
EP
SW
VL
6/18/2002
5.12
21
AZ
AZ0407095
01872
001
EP
SW
VL
12/16/2002
4.5
22
AZ
AZ0407098
00191
014
EP
SW
VL
1/9/2002
4.1
23
AZ
AZ0407098
01836
001
EP
SW
VL
5/1/2002
6.9
24
AZ
AZ0407098
01836
001
EP
SW
VL
5/5/2004
5.3
25
AZ
AZ0410112
00165
153
EP
GW
VL
1/4/2001
11.9
26
AZ
AZ0410112
00351
128
EP
GW
VL
7/30/2001
4.78
27
AZ
AZ0414004
00407
POE007
EP
SW
L
4/14/2004
4.03
28
AZ
AZ0414024
01813
001
EP
SW
VL
9/4/2001
4.7
29
AZ
AZ0414024
01816
002
EP
SW
VL
9/4/2001
4.1
30
AZ
AZ0414024
01813
001
EP
SW
VL
4/8/2002
6.1
31
AZ
AZ0414024
01816
002
EP
SW
VL
4/8/2002
6.4
32
AZ
AZ0414024
01813
001
EP
SW
VL
6/3/2002
4.2
33
AZ
AZ0414024
01816
002
EP
SW
VL
6/3/2002
4.7
34
AZ
AZ0415010
00831
001
EP
SW
S
2/16/2001
5.8
35
AZ
AZ0415010
00831
001
EP
SW
S
5/15/2001
5.9
36
AZ
AZ0415010
00831
001
EP
SW
S
8/20/2001
6
37
CA
CA1300549
00001T
1300549UCM R*0001
EP
SW
M
5/14/2002
6.22
38
CA
CA1300549
00001T
1300549UCM R*0001
EP
SW
M
11/13/2002
4.46
39
CA
CA1310001
00950
00760
EP
SW
L
3/4/2002
5.2
40
CA
CA1310001
00950
00760
EP
SW
L
6/5/2002
4.2
41
CA
CA1510031
00026
29S/27E-26B01
EP
GW
VL
5/13/2001
7.6
42
CA
CA1910007
00500
03K04
EP
SW
VL
12/26/2001
10
43
CA
CA1910007
00500
03K04
EP
SW
VL
6/19/2002
11
44
CA
CA1910017
00020
04N/16W-23F01
SR
SW
VL
10/31/2002
4.2
3
45
CA
CA1910022
00002
01S/09W-27Q03
SR
SW
7/29/2003
4.2
2
46
CA
CA1910022
00002
01S/09W-27Q03
SR
SW
12/16/2003
6.2
2
47
CA
CA1910022
00005
01S/09W-26C02
SR
SW
4/6/2004
4.9
2
48
CA
CA1910022
00002
01S/09W-27Q03
SR
SW
8/3/2004
5.1
2
49
CA
CA1910022
00005
01S/09W-26C02
SR
SW
8/3/2004
4.8
2
50
CA
CA1910033
00024
04S/13W-15F01
EP
SW
VL
12/11/2002
9.21
51
CA
CA1910036
00004
02S/12W-07Q04
EP
SW
VL
7/17/2001
7.4
52
CA
CA1910036
00004
02S/12W-07Q04
EP
SW
VL
8/6/2001
7.7
53
CA
CA1910036
00004
02S/12W-07Q04
EP
SW
VL
8/27/2001
6.2
54
CA
CA1910036
00004
02S/12W-07Q04
EP
SW
VL
9/17/2001
7
55
CA
CA1910062
00010
01S/08W-05E01
EP
SW
1/6/2004
10
56
CA
CA1910062
00012
01S/08W-07F06
EP
SW
1/6/2004
15
57
CA
CA1910062
00016
01S/08W-07F02
EP
SW
1/6/2004
16
58
CA
CA1910062
00018
01S/09W-12H01
EP
SW
1/6/2004
20
59
CA
CA1910062
00032
01S/08W-06H06
EP
SW
1/6/2004
11
60
CA
CA1910063
00003
01 N/12W-05Q02
SR
SW
12/10/2001
4.2
2
61
CA
CA1910063
00003
01 N/12W-05Q02
SR
SW
5/5/2002
4.8
2
62
CA
CA1910063
00003
01 N/12W-05Q02
SR
SW
8/3/2004
4
2
63
CA
CA1910063
17
1910063-026
EP
SW
8/3/2004
10
64
CA
CA1910063
00003
01 N/12W-05Q02
SR
SW
2/1/2005
4.8
2
65
CA
CA1910063
17
1910063-026
EP
SW
2/1/2005
15
66
CA
CA1910087
00003T
G19/087-SYSTMDP
EP
SW
VL
5/6/2002
4.1
67
CA
CA1910087
00008
G19/087-LMHDKEF
SR
SW
VL
5/6/2002
5.8
1
68
CA
CA1910087
00012
G19/087-LKESKN R
SR
SW
VL
5/6/2002
5.2
1
C-l
-------
EPA-OGWDW Appendix C. UCMR 1 Perchlorate Detections May 2019
Exhibit C-1. Perchlorate Detections in the UCMR 1 Dataset with Source Water Detection Categories Identified
State
PWSID
Facility ID
Sample Point ID
Sample
Point Type
Source
Water
Type
Size
Category
Sample Date
Result
Value
(Mfl/L)
Category1
69
CA
CA1910087
00015
G19/087-SANJNTT
SR
SW
VL
5/6/2002
6.7
1
70
CA
CA1910087
00023
G19/087-SYSTMSR
EP
sw
VL
5/6/2002
4.6
71
CA
CA1910087
00007
G19/087-LHNWHIN
SR
SW
VL
5/7/2002
6.6
1
72
CA
CA1910087
00008
G19/087-LMHDKEF
SR
sw
VL
7/1/2002
5
1
73
CA
CA1910087
00012
G19/087-LKESKN R
SR
sw
VL
7/1/2002
4.3
1
74
CA
CA1910087
00015
G19/087-SANJNTT
SR
sw
VL
7/1/2002
5.4
1
75
CA
CA1910087
00007
G19/087-LHNWHIN
SR
sw
VL
7/2/2002
6.1
1
76
CA
CA1910087
00008
G19/087-LMHDKEF
SR
sw
VL
10/7/2002
4.8
1
77
CA
CA1910087
00007
G19/087-LHNWHIN
SR
sw
VL
10/8/2002
5.1
1
78
CA
CA1910124
00006
01 N/12W-20B01
SR
sw
VL
5/9/2001
13
3
79
CA
CA1910124
00007
01 N/12W-23G01
SR
sw
VL
5/9/2001
5
4
80
CA
CA1910124
00010
01 N/12W-21K01
SR
sw
VL
5/9/2001
5
4
81
CA
CA1910124
00014
01 N/12W-23L01
SR
sw
VL
5/9/2001
4
4
82
CA
CA1910124
00018
01 N/12W-20A01
SR
sw
VL
5/9/2001
12
3
83
CA
CA1910124
00019
01 N/12W-05N01
SR
sw
VL
5/9/2001
7
3
84
CA
CA1910124
00020
01 N/12W-21K02
SR
sw
VL
5/9/2001
7
4
85
CA
CA1910124
00021
01 N/12W-05N02
SR
sw
VL
5/9/2001
35
3
86
CA
CA1910124
00022
01 N/12W-08D08
SR
sw
VL
5/9/2001
7
3
87
CA
CA1910124
00028
01 N/12W-20B03
SR
sw
VL
5/9/2001
7
3
88
CA
CA1910124
00006
01 N/12W-20B01
SR
sw
VL
10/3/2001
11
3
89
CA
CA1910124
00014
01 N/12W-23L01
SR
sw
VL
10/3/2001
5
4
90
CA
CA1910124
00018
01 N/12W-20A01
SR
sw
VL
10/3/2001
12
3
91
CA
CA1910124
00019
01 N/12W-05N01
SR
sw
VL
10/3/2001
6
3
92
CA
CA1910124
00020
01 N/12W-21K02
SR
sw
VL
10/3/2001
7
4
93
CA
CA1910124
00021
01 N/12W-05N02
SR
sw
VL
10/3/2001
28
3
94
CA
CA1910124
00022
01 N/12W-08D08
SR
sw
VL
10/3/2001
5
3
95
CA
CA1910124
00028
01 N/12W-20B03
SR
sw
VL
10/3/2001
8
3
96
CA
CA1910126
00023
01S/08W-33D01
SR
sw
VL
5/23/2001
8.3
4
97
CA
CA1910126
00025
01S/08W-33E01
SR
sw
VL
5/23/2001
4.4
4
98
CA
CA1910126
00049
1910126-049
SR
sw
VL
5/24/2001
6.5
4
99
CA
CA1910126
00002
01S/08W-28F01
SR
sw
VL
6/13/2001
5.8
4
100
CA
CA1910126
00003
01S/08W-18J02
SR
sw
VL
6/13/2001
10
3
101
CA
CA1910126
00010
01S/08W-28G02
SR
sw
VL
6/13/2001
7
4
102
CA
CA1910126
00030
01S/08W-21R01
SR
sw
VL
6/14/2001
6.2
3
103
CA
CA1910126
00013
01S/08W-09D01
SR
sw
VL
6/20/2001
4.2
4
104
CA
CA1910126
00051
1910126-051
SR
sw
VL
6/20/2001
5.8
4
105
CA
CA1910126
00021
01S/08W-31J01
SR
sw
VL
6/28/2001
6.4
3
106
CA
CA1910126
00002
01S/08W-28F01
SR
sw
VL
11/6/2001
4.8
4
107
CA
CA1910126
00021
01S/08W-31J01
SR
sw
VL
11/7/2001
6.7
3
108
CA
CA1910126
00025
01S/08W-33E01
SR
sw
VL
11/7/2001
4.5
4
109
CA
CA1910126
00023
01S/08W-33D01
SR
sw
VL
11/15/2001
8.3
4
110
CA
CA1910126
00049
1910126-049
SR
sw
VL
11/15/2001
5.7
4
111
CA
CA1910126
00010
01S/08W-28G02
SR
sw
VL
12/5/2001
6.9
4
112
CA
CA1910126
00051
1910126-051
SR
sw
VL
12/6/2001
6.9
4
113
CA
CA1910126
00007
01S/08W-17K02
SR
sw
VL
1/7/2003
12
3
114
CA
CA1910126
00050
1910126-050
SR
sw
VL
1/7/2003
11
3
115
CA
CA1910126
00026
01S/08W-33C01
SR
sw
VL
1/8/2003
5.2
4
116
CA
CA1910126
00002
01S/08W-28F01
SR
sw
VL
9/15/2004
5.2
4
117
CA
CA1910126
00010
01S/08W-28G02
SR
sw
VL
9/15/2004
5.5
4
118
CA
CA1910126
00023
01S/08W-33D01
SR
sw
VL
9/15/2004
7.5
4
119
CA
CA1910126
00025
01S/08W-33E01
SR
sw
VL
9/15/2004
4.1
4
120
CA
CA1910126
00026
01S/08W-33C01
SR
sw
VL
9/15/2004
8.9
4
121
CA
CA1910126
00049
1910126-049
SR
sw
VL
9/15/2004
5
4
122
CA
CA1910143
00002
03N/15W-34B02
SR
sw
11/5/2002
8.9
4
123
CA
CA1910144
00016
00016
EP
sw
6/12/2002
4.2
124
CA
CA1910154
00950
G19/154-NTBLRVW
EP
sw
6/20/2002
4.5
125
CA
CA1910167
00012
02S/13W-15E02
SR
sw
7/24/2002
5.42
3
126
CA
CA1910167
00012
02S/13W-15E02
SR
sw
12/18/2002
4.4
3
127
CA
CA1910205
00034
01S/10W-31G09
SR
sw
VL
10/21/2002
7.2
4
128
CA
CA2710010
00029
15S/03E-02G01
EP
GW
VL
12/12/2002
22.3
129
CA
CA2710010
00046
14S/03E-22E51
EP
GW
VL
2/25/2003
4.4
130
CA
CA3010001
00055
H30/001-TREAT
EP
sw
VL
5/6/2002
4.4
131
CA
CA3010001
00055
H30/001-TREAT
EP
sw
VL
8/5/2002
4.26
132
CA
CA3010001
00055
H30/001-TREAT
EP
sw
VL
11/5/2002
4.5
133
CA
CA3010001
00032
04S/11W-14K01
EP
sw
VL
6/23/2003
4.95
134
CA
CA3010001
00033
04S/10W-20M01
EP
sw
VL
9/24/2003
4.1
135
CA
CA3010001
00032
04S/11W-14K01
EP
sw
VL
11/14/2003
5.3
136
CA
CA3010001
00032
04S/11W-14K01
EP
sw
VL
5/18/2004
5
C-2
-------
EPA-OGWDW Appendix C. UCMR 1 Perchlorate Detections May 2019
Exhibit C-1. Perchlorate Detections in the UCMR 1 Dataset with Source Water Detection Categories Identified
State
PWSID
Facility ID
Sample Point ID
Sample
Point Type
Source
Water
Type
Size
Category
Sample Date
Result
Value
(Mfl/L)
Category1
137
CA
CA3010022
00022
04S/11W-23L03
EP
GW
VL
3/25/2003
6.2
138
CA
CA3010022
00025
04S/11W-24M02
EP
GW
VL
5/19/2003
4.3
139
CA
CA3010022
00020
04S/11W-26R01
EP
GW
VL
6/25/2003
5.7
140
CA
CA3010022
00022
04S/11W-23L03
EP
GW
VL
8/5/2003
4.9
141
CA
CA3010022
00024
04S/11W-25Q01
EP
GW
VL
11/21/2003
4
142
CA
CA3010022
00020
04S/11W-26R01
EP
GW
VL
12/17/2003
5.2
143
CA
CA3010022
00022
04S/11W-23L03
EP
GW
VL
2/25/2004
5.5
144
CA
CA3010038
00019
05S/10W-01E02
SR
SW
VL
11/18/2003
4.4
4
145
CA
CA3010046
00009
05S/09W-10L01
SR
GW
VL
5/7/2003
8.9
2
146
CA
CA3010046
00009
05S/09W-10L01
SR
GW
VL
7/16/2003
7.4
2
147
CA
CA3010046
00022
3010046-022
SR
GW
VL
7/16/2003
4.2
2
148
CA
CA3010046
00002
05S/09W-09J02
SR
GW
VL
11/12/2003
6.4
2
149
CA
CA3010046
00022
3010046-022
SR
GW
VL
12/3/2003
6.5
2
150
CA
CA3010046
00009
05S/09W-10L01
SR
GW
VL
12/31/2003
8.7
2
151
CA
CA3010046
00009
05S/09W-10L01
SR
GW
VL
5/4/2004
6.7
2
152
CA
CA3010062
00019
04S/10W-30E02
EP
SW
VL
6/24/2003
4
153
CA
CA3010062
00019
04S/10W-30E02
EP
SW
VL
11/20/2003
4.4
154
CA
CA3010092
00015
05S/09W-30G02
SR
GW
VL
2/12/2003
6
4
155
CA
CA3010094
00001
06S/07W-11P01
SR
SW
L
6/29/2004
5
3
156
CA
CA3310001
00147
06S/07E-16D02
EP
GW
VL
10/23/2001
5.9
157
CA
CA3310005
00013
03S/04E-36M01
EP
SW
VL
7/10/2001
5.8
158
CA
CA3310005
00013
03S/04E-36M01
EP
SW
VL
12/12/2001
5.4
159
CA
CA3310005
00024
04S/04E-02B01
EP
SW
VL
12/12/2001
4.2
160
CA
CA3310005
00039
03S/04E-34H02
EP
SW
VL
12/12/2001
4
161
CA
CA3310005
00023
03S/04E-34R01
EP
SW
VL
12/19/2001
5.8
162
CA
CA3310005
00023
03S/04E-34R01
EP
SW
VL
6/3/2003
5.4
163
CA
CA3310005
00032
03S/04E-34H01
EP
SW
VL
6/3/2003
4
164
CA
CA3310005
00039
03S/04E-34H02
EP
SW
VL
6/3/2003
4.2
165
CA
CA3310005
00024
04S/04E-02B01
EP
SW
VL
11/21/2003
5.7
166
CA
CA3310005
00029
03S/04E-35R01
EP
SW
VL
11/21/2003
4.1
167
CA
CA3310005
00032
03S/04E-34H01
EP
SW
VL
11/24/2003
4.4
168
CA
CA3310005
00019
03S/04E-30C01
EP
SW
VL
11/25/2003
4.3
169
CA
CA3310005
00023
03S/04E-34R01
EP
SW
VL
11/25/2003
6.6
170
CA
CA3310005
00039
03S/04E-34H02
EP
SW
VL
11/25/2003
6
171
CA
CA3310009
00042
03S/03W-06D04
SR
SW
VL
2/27/2002
7.5
4
172
CA
CA3310009
00047
3310009-047
SR
SW
VL
2/27/2002
5.2
4
173
CA
CA3310016
00003
05S/01W-22D02
SR
SW
2/18/2004
7.2
3
174
CA
CA3310016
00004
05S/01W-22D03
SR
SW
2/24/2004
4.7
2
175
CA
CA3310016
00003
05S/01W-22D02
SR
SW
3/17/2004
6
3
176
CA
CA3310016
00012
05S/01W-11A01
SR
SW
7/7/2004
5.9
2
177
CA
CA3310016
00012
05S/01W-11A01
SR
SW
8/25/2004
6.1
2
178
CA
CA3310021
00003
02S/06W-05A01
SR
GW
10/10/2002
4.6
4
179
CA
CA3310031
00027
01S/04W-23A02
SR
SW
VL
2/27/2001
11
4
180
CA
CA3310031
00028
01S/04W-23H01
SR
SW
VL
2/27/2001
7.4
4
181
CA
CA3310031
00031
01S/04W-13N01
SR
SW
VL
2/27/2001
29
4
182
CA
CA3310031
00036
01S/04W-23A05
SR
SW
VL
2/27/2001
31
4
183
CA
CA3310031
00111
01S/04W-13N07
SR
SW
VL
2/27/2001
10
4
184
CA
CA3310031
00085
01S/04W-02A03
SR
SW
VL
6/12/2001
12
4
185
CA
CA3310031
00100
01S/04W-22H04
SR
SW
VL
6/12/2001
6.4
4
186
CA
CA3310031
00120
01S/04W-02Q11
SR
SW
VL
6/12/2001
5.6
4
187
CA
CA3310031
00015
02S/04W-07L01
SR
SW
VL
6/14/2001
4.8
4
188
CA
CA3310031
00041
02S/05W-12C03
SR
SW
VL
6/14/2001
4.4
4
189
CA
CA3310031
00052
01S/04W-27A09
SR
SW
VL
6/14/2001
9.3
4
190
CA
CA3310031
00080
01S/04W-23C03
SR
SW
VL
6/14/2001
6.4
4
191
CA
CA3310031
00034
01S/04W-13F02
SR
SW
VL
6/19/2001
8
4
192
CA
CA3310031
00043
01S/04W-02Q03
SR
SW
VL
6/19/2001
14
4
193
CA
CA3310031
00051
01S/04W-27A11
SR
SW
VL
6/19/2001
8
4
194
CA
CA3310031
00053
01S/04W-27A10
SR
SW
VL
6/19/2001
8.4
4
195
CA
CA3310031
00083
01S/04W-02L01
SR
SW
VL
6/19/2001
6.7
4
196
CA
CA3310031
00031
01S/04W-13N01
SR
SW
VL
6/28/2001
41
4
197
CA
CA3310031
00035
01S/04W-13G02
SR
SW
VL
6/28/2001
11
4
198
CA
CA3310031
00078
01S/04W-23C02
SR
SW
VL
6/28/2001
12
4
199
CA
CA3310031
00111
01S/04W-13N07
SR
SW
VL
6/28/2001
20
4
200
CA
CA3310031
00027
01S/04W-23A02
SR
SW
VL
6/29/2001
10
4
201
CA
CA3310031
00028
01S/04W-23H01
SR
SW
VL
6/29/2001
9.4
4
202
CA
CA3310031
00029
01S/04W-23K01
SR
SW
VL
6/29/2001
12
4
203
CA
CA3310031
00030
01S/04W-23K02
SR
SW
VL
6/29/2001
11
4
204
CA
CA3310031
00036
01S/04W-23A05
SR
SW
VL
6/29/2001
42
4
C-3
-------
EPA-OGWDW Appendix C. UCMR 1 Perchlorate Detections May 2019
Exhibit C-1. Perchlorate Detections in the UCMR 1 Dataset with Source Water Detection Categories Identified
State
PWSID
Facility ID
Sample Point ID
Sample
Point Type
Source
Water
Type
Size
Category
Sample Date
Result
Value
(Mfl/L)
Category1
205
CA
CA3310031
00038
01S/04W-23G03
SR
SW
VL
6/29/2001
15
4
206
CA
CA3310031
00027
01S/04W-23A02
SR
sw
VL
11/8/2001
8.2
4
207
CA
CA3310031
00028
01S/04W-23H01
SR
SW
VL
11/8/2001
7.8
4
208
CA
CA3310031
00031
01S/04W-13N01
SR
sw
VL
11/8/2001
23
4
209
CA
CA3310031
00032
01S/04W-13N02
SR
sw
VL
11/8/2001
42
4
210
CA
CA3310031
00036
01S/04W-23A05
SR
sw
VL
11/8/2001
41
4
211
CA
CA3310031
00038
01S/04W-23G03
SR
sw
VL
11/8/2001
15
4
212
CA
CA3310031
00111
01S/04W-13N07
SR
sw
VL
11/8/2001
14
4
213
CA
CA3310031
00043
01S/04W-02Q03
SR
sw
VL
11/15/2001
12
4
214
CA
CA3310031
00085
01S/04W-02A03
SR
sw
VL
11/15/2001
12
4
215
CA
CA3310031
00120
01S/04W-02Q11
SR
sw
VL
11/21/2001
4
4
216
CA
CA3310037
00006
03S/06W-31D02
SR
sw
VL
1/29/2002
12
3
217
CA
CA3310037
00007
03S/06W-31D01
SR
sw
VL
1/29/2002
11
3
218
CA
CA3310037
00008
03S/07W-25J01
SR
sw
VL
1/29/2002
5.3
3
219
CA
CA3310037
00009
03S/07W-25M02
SR
sw
VL
1/29/2002
4.2
4
220
CA
CA3310037
00011
03S/07W-27G01
EP
sw
VL
1/29/2002
11
221
CA
CA3310037
00012
03S/07W-27F01
EP
sw
VL
1/29/2002
7.2
222
CA
CA3310037
00014
03S/07W-35C01
EP
sw
VL
1/29/2002
11
223
CA
CA3310037
00015
03S/07W-26G01
EP
sw
VL
1/29/2002
9.4
224
CA
CA3310037
00021
03S/07W-25L01
SR
sw
VL
1/29/2002
4.8
4
225
CA
CA3310037
00024
03S/07W-26J03
SR
sw
VL
1/29/2002
11
4
226
CA
CA3310037
00027
03S/07W-25E02
SR
sw
VL
1/29/2002
9.4
4
227
CA
CA3310037
00011
03S/07W-27G01
EP
sw
VL
6/20/2002
7.6
228
CA
CA3310037
00012
03S/07W-27F01
EP
sw
VL
6/20/2002
6.5
229
CA
CA3310037
00014
03S/07W-35C01
EP
sw
VL
6/20/2002
8.4
230
CA
CA3310037
00015
03S/07W-26G01
EP
sw
VL
6/20/2002
5.9
231
CA
CA3310037
00021
03S/07W-25L01
SR
sw
VL
6/20/2002
4.7
4
232
CA
CA3310037
00024
03S/07W-26J03
SR
sw
VL
6/20/2002
7.7
4
233
CA
CA3310037
00027
03S/07W-25E02
SR
sw
VL
6/20/2002
6.4
4
234
CA
CA3310037
00043
3310037-043
EP
sw
VL
6/20/2002
4.3
235
CA
CA3310037
00008
03S/07W-25J01
SR
sw
VL
12/12/2002
4.4
3
236
CA
CA3310037
00011
03S/07W-27G01
EP
sw
VL
12/12/2002
7.8
237
CA
CA3310037
00012
03S/07W-27F01
EP
sw
VL
12/12/2002
6.7
238
CA
CA3310037
00013
03S/06W-31K01
EP
sw
VL
12/12/2002
12
239
CA
CA3310037
00014
03S/07W-35C01
EP
sw
VL
12/12/2002
6.5
240
CA
CA3310037
00021
03S/07W-25L01
SR
sw
VL
12/12/2002
5.4
4
241
CA
CA3310037
00024
03S/07W-26J03
SR
sw
VL
12/12/2002
6.4
4
242
CA
CA3310037
00025
03S/07W-25L02
SR
sw
VL
12/12/2002
4.6
4
243
CA
CA3310037
00027
03S/07W-25E02
SR
sw
VL
12/12/2002
7.9
4
244
CA
CA3310037
00030
3310037-030
EP
sw
VL
12/12/2002
5.7
245
CA
CA3310037
00031
3310037-031
EP
sw
VL
2/13/2003
7
246
CA
CA3310037
00019
N33/037-TREAT
EP
sw
VL
6/12/2003
4.7
247
CA
CA3310037
00043
3310037-043
EP
sw
VL
6/12/2003
4
248
CA
CA3310037
00013
03S/06W-31K01
EP
sw
VL
7/8/2003
13
249
CA
CA3310037
00031
3310037-031
EP
sw
VL
7/8/2003
5.6
250
CA
CA3310037
00032
3310037-032
SR
sw
VL
7/8/2003
6
4
251
CA
CA3310037
00033
3310037-033
EP
sw
VL
7/8/2003
4.7
252
CA
CA3310037
00030
3310037-030
EP
sw
VL
7/9/2003
6.5
253
CA
CA3310037
00030
3310037-030
EP
sw
VL
12/11/2003
6.9
254
CA
CA3310037
00031
3310037-031
EP
sw
VL
12/11/2003
6.41
255
CA
CA3310037
00032
3310037-032
SR
sw
VL
12/11/2003
7.93
4
256
CA
CA3310037
00033
3310037-033
EP
sw
VL
12/11/2003
5.41
257
CA
CA3310038
00085
8S/1W-05M00
SR
sw
VL
6/18/2002
4.4
2
258
CA
CA3310044
00002
02S/05W-16H02
SR
GW
4/22/2003
10.1
4
259
CA
CA3310044
00004
02S/05W-11C02
SR
GW
4/22/2003
10.3
4
260
CA
CA3310044
00006
02S/05W-11C03
SR
GW
4/22/2003
9.7
4
261
CA
CA3310044
00002
02S/05W-16H02
SR
GW
10/1/2003
7.8
4
262
CA
CA3310044
00004
02S/05W-11C02
SR
GW
10/1/2003
7.8
4
263
CA
CA3310044
00006
02S/05W-11C03
SR
GW
10/1/2003
8
4
264
CA
CA3410004
00001
09N/06E-10M01
SR
sw
7/23/2002
4.14
3
265
CA
CA3610004
00031
3610004-031
EP
sw
1/9/2003
4.9
266
CA
CA3610004
00028
036/004-004
EP
sw
1/10/2003
7.5
267
CA
CA3610004
00028
036/004-004
EP
sw
7/18/2003
5.9
268
CA
CA3610004
00031
3610004-031
EP
sw
7/18/2003
4.7
269
CA
CA3610004
00034
01S/05W-24M02
SR
sw
7/18/2003
4.3
2
270
CA
CA3610004
00028
036/004-004
EP
sw
4/22/2004
6.6
271
CA
CA3610004
00031
3610004-031
EP
sw
4/22/2004
5.4
272
CA
CA3610004
00028
036/004-004
EP
sw
9/9/2004
6.5
C-4
-------
EPA-OGWDW Appendix C. UCMR 1 Perchlorate Detections May 2019
Exhibit C-1. Perchlorate Detections in the UCMR 1 Dataset with Source Water Detection Categories Identified
State
PWSID
Facility ID
Sample Point ID
Sample
Point Type
Source
Water
Type
Size
Category
Sample Date
Result
Value
(Mfl/L)
Category1
273
CA
CA3610004
00031
3610004-031
EP
SW
L
9/9/2004
4.4
274
CA
CA3610012
00008
01S/08W-35J03
SR
sw
VL
10/3/2002
12
2
275
CA
CA3610012
00009
01S/08W-35C05
SR
SW
VL
10/3/2002
21
2
276
CA
CA3610012
00013
01S/08W-26H02
SR
sw
VL
10/3/2002
11
2
277
CA
CA3610012
00004
01S/08W-35J01
SR
sw
VL
10/14/2002
7
2
278
CA
CA3610012
00004
01S/08W-35J01
SR
sw
VL
1/16/2003
8.6
2
279
CA
CA3610012
00005
02S/08W-11M01
EP
sw
VL
1/16/2003
5.5
280
CA
CA3610012
00008
01S/08W-35J03
SR
sw
VL
1/16/2003
16
2
281
CA
CA3610012
00009
01S/08W-35C05
SR
sw
VL
1/16/2003
17
2
282
CA
CA3610012
00011
01S/08W-35C07
SR
sw
VL
1/16/2003
16
2
283
CA
CA3610012
00013
01S/08W-26H02
SR
sw
VL
1/16/2003
9.6
2
284
CA
CA3610012
00004
01S/08W-35J01
SR
sw
VL
4/11/2003
6.2
2
285
CA
CA3610012
00008
01S/08W-35J03
SR
sw
VL
4/11/2003
12
2
286
CA
CA3610012
00009
01S/08W-35C05
SR
sw
VL
4/11/2003
14
2
287
CA
CA3610012
00011
01S/08W-35C07
SR
sw
VL
4/11/2003
11
2
288
CA
CA3610012
00013
01S/08W-26H02
SR
sw
VL
4/11/2003
6
2
289
CA
CA3610012
00004
01S/08W-35J01
SR
sw
VL
7/8/2003
00
00
2
290
CA
CA3610012
00008
01S/08W-35J03
SR
sw
VL
7/8/2003
18
2
291
CA
CA3610012
00009
01S/08W-35C05
SR
sw
VL
7/8/2003
18
2
292
CA
CA3610012
00011
01S/08W-35C07
SR
sw
VL
7/8/2003
16
2
293
CA
CA3610012
00013
01S/08W-26H02
SR
sw
VL
7/8/2003
12
2
294
CA
CA3610012
00005
02S/08W-11M01
EP
sw
VL
3/16/2004
6
295
CA
CA3610012
00015
R3
EP
sw
VL
3/16/2004
6.8
296
CA
CA3610012
00016
R4
EP
sw
VL
3/16/2004
4
297
CA
CA3610013
00009
01S/04W-24C01
SR
GW
L
7/22/2003
5
4
298
CA
CA3610014
00010
01S/04W-18G01
SR
GW
L
5/3/2004
5.6
2
299
CA
CA3610014
00012
01S/04W-18F01
SR
GW
L
5/3/2004
7.7
2
300
CA
CA3610018
00030
01N/07W-33L01
SR
sw
VL
1/16/2001
5
1
301
CA
CA3610018
00037
036/018-005
SR
sw
VL
1/16/2001
5.2
1
302
CA
CA3610018
00002
01S/07W-14E01
SR
sw
VL
1/17/2001
7.5
1
303
CA
CA3610018
00002
01S/07W-14E01
SR
sw
VL
5/23/2001
5
1
304
CA
CA3610018
00027
01N/07W-27P02
SR
sw
VL
5/23/2001
5
1
305
CA
CA3610018
00030
01N/07W-33L01
SR
sw
VL
5/23/2001
5.1
1
306
CA
CA3610018
00027
01N/07W-27P02
SR
sw
VL
8/8/2001
8
1
307
CA
CA3610018
00030
01N/07W-33L01
SR
sw
VL
8/8/2001
7.4
1
308
CA
CA3610018
00039
036/018-004
SR
sw
VL
8/8/2001
5.4
1
309
CA
CA3610018
00041
3610018-041
SR
sw
VL
8/8/2001
6.7
1
310
CA
CA3610018
00002
01S/07W-14E01
SR
sw
VL
11/27/2001
7.2
1
311
CA
CA3610018
00027
01N/07W-27P02
SR
sw
VL
11/27/2001
4
1
312
CA
CA3610018
00037
036/018-005
SR
sw
VL
11/27/2001
5.4
1
313
CA
CA3610018
00030
01N/07W-33L01
SR
sw
VL
11/28/2001
6.4
1
314
CA
CA3610018
00031
01N/07W-33E01
SR
sw
VL
11/28/2001
4
1
315
CA
CA3610018
00041
3610018-041
SR
sw
VL
11/28/2001
4.6
1
316
CA
CA3610018
00002
01S/07W-14E01
SR
sw
VL
3/25/2002
9
1
317
CA
CA3610018
00037
036/018-005
SR
sw
VL
3/25/2002
6
1
318
CA
CA3610018
00038
036/018-001
SR
sw
VL
3/25/2002
6.2
1
319
CA
CA3610018
00041
3610018-041
SR
sw
VL
3/25/2002
4.2
1
320
CA
CA3610018
00007
01S/07W-04B03
SR
sw
VL
3/28/2002
4.1
1
321
CA
CA3610018
00030
01N/07W-33L01
SR
sw
VL
3/28/2002
6
1
322
CA
CA3610029
00005
01S/08W-15H01
SR
sw
L
7/11/2003
4.4
2
323
CA
CA3610029
00027
01S/08W-13C01 S
SR
sw
L
12/9/2003
4.2
2
324
CA
CA3610034
00003
01S/07W-21D01
SR
GW
VL
11/13/2001
11
3
325
CA
CA3610034
00032
036/034-001
SR
GW
VL
11/13/2001
4.5
4
326
CA
CA3610034
00003
01S/07W-21D01
SR
GW
VL
12/27/2001
9.1
3
327
CA
CA3610034
00008
01S/07W-18G01
SR
GW
VL
12/27/2001
8
4
328
CA
CA3610034
00015
01S/07W-22B01
SR
GW
VL
12/27/2001
12
3
329
CA
CA3610034
00016
01S/07W-23D01
SR
GW
VL
12/27/2001
5
3
330
CA
CA3610034
00012
01S/08W-25Q02
SR
GW
VL
5/14/2002
4.9
3
331
CA
CA3610034
00012
01S/08W-25Q02
SR
GW
VL
5/28/2003
8
3
332
CA
CA3610034
00012
01S/08W-25Q02
SR
GW
VL
6/12/2003
8.5
3
333
CA
CA3610034
00008
01S/07W-18G01
SR
GW
VL
7/14/2003
5.2
4
334
CA
CA3610034
00012
01S/08W-25Q02
SR
GW
VL
5/28/2004
7.3
3
335
CA
CA3610034
00003
01S/07W-21D01
SR
GW
VL
6/7/2004
7
3
336
CA
CA3610034
00008
01S/07W-18G01
SR
GW
VL
8/10/2004
5.2
4
337
CA
CA3610034
00008
01S/07W-18G01
SR
GW
VL
8/11/2004
5
4
338
CA
CA3610034
00008
01S/07W-18G01
SR
GW
VL
8/17/2004
4.6
4
339
CA
CA3610036
00010
02S/08W-15C02
EP
SW
VL
2/10/2003
4.4
340
CA
CA3610037
00028
01S/03W-28K01
SR
SW
VL
12/17/2002
15
4
C-5
-------
EPA-OGWDW Appendix C. UCMR 1 Perchlorate Detections May 2019
Exhibit C-1. Perchlorate Detections in the UCMR 1 Dataset with Source Water Detection Categories Identified
State
PWSID
Facility ID
Sample Point ID
Sample
Point Type
Source
Water
Type
Size
Category
Sample Date
Result
Value
(Mfl/L)
Category1
341
CA
CA3610037
00044
01S/03W-21H07
EP
SW
VL
1/21/2003
62
342
CA
CA3610037
00047
01S/03W-22A02
SR
sw
VL
1/21/2003
18
4
343
CA
CA3610037
00028
01S/03W-28K01
SR
SW
VL
2/11/2003
13
4
344
CA
CA3610037
00038
01S/03W-35G07
SR
sw
VL
2/12/2003
6.7
4
345
CA
CA3610037
00041
01S/03W-35H03
SR
sw
VL
2/15/2003
5.2
4
346
CA
CA3610037
00004
02S/02W-03L01
EP
sw
VL
2/20/2003
7.2
347
CA
CA3610037
00045
01S/03W-21H01
SR
sw
VL
2/20/2003
18
4
348
CA
CA3610037
00052
01S/02W-34N02
EP
sw
VL
3/4/2003
10
349
CA
CA3610037
00037
01S/03W-35G08
EP
sw
VL
3/18/2003
6.7
350
CA
CA3610037
00039
01S/03W-35G09
EP
sw
VL
3/24/2003
5.8
351
CA
CA3610037
00038
01S/03W-35G07
SR
sw
VL
4/15/2003
6.6
4
352
CA
CA3610037
00052
01S/02W-34N02
EP
sw
VL
4/16/2003
10
353
CA
CA3610037
00044
01S/03W-21H07
EP
sw
VL
4/29/2003
67
354
CA
CA3610037
00049
01S/03W-26C01
SR
sw
VL
5/6/2003
4
4
355
CA
CA3610037
00047
01S/03W-22A02
SR
sw
VL
5/7/2003
17
4
356
CA
CA3610037
00028
01S/03W-28K01
SR
sw
VL
5/14/2003
17
4
357
CA
CA3610037
00039
01S/03W-35G09
EP
sw
VL
5/15/2003
5.3
358
CA
CA3610037
00004
02S/02W-03L01
EP
sw
VL
5/19/2003
6.4
359
CA
CA3610037
00037
01S/03W-35G08
EP
sw
VL
5/21/2003
4.8
360
CA
CA3610037
00045
01S/03W-21H01
SR
sw
VL
6/11/2003
16
4
361
CA
CA3610037
00047
01S/03W-22A02
SR
sw
VL
7/2/2003
10
4
362
CA
CA3610037
00031
01S/03W-23A05
EP
sw
VL
7/11/2003
5.3
363
CA
CA3610037
00102
3610037-102GA
EP
sw
VL
7/11/2003
4.9
364
CA
CA3610037
00028
01S/03W-28K01
SR
sw
VL
7/17/2003
15
4
365
CA
CA3610037
00054
3610037-054
SR
sw
VL
7/17/2003
5.5
4
366
CA
CA3610037
00051
01S/03W-28H01
SR
sw
VL
7/30/2003
11
4
367
CA
CA3610037
00038
01S/03W-35G07
SR
sw
VL
7/31/2003
6.9
4
368
CA
CA3610037
00044
01S/03W-21H07
EP
sw
VL
8/6/2003
66
369
CA
CA3610037
00037
01S/03W-35G08
EP
sw
VL
9/2/2003
7.6
370
CA
CA3610037
00041
01S/03W-35H03
SR
sw
VL
9/3/2003
5.6
4
371
CA
CA3610037
00004
02S/02W-03L01
EP
sw
VL
9/10/2003
6.7
372
CA
CA3610037
00039
01S/03W-35G09
EP
sw
VL
9/16/2003
5.8
373
CA
CA3610037
00038
01S/03W-35G07
SR
sw
VL
9/22/2003
6.8
4
374
CA
CA3610037
00044
01S/03W-21H07
EP
sw
VL
9/22/2003
59
375
CA
CA3610037
00016
01S/03W-32J02
EP
sw
VL
9/24/2003
5.3
376
CA
CA3610037
00045
01S/03W-21H01
SR
sw
VL
9/25/2003
17
4
377
CA
CA3610037
00051
01S/03W-28H01
SR
sw
VL
10/16/2003
10.5
4
378
CA
CA3610037
00028
01S/03W-28K01
SR
sw
VL
10/21/2003
14
4
379
CA
CA3610037
00052
01S/02W-34N02
EP
sw
VL
10/28/2003
7.9
380
CA
CA3610037
00041
01S/03W-35H03
SR
sw
VL
11/5/2003
4.8
4
381
CA
CA3610037
00031
01S/03W-23A05
EP
sw
VL
11/25/2003
5.3
382
CA
CA3610037
00044
01S/03W-21H07
EP
sw
VL
11/25/2003
62
383
CA
CA3610037
00047
01S/03W-22A02
SR
sw
VL
11/25/2003
17
4
384
CA
CA3610037
00004
02S/02W-03L01
EP
sw
VL
12/8/2003
7
385
CA
CA3610037
00054
3610037-054
SR
sw
VL
12/9/2003
5.1
4
386
CA
CA3610037
00038
01S/03W-35G07
SR
sw
VL
12/16/2003
7.5
4
387
CA
CA3610037
00045
01S/03W-21H01
SR
sw
VL
12/17/2003
17
4
388
CA
CA3610038
00010
036/038-005
SR
sw
2/21/2002
21
3
389
CA
CA3610038
00015
01S/05W-10H01
SR
sw
2/21/2002
9.8
3
390
CA
CA3610038
00017
01S/05W-02E02
SR
sw
2/21/2002
5.6
3
391
CA
CA3610038
00015
01S/05W-10H01
SR
sw
7/11/2002
6.8
3
392
CA
CA3610038
00014
01N/05W-34B01
SR
sw
7/26/2004
33
3
393
CA
CA3610039
00047
01N/04W-35C03
SR
GW
VL
11/27/2001
6.8
2
394
CA
CA3610039
00047
01N/04W-35C03
SR
GW
VL
11/23/2004
4.1
2
395
CA
CA3610041
00026
01S/05W-06D02
EP
sw
VL
6/14/2001
4
396
CA
CA3610041
00029
01S/05W-06J01
SR
sw
VL
6/14/2001
14
3
397
CA
CA3610041
00033
01S/06W-23D02
SR
sw
VL
6/14/2001
9.4
4
398
CA
CA3610041
00042
3610041-042
SR
sw
VL
6/14/2001
8.6
4
399
CA
CA3610041
00036
3610041-036
SR
sw
VL
6/15/2001
15
4
400
CA
CA3610041
00010
01S/05W-07R01
EP
sw
VL
11/29/2001
7.8
401
CA
CA3610041
00033
01S/06W-23D02
SR
sw
VL
11/29/2001
8.2
4
402
CA
CA3610041
00036
3610041-036
SR
sw
VL
11/29/2001
14
4
403
CA
CA3610041
00042
3610041-042
SR
sw
VL
11/29/2001
8
4
404
CA
CA3610041
00029
01S/05W-06J01
SR
sw
VL
11/30/2001
9.6
3
405
CA
CA3610043
00025
10N/01W-31Q02
SR
GW
L
10/22/2004
4.7
3
406
CA
CA3610057
00010
02S/04W-06R01
SR
GW
L
12/14/2001
5.2
2
407
CA
CA3610064
00018
01S/04W-02Q08
EP
sw
VL
2/6/2001
13
408
CA
CA3610064
00022
01N/04W-25A01
EP
sw
VL
2/6/2001
5.8
C-6
-------
EPA-OGWDW Appendix C. UCMR 1 Perchlorate Detections May 2019
Exhibit C-1. Perchlorate Detections in the UCMR 1 Dataset with Source Water Detection Categories Identified
State
PWSID
Facility ID
Sample Point ID
Sample
Point Type
Source
Water
Type
Size
Category
Sample Date
Result
Value
(Ufl/L)
Category1
409
CA
CA3610064
00023
01S/04W-12B06
EP
SW
VL
2/16/2001
6
410
CA
CA3610064
00026
01N/03W-30N01
EP
sw
VL
2/21/2001
7.4
411
CA
CA3610064
00028
01N/04W-25C04
EP
SW
VL
2/27/2001
9.8
412
CA
CA3610064
00017
01S/04W-02Q09
EP
sw
VL
7/23/2001
4.1
413
CA
CA3610064
00018
01S/04W-02Q08
EP
sw
VL
7/23/2001
16
414
CA
CA3610064
00020
01N/04W-26A03
EP
sw
VL
7/23/2001
6
415
CA
CA3610064
00022
01N/04W-25A01
EP
sw
VL
7/23/2001
8.5
416
CA
CA3610064
00021
01N/04W-25C02
EP
sw
VL
7/24/2001
4
417
CA
CA3610064
00023
01S/04W-12B06
EP
sw
VL
7/24/2001
7.8
418
CA
CA3610064
00026
01N/03W-30N01
EP
sw
VL
7/25/2001
11
419
CA
CA3610064
00028
01N/04W-25C04
EP
sw
VL
7/31/2001
14
420
CA
CA3610064
00018
01S/04W-02Q08
EP
sw
VL
5/7/2002
12
421
CA
CA3610064
00020
01N/04W-26A03
EP
sw
VL
5/7/2002
4.6
422
CA
CA3610064
00022
01N/04W-25A01
EP
sw
VL
5/7/2002
6
423
CA
CA3610064
00028
01N/04W-25C04
EP
sw
VL
5/30/2002
00
00
424
CA
CA3610064
00018
01S/04W-02Q08
EP
sw
VL
11/6/2002
11
425
CA
CA3610064
00022
01N/04W-25A01
EP
sw
VL
11/6/2002
4.1
426
CA
CA3610064
00021
01N/04W-25C02
EP
sw
VL
11/15/2002
4.3
427
CA
CA3610064
00023
01S/04W-12B06
EP
sw
VL
11/15/2002
5.8
428
CA
CA3610064
00028
01N/04W-25C04
EP
sw
VL
11/27/2002
00
00
429
CA
CA3610705
00014
036/705-004
EP
GW
L
8/17/2004
9.7
430
CA
CA3710006
00018
N37/006-PLNTEFF
EP
sw
VL
2/21/2001
4.3
431
CA
CA3710006
00019
N37/006-SDCWA
SR
sw
VL
8/14/2001
4.2
1
432
CA
CA3910001
00013
02N/06E-36A01
EP
sw
VL
12/16/2002
4.8
433
CA
CA3910011
00008
J39/011-TREAT
EP
sw
L
11/18/2002
21
434
CA
CA3910012
00030
02N/06E-20M02
SR
sw
VL
5/15/2001
6
3
435
CA
CA3910012
00027
02N/06E-16B01
SR
sw
VL
5/22/2001
7
2
436
CA
CA3910012
00029
02N/06E-09J01
SR
sw
VL
5/22/2001
10
2
437
CA
CA3910012
00033
02N/06E-15F01
SR
sw
VL
5/23/2001
16
2
438
CA
CA3910012
00038
02N/06E-10J03
SR
sw
VL
5/23/2001
5
2
439
CA
CA3910012
00039
02N/06E-15A01
SR
sw
VL
5/23/2001
5
2
440
CA
CA3910012
00040
02N/06E-15B01
SR
sw
VL
5/23/2001
11
2
441
CA
CA3910012
00043
02N/06E-11H03
SR
sw
VL
5/29/2001
7
2
442
CA
CA3910012
00085
3910012-084
SR
sw
VL
5/29/2001
4
2
443
CA
CA3910012
00003
01N/07E-29A02
SR
sw
VL
5/30/2001
19
2
444
CA
CA3910012
00004
01N/07E-31F01
SR
sw
VL
5/30/2001
10
2
445
CA
CA3910012
00005
01N/07E-31C01
SR
sw
VL
5/30/2001
12
2
446
CA
CA3910012
00083
J39/012-SSS3
SR
sw
VL
5/30/2001
7
2
447
CA
CA4310001
00020
07S/02W-01E02
EP
sw
VL
12/10/2001
4.7
448
CA
CA4310022
00007
08S/01E-12D10
EP
GW
VL
6/4/2002
4.4
449
CA
CA5010017
00006
SP002
SR
GW
6/25/2002
4.09
2
450
CA
CA5010017
00006
SP002
SR
GW
12/17/2002
4.4
2
451
FL
FL2160200
09001
02A
SR
GW
8/26/2002
200
2
452
FL
FL3490751
08004
FP-01
EP
GW
VL
6/14/2001
4.66
453
FL
FL4501242
08001
2002/12152
EP
GW
12/17/2003
17
454
FL
FL6280049
08001
WP#1
EP
GW
12/19/2001
16
455
FL
FL6280049
08002
WP #2
EP
GW
12/19/2001
14
456
FL
FL6280250
08001
001
EP
GW
12/20/2001
38
457
FL
FL6280250
08002
002
EP
GW
12/20/2001
46
458
FL
FL6280250
08004
004
EP
GW
12/20/2001
70
459
FL
FL6411132
08001
POE1
EP
SW
VL
1/31/2001
30
460
FL
FL6531812
08001
901
EP
GW
S
8/20/2002
4.7
461
GA
GA1130001
03775
305
EP
SW
VL
5/20/2003
5.2
462
GA
GA1530021
03905
308
EP
GW
10/10/2001
5.2
463
GA
GA2190000
15152
323
EP
SW
7/23/2001
38
464
IL
IL1610650
17079
TAP 01
EP
SW
9/9/2003
8.3
465
IL
IL1970450
33066
TAP 14
EP
GW
VL
12/1/2003
4
466
LA
LA1089001
00001T
3CAA-6
EP
SW
2/20/2001
24
467
MA
MA2064000
00011
24948
EP
SW
1/28/2002
6
468
MD
MD0120001
00001
0100000
EP
SW
3/27/2001
19.2
469
MD
MD0120002
00001
0100000
EP
SW
3/27/2001
19.9
470
MD
MD0210010
00001
0100000
EP
SW
VL
12/5/2001
4
471
MN
MN 1620009
00017
E03
EP
GW
9/21/2001
4.54
472
MN
MN 1660010
00006
E02
EP
GW
5/22/2001
6.02
473
MP
MP0000001
90009
01055
EP
GW
6/4/2001
4.66
474
MP
MP0000001
90049
01116
EP
GW
6/19/2001
12
475
MP
MP0000001
90009
01055
EP
GW
10/9/2001
8
476
MP
MP0000001
90049
01116
EP
GW
10/21/2001
14
C-7
-------
EPA-OGWDW Appendix C. UCMR 1 Perchlorate Detections May 2019
Exhibit C-1. Perchlorate Detections in the UCMR 1 Dataset with Source Water Detection Categories Identified
State
PWSID
Facility ID
Sample Point ID
Sample
Point Type
Source
Water
Type
Size
Category
Sample Date
Result
Value
(Mfl/L)
Category1
477
MS
MS0750005
00004T
7500502
EP
GW
M
12/5/2002
19.6
478
NC
NC0241020
00005
001
EP
SW
VL
12/5/2001
13.8
479
NC
NC0326332
00074
E26
EP
GW
1/14/2002
8.6
480
NC
NC0326332
00076
E28
EP
GW
1/14/2002
7.3
481
NC
NC0326332
00077
E29
EP
GW
1/14/2002
8
482
NC
NC0326332
00035
E09
EP
GW
1/21/2002
4.3
483
NC
NC0326332
00069
E21
EP
GW
1/21/2002
6.2
484
NC
NC0326332
00104
E35
EP
GW
1/23/2002
5.5
485
NC
NC0326332
00074
E26
EP
GW
6/12/2002
6.2
486
NC
NC0326332
00076
E28
EP
GW
6/12/2002
6
487
NC
NC0326332
00077
E29
EP
GW
6/12/2002
6.6
488
NC
NC0326332
00035
E09
EP
GW
6/17/2002
5.6
489
NC
NC0326332
00069
E21
EP
GW
6/26/2002
5.7
490
NC
NC0326332
00070
E22
EP
GW
6/26/2002
4
491
NC
NC0326332
00104
E35
EP
GW
6/26/2002
4.2
492
NC
NC0347025
00023
EP2
EP
GW
7/21/2003
4.07
493
NC
NC0347025
00048
EP8
EP
GW
7/21/2003
10.4
494
NC
NC0454010
00048
016
EP
GW
10/14/2002
4.2
495
NC
NC0464126
00001
901
EP
GW
VS
6/20/2001
5.8
496
NC
NC0464126
00001
901
EP
GW
VS
1/16/2002
6.2
497
NC
NC0465232
00058
011
EP
GW
11/21/2002
7.09
498
NC
NC0465232
00026
007
EP
GW
11/25/2002
5.89
499
NE
NE3111106
03581
EP1
EP
GW
1/27/2003
7.2
500
NE
NE3111106
03581
EP1
EP
GW
6/30/2003
4.9
501
NJ
NJ0113001
00003
NJ0113001-01
EP
GW
8/29/2002
4
502
NJ
NJ0247001
00036
NJ0247001-16
EP
GW
11/26/2002
5.1
503
NJ
NJ0247001
00036
NJ0247001-16
EP
GW
7/17/2003
13
504
NJ
NJ0614003
00012
NJ0614003-06
EP
GW
7/23/2003
6
505
NJ
NJ0614003
00012
NJ0614003-06
EP
GW
12/3/2003
6
506
NJ
NJ0713001
00003
NJ0713001-01
EP
SW
5/19/2003
5.3
507
NJ
NJ1225001
00027
NJ1225001-06
EP
SW
VL
5/23/2001
7.1
508
NJ
NJ1225001
00025
NJ1225001-05
EP
SW
VL
11/27/2001
5.2
509
NJ
NJ1225001
00027
NJ1225001-06
EP
SW
VL
11/27/2001
4.8
510
NJ
NJ1514001
00013
NJ1514001-06
EP
SW
VL
6/4/2002
5.2
511
NM
NM3527305
00036
SP273050361
EP
GW
5/14/2002
5.8
512
NM
NM3527305
00036
SP273050361
EP
GW
11/18/2002
5.1
513
NM
NM3528616
00003
003
SR
GW
5/14/2002
20
3
514
NM
NM3528616
00003
003
SR
GW
11/5/2002
16
3
515
NM
NM3528616
00003
003
SR
GW
5/2/2003
15
3
516
NV
NV0000076
00206
EP04
EP
SW
VL
11/19/2002
23
517
NV
NV0000076
00206
EP04
EP
SW
VL
2/13/2003
13
518
NV
NV0000076
00206
EP04
EP
SW
VL
5/21/2003
9.5
519
NV
NV0000076
00206
EP04
EP
SW
VL
8/27/2003
5.9
520
NV
NV0000289
00224
EP02
EP
SW
VL
11/19/2002
17.2
521
NV
NV0000289
00225
EP03
EP
SW
VL
11/19/2002
5.94
522
NV
NV0000289
00224
EP02
EP
SW
VL
2/13/2003
11
523
NV
NV0000289
00225
EP03
EP
SW
VL
2/13/2003
14
524
NV
NV0000289
00224
EP02
EP
SW
VL
5/21/2003
10
525
NV
NV0000289
00225
EP03
EP
SW
VL
5/21/2003
7.23
526
NV
NV0000289
00224
EP02
EP
SW
VL
8/27/2003
5.7
527
NV
NV0000289
00225
EP03
EP
SW
VL
8/27/2003
5.4
528
NV
NV0001048
00238
EP02
EP
SW
VS
3/4/2002
6.42
529
NV
NV0001048
00238
EP02
EP
SW
VS
6/3/2002
6.8
530
NV
NV0001048
00238
EP02
EP
SW
VS
9/9/2002
5.01
531
NV
NV0001048
00238
EP02
EP
SW
VS
12/4/2002
5.4
532
NY
NY2900000
33969
SRN08956
SR
GW
VL
1/27/2003
5.33
4
533
NY
NY2900000
33969
SRN08956
SR
GW
VL
6/9/2003
5
4
534
NY
NY2900000
33979
SRN08957
SR
GW
VL
6/9/2003
4.2
4
535
NY
NY2900000
33969
SRN08956
SR
GW
VL
8/6/2003
8.87
4
536
NY
NY2902817
34014
SRN8768
EP
GW
6/26/2001
4.2
537
NY
NY2902817
34015
SRN8767
EP
GW
6/26/2001
4.4
538
NY
NY2902817
34010
SRN3876
EP
GW
11/15/2001
5
539
NY
NY2902824
34060
SRN8339
SR
GW
6/27/2001
4.2
2
540
NY
NY2902826
34074
SRN09334
SR
GW
6/17/2002
4.02
4
541
NY
NY2902829
34093
SRN03878
EP
GW
6/27/2001
5.5
542
NY
NY2902829
34099
SRN07561
EP
GW
12/5/2001
6.3
543
NY
NY2902829
34106
SRN08778
EP
GW
12/11/2001
4.5
544
NY
NY2902829
22570
EPN03878
EP
GW
6/25/2002
6.41
C-8
-------
EPA-OGWDW Appendix C. UCMR 1 Perchlorate Detections May 2019
Exhibit C-1. Perchlorate Detections in the UCMR 1 Dataset with Source Water Detection Categories Identified
State
PWSID
Facility ID
Sample Point ID
Sample
Point Type
Source
Water
Type
Size
Category
Sample Date
Result
Value
(Mfl/L)
Category1
545
NY
NY2902829
22571
EPN06190
EP
GW
L
6/25/2002
7.7
546
NY
NY2902829
25282
EPN7561/9212
EP
GW
L
1/21/2003
5.6
547
NY
NY2902830
34122
SRN07650
EP
GW
VL
12/6/2001
4.7
548
NY
NY2902830
34132
SRN09151
EP
GW
VL
12/13/2001
5.6
549
NY
NY2902845
34291
SRN06580
SR
GW
L
5/29/2001
4.7
3
550
NY
NY2902845
34294
SRN07421
EP
GW
L
6/20/2001
7.5
551
NY
NY2902845
34290
SRN07526
SR
GW
L
6/27/2001
4.3
3
552
NY
NY2902845
34292
SRN06077
EP
GW
L
6/27/2001
11
553
NY
NY2902845
34292
EPN06077
EP
GW
L
11/5/2001
7.5
554
NY
NY2902845
34294
EPN 07421
EP
GW
L
11/5/2001
7.5
555
NY
NY2902845
34292
SRN06077
EP
GW
L
7/9/2002
6.49
556
NY
NY2902845
34294
SRN07421
EP
GW
L
7/9/2002
7.26
557
NY
NY2902856
34351
SRN08497
EP
GW
L
6/27/2001
6.7
558
NY
NY2902856
68556
SRN7353
EP
GW
L
6/27/2001
14
559
NY
NY2902856
68557
EPN07353
EP
GW
L
11/6/2001
11
560
NY
NY5103263
40721
SRS77126
EP
GW
VL
11/29/2001
5.4
561
NY
NY5103263
40730
SRS12079
EP
GW
VL
6/26/2002
4.8
562
NY
NY5103271
40759
SRS21134
EP
GW
L
7/25/2001
5.6
563
NY
NY5103271
40759
SRS21134
EP
GW
L
1/7/2002
4.6
564
NY
NY5110526
41220
SRS35939
EP
GW
VL
1/4/2001
12
565
NY
NY5110526
41077
SRS53593
EP
GW
VL
1/18/2001
6.8
566
NY
NY5110526
41220
SRS35939
EP
GW
VL
4/4/2001
12.1
567
NY
NY5110526
41220
EPSSS13
EP
GW
VL
4/4/2001
7.1
568
NY
NY5110526
82733
SRS115702
EP
GW
VL
5/22/2001
5.8
569
NY
NY5110526
82733
SRS115702
EP
GW
VL
6/13/2001
7
570
NY
NY5110526
41094
SRS68230
EP
GW
VL
6/15/2001
6.07
571
NY
NY5110526
68741
SRS22048
EP
GW
VL
6/16/2001
4.9
572
NY
NY5110526
41077
SRS53593
EP
GW
VL
7/18/2001
5.7
573
NY
NY5110526
41078
EPS23184
EP
GW
VL
7/18/2001
6.7
574
NY
NY5110526
41078
SRS23184
SR
GW
VL
7/18/2001
6.6
2
575
NY
NY5110526
41220
EPSSS13
EP
GW
VL
10/5/2001
10.5
576
NY
NY5110526
41220
SRS35939
EP
GW
VL
10/5/2001
11.7
577
NY
NY5110526
68636
SRS57354
EP
GW
VL
10/24/2001
5.4
578
NY
NY5110526
82733
SRS 115702
EP
GW
VL
11/1/2001
6.8
579
NY
NY5110526
41094
EPS68230TR
EP
GW
VL
11/27/2001
4.6
580
NY
NY5110526
82078
SRS 118363
EP
GW
VL
2/5/2002
4.6
581
NY
NY5110526
82733
SRS 115702
EP
GW
VL
6/15/2002
7.6
582
NY
NY5110526
41078
EPSSP12
EP
GW
VL
7/18/2002
5.92
583
OH
OH0900715
00008
EP001
EP
GW
5/8/2002
5.87
584
OH
OH0900715
00008
EP001
EP
GW
11/12/2002
27.1
585
OH
OH 1300812
00003
EP001
EP
GW
3/29/2001
7.05
586
OH
OH1800111
00002
EP001
EP
SW
1/14/2002
4.89
587
OH
OH2000111
00002
EP001
EP
SW
1/8/2002
5.71
588
OH
OH2903312
00014
EP2
EP
GW
2/6/2002
17.2
589
OH
OH4301611
00002
EP001
EP
SW
3/27/2001
9.22
590
OH
OH4401612
00006
EP001
EP
GW
1/22/2002
32.3
591
OH
OH6703211
00002
EP001
EP
SW
1/16/2002
5.27
592
OK
OK1020406
10880
UCM0001
EP
SW
1/30/2003
11
593
OK
OK1020419
10204
1020419
EP
SW
1/27/2003
17
594
OK
OK2001412
12300
UCM0016
EP
GW
1/20/2003
8.6
595
OK
OK2001412
12305
UCM0028
EP
GW
1/20/2003
9.7
596
OK
OK2001412
12292
UCM0019
EP
GW
1/21/2003
9.7
597
OK
OK2001412
20619
UCM0039
EP
GW
1/29/2003
13
598
OK
OK2002412
11032
UCM0001
EP
GW
7/24/2002
30
599
OK
OK2002445
11038
UCM0002
EP
GW
7/25/2002
10.3
600
OK
OK2007701
18386
EP001
EP
GW
1/22/2003
12
601
OK
OK2007701
18387
EP002
EP
GW
1/22/2003
13
602
PA
PA1090082
00102
00102E
EP
GW
7/17/2001
4.4
603
PA
PA1090082
00101
00101E
EP
GW
1/23/2002
4.7
604
PA
PA1460020
00103
00103E
EP
SW
6/7/2001
10
605
PA
PA1460020
00108
00108E
EP
SW
11/26/2003
8
606
PA
PA3060038
00105
00105E
EP
GW
6/21/2002
4
607
PA
PA4310012
00101
00101E
EP
SW
6/5/2001
6.7
608
PA
PA6200036
00100
00101E
EP
GW
2/13/2001
32.7
609
PA
PA6250028
00102
00102E
EP
SW
VL
11/18/2002
4.5
610
PA
PA7360123
00101
00101E
EP
SW
1/25/2001
12.1
611
PR
PR0002702
00004
2702004
EP
SW
2/27/2002
420
612
SC
SC0220005
00101T
0302153
EP
GW
S
7/7/2003
4.3
C-9
-------
EPA-OGWDW Appendix C. UCMR 1 Perchlorate Detections May 2019
Exhibit C-1. Perchlorate Detections in the UCMR 1 Dataset with Source Water Detection Categories Identified
State
PWSID
Facility ID
Sample Point ID
Sample
Point Type
Source
Water
Type
Size
Category
Sample Date
Result
Value
(Ufl/L)
Category1
613
SC
SC1620001
00402
0016004
EP
GW
L
11/27/2001
7.4
614
SC
SC2820005
00107T
0028108
EP
GW
L
2/3/2003
4.5
615
TN
TN0000150
00002T
000082B
EP
SW
L
11/19/2001
9
616
TX
TX1070190
04001
04001
EP
SW
L
5/6/2003
8.07
617
TX
TX1100002
04003
04003
EP
SW
L
4/9/2002
32
618
TX
TX1370001
04005
04005
EP
SW
L
9/10/2002
4.5
619
TX
TX1370001
04006
04006
EP
SW
L
9/10/2002
4
620
TX
TX1650001
04002
04002
EP
SW
VL
2/13/2002
7.92
621
VA
VA3001700
20368
EP001
EP
GW
S
7/30/2001
4.3
622
WA
WA5325200
00003
WELLHEAD
EP
SW
L
3/7/2002
6
623
WA
WA5325200
00013
WELLHEAD
EP
SW
L
3/7/2002
5
624
WA
WA5325200
00014
S014
EP
SW
L
3/7/2002
4
625
WA
WA5325200
00017
S017
EP
SW
L
3/7/2002
6
626
WA
WA5343500
00023
WA5343500-S23
EP
GW
L
7/22/2002
9
627
WA
WA5343500
00010
WA5343500-S10
EP
GW
L
7/24/2002
7
628
WA
WA5345550
00007
S07
EP
GW
VL
5/23/2002
6
629
WA
WA5345550
00016T
S16
EP
GW
VL
5/23/2002
5
630
WA
WA5345550
00019T
S19
EP
GW
VL
5/23/2002
6
631
WA
WA5345550
00021
S021
EP
GW
VL
5/23/2002
5
632
WA
WA5345550
00003
S03
EP
GW
VL
10/10/2002
4
633
WA
WA5370050
00001
SO-1
EP
SW
1/30/2002
4
634
WA
WA5370050
00005
SO-5
EP
SW
1/30/2002
5
635
WA
WA5370050
00008
SO-8
EP
SW
1/30/2002
8
636
WA
WA5370050
00001
SO-1
EP
SW
6/25/2002
4
637
WA
WA5382844
00007T
07T
EP
GW
10/13/2004
4
1 EPA excluded Category 1 and 2 source water detections (as well as non-detection records from the same sample points) from the Updated UCMR 1
Perchlorate Dataset that serves as the basis for all occurrence analyses, graphs, and maps presented in Section 4 of this report.
C-10
-------
Appendix D:
UCMR 1 State-Level Occurrence
Measures
-------
EPA - OGWDW
Appendix D. UCMR 1 State-Level Occurrence Measures
May 2019
Appendix D. UCMR 1 State-Level Occurrence Measures
This appendix presents UCMR 1 perchlorate occurrence results by state. These results are
based on the updated UCMR 1 Data set; see Section 4.1 of the report for more details. The
tabulated results here include straightforward, non-parametric counts of systems and population
served by systems with detections of perchlorate in drinking water samples collected under
UCMR 1 monitoring. These occurrence assessments, along with summary statistics of the
detected concentrations, are presented for each state and territory that conducted perchlorate
monitoring under the UCMR 1 program from 2001 to 2005.
Due to the limited size of the UCMR 1 small system sample, UCMR 1 small system
occurrence data are not representative at the state level. Therefore, the state-level occurrence
findings for small systems presented in this appendix can only be considered approximations of
occurrence in each state. In aggregate, however, the UCMR 1 small system occurrence findings
are statistically representative at the national level. The UCMR 1 large system monitoring, in
contrast, was conducted at all large systems so the large system occurrence findings presented
here are representative of perchlorate occurrence in each state and territory. Details of the
UCMR 1 sample design are discussed in Section 3.1 in the main portion this Perchlorate
Occurrence and Monitoring Report. Brief summaries of the five exhibits in this Appendix D,
Exhibits D-l through D-5, are provided below.
Exhibit D-l presents UCMR 1 occurrence for the number and percentages of systems
with perchlorate detections by state and system size category. The states with the largest number
of PWSs with perchlorate detections are California (50 PWSs) and New York (10 PWSs); all
other states had fewer than 10 PWSs with perchlorate detections. The states with the largest
percentage of PWSs with detections are N. Mariana Is. (33.33%) and Nevada (27.27%). Overall,
a higher percentage of large systems have at least one perchlorate detection compared to small
systems, but in four states (FL, MS, SC, VA), the percentage of small systems with detections is
greater.
Exhibit D-2 presents UCMR 1 occurrence data for the numbers and percentages of
systems with perchlorate detections by state and source water type. The states with the greatest
numbers of PWSs with detections were California (50), New York (10), and Arizona (9). All
other states had 8 or fewer PWSs with detections. Thirty-one states and tribes had no PWSs with
detections. The states with the largest percentages of PWSs with detections are N. Mariana Is.
(33.33%)), Nevada (27.27%), Arizona (15.25%), and California (12.35%). However, for both N.
Mariana Is. and Nevada, the numbers of PWSs conducting monitoring were low (3 and 11,
respectively). Approximately half of the PWSs with detections were ground water systems and
half were surface water systems.
Exhibit D-3 presents summary statistics for all UCMR 1 perchlorate occurrence data by
state. The states with the greatest numbers of detections were California (320), New York (49),
and Arizona (27). Many states had fewer than 10 detections, and many had none. The overall
median concentration in |ig/L was 4.66 |ig/L, the 99th percentile concentration was 9.25 |ig/L,
and the minimum was 4.0 |ig/L. The highest median concentrations were found in Puerto Rico
(420 |ig/L), Louisiana (24 |ig/L), and Mississippi (19.6 |ig/L). However, these territories and
Appendix D Page ii/ Introduction
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EPA - OGWDW
Appendix D. UCMR 1 State-Level Occurrence Measures
May 2019
states had very small numbers of detections (1, 1, and 3, respectively). California had a median
of 4.00 |ig/L and a 99th percentile value of 6.00 |ig/L. The median and 99th percentile values for
New York were 5.92 |ig/L and 13.09 |ig/L, respectively.
Exhibit D-4 presents the populations served by systems with UCMR 1 perchlorate
detections by states and system size category (small vs. large). Overall, more than 16 million
people are served by systems with detections, comprising 7.17% of the population served by
PWSs conducting UCMR 1 monitoring. The overwhelming majority are served by large systems.
Only 13,483 people are served by small systems. The states with the greatest numbers of people
served by PWSs with detections are California (8,387,543; 25.34%), Arizona (2,723,288;
64.12%), and New York (1,557,556; 7.82%). Percentages are reported as the percentage of
people served by PWSs conducting UCMR 1 monitoring. The highest percentages were found in
N. Mariana Is. (91.08%), Arizona (64.12%), Nevada (27.72%), and California (25.34%). N.
Mariana Is., however, only had three systems conducting monitoring and only four detections.
Nevada had 11 PWSs conducting monitoring, and Arizona had 59.
Exhibit D-5 presents the populations served by systems with UCMR 1 perchlorate
detections by state and source water type. Overall, almost 12,000,000 people are served by
surface water systems that have had perchlorate detections, and about 4,500,000 people are
served by ground water systems that have had detections. The states with the greatest numbers of
people served by ground water systems are California (1,091,068), New York (1,557,556), and
Arizona (675,000). The greatest numbers of people served by surface water systems with
detections were in California (7,296,475), Arizona (2,048,288), and New Jersey (477,465).
Percentages are reported as the percentage of people served by PWSs conducting monitoring.
The highest percentages of people served by ground water systems were in N. Mariana Is.
(95.97%)), Oklahoma (52.03%), and Arizona (42.16%). N. Mariana Is. only had three systems
monitoring and four detections. The states with the highest percentages of people served by
surface water systems were Arizona (77.42%), Nevada (28.11%), and California (28.06%).
Appendix D Page ii/ Introduction
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EPA - OGWDW
Appendix D. UCMR 1 State-Level Occurrence Measure
May 2019
Exhibit D-1. Systems With Perchlorate Detections by State and System Size Category -
Based on the Updated UCMR 1 Data set
State 12
Total #
Samples
Total Number of PWSs
Conducting UCMR 1 monitoring
Number of PWSs with
Perchlorate Detections
Percent of PWSs with
Perchlorate Detections
Total
Small
Large
Total
Small
Large
Total
Small
Large
Alaska
53
9
4
5
Alabama
786
98
15
83
4
0
4
4.08%
0.00%
4.82%
Arkansas
223
46
13
33
2
0
2
4.35%
0.00%
6.06%
Arizona
1,284
59
12
47
9
1
8
15.25%
8.33%
17.02%
California
8,872
405
48
357
50
1
49
12.35%
2.08%
13.73%
Colorado
401
56
10
46
Connecticut
370
41
6
35
D.C.
8
1
0
1
Delaware
102
8
2
6
Florida
1,179
238
31
207
6
1
5
2.52%
3.23%
2.42%
Georgia
551
101
22
79
3
0
3
2.97%
0.00%
3.80%
Guam
274
5
1
4
Hawaii
393
17
3
14
Iowa
214
47
16
31
Idaho
235
21
8
13
Illinois
753
133
28
105
2
0
2
1.50%
0.00%
1.90%
Indiana
395
86
20
66
Kansas
242
41
12
29
Kentucky
356
77
9
68
Louisiana
501
86
27
59
1
0
1
1.16%
0.00%
1.69%
Massachusetts
1,148
132
12
120
1
0
1
0.76%
0.00%
0.83%
Maryland
174
36
8
28
3
0
3
8.33%
0.00%
10.71%
Maine
90
19
6
13
Michigan
361
71
24
47
Minnesota
434
85
16
69
2
0
2
2.35%
0.00%
2.90%
Missouri
435
68
20
48
N. Mariana Is.
141
3
2
1
1
0
1
33.33%
0.00%
100.00%
Mississippi
521
72
30
42
1
1
0
1.39%
3.33%
0.00%
Montana
123
13
6
7
North Carolina
1,046
115
22
93
6
1
5
5.22%
4.55%
5.38%
North Dakota
40
13
4
9
Nebraska
231
20
8
12
1
0
1
5.00%
0.00%
8.33%
New Hampshire
134
21
6
15
New Jersey
1,046
128
16
112
6
0
6
4.69%
0.00%
5.36%
New Mexico
363
32
8
24
2
0
2
6.25%
0.00%
8.33%
Nevada
71
11
4
7
3
1
2
27.27%
25.00%
28.57%
New York
2,353
157
29
128
10
0
10
6.37%
0.00%
7.81%
Ohio
551
153
28
125
8
0
8
5.23%
0.00%
6.40%
Oklahoma
318
52
15
37
6
0
6
11.54%
0.00%
16.22%
Oregon
352
55
11
44
Pennsylvania
1,266
165
37
128
7
0
7
4.24%
0.00%
5.47%
Puerto Rico
716
86
9
77
1
0
1
1.16%
0.00%
1.30%
Rhode Island
119
13
2
11
South Carolina
289
59
11
48
3
1
2
5.08%
9.09%
4.17%
South Dakota
100
17
4
13
Tennessee
546
105
14
91
1
0
1
0.95%
0.00%
1.10%
Texas
1,721
255
71
184
4
0
4
1.57%
0.00%
2.17%
Utah
468
52
7
45
Virginia
295
58
16
42
1
1
0
1.72%
6.25%
0.00%
Virgin Islands
28
4
2
2
Vermont
40
10
4
6
Washington
634
80
17
63
5
0
5
6.25%
0.00%
7.94%
Wisconsin
516
76
21
55
West Virginia
171
35
10
25
Wyoming
68
11
3
8
Tribe - 05
2
1
1
0
Tribe - 06
2
1
1
0
Tribe - 07
4
1
1
0
Tribe - 08
6
2
2
0
Tribe - 09
17
3
2
1
Total
34,132
3,865
797
3,068
149
8
141
3.86%
1.00%
4.60%
1 The UCMR 1 small system data are not representative at the state level so the small system and total occurrence findings are only
approximations.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
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EPA - OGWDW
Appendix D. UCMR 1 State-Level Occurrence Measure
May 2019
Exhibit D-2. Systems With Perchlorate Detections by State and Source Water Type -
Based on the Updated UCMR 1 Data set
Total Number of PWSs Conducting
Number of PWSs with
Percent of PWSs with
State 12
UCMR 1 Monitoring
Perchlorate Detections
Perchlorate Detections
Total
GW
SW
Total
GW
SW
Total
GW
SW
Alaska
9
4
5
Alabama
98
42
56
4
3
1
4.08%
7.14%
1.79%
Arkansas
46
22
24
2
1
1
4.35%
4.55%
4.17%
Arizona
59
45
14
9
1
8
15.25%
2.22%
57.14%
California
405
177
228
50
12
38
12.35%
6.78%
16.67%
Colorado
56
15
41
Connecticut
41
11
30
D.C.
1
0
1
Delaware
8
4
4
Florida
238
220
18
6
5
1
2.52%
2.27%
5.56%
Georgia
101
38
63
3
1
2
2.97%
2.63%
3.17%
Guam
5
1
4
Hawaii
17
15
2
Iowa
47
27
20
Idaho
21
17
4
Illinois
133
84
49
2
1
1
1.50%
1.19%
2.04%
Indiana
86
64
22
Kansas
41
23
18
Kentucky
77
8
69
Louisiana
86
59
27
1
0
1
1.16%
0.00%
3.70%
Massachusetts
132
68
64
1
0
1
0.76%
0.00%
1.56%
Maryland
36
18
18
3
0
3
8.33%
0.00%
16.67%
Maine
19
6
13
Michigan
71
38
33
Minnesota
85
75
10
2
2
0
2.35%
2.67%
0.00%
Missouri
68
43
25
N. Mariana Is.
3
2
1
1
1
0
33.33%
50.00%
0.00%
Mississippi
72
70
2
1
1
0
1.39%
1.43%
0.00%
Montana
13
6
7
North Carolina
115
38
77
6
5
1
5.22%
13.16%
1.30%
North Dakota
13
6
7
Nebraska
20
18
2
1
1
0
5.00%
5.56%
0.00%
New Hampshire
21
8
13
New Jersey
128
88
40
6
3
3
4.69%
3.41%
7.50%
New Mexico
32
25
7
2
2
0
6.25%
8.00%
0.00%
Nevada
11
4
7
3
0
3
27.27%
0.00%
42.86%
New York
157
69
88
10
10
0
6.37%
14.49%
0.00%
Ohio
153
85
68
8
4
4
5.23%
4.71%
5.88%
Oklahoma
52
15
37
6
4
2
11.54%
26.67%
5.41 %
Oregon
55
20
35
Pennsylvania
165
43
122
7
3
4
4.24%
6.98%
3.28%
Puerto Rico
86
24
62
1
0
1
1.16%
0.00%
1.61 %
Rhode Island
13
6
7
South Carolina
59
15
44
3
3
0
5.08%
20.00%
0.00%
South Dakota
17
8
9
Tennessee
105
19
86
1
0
1
0.95%
0.00%
1.16%
Texas
255
122
133
4
0
4
1.57%
0.00%
3.01 %
Utah
52
17
35
Virginia
58
14
44
1
1
0
1.72%
7.14%
0.00%
Virgin Islands
4
0
4
Vermont
10
3
7
Washington
80
53
27
5
3
2
6.25%
5.66%
7.41 %
Wisconsin
76
58
18
West Virginia
35
3
32
Wyoming
11
2
9
Tribe - 05
1
1
Tribe - 06
1
1
Tribe - 07
1
1
Tribe - 08
2
1
1
Tribe - 09
3
1
2
Total
3,865
1,969
1,896
149
67
82
3.86%
3.40%
4.32%
The UCMR 1 data for small systems are not representative at the state level so these occurrence findings are approximations.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
D-2
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EPA - OGWDW
Appendix D. UCMR 1 State-Level Occurrence Measure
May 2019
Exhibit D-3. Summary Statistics for All Perchlorate Detections by State -
Based on the Updated UCMR 1 Data set
State12
Total #
Detections
Summary Statistics for Detections (in ug/L)
Minimum
Median
99th
Percentile
Maximum
Alaska
Alabama
6
5.50
8.45
11.00
11.00
Arkansas
3
4.50
5.50
6.60
6.60
Arizona
27
4.03
5.12
11.90
11.90
California
320
4.00
4.00
6.00
9.70
Colorado
Connecticut
D.C.
Delaware
Florida
9
4.66
17.00
68.08
70.00
Georgia
3
5.20
5.20
38.00
38.00
Guam
Hawaii
Iowa
Idaho
Illinois
2
4.00
6.15
8.30
8.30
Indiana
Kansas
Kentucky
Louisiana
1
24.00
24.00
24.00
24.00
Massachusetts
1
6.00
6.00
6.00
6.00
Maryland
3
4.00
19.20
19.90
19.90
Maine
Michigan
Minnesota
2
4.54
5.28
6.02
6.02
Missouri
N. Mariana Is.
4
4.66
10.00
14.00
14.00
Mississippi
1
19.60
19.60
19.60
19.60
Montana
North Carolina
21
4.00
6.00
13.80
13.80
North Dakota
Nebraska
2
4.90
6.05
7.20
7.20
New Hampshire
New Jersey
10
4.00
5.25
13.00
13.00
New Mexico
5
5.10
15.00
20.00
20.00
Nevada
16
5.01
7.02
23.00
23.00
New York
49
4.02
5.92
13.09
14.00
Ohio
9
4.89
7.05
32.30
32.30
Oklahoma
10
8.60
11.50
30.00
30.00
Oregon
Pennsylvania
9
4.00
6.70
32.70
32.70
Puerto Rico
1
420.00
420.00
420.00
420.00
Rhode Island
South Carolina
3
4.30
4.50
7.40
7.40
South Dakota
Tennessee
1
9.00
9.00
9.00
9.00
Texas
5
4.00
7.92
32.00
32.00
Utah
Virginia
1
4.30
4.30
4.30
4.30
Virgin Islands
Vermont
Washington
16
4.00
5.00
9.00
9.00
Wisconsin
West Virginia
Wyoming
Tribe - 05
Tribe - 06
Tribe - 07
Tribe - 08
Tribe - 09
Total
540
4.00
4.66
9.25
420.00
1 The UCMR 1 data for small systems are not representative at the state level so these occurrence
findings are approximations.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
D-3
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EPA-OGWDW Appendix D. IJCMR 1 State-Level Occurrence Measure May 2019
Exhibit D-4. Populations-Served By Systems With Perchlorate Detections- State & Size Category -
Based on the Updated UCMR 1 Data set
State 12
Total # of
PWSs
Conducting
UCMR 1
Monitoring
Total Population Served by PWSs
Conducting UCMR 1 Monitoring
Population Served by PWSs
with Perchlorate Detections
% Pop Served by PWSs with
Perchlorate Detections
Total
Small
Large
Total
Small
Large
Total
Small
Large
Alaska
9
239,991
3,454
236,537
Alabama
98
3,966,808
74,457
3,892,351
310,534
0
310,534
7.83%
0.00%
7.98%
Arkansas
46
1,379,357
54,195
1,325,162
72,075
0
72,075
5.23%
0.00%
5.44%
Arizona
59
4,246,932
41,298
4,205,634
2,723,288
1,606
2,721,682
64.12%
3.89%
64.72%
California
405
33,093,978
159,389
32,934,589
8,387,543
4,054
8,383,489
25.34%
2.54%
25.45%
Colorado
56
4,085,452
37,427
4,048,025
Connecticut
41
2,390,100
19,834
2,370,266
D.C.
1
927,055
0
927,055
Delaware
8
536,260
6,800
529,460
Florida
238
15,323,786
117,516
15,206,270
381,037
228
380,809
2.49%
0.19%
2.50%
Georgia
101
6,750,245
61,722
6,688,523
96,494
0
96,494
1.43%
0.00%
1.44%
Guam
5
105,219
5,504
99,715
Hawaii
17
1,110,726
15,462
1,095,264
Iowa
47
1,686,720
26,705
1,660,015
Idaho
21
580,914
38,297
542,617
Illinois
133
7,645,947
117,151
7,528,796
145,905
0
145,905
1.91 %
0.00%
1.94%
Indiana
86
3,539,721
112,990
3,426,731
Kansas
41
1,739,325
38,626
1,700,699
Kentucky
77
3,499,097
40,419
3,458,678
Louisiana
86
3,188,079
88,423
3,099,656
24,081
0
24,081
0.76%
0.00%
0.78%
Massachusetts
132
6,456,374
63,293
6,393,081
13,000
0
13,000
0.20%
0.00%
0.20%
Maryland
36
4,676,636
18,501
4,658,135
100,802
0
100,802
2.16%
0.00%
2.16%
Maine
19
348,285
8,110
340,175
Michigan
71
5,492,931
78,697
5,414,234
Minnesota
85
3,005,782
58,334
2,947,448
39,147
0
39,147
1.30%
0.00%
1.33%
Missouri
68
3,619,103
51,747
3,567,356
N. Mariana Is.
3
68,836
6,140
62,696
62,696
0
62,696
91.08%
0.00%
100.00%
Mississippi
72
1,273,562
78,999
1,194,563
4,309
4,309
0
0.34%
5.45%
0.00%
Montana
13
350,315
15,516
334,799
North Carolina
115
5,093,736
98,839
4,994,897
162,526
56
162,470
3.19%
0.06%
3.25%
North Dakota
13
320,270
7,619
312,651
Nebraska
20
965,769
23,535
942,234
25,000
0
25,000
2.59%
0.00%
2.65%
New Hampshire
21
494,401
16,250
478,151
New Jersey
128
8,122,662
76,320
8,046,342
536,024
0
536,024
6.60%
0.00%
6.66%
New Mexico
32
1,112,569
7,195
1,105,374
47,500
0
47,500
4.27%
0.00%
4.30%
Nevada
11
1,625,791
5,856
1,619,935
450,663
463
450,200
27.72%
7.91%
27.79%
New York
157
19,908,264
94,031
19,814,233
1,557,556
0
1,557,556
7.82%
0.00%
7.86%
Ohio
153
8,541,989
123,119
8,418,870
164,836
0
164,836
1.93%
0.00%
1.96%
Oklahoma
52
2,221,224
67,039
2,154,185
115,920
0
115,920
5.22%
0.00%
5.38%
Oregon
55
2,515,862
31,893
2,483,969
Pennsylvania
165
9,008,128
92,665
8,915,463
286,921
0
286,921
3.19%
0.00%
3.22%
Puerto Rico
86
4,832,111
36,651
4,795,460
25,972
0
25,972
0.54%
0.00%
0.54%
Rhode Island
13
824,052
4,740
819,312
South Carolina
59
2,669,268
50,104
2,619,164
63,099
1,467
61,632
2.36%
2.93%
2.35%
South Dakota
17
353,547
10,156
343,391
Tennessee
105
4,269,873
73,215
4,196,658
15,938
0
15,938
0.37%
0.00%
0.38%
Texas
255
15,675,049
251,073
15,423,976
165,517
0
165,517
1.06%
0.00%
1.07%
Utah
52
2,011,035
32,702
1,978,333
Virginia
58
5,137,941
22,928
5,115,013
1,300
1,300
0
0.03%
5.67%
0.00%
Virgin Islands
4
64,400
400
64,000
Vermont
10
220,439
11,169
209,270
Washington
80
4,465,081
41,836
4,423,245
192,882
0
192,882
4.32%
0.00%
4.36%
Wisconsin
76
2,769,896
88,774
2,681,122
West Virginia
35
781,825
34,761
747,064
Wyoming
11
245,695
1,680
244,015
Tribe - 05
1
191
191
0
Tribe - 06
1
2,300
2,300
0
Tribe - 07
1
498
498
0
Tribe - 08
2
825
825
0
Tribe - 09
3
31,444
13,200
18,244
Total
3,865
225,613,671
2,760,570
222,853,101
16,172,565
13,483
16,159,082
7.17%
0.49%
7.25%
1 The UCMR 1 small system data are not representative at the state level so the small system and total occurrence findings are only approximations.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
D-4
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EPA - OGWDW
Appendix D. UCMR 1 State-Level Occurrence Measure
May 2019
Exhibit D-5. Populations-Served By Systems With Perchlorate Detections by State & Source Water Type -
Based on the Updated UCMR 1 Data set
Total Population Served by PWSs
Population Served by PWSs
% Pop. Served by PWSs with
State 12
Conducting UCMR 1 Monitoring
with Perchlorate Detections
Perchlorate Detections
Total
GW
SW
Total
GW
SW
Total
GW
SW
Alaska
239,991
61,692
178,299
Alabama
3,966,808
770,193
3,196,615
310,534
70,974
239,560
7.83%
9.22%
7.49%
Arkansas
1,379,357
352,628
1,026,729
72,075
12,075
60,000
5.23%
3.42%
5.84%
Arizona
4,246,932
1,601,104
2,645,828
2,723,288
675,000
2,048,288
64.12%
42.16%
77.42%
California
33,093,978
7,086,529
26,007,449
8,387,543
1,091,068
7,296,475
25.34%
15.40%
28.06%
Colorado
4,085,452
306,580
3,778,872
Connecticut
2,390,100
123,040
2,267,060
D.C.
927,055
0
927,055
Delaware
536,260
60,130
476,130
Florida
15,323,786
12,501,454
2,822,332
381,037
182,537
198,500
2.49%
1.46%
7.03%
Georgia
6,750,245
744,191
6,006,054
96,494
29,806
66,688
1.43%
4.01%
1.11%
Guam
105,219
12,500
92,719
Hawaii
1,110,726
1,025,526
85,200
Iowa
1,686,720
534,972
1,151,748
Idaho
580,914
377,665
203,249
Illinois
7,645,947
1,642,735
6,003,212
145,905
106,221
39,684
1.91%
6.47%
0.66%
Indiana
3,539,721
1,299,570
2,240,151
Kansas
1,739,325
327,349
1,411,976
Kentucky
3,499,097
187,546
3,311,551
Louisiana
3,188,079
1,384,682
1,803,397
24,081
0
24,081
0.76%
0.00%
1.34%
Massachusetts
6,456,374
1,443,348
5,013,026
13,000
0
13,000
0.20%
0.00%
0.26%
Maryland
4,676,636
534,638
4,141,998
100,802
0
100,802
2.16%
0.00%
2.43%
Maine
348,285
29,995
318,290
Michigan
5,492,931
682,593
4,810,338
Minnesota
3,005,782
1,753,601
1,252,181
39,147
39,147
0
1.30%
2.23%
0.00%
Missouri
3,619,103
805,343
2,813,760
N. Mariana Is.
68,836
65,327
3,509
62,696
62,696
0
91.08%
95.97%
0.00%
Mississippi
1,273,562
951,094
322,468
4,309
4,309
0
0.34%
0.45%
0.00%
Montana
350,315
96,096
254,219
North Carolina
5,093,736
711,126
4,382,610
162,526
74,106
88,420
3.19%
10.42%
2.02%
North Dakota
320,270
74,450
245,820
Nebraska
965,769
434,460
531,309
25,000
25,000
0
2.59%
5.75%
0.00%
New Hampshire
494,401
87,020
407,381
New Jersey
8,122,662
2,146,187
5,976,475
536,024
58,559
477,465
6.60%
2.73%
7.99%
New Mexico
1,112,569
954,906
157,663
47,500
47,500
0
4.27%
4.97%
0.00%
Nevada
1,625,791
22,393
1,603,398
450,663
0
450,663
27.72%
0.00%
28.11%
New York
19,908,264
3,509,155
16,399,109
1,557,556
1,557,556
0
7.82%
44.39%
0.00%
Ohio
8,541,989
1,788,032
6,753,957
164,836
89,316
75,520
1.93%
5.00%
1.12%
Oklahoma
2,221,224
190,419
2,030,805
115,920
99,084
16,836
5.22%
52.03%
0.83%
Oregon
2,515,862
402,978
2,112,884
Pennsylvania
9,008,128
484,457
8,523,671
286,921
49,800
237,121
3.19%
10.28%
2.78%
Puerto Rico
4,832,111
470,189
4,361,922
25,972
0
25,972
0.54%
0.00%
0.60%
Rhode Island
824,052
98,740
725,312
South Carolina
2,669,268
228,191
2,441,077
63,099
63,099
0
2.36%
27.65%
0.00%
South Dakota
353,547
82,540
271,007
Tennessee
4,269,873
1,080,708
3,189,165
15,938
0
15,938
0.37%
0.00%
0.50%
Texas
15,675,049
3,018,842
12,656,207
165,517
0
165,517
1.06%
0.00%
1.31%
Utah
2,011,035
367,611
1,643,424
Virginia
5,137,941
54,564
5,083,377
1,300
1,300
0
0.03%
2.38%
0.00%
Virgin Islands
64,400
0
64,400
Vermont
220,439
2,149
218,290
Washington
4,465,081
1,529,808
2,935,273
192,882
142,332
50,550
4.32%
9.30%
1.72%
Wisconsin
2,769,896
1,111,260
1,658,636
West Virginia
781,825
60,546
721,279
Wyoming
245,695
26,099
219,596
Tribe - 05
191
191
0
Tribe - 06
2,300
2,300
0
Tribe - 07
498
0
498
Tribe - 08
825
325
500
Tribe - 09
31,444
3,200
28,244
Total
225,613,671
55,704,967
169,908,704
16,172,565
4,481,485
11,691,080
7.17%
8.05%
6.88%
1 The UCMR 1 small system data are not representative at the state level so these occurrence findings are approximations.
2 States are arranged alphabetically based on their 2-digit State abbreviation.
D-5
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