Occurrence Data 

from the Second 

Unregulated 

Contaminant 

Monitoring 

Regulation (UCMR 2) 
Office of Water (4607M) 

EPA-815-R-15-013 

December 2015
EPA-OGWDW Occurrence Data from the UCMR 2

iii

Executive Summary

This report presents the United States Environmental Protection Agency’s (EPA) analysis 

of the national occurrence of unregulated contaminants that were monitored in public water 

systems (PWSs) under the second Unregulated Contaminant Monitoring Regulation (UCMR 2). 

The UCMR 2 monitoring was conducted for selected unregulated contaminants in drinking water 

under the authority of Section 1445(a)(2) of the Safe Drinking Water Act (SDWA), as amended 

in 1996. This report also presents an overview of the regulatory background for unregulated 

contaminant monitoring, the design and implementation of the UCMR 2 monitoring program, 

data management and quality assurance/quality control (QA/QC), and the occurrence measures 

used and any limitations of those measures.

The UCMR program specifies a three-tiered approach for contaminant monitoring based 

on the availability of analytical methods and contaminant prioritization. Assessment Monitoring 

(List 1) is the largest in scope of the three monitoring components (or tiers). Assessment 

Monitoring typically relies on analytical methods, techniques or technologies that are in common 

use by drinking water laboratories. Screening Survey (List 2) monitoring typically relies on newer 

analytical methods that are not as commonly used, such that laboratory capacity to perform List 2 

analyses may be limited. Pre-Screen Testing (List 3) is often associated with analytical methods that 

are very recently developed and/or are particularly complex. The Pre-Screen Testing provisions of 

the UCMR program were not required under UCMR 2. 

The UCMR 2 program specified that all large (serving 10,001 – 100,000 people) and very 

large (serving more than 100,000 people) community water systems (CWSs) and non-transient 

non-community water systems (NTNCWSs), plus a statistically representative national sample of 

800 small (serving 10,000 or fewer people) CWSs and NTNCWSs were required to monitor for 

the 10 Assessment Monitoring contaminants. Additionally, UCMR 2 required monitoring of the 

15 Screening Survey contaminants by all very large systems, 320 selected large systems, and 480 

selected small systems. 

The UCMR 2 sampling was conducted from January 2008 to December 2010. The data 

were collected from PWSs in all 50 states and 6 additional primacy entities. All of the applicable

PWSs participated in the UCMR 2 monitoring, and collectively the systems submitted 

monitoring data of high quality. The UCMR 2 Data Quality Objectives (DQOs) required a small 

systems participation rate of at least 82.375%, and required that at least 90% of all submitted 

data meet the established data acceptance criteria; both requirements were met and surpassed. 

EPA developed a two-stage analytical approach to evaluate the UCMR 2 contaminant 

occurrence data. In Stage 1, the data are first reviewed, quality-checked, and characterized, and 

then analyzed to generate simple, clear non-parametric estimates of contaminant occurrence. For 

example, simple counts are made of the number of systems, and populations served by those 

systems, with at least one observed detection that has a concentration greater than the HRL, 

greater than 1⁄2 the HRL, or greater than or equal to the Minimum Reporting Level (MRL). Based 

on the Stage 1 analysis, any contaminant found to have significant occurrence can be analyzed 

with a more rigorous Stage 2 analysis. In Stage 2, statistical modeling is used to generate 

national probability estimates of contaminant occurrence based on estimated annual (or longer-
EPA-OGWDW Occurrence Data from the UCMR 2

iv

term) mean concentrations of contaminants along with statistical measures of uncertainty and 

error. This report presents the Stage 1 analysis only. 

Occurrence measures are presented for different categories of systems so that occurrence 

can be assessed based on system characteristics such as source water type or system size. Given 

that ground water systems and surface water systems have different sampling schedules, it is 

important to evaluate occurrence separately for the two source water types. EPA has also 

evaluated contaminant occurrence separately for the different UCMR 2 system size categories. A 

census of large and very large systems, plus a sample of small systems, monitored for 10 

Assessment Monitoring contaminants. A census of very large systems, plus a statistical sample 

of large and small systems monitored for 15 Screening Survey contaminants. UCMR 2 

occurrence data from the large and very large systems that monitored for the Assessment 

Monitoring contaminants; and from very large systems that monitored for the Screening Survey 

contaminants support contaminant occurrence analyses that are representative (statistically valid) 

at the state level. The statistical samples of small systems were insufficient to support a 

statistically rigorous state-level occurrence analysis; however, summary tables of all UCMR 2 

monitoring results are presented for each state, territory, and tribe to provide a complete record 

of monitoring results by state are included in the Appendix. 

In the final UCMR 2 data set, an average of 32,148 samples from 4,140 PWSs were 

collected for each of 10 Assessment Monitoring contaminants. Only 2 of the 10 Assessment 

Monitoring contaminants were detected – RDX and terbufos sulfone. Four detections of RDX 

(ranging from 1 μg/L to 1.1 μg/L) were reported; none of these detections were greater than the 

HRL of 21 μg/L. One detection of terbufos sulfone was reported; this detection (equal to 

0.42 μg/L) was greater than the HRL of 0.35 μg/L. The remaining eight Assessment Monitoring 

contaminants (BDE-47, BDE-99, BDE-100, BDE-153, dimethoate, 1,3-dinitrobenzene, HBB, 

and TNT) were not detected. 

In the final UCMR 2 data set, an average of 11,169 samples from 1,198 PWSs were 

collected for each of the nine acetanilide parent and degradate herbicides monitored under the 

Screening Survey. An average of 18,101 samples from 1,198 PWSs were collected for each of 

the six nitrosamines monitored under the Screening Survey. Ten of the 15 Screening Survey 

contaminants were detected – acetochlor ESA, alachlor ESA, metolachlor, metolachlor ESA, 

metolachlor OA, NDBA, NDEA, NDMA, NMEA, and NPYR. UCMR 2 monitoring found no 

analytical detections for five Screening Survey contaminants (acetochlor, acetochlor OA, 

alachlor, alachlor OA, and NDPA). Of the 10 Screening Survey contaminants detected, 7 

contaminants had at least one detection greater than their respective HRLs – acetochlor ESA, 

alachlor ESA, NDBA, NDEA, NDMA, NMEA, and NPYR. By far, the contaminant with the 

most detections was NDMA. NDMA was detected in 1,861 samples reported from 324 PWSs. 

NDMA detections ranged from 0.002 μg/L to 0.63 μg/L. All detections were greater than 

NDMA’s HRL of 0.0006 μg/L. 
EPA-OGWDW Occurrence Data from the UCMR 2

v 

Contents

Executive Summary ....................................................................................................................... iii

Contents .......................................................................................................................................... v

Exhibits ......................................................................................................................................... vii

Acronyms ....................................................................................................................................... ix

1 Introduction .................................................................................................................. 1

1.1 Regulatory Background ............................................................................................... 1

1.2 Two-Stage Analytical Approach .................................................................................. 2

1.3 Analytical Tools ........................................................................................................... 3

2 UCMR 2 Program Overview ....................................................................................... 4

2.1 UCMR 2 Monitoring Design and Contaminant List .................................................... 4

2.2 Assessment Monitoring ................................................................................................ 7

2.3 Screening Survey ......................................................................................................... 8

3 UCMR 2 Data Description ......................................................................................... 10

3.1 Data Submittal Process .............................................................................................. 10

3.2 Data Management and Quality Assurance ................................................................. 11

3.3 Assessments of Data Representativeness and Completeness ..................................... 13

3.3.1 Data Representativeness ............................................................................................. 13

3.3.2 Completeness ............................................................................................................. 14

3.4 Additional Data Management Considerations ........................................................... 15

3.4.1 Population Adjustments ............................................................................................. 15

3.4.2 Temporal Information ................................................................................................ 15

4 Description of Stage 1 Analytical Method ................................................................. 17

4.1 Stage 1 Analysis ......................................................................................................... 17

4.2 Threshold Evaluations ................................................................................................ 18

4.3 Additional Considerations for Stage 1 Analysis ........................................................ 19

4.3.1 Ground Water and Surface Water Comparisons ........................................................ 19

4.3.2 Large System and Small System Totals ..................................................................... 20

4.3.3 Extrapolation of the Results ....................................................................................... 20

4.3.4 Stage 1 Analyses and the Statistically-Weighted Sample of Small Systems ............. 21

5 Stage 1 Occurrence Estimates .................................................................................... 23

5.1 Assessment Monitoring Contaminants ...................................................................... 26

5.1.1 RDX ........................................................................................................................... 26

5.1.2 Terbufos Sulfone ........................................................................................................ 27

5.2 Screening Survey Contaminants with Detections ...................................................... 30

5.2.1 Acetochlor ESA ......................................................................................................... 31

5.2.2 Alachlor ESA ............................................................................................................. 35

5.2.3 Metolachlor ................................................................................................................ 38

5.2.4 Metolachlor ESA ........................................................................................................ 40

5.2.5 Metolachlor OA ......................................................................................................... 42
EPA-OGWDW Occurrence Data from the UCMR 2

vi

5.2.6 NDBA ........................................................................................................................ 43

5.2.7 NDEA ......................................................................................................................... 46

5.2.8 NDMA ........................................................................................................................ 50

5.2.9 NMEA ........................................................................................................................ 54

5.2.10 NPYR ......................................................................................................................... 58

6 References .................................................................................................................. 62
EPA-OGWDW Occurrence Data from the UCMR 2

vii

Exhibits

Exhibit 2-1: Contaminants Monitored Under UCMR 2 ................................................................. 4

Exhibit 2-2: Number of PWSs that Monitored Under UCMR 2 .................................................... 9

Exhibit 3-1: UCMR 2 Required Data Elements ........................................................................... 11

Exhibit 4-1: Minimum Reporting Levels (MRLs) and Health Reference Levels (HRLs) 

for UCMR 2 Contaminants ............................................................................................... 18

Exhibit 4-2: Example Calculation of National Estimates (Extrapolations) for UCMR 2 Small and 

Large Systems (serving ≤ 100,000 people) for Screening Survey Contaminants ............ 21

Exhibit 5-1: Summary of Stage 1 Occurrence Results for 10 Assessment Monitoring 

Contaminants and 15 Screening Survey Contaminants .................................................... 24

Exhibit 5-2: Summary of Stage 1 Occurrence Results for 10 Assessment Monitoring 

Contaminants and 15 Screening Survey Contaminants .................................................... 25

Exhibit 5-3: RDX National Occurrence Measures from UCMR 2 Assessment Monitoring Data - 

Summary of System and Population Served Data - All Detections .................................. 26

Exhibit 5-4: Terbufos Sulfone National Occurrence Measures from UCMR 2 Assessment 

Monitoring Data - Summary of System and Population Served Data - All Detections ... 28

Exhibit 5-5: Terbufos Sulfone National Occurrence Measures from UCMR 2 Assessment 

Monitoring Data - Summary of System and Population Served Data - Detections > 1⁄2 

HRL................................................................................................................................... 29

Exhibit 5-6: Terbufos Sulfone National Occurrence Measures from UCMR 2 Assessment 

Monitoring Data - Summary of System and Population Served Data - Detections > HRL

........................................................................................................................................... 30

Exhibit 5-7: Acetochlor ESA National Occurrence Measures from UCMR 2 Screening Survey 

Data - Summary of System and Population Served Data - All Detections ....................... 31

Exhibit 5-8: Acetochlor ESA National Occurrence Measures from UCMR 2 Screening Survey 

Data - Summary of System and Population Served Data - Detections > 1⁄2 HRL............. 33

Exhibit 5-9: Acetochlor ESA National Occurrence Measures from UCMR 2 Screening Survey 

Data - Summary of System and Population Served Data - Detections > HRL................. 34

Exhibit 5-10: Alachlor ESA National Occurrence Measures from UCMR 2 Screening Survey 

Data - Summary of System and Population Served Data - All Detections ....................... 35

Exhibit 5-11: Alachlor ESA National Occurrence Measures from UCMR 2 Screening Survey 

Data - Summary of System and Population Served Data - Detections > 1⁄2 HRL............. 37

Exhibit 5-12: Alachlor ESA National Occurrence Measures from UCMR 2 Screening Survey 

Data - Summary of System and Population Served Data - Detections > HRL................. 38

Exhibit 5-13: Metolachlor National Occurrence Measures from UCMR 2 Screening Survey Data 

- Summary of System and Population Served Data - All Detections ............................... 39

Exhibit 5-14: Metolachlor ESA National Occurrence Measures from UCMR 2 Screening Survey 

Data - Summary of System and Population Served Data - All Detections ....................... 41
EPA-OGWDW Occurrence Data from the UCMR 2

viii

Exhibit 5-15: Metolachlor OA National Occurrence Measures from UCMR 2 Screening Survey 

Data - Summary of System and Population Served Data - All Detections ....................... 42

Exhibit 5-16: NDBA National Occurrence Measures from UCMR 2 Screening Survey Data - 

Summary of System and Population Served Data - All Detections .................................. 44

Exhibit 5-17: NDBA National Occurrence Measures from UCMR 2 Screening Survey Data - 

Summary of System and Population Served Data - Detections > 1⁄2 HRL ....................... 45

Exhibit 5-18: NDBA National Occurrence Measures from UCMR 2 Screening Survey Data - 

Summary of System and Population Served Data - Detections > HRL ........................... 46

Exhibit 5-19: NDEA National Occurrence Measures from UCMR 2 Screening Survey Data - 

Summary of System and Population Served Data - All Detections .................................. 47

Exhibit 5-20: NDEA National Occurrence Measures from UCMR 2 Screening Survey Data - 

Summary of System and Population Served Data - Detections > 1⁄2 HRL ....................... 48

Exhibit 5-21: NDEA National Occurrence Measures from UCMR 2 Screening Survey Data - 

Summary of System and Population Served Data - Detections > HRL ........................... 49

Exhibit 5-22: NDMA National Occurrence Measures from UCMR 2 Screening Survey Data - 

Summary of System and Population Served Data - All Detections .................................. 51

Exhibit 5-23: NDMA National Occurrence Measures from UCMR 2 Screening Survey Data - 

Summary of System and Population Served Data - Detections > 1⁄2 HRL ....................... 52

Exhibit 5-24: NDMA National Occurrence Measures from UCMR 2 Screening Survey Data - 

Summary of System and Population Served Data - Detections > HRL ........................... 53

Exhibit 5-25: NMEA National Occurrence Measures from UCMR 2 Screening Survey Data - 

Summary of System and Population Served Data - All Detections .................................. 55

Exhibit 5-26: NMEA National Occurrence Measures from UCMR 2 Screening Survey Data - 

Summary of System and Population Served Data – Detections > 1⁄2 HRL ....................... 56

Exhibit 5-27: NMEA National Occurrence Measures from UCMR 2 Screening Survey Data - 

Summary of System and Population Served Data - Detections > HRL ........................... 57

Exhibit 5-28: NPYR National Occurrence Measures from UCMR 2 Screening Survey Data - 

Summary of System and Population Served Data - All Detections .................................. 58

Exhibit 5-29: NPYR National Occurrence Measures from UCMR 2 Screening Survey Data - 

Summary of System and Population Served Data - Detections > 1⁄2 HRL ....................... 60

Exhibit 5-30: NPYR National Occurrence Measures from UCMR 2 Screening Survey Data - 

Summary of System and Population Served Data - Detections > HRL ........................... 61
EPA-OGWDW Occurrence Data from the UCMR 2

ix

Acronyms

BDE-47 2,2',4,4'-Tetrabromodiphenyl ether

BDE-99 2,2',4,4',5-Pentabromodiphenyl ether

BDE-100 2,2',4,4',6-Pentabromodiphenyl ether

BDE-153 2,2',4,4',5,5'-Hexabromodiphenyl ether

CAS RN Chemical Abstract Services Registry Number

CCL Candidate Contaminant List

CDX Central Data Exchange

CWS Community Water System

CWSS Community Water System Survey

DQO Data Quality Objective

DSMRT Distribution System Maximum Residence Time

EPTDS Entry Point to the Distribution System

EPA Environmental Protection Agency

ESA Ethane Sulfonic Acid

GW Ground Water

GUDI Ground Water Under Direct Influence (of Surface Water)

HBB 2,2',4,4',5,5'-Hexabromobiphenyl

HRL Health Reference Level

MCL Maximum Contaminant Level

MRL Minimum Reporting Level (or Limit)

NCOD National Contaminant Occurrence Database

NDBA N-Nitroso-di-n-butylamine

NDEA N-Nitroso-diethylamine

NDMA N-Nitroso-dimethylamine

NDPA N-Nitroso-di-n-propylamine

NMEA N-Nitroso-methylethylamine

NPDWR National Primary Drinking Water Regulations

NPYR N-Nitroso-pyrrolidine

NTNCWS Non-Transient Non-Community Water System

OA Oxanilic Acid

OGWDW Office of Ground Water and Drinking Water
EPA-OGWDW Occurrence Data from the UCMR 2

x 

PWS Public Water System

PWSID Public Water System Identification Number

QA Quality Assurance

QC Quality Control

RD Regulatory Determination

RDX Hexahydro-1,3,5-trinitro 1,3,5-triazine

SDWA Safe Drinking Water Act

SDWARS Safe Drinking Water Accession and Review System

SDWIS/Fed Safe Drinking Water Information System / Federal Version

SW Surface Water

TNCWS Transient Non-Community Water System

TNT 2,4,6-Trinitrotoluene

UCM Unregulated Contaminant Monitoring

UCMR Unregulated Contaminant Monitoring Regulation

USEPA United States Environmental Protection Agency
EPA-OGWDW Occurrence Data from the UCMR 2

1 

1 Introduction

The United States Environmental Protection Agency (EPA) conducted drinking water 

monitoring under the agency’s second Unregulated Contaminant Monitoring Regulation 

(UCMR 2). UCMR 2 monitoring was conducted for selected unregulated contaminants in 

drinking water under the authority of Section 1445(a)(2) of the Safe Drinking Water Act 

(SDWA), as amended in 1996. Unregulated contaminants are contaminants for which there is no 

established or proposed National Primary Drinking Water Regulation (NPDWR). The intent of 

this monitoring is to gather more scientific information on these unregulated contaminants to 

support EPA assessments of national occurrence in drinking water to determine whether 

additional drinking water regulations are needed.

This report presents EPA’s analysis of the national occurrence of unregulated 

contaminants that were monitored at PWSs under the UCMR 2. The report additionally provides 

an overview of the regulatory background for unregulated contaminant monitoring, the design 

and implementation of the UCMR 2 monitoring program, data management and quality 

assurance/quality control (QA/QC), and the occurrence measures used and any limitations of 

those measures.

The analyses presented in this report are based on the final UCMR 2 data set, which 

includes analytical results of water samples from all 4,620 systems that were expected to submit 

UCMR 2 data (100% compliance). To accommodate final (late) UCMR 2 reporting, the data 

system remained open for submission of data through December 31, 2011. The final data set, 

including the sample data submitted through December 2011, is available on the UCMR website 

(http://www.epa.gov/dwucmr/occurrence-data-unregulated-contaminant-monitoring-rule#2). 

This document also provides detailed descriptions of EPA’s management and analysis of the 

data.

1.1 Regulatory Background 

SDWA, as amended in 1986, required PWSs to monitor for specified unregulated 

contaminants on a five-year cycle and to report the monitoring results to the states. Monitoring of 

unregulated drinking water contaminants was historically conducted under the Unregulated 

Contaminant Monitoring (UCM) program. Data from the first round of monitoring (UCM Round 

1) were collected from 1988 to 1992. All community water systems (CWSs) and non-transient 

non-community water systems (NTNCWSs) that had more than 150 service connections were 

required to conduct monitoring for select unregulated contaminants in drinking water. Smaller 

systems (those with 150 service connections or fewer) were not universally required to 

participate in the monitoring, but they were required to be available for monitoring if the state 

decided such monitoring was necessary. In 1993, Congress amended SDWA to add new 

contaminants for unregulated contaminant monitoring. Data from UCM Round 2 monitoring 

were collected from 1993 to 1997. 

The 1996 SDWA Amendments directed EPA to develop a revised program for the 

monitoring of unregulated contaminants and to, once every 5 years, identify no more than 30 

contaminants to be monitored. The first UCMR (UCMR 1), and related rules, replaced the older 

UCM requirements. The details of UCMR 1 were formally published in the Federal Register on 
EPA-OGWDW Occurrence Data from the UCMR 2

2 

September 17, 1999 (64 FR 50556; USEPA, 1999). The UCMR program was designed to 

provide a national assessment of the occurrence of select unregulated contaminants in PWSs. 

UCMR 1 provided for the selection of the contaminants to be monitored, the requirements for 

PWSs that must conduct monitoring (from 2001-2005), and establishment of the process to 

report all UCMR monitoring results to EPA. The second UCMR (UCMR 2; USEPA, 2007) 

established a somewhat revised monitoring program; this monitoring was primarily conducted 

between January 2008 and December 2010. 

The 1996 amendments to SDWA instituted the Candidate Contaminant List (CCL) and 

the National Contaminant Occurrence Database (NCOD) in addition to the UCMR programs. 

Development of each successive UCMR is coordinated with the CCL and the NCOD to provide 

the information EPA needs to determine which drinking water contaminants have the greatest 

potential to present a meaningful opportunity to reduce health risk through an NPWDR. UCMR 

provides EPA with the data necessary to identify contaminants that may require regulation as 

part of the CCL (USEPA, 2002) and to determine if a contaminant occurs at a frequency and 

level of public health concern to inform the Regulatory Determination (RD) process (USEPA, 

2008a). The UCMR, CCL and RD are coordinated parts of EPA’s risk management process, and 

they support and inform each other. The data collected through the UCMR program are stored in 

the NCOD to facilitate review of contaminant occurrence in drinking water. These data may 

guide the development of subsequent CCLs and ultimately support the EPA Administrator's 

regulatory determinations. 

Data from UCMR 2 were used by EPA to evaluate the occurrence of contaminants on the 

third Contaminant Candidate List (CCL 3) for possible inclusion in the third round of Regulatory 

Determinations (RD 3). Sixteen UCMR 2 contaminants were included on CCL 3: 1,3-

dinitrobenzene, acetochlor, acetochlor ethane sulfonic acid (ESA), acetochlor oxanilic acid (OA), 

alachlor ESA, alachlor OA, dimethoate, metolachlor, metolachlor ESA, metolachlor OA, Nnitroso-diethylamine (NDEA), N-nitroso-dimethylamine (NDMA), N-nitroso-di-n-propylamine 

(NDPA), N-nitroso-pyrrolidine (NPYR), hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), and 

terbufos sulfone. The nine UCMR 2 contaminants that are not on CCL 3 are: alachlor, 

2,2',4,4',5,5'-hexabromodiphenyl ether (BDE-153), 2,2',4,4',5-pentabromodiphenyl ether (BDE99), 2,2',4,4',6-pentabromodiphenyl ether (BDE-100), 2,2',4,4'-tetrabromodiphenyl ether (BDE47), 2,2',4,4',5,5'-hexabromobiphenyl (HBB), N-nitroso-di-n-butylamine (NDBA), N-nitrosomethylethylamine (NMEA), and 2,4,6-trinitrotoluene (TNT). For more information about the 

RD 3 program, see the Regulatory Determination 3 Support Document (USEPA, 2015) and the 

Protocol for the Regulatory Determination 3 (USEPA, 2014a). 

To meet agency deadlines, EPA made use of UCMR data submitted through June 2011 in

the deliberative process for RD 3. A draft version of this document, included in the docket for 

the preliminary regulatory determinations under RD 3 (79 FR 62715-62750; USEPA, 2014b), 

presented the data through June 2011 in the appendix. The June 2011 data are only slightly 

different from the final December 2011 UCMR 2 data set described in this report. 

1.2 Two-Stage Analytical Approach 

EPA developed a two-stage analytical approach to evaluate the UCMR 2 contaminant 

occurrence data. This two-stage analytical approach was previously developed (and peer

reviewed) for other EPA Office of Ground Water and Drinking Water (OGWDW) national 
EPA-OGWDW Occurrence Data from the UCMR 2

3 

occurrence studies, including the first Six-Year Review of National Primary Drinking Water 

Regulations (USEPA, 2003a), UCMR 1 (USEPA, 2008b), and previous rounds of the CCL and 

RD process (USEPA, 2002; USEPA, 2008a). 

The first stage of analysis provides a straightforward evaluation of occurrence of all 

contaminants under consideration. This “Stage 1 analysis” of occurrence assesses the quality and 

characteristics of the data and then uses the data to conduct simple, conservative assessments for 

a broad evaluation of contaminant occurrence and population exposure.1 Occurrence for each 

UCMR 2 contaminant was assessed based on samples, systems, and population served by 

systems. A typical Stage 1 analysis is the actual count (or percentage) of systems with at least 

one analytical detection2 of a specific contaminant.

Based on the Stage 1 analysis, any contaminant found to have significant occurrence can 

be analyzed with a more rigorous “Stage 2 analysis.” The Stage 2 analysis is a parametric 

estimation based on calculation of mean contaminant concentrations at each system, and can 

provide occurrence estimates that help characterize contaminant occurrence at concentrations 

below the MRL. The Stage 2 occurrence analyses are less conservative than Stage 1 (since the 

Stage 2 analysis is based on estimated mean concentrations) and also provide occurrence 

estimates that may be more reflective of the potential for chronic exposure. This report presents 

only Stage 1 analyses.

1.3 Analytical Tools 

Database manipulation, data quality checks, and overall data management were 

conducted in Microsoft Access. The data analyses were also conducted with Microsoft Access. 

Upon completion, results of the analyses were exported into Microsoft Excel for development of 

report tables that present the occurrence findings. 

 

1 These analyses are conservative in that they are protective of human health (i.e., they are more likely to 

overestimate risks to human health than underestimate them).

2 By definition, an analytical detection is a quantified concentration that is equal to or greater than the laboratory 

method minimum reporting level, the MRL.
EPA-OGWDW Occurrence Data from the UCMR 2

4 

2 UCMR 2 Program Overview

2.1 UCMR 2 Monitoring Design and Contaminant List 

The UCMR program design includes a three-tiered approach for monitoring of 

contaminants based on the availability of analytical methods (and related laboratory capacity) as 

well as risk-based contaminant prioritization. Assessment Monitoring (List 1) is the largest in 

scope of the three monitoring components (or tiers) and typically relies on analytical methods, 

techniques or technologies that are in common use by drinking water laboratories. Screening Survey 

(List 2) monitoring typically relies on newer analytical methods that are not as commonly used, such 

that laboratory capacity to perform List 2 analyses may be limited. Pre-Screen Testing (List 3) is 

often associated with analytical methods that are very recently developed and/or are particularly 

complex. 

Exhibit 2-1 presents the list of 10 Assessment Monitoring contaminants and 15 Screening 

Survey contaminants monitored under UCMR 2. The Assessment Monitoring contaminants fall 

into three main groups: insecticides and insecticide degradates, flame retardants, and explosives. 

The Screening Survey contaminants fall into two main groups: acetanilide herbicides with their 

degradation products, and nitrosamines. The Pre-Screen Testing provisions of the UCMR 

program were not implemented under UCMR 2. 

Exhibit 2-1: Contaminants Monitored Under UCMR 2 

Contaminant Name

Chemical 

Abstract 

Services 

Registry 

Number 

(CAS RN)

Minimum 

Reporting 

Level 

(MRL)

Analytical 

Method Contaminant Use and Description

. . ASSESSMENT MONITORING . .

. . Insecticide and Insecticide Degradate . . 

Dimethoate 60-51-5 0.7 μg/L EPA 527

Insecticide used on cotton and other 

field crops, orchard crops, vegetable 

crops, in forestry, and residential uses.

Terbufos sulfone 56070-16-7 0.4 μg/L EPA 527

Parent compound (terbufos) used for 

systemic control of soil-borne insects 

and nematodes in fields of corn, grain 

sorghum, and sugar beets.
EPA-OGWDW Occurrence Data from the UCMR 2

5

Contaminant Name

Chemical 

Abstract 

Services 

Registry 

Number 

(CAS RN)

Minimum 

Reporting 

Level 

(MRL)

Analytical 

Method Contaminant Use and Description

. . Flame Retardants . .

2,2',4,4'-tetrabromodiphenyl 

ether (BDE-47) 5436-43-1 0.3 μg/L EPA 527

Flame retardant added to other 

materials (for products such as 

computer monitors, televisions, 

textiles, and plastic foams).

2,2',4,4',5-

pentabromodiphenyl ether 

(BDE-99)

60348-60-9 0.9 μg/L EPA 527

Flame retardant added to other 

materials (for products such as 

computer monitors, televisions, 

textiles, and plastic foams).

2,2',4,4',5,5'-

hexabromodiphenyl ether 

(BDE-153)

68631-49-2 0.8 μg/L EPA 527

Flame retardant added to other 

materials (for products such as 

computer monitors, televisions, 

textiles, and plastic foams).

2,2',4,4',6-

pentabromodiphenyl ether 

(BDE-100)

189084-64-

8 0.5 μg/L EPA 527

Flame retardant added to other 

materials (for products such as 

computer monitors, televisions, 

textiles, and plastic foams).

2,2',4,4',5,5'-

hexabromobiphenyl (HBB) 59080-40-9 0.7 μg/L EPA 527

Flame retardant additive; production of 

PBBEs ended in 1976 in US after an 

incident of significant accidental 

agricultural contamination in 1973.

. . Explosives . .

2,4,6-trinitrotoluene (TNT) 118-96-7 0.8 μg/L EPA 529

Used as an explosive in bombs and 

grenades and as a propellant; small 

amounts used for industrial explosive 

applications, such as deep well and 

underwater blasting; chemical 

intermediate in manufacture of 

dyestuffs and photographic chemicals.

1,3-dinitrobenzene 99-65-0 0.8 μg/L EPA 529

Used in explosives; also formed as a 

by-product during the manufacture of 

the explosive trinitrotoluene (TNT); 

used in the manufacture of aramid 

fibers, spandex, and dyes.

Hexahydro-1,3,5-trinitro1,3,5-triazine (RDX) 121-82-4 1 μg/L EPA 529

Used in detonators, primers, mines, 

rocket boosters, and plastic 

explosives; also used in fireworks and 

demolition blocks, and as a 

rodenticide.

. . SCREENING SURVEY . .

. . Acetanilide Parent Herbicides and Acetanilide Herbicide Degradates . .

Acetochlor 34256-82-1 2 μg/L EPA 525.2

The active ingredient in a number of 

herbicides used on corn crops to 

control annual grasses and certain 

broadleaf weeds.

Alachlor 15972-60-8 2 μg/L EPA 525.2

Widely used herbicide; primarily used 

in the Midwest to control annual 

grasses and certain broadleaf weeds 

on crops such as corn, sorghum, and 

soybeans.
EPA-OGWDW Occurrence Data from the UCMR 2

6 

Contaminant Name

Chemical 

Abstract 

Services 

Registry 

Number 

(CAS RN)

Minimum 

Reporting 

Level 

(MRL)

Analytical 

Method Contaminant Use and Description

Metolachlor 51218-45-2 1 μg/L EPA 525.2

Broad spectrum herbicide used for 

general weed control in non-crop 

areas; widely used on crops such as 

corn, cotton, peanuts, grass for seed 

production, nurseries, hedgerows/ 

fencerows, and landscape plantings.

Acetochlor ethane sulfonic 

acid (ESA)

187022-11-

3 1 μg/L EPA 535 Degradation products of acetochlor. 

Acetochlor oxanilic acid 

(OA)

184992-44-

4 2 μg/L EPA 535 Degradation products of acetochlor. 

Alachlor ethane sulfonic 

acid (ESA)

142363-53-

9 1 μg/L EPA 535 Degradation products of alachlor. 

Alachlor oxanilic acid (OA) 171262-17-

2 2 μg/L EPA 535 Degradation products of alachlor. 

Metolachlor ethane sulfonic 

acid (ESA)

171118-09-

5 1 μg/L EPA 535 Degradation products of metolachlor. 

Metolachlor oxanilic acid 

(OA)

152019-73-

3 2 μg/L EPA 535 Degradation products of metolachlor. 

. . Nitrosamines . . 

N-nitroso-diethylamine 

(NDEA) 55-18-5 0.005 μg/L EPA 521 See description below table1 

N-nitroso-dimethylamine 

(NDMA) 62-75-9 0.002 μg/L EPA 521 See description below table1 

N-nitroso-di-n-butylamine 

(NDBA) 924-16-3 0.004 μg/L EPA 521 See description below table1 

N-nitroso-di-n-propylamine 

(NDPA) 621-64-7 0.007 μg/L EPA 521 See description below table1 

N-nitroso-methylethylamine 

(NMEA) 10595-95-6 0.003 μg/L EPA 521 See description below table1 

N-nitroso-pyrrolidine 

(NPYR) 930-55-2 0.002 μg/L EPA 521 See description below table1 

1 Nitrosamines can form as intermediates and byproducts in chemical synthesis and manufacture of rubber, leather, 

and plastics; can form spontaneously by reaction of precursor amines with nitrosating agents (nitrate and related 

compounds), or by action of nitrate-reducing bacteria. Foods such as bacon and malt beverages can contain 

nitrosamines; there also is evidence that they form in the upper gastrointestinal tract. Research suggests 

nitrosamines may also be produced as disinfection byproducts, particularly as a result of chloramination of drinking

water.

The final UCMR 2 rule maintains the basic program design of the original UCMR, 

building upon the structure established by the original rule for this cyclical program. The primary 

design changes between UCMR 1 and UCMR 2 include: (1) strengthening the Screening Survey 

statistical sample by increasing the number of systems monitoring; (2) revising and clarifying the 

list of required “data elements”; and, (3) specifying both entry point and distribution system 

monitoring for certain contaminants. Other minor revisions reflected “lessons learned” during 

UCMR 1. 
EPA-OGWDW Occurrence Data from the UCMR 2

7 

UCMR 2 monitoring requirements for PWSs varied according to system size. The three 

size categories under the program are “small” (serving 10,000 or fewer people), “large” (serving 

between 10,001 and 100,000 people) and “very large” (serving more than 100,000 people). 

UCMR 2 required all large and very large CWSs and NTNCWSs, plus a statistically 

representative national sample of 800 small CWSs and NTNCWSs, to monitor for the 

Assessment Monitoring contaminants. The sample of 800 small systems represents the 

approximately 62,000 small systems operating nationally. Additionally, EPA required 

monitoring of the 15 Screening Survey contaminants by all very large PWSs, 320 selected large 

PWSs, and 480 selected small PWSs. The Screening Survey sample of 800 small and large 

systems was designed to be representative of the approximately 65,000 small and large systems 

operating nationally. See Section 4.3.3 for more detail on national extrapolation of monitoring 

results based on the representative system sampling. 

Both Assessment Monitoring and the Screening Survey had the same monitoring 

requirements for ground water (GW) and surface water (SW) systems. Surface water and ground 

water under direct influence (GUDI) of surface water systems were required to sample for four 

consecutive quarters (per entry point to the distribution system) over a 12-month period, with 

samples collected 3 months apart. Ground water systems had to sample only twice (per entry 

point), 5 to 7 months apart within a 12-month period. EPA, in coordination with the states, 

assigned individual monitoring schedules (year and month of monitoring) to each PWS subject 

to UCMR 2. 

Two categories of PWSs were exempt from UCMR 2 monitoring. First, PWSs that 

purchase their entire water supply from another PWS were not included since monitoring at these 

systems could result in double-counting of estimated population exposure (i.e., the PWSs selling 

water are also monitoring and reporting their contaminant occurrence findings). Second, 

transient non-community water systems (TNCWSs) were excluded since estimating contaminant 

exposure for transient populations can be difficult and inconclusive. The exclusion of these two 

categories of PWSs from UCMR 2 monitoring is consistent with the exclusion of the same two 

categories of PWSs from most compliance monitoring requirements. Sections 2.2 and 2.3 

describe the PWSs that were required to conduct UCMR 2 monitoring. See Exhibit 2-2 for the 

full breakdown of each program component by system size and source water type. Note that the 

small and large systems were further subdivided into narrower categories for the purpose of 

constructing a stratified random sample. See Reference Guide for the Second Cycle of the 

Unregulated Contaminant Monitoring Regulation (UCMR 2) (USEPA, 2006) for additional 

information about implementation of UCMR 2. 

2.2 Assessment Monitoring 

EPA maintained the same basic statistical design used for UCMR 1 for its UCMR 2 

national representative sample of 800 small systems for Assessment Monitoring. The sample size 

was determined by a combination of statistical and budgetary considerations. A sample of 800 

systems is more than the approximately 720 systems (659 CWSs and 61 NTNCWSs) needed to 

meet programmatic data quality objectives (DQOs). It also enables the selection of at least two 

PWSs in each state to ensure a broad and diverse geographic coverage. The small system 

representative sample was designed to account for different system sizes, types of systems, 

sources of water supply, contaminants likely to be found, and geographic location (70 FR 49093; 
EPA-OGWDW Occurrence Data from the UCMR 2

8 

USEPA, 2005). The UCMR 1 design was subjected to peer review and improved by 

recommendations of the peer reviewers, as well as suggestions made during the public comment 

and response process in developing UCMR 1. The details of the UCMR 1 design are included in 

USEPA (2001). 

As with UCMR 1, UCMR 2 required that all large and very large CWSs and NTNCWSs 

that do not purchase all of their water from another system, monitor their water for the presence 

of the 10 Assessment Monitoring contaminants. 

A total of 4,140 systems (800 small, 2,942 large, and 398 very large) submitted 

Assessment Monitoring results. 

Assessment Monitoring samples were collected at the entry point(s) to the distribution 

system (EPTDSs) (for systems with multiple EPTDSs, samples were required to be collected 

from every entry point3). PWSs were allowed to collect “raw source water” samples only in 

those instances where groundwater enters the distribution system untreated at the EPTDS, was a 

change from UCMR 1.

2.3 Screening Survey

In addition to UCMR 2 Assessment Monitoring, UCMR 2 required monitoring for 15 

Screening Survey contaminants. The UCMR 2 Screening Survey was designed to increase the 

statistical strength of the sampling results compared to the UCMR 1 Screening Survey design. 

This was accomplished in two ways. First, the UCMR 2 Screening Survey used a larger stratified 

random sample of approximately 800 systems, as compared to 300 under UCMR 1. The sample 

size was derived from the same rationale as that for Assessment Monitoring, but the sample 

frame was expanded to include large systems. Second, this Screening Survey included a census 

of very large PWSs. This approach minimizes the possibility of missing contaminant occurrence 

at the systems that serve the largest portion of the population while keeping the number of 

systems required to conduct the Screening Survey monitoring relatively small. No small systems 

were selected to participate in more than one component of UCMR 2 (i.e., if a small system was 

selected for Assessment Monitoring, it was excluded from possible selection for the Screening 

Survey). The sample of 800 systems serving 100,000 or fewer people was divided uniformly 

across 10 system size and water source strata (as was done for the prior Screening Survey under 

UCMR 1). For more detailed information on the selection of the Screening Survey PWSs, refer 

to the Unregulated Contaminant Monitoring Regulation (UCMR) for Public Water Systems 

Revisions; Proposed Rule (70 FR 49093; USEPA, 2005). 

For UCMR 1, the Screening Survey sample size was limited to 300 systems (120 large 

and 180 small PWSs). Screening Survey data from UCMR 1 were generally expected to provide 

only enough information for EPA to determine whether a contaminant should be elevated to 

future Assessment Monitoring. The resulting data of all systems combined were designed to be 

used for national estimates. Individual system strata had variances that were too large to provide 

meaningful estimates. The increased sample size of the UCMR 2 Screening Survey enables 

 

3 Ground water systems could limit monitoring to representative entry points if they had appropriate documentation 

and state approval.
EPA-OGWDW Occurrence Data from the UCMR 2

9 

national estimates for each of the system size strata. A total of 1,198 systems (480 small, 320 

large, and 398 very large) submitted Screening Survey results. 

As for Assessment Monitoring, Screening Survey samples were also collected at the 

EPTDSs for all Screening Survey contaminants. However, for those systems that utilize chemical 

disinfection, additional samples were collected for nitrosamines at the distribution system 

maximum residence time (DSMRT) sampling point associated with each plant/water source.

Exhibit 2-2: Number of PWSs that Monitored Under UCMR 2 

Size 

Category Population served

Assessment Monitoring 

Systems . Screening Survey 

Systems .

Total

.

. GW SW + GUDI GW SW + GUDI .

. 25 to 500 104 5 80 80 269

. 501 to 3,300 259 48 80 80 467

. 3,301 to 10,000 255 129 80 80 544

Small1

Systems serving 

25 to 10,000 

people

618 182 240 240 1,280

. 10,001 to 50,000 1,239 1,246

752

(subset of 

the 1,239)

852

(subset of the 

1,246)

2,485 

. 50,001 to 100,000 135 322

762

(subset of 

the 135)

842

(subset of the 

322)

457

Large1

Systems serving 

10,001 to 100,000 

people

1,374 1,568

1512

(subset of 

the 1,374)

1692

(subset of 

the 1,568)

2,942 

Very 

Large

Systems serving 

over 100,000

people

63 335 63 335 398

Total UCMR 2 Systems . 2,055 2,085 454 744 4,620

1 For the purpose of constructing stratified random samples, the small PWSs were grouped into three subcategories

and the large PWSs were grouped into two subcategories. 

2 The number of systems included in these cells are excluded from row totals (as they are a subset of the systems 

conducting Assessment Monitoring), but are included in the column totals to show the overall total number of systems 

conducting Screening Survey monitoring. 
EPA-OGWDW Occurrence Data from the UCMR 2

10

3 UCMR 2 Data Description

This section of the report describes the process of submitting, managing, and quality 

checking the UCMR 2 occurrence data. It also describes the assessment of the representativeness 

and completeness of the data set as well as various temporal, geographical, and other 

characteristics of the data. 

The analyses presented in this report are based on the final UCMR 2 data set, which 

includes analytical results of water samples from all 4,620 systems that were expected to submit 

UCMR 2 data (100% compliance). To accommodate final (late) UCMR 2 reporting, the data 

system remained open for submission of data through December 31, 2011. The final data set, 

including the sample data submitted through December 2011, is available on the UCMR website 

(http://www.epa.gov/dwucmr/occurrence-data-unregulated-contaminant-monitoring-rule#2). 

This document also provides detailed descriptions of EPA’s management and analysis of the 

data.

3.1 Data Submittal Process 

This section describes the process by which the UCMR 2 data were submitted by PWSs

and laboratories. 

Laboratories conducting UCMR sample analysis were also responsible for posting the 

sample analytical data to the Safe Drinking Water Accession and Review System (SDWARS). 

Access to SDWARS, which is the main database for upload, review, and storage of UCMR 2 

data, is through the Central Data Exchange (CDX), EPA’s electronic reporting system. The CDX 

is the point of entry on the Environmental Information Exchange Network where PWSs, 

laboratories, states, and EPA submit, view, review, and (in the case of UCMR large systems) 

approve UCMR 2 occurrence data. Numerous security controls have been established to prevent 

unauthorized entry into the CDX and the SDWARS/UCMR storage system, and to prevent the 

potential loss of data or inappropriate transformations. CDX required users to register prior to 

being allowed access to data reporting and reviewing sections (only records from registered 

laboratories and systems could be uploaded into the database). In addition, the SDWARS/UCMR 

system has a number of electronic back-up provisions to minimize the risk of data being lost 

through tampering, system failure, or inadvertent deletion. 

For the large systems, data were posted directly to SDWARS by laboratories. PWSs 

accessed SDWARS to review the data and approve its release to EPA. Large PWSs had 60 days 

to review the data posted by their laboratories. After 60 days, if a PWS had not reviewed its 

UCMR 2 data, it was automatically approved and released to EPA (and concurrently to the state) 

as the system’s official UCMR 2 results. 

EPA collected and reviewed occurrence data for small systems. EPA performed a 

thorough QC review of the data for small systems as part of the agency’s oversight of the 

contract laboratories performing sample collection and analyses. Small PWSs were authorized to 

review their data in SDWARS, but were not responsible for final data approval. The QC review 

was provided to states for review and comment. 
EPA-OGWDW Occurrence Data from the UCMR 2

11

For all system sizes, when the EPA QC review was complete and the system’s 60-day 

review period had passed, the data were considered valid. Data that passed final quality 

assessments were made available to the public through the National Contaminant Occurrence 

Database (NCOD), which is accessible through the EPA website. 

3.2 Data Management and Quality Assurance 

This section describes how the UCMR 2 data were collected, maintained, and organized 

by EPA. QA/QC procedures are also described. Data discussed in this section include the water 

sample analytical data (monitoring results that define contaminant occurrence) and PWS 

inventory information (data that define characteristics of the participating PWSs). Exhibit 3-1

defines the data elements that were required to be provided with UCMR 2 sample results. 

Exhibit 3-1: UCMR 2 Required Data Elements

Data Element Definition

Public Water 

System 

Identification 

(PWSID) Code

The code used to identify each PWS. The code begins with the standard 2-character 

postal state abbreviation or Region code; the remaining 7 numbers are unique to each 

PWS in the state. The same identification code must be used to represent the PWS 

identification for all current and future UCMR monitoring.

Public Water 

System Facility 

Identification Code

An identification code established by the state or, at the state’s discretion, by the PWS, 

following the format of a 5-digit number unique within each PWS for each applicable 

facility (i.e., for each source of water, treatment plant, distribution system, or any other 

facility associated with water treatment or delivery). The same identification code must be 

used to represent the facility for all current and future UCMR monitoring.

Water Source Type The type of source water that supplies a water system and sampling location. Systems 

must report one of the following codes for each sampling location:

SW Surface water (to be reported for water facilities that are served all or in part by a surface 

water source at any time during the 12-month period).

GW Ground water (to be reported for water facilities that are served entirely by a ground water 

source).

GU

Ground water under the direct influence of surface water (to be reported for water 

facilities that are served all or in part by ground water under the direct influence of surface 

water at any time during the 12-month sampling period), and are not served at all by 

surface water during this period.

MX Any combination of the three water types listed above.

Sampling Point 

Identification Code

An identification code established by the state, or at the state’s discretion, by the PWS, 

that uniquely identifies each sampling point. Each sampling code must be unique within 

each applicable facility, for each applicable sampling location (i.e., entry point to the 

distribution system or distribution system sample at maximum residence time). The same 

identification code must be used to represent the sampling location for all current and 

future UCMR monitoring.

Sampling Point 

Type Code A code that corresponds to the location of the sampling point. 

EP Entry point to the distribution system.

MR Distribution system sample at maximum residence time.

Disinfectant 

Residual Type

The type of disinfectant in use at the time of UCMR sampling to maintain a residual in the 

distribution system for each Screening Survey sampling point. To be reported by systems

required to conduct Screening Survey monitoring. Systems must report using the 

following codes for each Screening Survey sampling location (i.e., EP, MR):

CL Chlorine.
EPA-OGWDW Occurrence Data from the UCMR 2

12

Data Element Definition

CA Chloramine.

OT All other types of disinfectant (e.g., chlorine dioxide).

ND No disinfectant used.

Sample Collection 

Date

The date the sample is collected, reported as 2-digit month, 2-digit day, and 4-digit year

(i.e., 01152008).

Sample 

Identification Code

An alphanumeric value up to 30 characters assigned by the laboratory to uniquely identify 

containers, or groups of containers, containing water samples collected at the same 

sampling location for the same sampling date.

Contaminant The unregulated contaminant for which the sample is being analyzed.

Analytical Method 

Code The identification code of the analytical method used.

Sample Analysis 

Type

The type of sample collected and/or prepared, as well as the fortification level. Permitted 

values include:

FS Field sample; sample collected and submitted for analysis under this rule.

LFSM Laboratory fortified sample matrix; a UCMR field sample with a known amount of the 

contaminant of interest added.

LFSMD Laboratory fortified sample matrix duplicate; duplicate of the laboratory fortified sample 

matrix.

CF Concentration fortified; reported with sample analysis types LFSM and LFSMD, the 

concentration of a known contaminant added to a field sample.

Analytical Result—

Sign 

A value indicating whether the sample analysis result was: (<) “less than” means the 

contaminant was not detected, or was detected at a level below the Minimum Reporting 

Level. (=) “equal to” means the contaminant was detected at the level reported in 

“Analytical Result—Value.”

Analytical Result—

Value

The actual numeric value of the analytical results for: field samples; laboratory fortified 

matrix samples; laboratory fortified sample matrix duplicates; and concentration fortified.

Laboratory 

Identification Code

The code, assigned by EPA, used to identify each laboratory. The code begins with the 

standard two-character state postal abbreviation; the remaining five numbers are unique 

to each laboratory in the state.

Sample Event Code

A code assigned by the PWS for each sample event. This will associate samples with the 

PWS monitoring plan to allow EPA to track compliance and completeness. Systems must 

assign the following codes:

SE1 Represents samples collected to meet the UCMR monitoring requirement for the first 

sampling period (all source types).

SE2 Represents samples collected to meet the UCMR monitoring requirement for the second 

sampling period (all source types).

SE3 Represents samples collected to meet the UCMR monitoring requirement for the third 

sampling period (SW and GU sources only).

SE4 Represents samples collected to meet the UCMR monitoring requirement for the fourth 

sampling period (SW and GU sources only).

UCMR 2 data that were ready for EPA review were extracted on a monthly basis from 

SDWARS via the CDX. EPA reviewed all UCMR 2 data that had already passed the laboratory 

and PWS reviews. In addition, the SDWARS database was developed with several automated 

data quality criteria checks designed into the database structure so only data that passed QA 

measures could be successfully imported into the database. The database conducts an automated 

data review and flags questionable records. Reasons for flagging records include, but are not 

limited to, missing required fields, or records that are duplicates (i.e., having the same PWSID, 
EPA-OGWDW Occurrence Data from the UCMR 2

13

PWS Facility ID, Sampling Point ID, contaminant, and sample collection date).4 In addition, the 

database includes a “range check” that identifies data outliers or possible unit problems. For 

example, any reported contaminant concentration values that are a thousand-fold lower than 

most other low contaminant concentration values would be flagged and investigated, since such 

significantly lower results likely reflect an analytical unit conversion problem (mg/L versus 

μg/L) in the original raw data. 

For more details on the data quality review applied to the small system data, refer to the 

Standard Operating Procedure: NCOD Data Import for Small Systems for the Second Cycle of 

the Unregulated Contaminant Monitoring Regulation, Revision 1.0 (USEPA, 2009). For more 

details on the data quality review of the large system occurrence data, refer to the Quality 

Assurance Project Plan for the Implementation of the Unregulated Contaminant Monitoring 

Regulation (USEPA, 2003b). 

3.3 Assessments of Data Representativeness and Completeness 

To ensure that the UCMR 2 data and occurrence estimates dependably reflect national 

conditions, the representativeness and completeness of the UCMR 2 contaminant sample data 

were assessed. This section describes how the UCMR 2 data were assessed for 

representativeness and completeness.

3.3.1 Data Representativeness

 Assessment Monitoring - Small Systems (Serving ≤ 10,000 Persons) 

The UCMR 2 small system sampling design incorporated a stratified sampling approach 

to enable statistically valid national occurrence analyses according to system size (based on 

population served) and water source type (e.g. surface water, ground water).5 This stratified, 

population-weighted, random selection process is the same process used for UCMR 1 and is 

described in detail in the Statistical Design and Sample Selection for the Unregulated 

Contaminant Monitoring Regulation (USEPA, 2001). Statistical design and program DQOs, as 

well as cost and scheduling considerations resulted in a sample design that selected 800 small 

PWSs that collectively provide nationally representative contaminant occurrence data. 

EPA identified DQOs for the representative sample of small systems to include the 

following: data should provide unbiased national exposure estimates; and margins of error must 

be kept to ±1% with 99% confidence for CWSs and ±2.5% with 95% confidence for NTNCWSs. 

If the estimated percentage of PWSs with a detection is 1%, EPA must be able to state with 99% 

confidence that the true exposure fraction is between 0% and 2%. In other words, if the sampling 

plan were to be repeated many times, the true occurrence and exposure values would fall within 

the 1% margin of error around the estimate in 99% of all cases. 

 

4 Note that some duplicate records are legitimate and are retained in the data set. If a system sampled and got a high 

detection of a contaminant, and then re-sampled, both results are retained in the database. At the time of data 

analysis, the largest detection value would be used for all occurrence analyses.

5 The number of NTNCWSs designated and selected for monitoring does not support a statistically valid analysis of 

only NTNCWSs.
EPA-OGWDW Occurrence Data from the UCMR 2

14

Meeting the representativeness objective required that the designated sample of small 

systems conducting monitoring be stratified and implemented correctly. In a small number of 

cases, the originally selected small systems could not participate (due to closing, change in 

status, etc.). Replacement systems were statistically selected in the event that the original (or first 

or second replacement) system could not participate. 

 Assessment Monitoring - Large and Very Large Systems (Serving > 10,000 Persons)

A census, such as that required for all eligible large systems under UCMR 2 Assessment 

Monitoring, is by definition the most representative type of sample design. All PWSs serving 

more than 10,000 people that submitted Assessment Monitoring UCMR 2 data. 

 Screening Survey - Small and Large Systems (Serving ≤ 100,000 Persons) 

Screening Survey systems were selected from all large and small system subcategories, 

with each of the five subcategories given equal importance.6 Therefore, 160 systems were 

selected from each size subcategory. Within each subcategory, selected systems were distributed 

evenly between surface water and ground water systems wherever possible. 

 Screening Survey - Very Large Systems (Serving > 10,000 Persons) 

All PWSs serving more than 100,000 people (approximately 400 systems) were required 

to conduct Screening Survey monitoring. 

3.3.2 Completeness

The DQO for completeness of the occurrence data has two components: that 90% of data 

submitted are acceptable (i.e., conform to QC criteria with all data elements present and 

accurate), and that acceptable data are obtained from 82.375% of selected PWSs. Although, as 

designed, all selected PWSs (i.e., 100%) are required to collect and report UCMR 2 occurrence

data, in practice some samples may not be collected and some results may not be reported. This 

DQO provides for adequate data quality for end-use applications while recognizing the practical 

realities of PWS monitoring that some required data are not generated and/or reported. The DQO 

to obtain acceptable data from 82.375% of PWSs is based on a calculation of the minimum 

requirements to produce nationally representative estimates of PWS contaminant occurrence 

with a 99% confidence interval and a 1% margin of error.

All (100%) of the 4,620 small, large, and very large PWSs required to participate in 

UCMR 2 collected and reported UCMR 2 occurrence data, surpassing the DQO goal of 

82.375%. Furthermore, as described earlier, the SDWARS database contained several data 

quality criteria checks, so only data that passed QA measures were successfully imported into the 

database. Thus, the DQO of 90% for acceptable data was also surpassed. 

 

6 Unlike Assessment Monitoring, system selection for the Screening Survey was not proportionately weighted by 

population served or by the proportion of systems in each size category. If the sample was weighted by population

served, a disproportionate number of large systems would be included in the Screening Surveys. If the sample were 

weighted by the number of systems in each size category, a disproportionate number of small systems would be 

represented.
EPA-OGWDW Occurrence Data from the UCMR 2

15

3.4 Additional Data Management Considerations 

Additional QA/QC measures were applied to the UCMR 2 data set to evaluate other 

quality aspects of the occurrence data and system inventory data. The following section 

addresses data management steps taken with the UCMR 2 systems’ population-served values as 

they relate to consecutive systems, seller/purchaser relations, and the resulting potential doublecounting of populations served by systems. 

3.4.1 Population Adjustments

As described in Section 2.1, all “purchased systems” (systems purchasing 100% of their 

water from other systems) were exempt from UCMR 2 monitoring. However, exclusion of these 

systems meant the populations served by those systems would also be excluded from the 

exposure estimates conducted for the UCMR 2 analyses. Therefore, the populations served by 

the purchased systems were assigned to the systems they purchased from (the “wholesale 

systems”). To do this, EPA compiled a list of all purchased systems that sell water directly to the 

consumer. EPA then identified the wholesale system(s) from which each system on the list

purchases water. If a purchased system purchased 100% of its water from a single wholesale 

system, the population served by each purchased system was assigned to the wholesale system 

and added to wholesale system’s total population served. The contaminant occurrence measures 

that include these wholesale systems with their “adjusted” population-served values include the 

population served by the purchased systems. 

A total of 386 purchased systems purchase water from more than one seller. To avoid 

double-counting in these cases, the population served by the purchasing systems was assigned 

fractionally to its wholesalers. Since no data were available on the relative quantities of water 

purchased from the different wholesalers, a uniform distribution was assumed. To illustrate this 

simple uniform distribution, consider a single large system serving a population of 60,300 that 

purchases 100% of its water from three different systems. The compliance occurrence data from 

that purchasing system is excluded from the occurrence analyses because it is a purchased 

system; however, one-third of its population served (60,300 ÷ 3 = 20,100) is assigned to each of 

the three systems from which it purchases water. This way, the population served by purchased 

systems is included in the analyses and considerations for UCMR 2. 

3.4.2 Temporal Information 

The UCMR 2 program was designed with concerns about temporal variability in mind. 

The study design addressed temporal variability in contaminant occurrence by defining a 

vulnerable period (i.e., the season of greatest likelihood of contaminant occurrence; generally the 

months of late spring and early summer, which are characterized by high volumes of surface 

water runoff and ground water recharge). At least one UCMR 2 sample at each applicable 

sampling point were required to be collected during that period. Each system was required to 

monitor for one year (12 consecutive months) during the three years of UCMR 2 monitoring 

(2008 – 2010). For small systems, approximately one-third were scheduled to conduct 

monitoring in each of the three years; with UCMR 2 schedules staggered to ensure that results 

were collected from every month in every part of the country. Large systems could conduct their 

12 consecutive months of monitoring anytime during the UCMR 2 period. Like small systems, 
EPA-OGWDW Occurrence Data from the UCMR 2

16

their monitoring schedules were spread throughout the year and included one monitoring period 

during their most vulnerable season. By staggering system monitoring schedules and requiring 

monitoring during at least one vulnerable period, EPA ensured that the UCMR 2 results reflected

multiple seasons and multiple years of climatic conditions throughout the country and were not 

directly affected (or biased) by weather conditions of a single season, year, or geographic region. 
EPA-OGWDW Occurrence Data from the UCMR 2

17

4 Description of Stage 1 Analytical Method

The Stage 1 analysis consists of simple, non-parametric measures of occurrence using the 

UCMR 2 data. Based on the occurrence findings of the Stage 1 analyses, among other 

considerations, more statistically rigorous parametric analyses for select contaminants can be 

conducted. These parametric occurrence analyses are referred to as Stage 2 analyses. This twostage analytical approach has been peer reviewed and used to conduct other occurrence analyses 

that supported Regulatory Determination 1 and 2 (USEPA, 2002; USEPA, 2008a) and Six-Year

Review (USEPA, 2003a). This section is a discussion of the Stage 1 analyses. Stage 2 analysis is 

briefly described in Section 1 of this document. The occurrence estimates conducted using 

UCMR 2 data and presented in Section 5 of this document involve Stage 1 analyses only. 

4.1 Stage 1 Analysis 

The basic Stage 1 analytical methodology is a conservative approach: occurrence 

measures are based on actual counts of whether a PWS has at least one sample analytical result 

greater than a specified concentration threshold. This is roughly analogous to a measure based 

conservatively on peak contaminant occurrence (i.e., when a system’s occurrence is represented 

by the maximum concentration even if numerous other samples collected by the system were 

non-detections or had lower concentrations). The Stage 1 statistical analysis of the UCMR 2 data 

consists of direct counts and descriptive statistics of analytical sample data for each of the 

monitored contaminants. The analytical sample data define the presence or absence of a 

contaminant relative to the analytical method minimum reporting level (MRL) and, if present, 

the concentration of the detected contaminant. 

These analyses were conducted to characterize occurrence by samples, systems, and 

populations served by systems. At the sample level, occurrence measures included: the number 

and percent of samples for each contaminant with analytical detections; and the minimum, 

median, maximum, 90th and 99th percentile concentration values of those detections. Systemlevel occurrence measures include the number and percent of systems with one or more 

analytical detections by contaminant. At the level of populations served, occurrence measures 

include the number and percent of customers served by systems with one or more analytical 

detections by contaminant. 

All occurrence analyses presented in this report were stratified by water system source 

water type. The stratification by source water type was consistent with source water type

classification protocols used for past efforts (i.e., systems using GUDI and those using a mix of 

ground water and surface/GUDI sources were classified as surface water systems). 

The Stage 1 approach incorporates another conservative assumption: if a detection occurs 

in a single entry point in a system, then the entire population served by the system is exposed to 

the detected contaminant (i.e., even if there are other entry points with no detections that might 

dilute the concentration found in the single entry point sample). For example, if a PWS serves a 

population of 10,000 and finds a detection of a UCMR 2 contaminant in one of its two entry 

points on one occasion, the Stage 1 analytical methodology would estimate that the entire 

population served by the system (i.e., all 10,000 persons) was exposed to the maximum detected 

levels of the contaminant. 
EPA-OGWDW Occurrence Data from the UCMR 2

18

In reality, many systems get water from multiple water sources (a mix of multiple wells, 

or more than one surface water source, or a combination of ground water and surface water 

sources). 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. 

Entry point-level occurrence measures can also be part of the Stage 1 analyses. EPA did 

not perform entry point-level analyses on any of the contaminants evaluated in this report. 

4.2 Threshold Evaluations 

EPA performed occurrence evaluations of UCMR 2 contaminants relative to multiple 

concentration thresholds. One occurrence analysis was conducted relative to the MRL for each 

UCMR 2 contaminant. In this analysis, any concentration equal to or greater than the MRL was 

considered an analytical detection. Evaluations of occurrence relative to the MRL provide a 

baseline measure of occurrence.

Detections of UCMR 2 contaminants were also evaluated relative to two other 

concentration thresholds: the Health Reference Level (HRL) and one-half the HRL (1⁄2 HRL). 

The HRL is an EPA-defined risk-derived concentration for evaluating contaminant occurrence 

based on health effects information.7 There are two general approaches to the derivation of an 

HRL. One approach is used for chemicals that cause cancer and exhibit a linear response to dose, 

and the other applies to non-carcinogens and carcinogens evaluated using a non-linear approach. 

See Appendix B of the Protocol for the Regulatory Determination 3 USEPA (2014a) for detailed 

discussion of HRLs, including descriptions of the linear and non-linear approaches to HRL

derivation. Conducting occurrence assessments relative to the health-based thresholds in addition 

to the MRL gives additional information on the degree as well as the frequency of contaminant 

occurrence and helps to better characterize the distribution of occurrence. 

Exhibit 4-1: Minimum Reporting Levels (MRLs) and Health Reference Levels 

(HRLs) for UCMR 2 Contaminants

Contaminant MRL

(μg/L)

HRL1

(μg/L)

. Assessment Monitoring Contaminants .

BDE-47 0.3 -- 

BDE-99 0.9 -- 

BDE-100 0.5 -- 

BDE-153 0.8 -- 

Dimethoate 0.7 15.4

 

7 EPA evaluates the best available, peer-reviewed assessments and studies to characterize the human health effects 

that may result from exposure to individual contaminants when found in drinking water. Based on this 

characterization, the agency estimates an HRL for each contaminant. HRLs are not final determinations of the level 

of a contaminant in drinking water that is necessary to protect any particular population and are derived prior to the 

development of a complete exposure assessment.
EPA-OGWDW Occurrence Data from the UCMR 2

19

Contaminant MRL

(μg/L)

HRL1

(μg/L)

1,3-Dinitrobenzene 0.8 0.7

HBB 0.7 -- 

RDX 1 21

Terbufos sulfone 0.4 0.35

TNT 0.8 -- 

. Screening Survey Contaminants .

Acetochlor 2 1 

Acetochlor ESA 1 1 

Acetochlor OA 2 1 

Alachlor 2 22

Alachlor ESA 1 0.4

Alachlor OA 2 0.4

Metolachlor 1 700

Metolachlor ESA 1 700

Metolachlor OA 2 700

NDBA 0.004 0.033

NDEA 0.005 0.0004

NDMA 0.002 0.0006

NDPA 0.007 0.007

NMEA 0.003 0.0033

NPYR 0.002 0.002 

1 Note: "--" indicates that there is no HRL for this contaminant. These 

UCMR 2 contaminants are not on CCL 3. 2 Alachlor is a regulated drinking water contaminant with a Maximum 

Contaminant Level (MCL) of 2 μg/L.

3 NDBA and NMEA are not on CCL 3; however, they do have HRLs, 

since they are being evaluated by EPA alongside the other 

nitrosamines, as part of a nitrosamine group. 

4.3 Additional Considerations for Stage 1 Analysis 

4.3.1 Ground Water and Surface Water Comparisons

Given the different sampling schedules of ground water systems (two samples per year) 

and surface water systems (four samples per year), care must be taken regarding any samplelevel comparative analyses between the two source water types. For example, if the true rate of 

detection for a given contaminant were identical for both ground water and surface water

systems, one would expect to see roughly twice the number of detections in the surface water

systems simply because surface water systems collect twice as many samples. Estimating the 

percentage of detections by source water type (i.e., dividing the number of detections by number 

of samples taken for a particular source type) corrects for this difference and provides a fair 

comparison of detection rates across surface water and ground water systems. System-level and 

population-served-level analyses also account for the different sampling frequencies. 
EPA-OGWDW Occurrence Data from the UCMR 2

20

4.3.2 Large System and Small System Totals 

When presenting the Stage 1 Analyses, it is sometimes useful to summarize the 

occurrence of a contaminant as a single number or percentage. When doing so for the 

Assessment Monitoring contaminants, however, consideration should be given to the distinction 

between analytical results from the small system sample and large system census. Simply adding 

the number of both small and large systems’ detections may undercount the actual number of 

detections at the nation’s small systems because of the differences in UCMR 2 monitoring for 

small and large systems (see Section 2.1). While such simple summaries accurately present the 

UCMR 2 monitoring results themselves, reasonable estimates of national contaminant 

occurrence require national extrapolation of the small system Assessment Monitoring occurrence 

data. These same considerations are applicable for the Screening Survey contaminants when 

summarizing occurrence as a single number or percentage using analytical results from the 

sample of small and large systems and the census of very large systems. 

4.3.3 Extrapolation of the Results

Under UCMR 2 Assessment Monitoring, the 800 small systems (serving 10,000 or fewer 

people) selected to conduct monitoring were a stratified, random, statistically-weighted sample 

of the nation’s small systems. These 800 small systems were chosen to represent the distribution 

of small system characteristics found at the national level. Consequently, contaminant 

occurrence findings for those 800 UCMR 2 small systems are representative of occurrence at the 

approximately 62,000 small systems operating nationally.8

 Moreover, the 2.7 million persons 

served by the 800 UCMR 2 sampled systems are representative of the approximately 47 million 

served by all small systems nationally.

For the UCMR 2 Screening Survey, monitoring was required by 320 large PWSs serving 

10,001-100,000 people, and 480 small PWSs serving 10,000 or fewer people. These 800 small 

and large systems were chosen to represent the distribution of small and large system 

characteristics found at the national level. Thus, Screening Survey occurrence findings UCMR 2 

are representative of occurrence at the approximately 65,000 small and large systems operating 

nationally, and the approximately 130 million served by those small and large systems. 

To calculate national extrapolations, the percent of systems (or of populations served by 

systems) estimated to exceed a specified threshold is multiplied by the total number of systems 

(or population served) in the nation (see Exhibit 4-2). Estimates of national system and 

population-served numbers were developed from a combination of EPA’s Safe Drinking Water 

Information System (SDWIS), the Community Water System Survey (CWSS), and the UCMR. 

Analogous national extrapolations can also be made for the occurrence results of the Screening 

Survey small and large systems. However, for the Screening Survey, only aggregated national 

estimates are appropriate because the error margin may be too large in small subcategories to be 

conclusive, particularly in cases where no detections occur. Monitoring results are carefully 

analyzed to assess the possible implications of results. 

 

8 This national estimate of systems and population served by systems was developed from EPA’s Safe Drinking 

Water Information System (SDWIS), the Community Water System Survey (CWSS), and UCMR.
EPA-OGWDW Occurrence Data from the UCMR 2

21

Exhibit 4-2 presents results from NDMA to illustrate how system-level estimates of 

national contaminant occurrence are calculated by extrapolation of UCMR 2 Screening Survey 

monitoring results for small and large systems. To estimate the national number of small ground 

water systems that are expected to have detections, the percentage of systems of that source 

water type/system size strata with detections of the contaminant (in this example, approximately 

4.17%) is multiplied by the estimated total number of small ground water systems in the nation 

(57,818 systems). The result is an estimate of 2,409 small ground water systems that are 

expected to have detectable concentrations of the contaminant (assuming monitoring protocols 

similar to that used under UCMR 2). Note that the calculations used to produce the national 

estimates involve more significant digits than are shown in the table. Thus, due to rounding, 

some calculations (including the one above) may appear to be incorrect. Comparable calculations 

are used to estimate the population served nationally by systems in that source water type/system 

size category, and to make the corresponding extrapolations in the other source water 

type/system size categories. The national estimates for “All Small Systems” and “All Large 

Systems” were calculated by summing extrapolated ground water and surface water results in 

each category. 

Exhibit 4-2: Example Calculation of National Estimates (Extrapolations) for 

UCMR 2 Small and Large Systems (serving ≤ 100,000 people) for 

Screening Survey Contaminants

Water Type National Inventory 1 . Percentage ≥ MRL

(based on UCMR 2) . National Estimate .

. Systems Population Systems Population Systems Population

. . . Small Systems (serving ≤ 10,000 people) . . . 

Ground Water 57,818 37,685,557 4.17% 4.75% 2,409 1,790,869

Surface Water 3,866 8,928,745 30.83% 39.25% 1,192 3,504,746

All Small Systems 61,684 46,614,302 17.50% 23.60% 3,601 5,295,615

. . . Large Systems (serving 10,001 - 100,000 people) . . . 

Ground Water 1,506 38,870,272 8.61% 11.23% 130 4,363,960

Surface Water 1,366 44,536,172 34.32% 37.51% 469 16,707,724

All Large Systems 2,872 83,406,444 22.19% 25.18% 598 21,071,684

1 National inventory data for systems and populations were developed from EPA’s SDWIS, the CWSS, and UCMR.

4.3.4 Stage 1 Analyses and the Statistically-Weighted Sample of Small Systems 

The Stage 1 occurrence analysis consists of simple, non-parametric, descriptive statistics 

based directly upon the contaminant occurrence data. The 800 small systems required to conduct 

UCMR 2 Assessment Monitoring were selected as a statistically-weighted (primarily populationweighted) stratified sample, in a similar fashion that 800 small systems were selected for 

UCMR 1 monitoring. Because of the difficulties in calculating the statistical weighting 

parameters, the UCMR 1 occurrence findings did not incorporate adjustments for the 

statistically-weighted sample selection of the UCMR 1 small systems. However, a sensitivity 

analysis was conducted on the 800 UCMR 1 small systems to address the issue of adjusting the 

occurrence findings to account for the statistically-weighted sample of small systems. At every 

detection level, the analysis found no significant statistical difference between estimates of the 

weighted and unweighted means (USEPA, 2008b). Since the 800 UCMR 2 small systems were 
EPA-OGWDW Occurrence Data from the UCMR 2

22

selected in a similar fashion, it is expected that there would be no significant statistical difference 

between estimates of the weighted and unweighted means for UCMR 2 as well.
EPA-OGWDW Occurrence Data from the UCMR 2

23

5 Stage 1 Occurrence Estimates

This section presents summary Stage 1 occurrence findings for the 25 contaminants 

monitored under UCMR 2. The following exhibits, evaluated together with the other analytical 

results included within this report and report appendices, provide a multi-faceted presentation of 

the frequency, degree, and distribution of the occurrence of those contaminants as sampled and 

reported under UCMR 2. 

Basic occurrence information for all 25 UCMR 2 contaminants is summarized in Exhibit 

5-1 and Exhibit 5-2. Exhibit 5-1 shows sample-level results, including minimum, median, and 

maximum concentrations. Exhibit 5-2 shows system-level results, including data on populations 

served by systems with detections. Separate contaminant-specific sections and exhibits follow 

which provide more details on the occurrence results. These more detailed occurrence results are 

included only for contaminants with at least one detection. 

In the final UCMR 2 data set, 13 of the 25 contaminants were not detected in any of the 

large or small systems that sampled under UCMR 2. Eight of the 13 contaminants with no 

detections were from the Assessment Monitoring component: BDE-47, BDE-99, DBE-100, 

DBE-153, dimethoate, 1,3-dinitrobenzene, HBB, and TNT. The remaining five contaminants 

with no detections were from the Screening Survey component: acetochlor, acetochlor OA, 

alachlor, alachlor OA, and NDPA. One of the 25 contaminants, terbufos sulfone, had only a 

single detection. The remaining 11 UCMR 2 contaminants had multiple detections in small 

and/or large systems.

Additional occurrence findings are contained in Appendices A, B, and C. Appendix A 

provides detailed occurrence findings at the level of samples, systems, and population served for 

all UCMR 2 contaminants (including contaminants that had no detections). In Appendix B, the 

number of systems that monitored for each UCMR 2 contaminant, the number of samples taken

at those systems, and the population served by the systems are listed and broken out by state. 

Appendix C includes more detailed occurrence numbers for the 12 UCMR 2 contaminants with 

detections, including summary statistics by source water type and system size and the number 

and percentage of samples that exceeded the HRL. 
EPA-OGWDW Occurrence Data from the UCMR 2

24

Exhibit 5-1: Summary of Stage 1 Occurrence Results for 10 Assessment Monitoring 

Contaminants and 15 Screening Survey Contaminants: Sample-Level Results 

Contaminant . Samples . . Detected Concentration . 

. Number of 

Samples Detections . Minimum(μg/L)

Median

(μg/L)

Maximum

(μg/L)

. . Number Percent . . .

. . . Assessment Monitoring Contaminants . . . 

BDE-47 32,149 0 0.00% ND ND ND

BDE-99 32,149 0 0.00% ND ND ND

BDE-100 32,149 0 0.00% ND ND ND

BDE-153 32,139 0 0.00% ND ND ND

Dimethoate 32,150 0 0.00% ND ND ND

1,3-Dinitrobenzene 32,152 0 0.00% ND ND ND

HBB 32,143 0 0.00% ND ND ND

RDX 32,150 4 0.01% 1 1.1 1.1

Terbufos sulfone 32,149 1 0.003% 0.42 0.42 0.42

TNT 32,151 0 0.00% ND ND ND

. . . Screening Survey Contaminants . . . 

Acetochlor 11,193 0 0.00% ND ND ND

Acetochlor ESA 11,157 2 0.02% 1.10526 1.15263 1.2

Acetochlor OA 11,157 0 0.00% ND ND ND

Alachlor 11,193 0 0.00% ND ND ND

Alachlor ESA 11,156 5 0.04% 1 1.2 1.3

Alachlor OA 11,157 0 0.00% ND ND ND

Metolachlor 11,192 3 0.03% 1.152 1.4 2.73235

Metolachlor ESA 11,157 52 0.47% 1 1.44131 3.95455

Metolachlor OA 11,157 3 0.03% 2.502 3.078 3.539

NDBA 18,101 9 0.05% 0.004 0.00666 0.02062

NDEA 18,096 46 0.25% 0.005 0.007 0.1

NDMA 18,098 1,861 10.28% 0.002 0.004 0.63

NDPA 18,107 0 0.00% ND ND ND

NMEA 18,101 3 0.02% 0.0036 0.0045 0.0049

NPYR 18,101 41 0.23% 0.00207 0.0039 0.0238

NOTE: “ND“ indicates no detection of contaminant.
EPA-OGWDW Occurrence Data from the UCMR 2

25

Exhibit 5-2: Summary of Stage 1 Occurrence Results for 10 Assessment Monitoring 

Contaminants and 15 Screening Survey Contaminants: System-Level Results

Contaminant . Systems . . Population Served .

. 

Number 

of 

Systems

Systems with

Detection(s) .

Total 

Population 

Served

by Systems

Population Served by 

Systems with

Detection(s)

.

. . Number Percent . Number Percent

. . . Assessment Monitoring Contaminants . . . 

BDE-47 4,140 0 0.00% 229,237,740 0 0.00%

BDE-99 4,140 0 0.00% 229,237,740 0 0.00%

BDE-100 4,140 0 0.00% 229,237,740 0 0.00%

BDE-153 4,140 0 0.00% 229,237,740 0 0.00%

Dimethoate 4,140 0 0.00% 229,237,740 0 0.00%

1,3-Dinitrobenzene 4,139 0 0.00% 229,225,740 0 0.00%

HBB 4,140 0 0.00% 229,237,740 0 0.00%

RDX 4,139 3 0.07% 229,225,740 96,033 0.04%

Terbufos sulfone 4,140 1 0.02% 229,237,740 44,600 0.02%

TNT 4,139 0 0.00% 229,225,740 0 0.00%

. . . Screening Survey Contaminants . . . 

Acetochlor 1,198 0 0.00% 157,219,620 0 0.00%

Acetochlor ESA 1,198 2 0.17% 157,219,620 3,832,155 2.44%

Acetochlor OA 1,198 0 0.00% 157,219,620 0 0.00%

Alachlor 1,198 0 0.00% 157,219,620 0 0.00%

Alachlor ESA 1,198 3 0.25% 157,219,620 3,910,398 2.49%

Alachlor OA 1,198 0 0.00% 157,219,620 0 0.00%

Metolachlor 1,198 3 0.25% 157,219,620 107,510 0.07%

Metolachlor ESA 1,198 19 1.59% 157,219,620 5,873,985 3.74%

Metolachlor OA 1,198 1 0.08% 157,219,620 1,045,522 0.67%

NDBA 1,198 5 0.42% 157,219,620 1,685,983 1.07%

NDEA 1,198 26 2.17% 157,219,620 11,232,194 7.14%

NDMA 1,198 324 27.05% 157,219,620 65,311,764 41.54%

NDPA 1,198 0 0.00% 157,219,620 0 0.00%

NMEA 1,198 3 0.25% 157,219,620 4,480 0.003%

NPYR 1,198 21 1.75% 157,219,620 7,431,551 4.73%
EPA-OGWDW Occurrence Data from the UCMR 2

26

5.1 Assessment Monitoring Contaminants 

This section presents summaries of occurrence results for Assessment Monitoring 

contaminants with at least one detection. In the final UCMR 2 data set, only 2 of the 10 

Assessment Monitoring contaminants had at least one detection – RDX and terbufos sulfone. See 

Exhibit 2-1 for the list of Assessment Monitoring contaminants, and their applicable methods 

and MRLs. The following two sections present detailed occurrence findings on those 

contaminants. The remaining eight Assessment Monitoring contaminants did not have any 

detections (BDE-47, BDE-99, BDE-100, BDE-153, dimethoate, 1,3-dinitrobenzene, HBB, and 

TNT); see Exhibit 5-1, Exhibit 5-2, and Appendix A. The number of systems and samples, by 

state, are included for all 10 Assessment Monitoring contaminants in Appendix B. 

5.1.1 RDX

As indicated in Appendices A and B, under UCMR 2 Assessment Monitoring 32,150 

samples of RDX were collected from 4,139 PWSs. Of these, 4 samples (0.01%) had analytical 

detections of RDX at or above the MRL of 1 μg/L. The maximum detected concentration of 

RDX was 1.1 μg/L and the median value was also 1.1 μg/L. Appendix C includes more detailed 

occurrence numbers for RDX, such as summary statistics by source water type and system size 

and the number and percentage of samples with detections exceeding the HRL. 

The four RDX detections occurred in 3 large surface water systems (0.10%) in 2 states 

(Tennessee and Texas). These systems served a combined population of 96,033 people, or 

0.11%, of the national total population served by water systems of the same size. The percentage 

of all small, large, and very large UCMR 2 Assessment Monitoring systems with at least one 

detection of RDX was 0.07%. A summary of the number of systems with RDX detections and 

the population served by them is presented in Exhibit 5-3. 

The design of the UCMR 2 Assessment Monitoring enables extrapolation of national 

estimates of occurrence of contaminants detected in small water systems (see Section 4.3.3). 

Occurrence results from the large and very large systems are already nationally representative so 

national extrapolations are not necessary. These findings suggest that an estimated 3 PWSs 

serving approximately 96,000 customers nationally have RDX detections. 

Exhibit 5-3: RDX National Occurrence Measures from UCMR 2 

Assessment Monitoring Data - Summary of System and Population Served Data - 

All Detections

Source Water 

Type UCMR 2 Sample .

Number (and 

Percent) of 

Detections in the 

UCMR 2 Sample

. National Inventory .

National Estimate1

of the Number (and 

Percent) of 

Detections

.

. Systems Population Systems Population Systems Population Systems Population

. . . . Small Systems (serving ≤ 10,000 people) . . . . 

Ground Water 618 1,790,743 0 

(0%)

0 

(0%) 57,818 37,685,557 0 

(0%)

0 

(0%)

Surface Water 182 878,262 0 

(0%)

0 

(0%) 3,866 8,928,745 0 (0%)

0 

(0%)
EPA-OGWDW Occurrence Data from the UCMR 2

27

Source Water 

Type UCMR 2 Sample .

Number (and 

Percent) of 

Detections in the 

UCMR 2 Sample

. National Inventory .

National Estimate1

of the Number (and 

Percent) of 

Detections

.

. Systems Population Systems Population Systems Population Systems Population

All Small 

Systems 800 2,669,004 0 (0%)

0 

(0%) 61,684 46,614,302 0 (0%)

0 

(0%)

. . . . Large Systems (serving 10,001 - 100,000 people) -- CENSUS . . . . 

Ground Water 1,373 34,816,693 0 

(0%)

0 

(0%) 1,373 34,816,693 0 (0%)

0 

(0%)

Surface Water 1,568 49,758,358 3 

(0.19%)

96,033

(0.19%) 1,568 49,758,358 3 (0.19%)

96,033

(0.19%)

All Large 

Systems 2,941 84,575,051 3 (0.1%)

96,033

(0.11%) 2,941 84,575,051 3 (0.1%)

96,033

(0.11%)

. . . . Very Large Systems (serving > 100,000 people) -- CENSUS . . . . 

Ground Water 63 17,269,919 0 

(0%)

0 

(0%) 63 17,269,919 0 (0%)

0 

(0%)

Surface Water 335 124,711,765 0 

(0%)

0 

(0%) 335 124,711,765 0 (0%)

0 

(0%)

All Very 

Large 

Systems

398 141,981,684 0 

(0%)

0 

(0%) 398 141,981,684 0 (0%)

0 

(0%)

. . . . All Systems . . . . 

All Water 

Systems 4,139 229,225,740 3 (0.07%)

96,033

(0.04%) 65,023 273,171,037 3 (0.005%)

96,033

(0.04%)

1 National estimates for the small systems are extrapolations, generated by multiplying the UCMR 2 national statistical sample 

findings of system/population percentages and national system/population inventory numbers for PWSs developed from EPA’s 

SDWIS, the CWSS, and UCMR. National estimates for the large and very large systems are based directly on the UCMR 2 results, 

since this was a census, i.e., all large and very large systems were required to conduct UCMR 2 Assessment Monitoring. Due to 

rounding, some calculations may appear to be incorrect. 

RDX was evaluated relative to an HRL of 21 μg/L. None of the RDX detections 

exceeded the one-half HRL (10.5 μg/L) or the full HRL (21 μg/L); thus no occurrence tables 

relative to the HRL are included below. 

5.1.2 Terbufos Sulfone

As indicated in Appendices A and B, under UCMR 2 Assessment Monitoring 32,149 

samples of terbufos sulfone were collected from 4,140 PWSs. Of these, a single sample (0.003% 

of all samples) had an analytical detection of terbufos sulfone at or above the MRL of 0.4 μg/L 

(therefore above the HRL). The single detected concentration of terbufos sulfone was equal to 

0.42 μg/L. Appendix C includes more detailed occurrence numbers for terbufos sulfone, such as 

summary statistics by source water type and system size and the number and percentage of 

samples with detections exceeding the HRL. 

The terbufos sulfone detection occurred in a single large ground water system (0.02% of 

all systems sampled for terbufos sulfone) in the State of New York. This system served a 

population of 44,600 people or 0.05% of the national total population served by water systems of 
EPA-OGWDW Occurrence Data from the UCMR 2

28

the same size. The percentage of all small, large, and very large UCMR 2 Assessment 

Monitoring systems with at least one detection of terbufos sulfone was 0.02%. A summary of the 

number of systems with detections and the population served by them is presented in Exhibit 5-4. 

As described previously, the design of the UCMR 2 Assessment Monitoring enables 

national extrapolation of estimates of contaminant occurrence in small water systems (see 

Section 4.3.3). Occurrence results from the large and very large systems are already nationally 

representative so national extrapolations are not necessary. These findings suggest that one PWS 

serving approximately 44,600 nationally has detected terbufos sulfone. 

Exhibit 5-4: Terbufos Sulfone National Occurrence Measures from UCMR 2 

Assessment Monitoring Data - Summary of System and Population Served Data - 

All Detections

Source Water 

Type UCMR 2 Sample .

Number (and 

Percent) of 

Detections in the 

UCMR 2 Sample

. National Inventory .

National Estimate1

of the Number (and 

Percent) of 

Detections

.

. Systems Population Systems Population Systems Population Systems Population

. . . . Small Systems (serving ≤ 10,000 people) . . . . 

Ground Water 618 1,790,743 0 

(0%)

0 

(0%) 57,818 37,685,557 0 (0%)

0 

(0%)

Surface Water 182 878,262 0 

(0%)

0 

(0%) 3,866 8,928,745 0 (0%)

0 

(0%)

All Small 

Systems 800 2,669,004 0 (0%)

0 

(0%) 61,684 46,614,302 0 (0%)

0 

(0%)

. . . . Large Systems (serving 10,001 - 100,000 people) -- CENSUS . . . . 

Ground Water 1,374 34,828,693 1 

(0.07%)

44,600

(0.13%) 1,374 34,828,693 1 (0.07%)

44,600

(0.13%)

Surface Water 1,568 49,758,358 0 

(0%)

0 

(0%) 1,568 49,758,358 0 (0%)

0 

(0%)

All Large 

Systems 2,942 84,587,051 1 (0.03%)

44,600

(0.05%) 2,942 84,587,051 1 (0.03%)

44,600

(0.05%)

. . . . Very Large Systems (serving > 100,000 people) -- CENSUS . . . . 

Ground Water 63 17,269,919 0 

(0%)

0 

(0%) 63 17,269,919 0 (0%)

0 

(0%)

Surface Water 335 124,711,765 0 

(0%)

0 

(0%) 335 124,711,765 0 (0%)

0 

(0%)

All Very Large 

Systems 398 141,981,684 0 (0%)

0 

(0%) 398 141,981,684 0 (0%)

0 

(0%)

. . . . All Systems . . . . 

All Water 

Systems 4,140 229,237,740 1 (0.02%)

44,600

(0.02%) 65,024 273,183,037 1 (0.002%)

44,600

(0.02%)

1 National estimates for the small systems are extrapolations generated by multiplying the UCMR 2 national statistical sample 

findings of system/population percentages by the national system/population inventory numbers for PWSs developed from EPA’s 

SDWIS, the CWSS, and UCMR. National estimates for the large and very large systems are based directly on the UCMR 2 results, 

since this was a census, i.e., all large and very large systems were required to conduct UCMR 2 Assessment Monitoring. See 

Section 4.3.3 for a full description of national extrapolations. Due to rounding, some calculations may appear to be incorrect. 
EPA-OGWDW Occurrence Data from the UCMR 2

29

Terbufos sulfone was evaluated relative to an HRL of 0.35 μg/L. Exhibit 5-5 and Exhibit 

5-6 present the number of systems and the population they serve with detections greater than 

one-half the HRL and the HRL, respectively. The single detection of terbufos sulfone was equal 

to 0.42 μg/L, which exceeds one-half the HRL and the HRL. These findings suggest that an 

estimated one PWS serving 44,600 people nationally has terbufos sulfone detections greater than 

one-half the HRL and the HRL. (Note that the estimates of national exceedance of these health 

thresholds are identical to the estimated terbufos sulfone national occurrence presented in Exhibit 

5-4 above, since the single detection of terbufos sulfone was greater than the HRL.)

Exhibit 5-5: Terbufos Sulfone National Occurrence Measures from UCMR 2 

Assessment Monitoring Data - Summary of System and Population Served Data - 

Detections > 1⁄2 HRL

Source Water 

Type UCMR 2 Sample .

Number (and 

Percent) of 

Detections > 1/2 

HRL (0.175 μg/L) in 

the UCMR 2 Sample

. National Inventory .

National Estimate1 of 

the Number (and 

Percent) of 

Detections > 1/2 HRL 

(0.175 μg/L)

.

. Systems Population Systems Population Systems Population Systems Population

. . . . Small Systems (serving ≤ 10,000 people) . . . . 

Ground Water 618 1,790,743 0 

(0%)

0 

(0%) 57,818 37,685,557 0 (0%)

0 

(0%)

Surface Water 182 878,262 0 

(0%)

0 

(0%) 3,866 8,928,745 0 (0%)

0 

(0%)

All Small 

Systems 800 2,669,004 0 (0%)

0 

(0%) 61,684 46,614,302 0 (0%)

0 

(0%)

. . . . Large Systems (serving 10,001 - 100,000 people) -- CENSUS . . . . 

Ground Water 1,374 34,828,693 1 

(0.07%)

44,600

(0.13%) 1,374 34,828,693 1 (0.07%)

44,600

(0.13%)

Surface Water 1,568 49,758,358 0 

(0%)

0 

(0%) 1,568 49,758,358 0 (0%)

0 

(0%)

All Large 

Systems 2,942 84,587,051 1 (0.03%)

44,600

(0.05%) 2,942 84,587,051 1 (0.03%)

44,600

(0.05%)

. . . . Very Large Systems (serving > 100,000 people) -- CENSUS . . . . 

Ground Water 63 17,269,919 0 

(0%)

0 

(0%) 63 17,269,919 0 (0%)

0 

(0%)

Surface Water 335 124,711,765 0 

(0%)

0 

(0%) 335 124,711,765 0 (0%)

0 

(0%)

All Very Large 

Systems 398 141,981,684 0 (0%)

0 

(0%) 398 141,981,684 0 (0%)

0 

(0%)

. . . . All Systems . . . . 

All Water 

Systems 4,140 229,237,740 1 (0.02%)

44,600

(0.02%) 65,024 273,183,037 1 (0.002%)

44,600

(0.02%)

1 National estimates for the small systems are extrapolations generated by multiplying the UCMR 2 national statistical sample 

findings of system/population percentages by the national system/population inventory numbers for PWSs developed from EPA’s 

SDWIS, the CWSS, and UCMR. National estimates for the large and very large systems are based directly on the UCMR 2 results, 

since this was a census, i.e., all large and very large systems were required to conduct UCMR 2 Assessment Monitoring. See 

Section 4.3.3 for a full description of national extrapolations. Due to rounding, some calculations may appear to be incorrect. 
EPA-OGWDW Occurrence Data from the UCMR 2

30

Exhibit 5-6: Terbufos Sulfone National Occurrence Measures from UCMR 2 

Assessment Monitoring Data - Summary of System and Population Served Data - 

Detections > HRL

Source Water 

Type UCMR 2 Sample .

Number (and 

Percent) of 

Detections > HRL 

(0.35 μg/L) in the 

UCMR 2 Sample

. National Inventory .

National Estimate1 of 

the Number (and 

Percent) of 

Detections > HRL 

(0.35 μg/L)

.

. Systems Population Systems Population Systems Population Systems Population

. . . . Small Systems (serving ≤ 10,000 people) . . . . 

Ground Water 618 1,790,743 0 

(0%)

0 

(0%) 57,818 37,685,557 0 (0%)

0 

(0%)

Surface Water 182 878,262 0 

(0%)

0 

(0%) 3,866 8,928,745 0 (0%)

0 

(0%)

All Small 

Systems 800 2,669,004 0 (0%)

0 

(0%) 61,684 46,614,302 0 (0%)

0 

(0%)

. . . . Large Systems (serving 10,001 - 100,000 people) -- CENSUS . . . . 

Ground Water 1,374 34,828,693 1 

(0.07%)

44,600

(0.13%) 1,374 34,828,693 1 (0.07%)

44,600

(0.13%)

Surface Water 1,568 49,758,358 0 

(0%)

0 

(0%) 1,568 49,758,358 0 (0%)

0 

(0%)

All Large 

Systems 2,942 84,587,051 1 (0.03%)

44,600

(0.05%) 2,942 84,587,051 1 (0.03%)

44,600

(0.05%)

. . . . Very Large Systems (serving > 100,000 people) -- CENSUS . . . . 

Ground Water 63 17,269,919 0 

(0%)

0 

(0%) 63 17,269,919 0 (0%)

0 

(0%)

Surface Water 335 124,711,765 0 

(0%)

0 

(0%) 335 124,711,765 0 (0%)

0 

(0%)

All Very Large 

Systems 398 141,981,684 0 (0%)

0 

(0%) 398 141,981,684 0 (0%)

0 

(0%)

. . . . All Systems . . . . 

All Water 

Systems 4,140 229,237,740 1 (0.02%)

44,600

(0.02%) 65,024 273,183,037 1 (0.002%)

44,600

(0.02%)

1 National estimates for the small systems are extrapolations generated by multiplying the UCMR 2 national statistical sample 

findings of system/population percentages by the national system/population inventory numbers for PWSs developed from EPA’s 

SDWIS, the CWSS, and UCMR. National estimates for the large and very large systems are based directly on the UCMR 2 results, 

since this was a census, i.e., all large and very large systems were required to conduct UCMR 2 Assessment Monitoring. See 

Section 4.3.3 for a full description of national extrapolations. Due to rounding, some calculations may appear to be incorrect. 

5.2 Screening Survey Contaminants with Detections 

This section presents summaries of occurrence results for Screening Survey contaminants 

with at least one detection. In the final UCMR 2 data set, 10 of the 15 Screening Survey 

contaminants had at least one detection. See Exhibit 2-1 for the list of Screening Survey 

contaminants, and their applicable analytical methods and MRLs. The following 10 subsections 

present detailed occurrence findings on those contaminants. UCMR 2 monitoring found no 

analytical detections for five Screening Survey contaminants (acetochlor, acetochlor OA, 
EPA-OGWDW Occurrence Data from the UCMR 2

31

alachlor, alachlor OA, and NDPA); as such these contaminants are not discussed in more detail 

here. Summary occurrence findings for these contaminants are presented in Exhibit 5-1, Exhibit 

5-2, and Appendix A. Counts of the number of systems and samples, by state, are included for all 

15 Screening Survey contaminants in Appendix B. 

5.2.1 Acetochlor ESA

As indicated in Appendices A and B, under the UCMR 2 Screening Survey 11,157 

samples of acetochlor ESA were collected from 1,198 PWSs. Of these, 2 (0.02%) samples had 

analytical detections of acetochlor ESA at or above the MRL of 1 μg/L. The maximum detected 

concentration of acetochlor ESA was 1.2 μg/L, and the median value was 1.15263 μg/L. 

Appendix C includes more detailed occurrence numbers for acetochlor ESA, such as summary 

statistics by source water type and system size and the number and percentage of samples with 

detections exceeding the HRL.

One acetochlor ESA detection occurred in a small surface water system in Ohio; the other 

acetochlor ESA detection occurred in a very large surface water system in California. These two 

systems served a cumulative population of 3,832,155 people or 2.44% of the total population 

served by UCMR 2 Screening Survey PWSs. The percentage of all small, large, and very large 

UCMR 2 Screening Survey systems with at least one detection of acetochlor ESA was 0.17%. A 

summary of the number of systems with detections and the population served by them are 

presented in Exhibit 5-7. 

The design of the UCMR 2 Screening Survey enables extrapolation of national estimates 

of occurrence of contaminants detected in small and large water systems (see Section 4.3.3). 

Occurrence results from the very large systems are already nationally representative so national 

extrapolations are not necessary.

Acetochlor ESA is estimated to occur nationally in 16 small systems serving an estimated 

46,701 people. Acetochlor ESA also occurred in one very large system serving 3,828,700 people. 

These findings suggest that an estimated 17 PWSs serving approximately 3.9 million people 

nationally have acetochlor ESA detections.

Exhibit 5-7: Acetochlor ESA National Occurrence Measures from UCMR 2 

Screening Survey Data - Summary of System and Population Served Data - 

All Detections

Source Water 

Type UCMR 2 Sample .

Number (and 

Percent) of 

Detections in the 

UCMR 2 Sample

. National Inventory .

National Estimate1 of 

the Number (and 

Percent) of 

Detections

.

. Systems Population Systems Population Systems Population Systems Population

. . . . Small Systems (serving ≤ 10,000 people) . . . . 

Ground Water 240 548,364 0 

(0%)

0 

(0%) 57,818 37,685,557 0 (0%)

0 

(0%)

Surface Water 240 660,557 1 

(0.42%)

3,455

(0.52%) 3,866 8,928,745 16

(0.42%)

46,701

(0.52%)
EPA-OGWDW Occurrence Data from the UCMR 2

32

Source Water 

Type UCMR 2 Sample .

Number (and 

Percent) of 

Detections in the 

UCMR 2 Sample

. National Inventory .

National Estimate1 of 

the Number (and 

Percent) of 

Detections

.

. Systems Population Systems Population Systems Population Systems Population

All Small 

Systems 480 1,208,921 1 (0.21%)

3,455

(0.29%) 61,684 46,614,302 16(0.03%)

46,701

(0.1%)

. . . . Large Systems (serving 10,001 - 100,000 people) . . . . 

Ground Water 151 6,584,184 0 

(0%)

0 

(0%) 1,506 38,870,272 0 (0%)

0 

(0%)

Surface Water 169 7,444,830 0 

(0%)

0 

(0%) 1,366 44,536,172 0 (0%)

0 

(0%)

All Large 

Systems 320 14,029,015 0 (0%)

0 

(0%) 2,872 83,406,444 0 (0%)

0 

(0%)

. . . . Very Large Systems (serving > 100,000 people) -- CENSUS . . . . 

Ground Water 63 17,269,919 0 

(0%)

0 

(0%) 63 17,269,919 0 (0%)

0 

(0%)

Surface Water 335 124,711,765 1 

(0.3%)

3,828,700

(3.07%) 335 124,711,765 1 (0.3%)

3,828,700

(3.07%)

All Very Large 

Systems 398 141,981,684 1 (0.25%)

3,828,700

(2.7%) 398 141,981,684 1 (0.25%)

3,828,700

(2.7%)

. . . . All Systems . . . . 

All Water 

Systems 1,198 157,219,620 2 (0.17%)

3,832,155

(2.44%) 64,954 272,002,430 17(0.03%)

3,875,401

(1.42%)

1 National estimates for the small and large systems are extrapolations generated by multiplying the UCMR 2 national statistical 

sample findings of system/population percentages by the national system/population inventory numbers for PWSs developed from 

EPA’s SDWIS, the CWSS, and UCMR. National estimates for the very large systems are based directly on the UCMR 2 results, 

since this was a census, i.e., all very large systems were required to conduct UCMR 2 Screening Survey. See Section 4.3.3 for a full 

description of national extrapolations. Due to rounding, some calculations may appear to be incorrect. 

Acetochlor ESA was evaluated relative to an HRL of 1 μg/L. Exhibit 5-8 and Exhibit 5-9 

present the number of systems and the population they serve with detections greater than onehalf the HRL (0.5 μg/L) and the HRL (1 μg/L), respectively. 

Nationally, acetochlor ESA is estimated to exceed one-half the HRL and the HRL in 16 

small systems serving an estimated 46,701 people. Acetochlor ESA also exceeded one-half the 

HRL and the HRL in one very large system serving 3,828,700 people. Therefore, an estimated 

17 PWSs serving approximately 3.9 million people nationally are expected to have acetochlor 

ESA detections greater than one-half the HRL and the HRL. (Note that since all of the acetochlor 

ESA detections are greater than the HRL of 1 μg/L, the estimates of national exceedance of onehalf the HRL and the HRL are identical to the estimated acetochlor ESA national occurrence 

presented in Exhibit 5-7 above.) 
EPA-OGWDW Occurrence Data from the UCMR 2

33

Exhibit 5-8: Acetochlor ESA National Occurrence Measures from UCMR 2 

Screening Survey Data - Summary of System and Population Served Data - 

Detections > 1⁄2 HRL

Source Water 

Type UCMR 2 Sample .

Number (and 

Percent) of 

Detections > 1/2 

HRL (0.5 μg/L) in the 

UCMR 2 Sample

. National Inventory .

National Estimate1 of 

the Number (and 

Percent) of 

Detections > 1/2 HRL 

(0.5 μg/L)

.

. Systems Population Systems Population Systems Population Systems Population

. . . . Small Systems (serving ≤ 10,000 people) . . . . 

Ground Water 240 548,364 0 

(0%)

0 

(0%) 57,818 37,685,557 0 (0%)

0 

(0%)

Surface Water 240 660,557 1 

(0.42%)

3,455

(0.52%) 3,866 8,928,745 16(0.42%)

46,701

(0.52%)

All Small 

Systems 480 1,208,921 1 (0.21%)

3,455

(0.29%) 61,684 46,614,302 16(0.03%)

46,701

(0.1%)

. . . . Large Systems (serving 10,001 - 100,000 people) . . . . 

Ground Water 151 6,584,184 0 

(0%)

0 

(0%) 1,506 38,870,272 0 (0%)

0 

(0%)

Surface Water 169 7,444,830 0 

(0%)

0 

(0%) 1,366 44,536,172 0 (0%)

0 

(0%)

All Large 

Systems 320 14,029,015 0 (0%)

0 

(0%) 2,872 83,406,444 0 (0%)

0 

(0%)

. . . . Very Large Systems (serving > 100,000 people) -- CENSUS . . . . 

Ground Water 63 17,269,919 0 

(0%)

0 

(0%) 63 17,269,919 0 (0%)

0 

(0%)

Surface Water 335 124,711,765 1 

(0.3%)

3,828,700

(3.07%) 335 124,711,765 1 (0.3%)

3,828,700

(3.07%)

All Very Large 

Systems 398 141,981,684 1 (0.25%)

3,828,700

(2.7%) 398 141,981,684 1 (0.25%)

3,828,700

(2.7%)

. . . . All Systems . . . . 

All Water 

Systems 1,198 157,219,620 2 (0.17%)

3,832,155

(2.44%) 64,954 272,002,430 17(0.03%)

3,875,401

(1.42%)

1 National estimates for the small and large systems are extrapolations generated by multiplying the UCMR 2 national statistical 

sample findings of system/population percentages by the national system/population inventory numbers for PWSs developed from 

EPA’s SDWIS, the CWSS, and UCMR. National estimates for the very large systems are based directly on the UCMR 2 results, 

since this was a census, i.e., all very large systems were required to conduct UCMR 2 Screening Survey. See Section 4.3.3 for a full 

description of national extrapolations. Due to rounding, some calculations may appear to be incorrect. 
EPA-OGWDW Occurrence Data from the UCMR 2

34

Exhibit 5-9: Acetochlor ESA National Occurrence Measures from UCMR 2 

Screening Survey Data - Summary of System and Population Served Data - 

Detections > HRL

Source Water 

Type UCMR 2 Sample .

Number (and 

Percent) of 

Detections > HRL 

(1 μg/L) in the 

UCMR 2 Sample

. National Inventory .

National Estimate1 of 

the Number (and 

Percent) of 

Detections > HRL (1 

μg/L)

.

. Systems Population Systems Population Systems Population Systems Population

. . . . Small Systems (serving ≤ 10,000 people) . . . . 

Ground Water 240 548,364 0 

(0%)

0 

(0%) 57,818 37,685,557 0 (0%)

0 

(0%)

Surface Water 240 660,557 1 

(0.42%)

3,455

(0.52%) 3,866 8,928,745 16(0.42%)

46,701

(0.52%)

All Small 

Systems 480 1,208,921 1 (0.21%)

3,455

(0.29%) 61,684 46,614,302 16(0.03%)

46,701

(0.1%)

. . . . Large Systems (serving 10,001 - 100,000 people) . . . . 

Ground Water 151 6,584,184 0 

(0%)

0 

(0%) 1,506 38,870,272 0 (0%)

0 

(0%)

Surface Water 169 7,444,830 0 

(0%)

0 

(0%) 1,366 44,536,172 0 (0%)

0 

(0%)

All Large 

Systems 320 14,029,015 0 (0%)

0 

(0%) 2,872 83,406,444 0 (0%)

0 

(0%)

. . . . Very Large Systems (serving > 100,000 people) -- CENSUS . . . . 

Ground Water 63 17,269,919 0 

(0%)

0 

(0%) 63 17,269,919 0 (0%)

0 

(0%)

Surface Water 335 124,711,765 1 

(0.3%)

3,828,700

(3.07%) 335 124,711,765 1 (0.3%)

3,828,700

(3.07%)

All Very Large 

Systems 398 141,981,684 1 (0.25%)

3,828,700

(2.7%) 398 141,981,684 1 (0.25%)

3,828,700

(2.7%)

. . . . All Systems . . . . 

All Water 

Systems 1,198 157,219,620 2 (0.17%)

3,832,155

(2.44%) 64,954 272,002,430 17(0.03%)

3,875,401

(1.42%)

1 National estimates for the small and large systems are extrapolations generated by multiplying the UCMR 2 national statistical 

sample findings of system/population percentages by the national system/population inventory numbers for PWSs developed from 

EPA’s SDWIS, the CWSS, and UCMR. National estimates for the very large systems are based directly on the UCMR 2 results, 

since this was a census, i.e., all very large systems were required to conduct UCMR 2 Screening Survey. See Section 4.3.3 for a full 

description of national extrapolations. Due to rounding, some calculations may appear to be incorrect. 
EPA-OGWDW Occurrence Data from the UCMR 2

35

5.2.2 Alachlor ESA

As indicated in Appendices A and B, under the UCMR 2 Screening Survey 11,156 

samples of alachlor ESA were collected from 1,198 PWSs. Of these, 5 samples (0.04%) had 

analytical detections of alachlor ESA at or above the MRL of 1 μg/L. The maximum detected 

concentration of alachlor ESA was 1.3 μg/L and the median value was 1.2 μg/L. Appendix C 

includes more detailed occurrence numbers for alachlor ESA, such as summary statistics by 

source water type and system size and the number and percentage of samples with detections 

exceeding the HRL.

All but one of the alachlor ESA detections occurred in surface water systems. Alachlor 

ESA was detected in three systems in three states (California, Iowa, and Indiana). The systems 

with detections of alachlor ESA served a cumulative population of 3,910,398 people or 2.49% of 

the total population served by UCMR 2 Screening Survey PWSs. The percentage of all small, 

large, and very large UCMR 2 Screening Survey systems with at least one detection of alachlor 

ESA was 0.25%. A summary of the number of systems with detections and the population served 

by them are presented in Exhibit 5-10. 

The design of the UCMR 2 Screening Survey enables extrapolation of national estimates 

of occurrence of contaminants detected in small and large water systems (see Section 4.3.3). 

Occurrence results from the very large systems are already nationally representative so national 

extrapolations are not necessary.

Alachlor ESA is estimated to occur nationally in 16 small systems serving approximately 

105,000 people. It is also estimated to occur nationally in 10 large systems serving 

approximately 437,000 people. Alachlor ESA also occurred in one very large system serving 

3,828,700 people. These findings suggest that an estimated 27 PWSs serving almost 4.4 million 

people nationally have alachlor ESA detections. 

Exhibit 5-10: Alachlor ESA National Occurrence Measures from UCMR 2 

Screening Survey Data - Summary of System and Population Served Data - All 

Detections

Source Water 

Type UCMR 2 Sample .

Number (and 

Percent) of 

Detections in the 

UCMR 2 Sample

. National Inventory .

National Estimate1 of 

the Number (and 

Percent) of 

Detections

.

. Systems Population Systems Population Systems Population Systems Population

. . . . Small Systems (serving ≤ 10,000 people) . . . . 

Ground Water 240 548,364 0 

(0%)

0 

(0%) 57,818 37,685,557 0 (0%)

0 

(0%)

Surface Water 240 660,557 1 

(0.42%)

7,705

(1.17%) 3,866 8,928,745 16

(0.42%)

104,148

(1.17%)

All Small 

Systems 480 1,208,921 1 (0.21%)

7,705

(0.64%) 61,684 46,614,302 16(0.03%)

104,148

(0.22%)
EPA-OGWDW Occurrence Data from the UCMR 2

36

Source Water 

Type UCMR 2 Sample .

Number (and 

Percent) of 

Detections in the 

UCMR 2 Sample

. National Inventory .

National Estimate1 of 

the Number (and 

Percent) of 

Detections

.

. Systems Population Systems Population Systems Population Systems Population

. . . . Large Systems (serving 10,001 - 100,000 people) . . . . 

Ground Water 151 6,584,184 1 

(0.66%)

73,993

(1.12%) 1,506 38,870,272 10(0.66%)

436,824

(1.12%)

Surface Water 169 7,444,830 0 

(0%)

0 

(0%) 1,366 44,536,172 0 (0%)

0 

(0%)

All Large 

Systems 320 14,029,015 1 (0.31%)

73,993

(0.53%) 2,872 83,406,444 10(0.35%)

436,824

(0.52%)

. . . . Very Large Systems (serving > 100,000 people) -- CENSUS . . . . 

Ground Water 63 17,269,919 0 

(0%)

0 

(0%) 63 17,269,919 0 (0%)

0 

(0%)

Surface Water 335 124,711,765 1 

(0.3%)

3,828,700

(3.07%) 335 124,711,765 1 (0.3%)

3,828,700

(3.07%)

All Very Large 

Systems 398 141,981,684 1 (0.25%)

3,828,700

(2.7%) 398 141,981,684 1 (0.25%)

3,828,700

(2.7%)

. . . . All Systems . . . . 

All Water 

Systems 1,198 157,219,620 3 (0.25%)

3,910,398

(2.49%) 64,954 272,002,430 27(0.04%)

4,369,672

(1.61%)

1 National estimates for the small and large systems are extrapolations generated by multiplying the UCMR 2 national statistical 

sample findings of system/population percentages by the national system/population inventory numbers for PWSs developed from 

EPA’s SDWIS, the CWSS, and UCMR. National estimates for the very large systems are based directly on the UCMR 2 results, 

since this was a census, i.e., all very large systems were required to conduct UCMR 2 Screening Survey. See Section 4.3.3 for a full 

description of national extrapolations. Due to rounding, some calculations may appear to be incorrect. 

Alachlor ESA was evaluated relative to an HRL of 0.4 μg/L. Exhibit 5-11 and Exhibit 

5-12 present the number of systems and the population they serve with detections greater than 

one-half the HRL (0.2 μg/L) and the HRL (0.4 μg/L), respectively. 

Nationally, alachlor ESA is estimated to exceed one-half the HRL and the HRL in 16 

small systems serving an estimated 104,148 people and 10 large systems serving an estimated 

436,824 people. Alachlor ESA also exceeded one-half the HRL and the HRL in one very large 

system serving 3,828,700 people. These findings suggest that an estimated 27 PWSs serving 

almost 4.4 million people nationally have alachlor ESA detections greater than one-half the HRL 

and the HRL. (Note that since all of the alachlor ESA detections are greater than the HRL of 0.4 

μg/L, the estimates of national exceedance of one-half the HRL and the HRL are identical to the 

estimated alachlor ESA national occurrence presented in Exhibit 5-10 above.) 
EPA-OGWDW Occurrence Data from the UCMR 2

37

Exhibit 5-11: Alachlor ESA National Occurrence Measures from UCMR 2 

Screening Survey Data - Summary of System and Population Served Data - 

Detections > 1⁄2 HRL

Source Water 

Type UCMR 2 Sample .

Number (and 

Percent) of 

Detections > 1/2 

HRL (0.2 μg/L) in the 

UCMR 2 Sample

. National Inventory .

National Estimate1 of 

the Number (and 

Percent) of 

Detections > 1/2 HRL 

(0.2 μg/L)

.

. Systems Population Systems Population Systems Population Systems Population

. . . . Small Systems (serving ≤ 10,000 people) . . . . 

Ground Water 240 548,364 0 

(0%)

0 

(0%) 57,818 37,685,557 0 (0%)

0 

(0%)

Surface Water 240 660,557 1 

(0.42%)

7,705

(1.17%) 3,866 8,928,745 16(0.42%)

104,148

(1.17%)

All Small 

Systems 480 1,208,921 1 (0.21%)

7,705

(0.64%) 61,684 46,614,302 16(0.03%)

104,148

(0.22%)

. . . . Large Systems (serving 10,001 - 100,000 people) . . . . 

Ground Water 151 6,584,184 1 

(0.66%)

73,993

(1.12%) 1,506 38,870,272 10(0.66%)

436,824

(1.12%)

Surface Water 169 7,444,830 0 

(0%)

0 

(0%) 1,366 44,536,172 0 (0%)

0 

(0%)

All Large 

Systems 320 14,029,015 1 (0.31%)

73,993

(0.53%) 2,872 83,406,444 10(0.35%)

436,824

(0.52%)

. . . . Very Large Systems (serving > 100,000 people) -- CENSUS . . . . 

Ground Water 63 17,269,919 0 

(0%)

0 

(0%) 63 17,269,919 0 (0%)

0 

(0%)

Surface Water 335 124,711,765 1 

(0.3%)

3,828,700

(3.07%) 335 124,711,765 1 (0.3%)

3,828,700

(3.07%)

All Very Large 

Systems 398 141,981,684 1 (0.25%)

3,828,700

(2.7%) 398 141,981,684 1 (0.25%)

3,828,700

(2.7%)

. . . . All Systems . . . . 

All Water 

Systems 1,198 157,219,620 3 (0.25%)

3,910,398

(2.49%) 64,954 272,002,430 27(0.04%)

4,369,672

(1.61%)

1 National estimates for the small and large systems are extrapolations generated by multiplying the UCMR 2 national statistical 

sample findings of system/population percentages by the national system/population inventory numbers for PWSs developed from 

EPA’s SDWIS, the CWSS, and UCMR. National estimates for the very large systems are based directly on the UCMR 2 results, 

since this was a census, i.e., all very large systems were required to conduct UCMR 2 Screening Survey. See Section 4.3.3 for a full 

description of national extrapolations. Due to rounding, some calculations may appear to be incorrect. 
EPA-OGWDW Occurrence Data from the UCMR 2

38

Exhibit 5-12: Alachlor ESA National Occurrence Measures from UCMR 2 

Screening Survey Data - Summary of System and Population Served Data - 

Detections > HRL

Source Water 

Type UCMR 2 Sample .

Number (and 

Percent) of 

Detections > HRL 

(0.4 μg/L) in the 

UCMR 2 Sample

. National Inventory .

National Estimate1 of 

the Number (and 

Percent) of 

Detections > HRL 

(0.4 μg/L)

. Systems Population Systems Population Systems Population Systems Population

. . . . Small Systems (serving ≤ 10,000 people) . . . . 

Ground Water 240 548,364 0 

(0%)

0 

(0%) 57,818 37,685,557 0 (0%)

0 

(0%)

Surface Water 240 660,557 1 

(0.42%)

7,705

(1.17%) 3,866 8,928,745 16(0.42%)

104,148

(1.17%)

All Small 

Systems 480 1,208,921 1 (0.21%)

7,705

(0.64%) 61,684 46,614,302 16(0.03%)

104,148

(0.22%)

. . . . Large Systems (serving 10,001 - 100,000 people) . . . . 

Ground Water 151 6,584,184 1 

(0.66%)

73,993

(1.12%) 1,506 38,870,272 10(0.66%)

436,824

(1.12%)

Surface Water 169 7,444,830 0 

(0%)

0 

(0%) 1,366 44,536,172 0 (0%)

0 

(0%)

All Large 

Systems 320 14,029,015 1 (0.31%)

73,993

(0.53%) 2,872 83,406,444 10(0.35%)

436,824

(0.52%)

. . . . Very Large Systems (serving > 100,000 people) -- CENSUS . . . . 

Ground Water 63 17,269,919 0 

(0%)

0 

(0%) 63 17,269,919 0 (0%)

0 

(0%)

Surface Water 335 124,711,765 1 

(0.3%)

3,828,700

(3.07%) 335 124,711,765 1 (0.3%)

3,828,700

(3.07%)

All Very Large 

Systems 398 141,981,684 1 (0.25%)

3,828,700

(2.7%) 398 141,981,684 1 (0.25%)

3,828,700

(2.7%)

. . . . All Systems . . . . 

All Water 

Systems 1,198 157,219,620 3 (0.25%)

3,910,398

(2.49%) 64,954 272,002,430 27(0.04%)

4,369,672

(1.61%)

1 National estimates for the small and large systems are extrapolations generated by multiplying the UCMR 2 national statistical 

sample findings of system/population percentages by the national system/population inventory numbers for PWSs developed from 

EPA’s SDWIS, the CWSS, and UCMR. National estimates for the very large systems are based directly on the UCMR 2 results, 

since this was a census, i.e., all very large systems were required to conduct UCMR 2 Screening Survey. See Section 4.3.3 for a full 

description of national extrapolations. Due to rounding, some calculations may appear to be incorrect. 

5.2.3 Metolachlor

As indicated in Appendices A and B, under the UCMR 2 Screening Survey 11,192 

samples of metolachlor were collected from 1,198 PWSs. Of these, 3 samples (0.03%) had 

analytical detections of metolachlor at or above the MRL of 1 μg/L. The maximum detected 

concentration of metolachlor was 2.73235 μg/L and the median value was 1.4 μg/L. Appendix C 

includes more detailed occurrence numbers for metolachlor, such as summary statistics by 

source water type and system size.
EPA-OGWDW Occurrence Data from the UCMR 2

39

All three metolachlor detections occurred in surface water systems, of which two 

detections were small systems and one was a very large system, in three states (Delaware, 

Indiana, and Oklahoma). These systems served a cumulative population of 107,510 people or 

0.07% of the total population served by UCMR 2 Screening Survey PWSs. The percentage of all 

small, large, and very large UCMR 2 Screening Survey systems with at least one detection of 

metolachlor was 0.25%. A summary of the number of systems with detections and the population 

served by them are presented in Exhibit 5-13. 

The design of the UCMR 2 Screening Survey enables extrapolation of national estimates 

of occurrence of contaminants detected in small and large water systems (see Section 4.3.3). 

Occurrence results from the very large systems are already nationally representative so national 

extrapolations are not necessary.

Metolachlor is estimated to occur nationally in 32 small systems serving approximately 

30,000 people. Metolachlor also occurred in one very large system serving 105,270 people. 

These findings suggest that an estimated 33 PWSs serving approximately 136,000 people 

nationally have metolachlor detections. 

Exhibit 5-13: Metolachlor National Occurrence Measures from UCMR 2 Screening 

Survey Data - Summary of System and Population Served Data - All Detections

Source Water 

Type UCMR 2 Sample .

Number (and 

Percent) of 

Detections in the 

UCMR 2 Sample

. National Inventory .

National Estimate1 of 

the Number (and 

Percent) of 

Detections

.

. Systems Population Systems Population Systems Population Systems Population

. . . . Small Systems (serving ≤ 10,000 people) . . . . 

Ground Water 240 548,364 0 

(0%)

0 

(0%) 57,818 37,685,557 0 (0%)

0 

(0%)

Surface Water 240 660,557 2 

(0.83%)

2,240

(0.34%) 3,866 8,928,745 32(0.83%)

30,278

(0.34%)

All Small 

Systems 480 1,208,921 2 (0.42%)

2,240

(0.19%) 61,684 46,614,302 32(0.05%)

30,278

(0.06%)

. . . . Large Systems (serving 10,001 - 100,000 people) . . . . 

Ground Water 151 6,584,184 0 

(0%)

0 

(0%) 1,506 38,870,272 0 (0%)

0 

(0%)

Surface Water 169 7,444,830 0 

(0%)

0 

(0%) 1,366 44,536,172 0 (0%)

0 

(0%)

All Large 

Systems 320 14,029,015 0 (0%)

0 

(0%) 2,872 83,406,444 0 (0%)

0 

(0%)

. . . . Very Large Systems (serving > 100,000 people) -- CENSUS . . . . 

Ground Water 63 17,269,919 0 

(0%)

0 

(0%) 63 17,269,919 0 (0%)

0 

(0%)
EPA-OGWDW Occurrence Data from the UCMR 2

40

Source Water 

Type UCMR 2 Sample .

Number (and 

Percent) of 

Detections in the 

UCMR 2 Sample

. National Inventory .

National Estimate1 of 

the Number (and 

Percent) of 

Detections

.

. Systems Population Systems Population Systems Population Systems Population

Surface Water 335 124,711,765 1 

(0.3%)

105,270

(0.08%) 335 124,711,765 1 (0.3%)

105,270

(0.08%)

All Very Large 

Systems 398 141,981,684 1 (0.25%)

105,270

(0.07%) 398 141,981,684 1 (0.25%)

105,270

(0.07%)

. . . . All Systems . . . . 

All Water 

Systems 1,198 157,219,620 3 (0.25%)

107,510

(0.07%) 64,954 272,002,430 33(0.05%)

135,548

(0.05%)

1 National estimates for the small and large systems are extrapolations generated by multiplying the UCMR 2 national statistical 

sample findings of system/population percentages by the national system/population inventory numbers for PWSs developed from 

EPA’s SDWIS, the CWSS, and UCMR. National estimates for the very large systems are based directly on the UCMR 2 results, 

since this was a census, i.e., all very large systems were required to conduct UCMR 2 Screening Survey. See Section 4.3.3 for a full 

description of national extrapolations. Due to rounding, some calculations may appear to be incorrect. 

Metolachlor was evaluated relative to an HRL of 700 μg/L. None of the metolachlor 

detections exceeded one-half the HRL (350 μg/L) or the HRL (700 μg/L); thus no occurrence 

tables relative to the HRL are included below.

5.2.4 Metolachlor ESA

As indicated in Appendices A and B, under the UCMR 2 Screening Survey 11,157 

samples of metolachlor ESA were collected from 1,198 PWSs. Of these, 52 samples (0.47%) had 

analytical detections of metolachlor ESA at or above the MRL of 1 μg/L. The maximum 

detected concentration of metolachlor ESA was 3.95455 μg/L and the median value was 1.44131 

μg/L. Appendix C includes more detailed occurrence numbers for metolachlor ESA, such as 

summary statistics by source water type and system size.

Detections of metolachlor ESA occurred in 7 ground water and 12 surface water systems 

in 10 states. These 19 systems served a cumulative population of approximately 5.9 million 

people or 3.74% of the total population served by UCMR 2 Screening Survey PWSs. The 

percentage of all small, large, and very large UCMR 2 Screening Survey systems with at least 

one detection of metolachlor ESA was 1.59%. A summary of the number of systems with 

detections and the population served by them are presented in Exhibit 5-14. 

The design of the UCMR 2 Screening Survey enables extrapolation of national estimates 

of occurrence of contaminants detected in small and large water systems (see Section 4.3.3). 

Occurrence results from the very large systems are already nationally representative so national 

extrapolations are not necessary.

Metolachlor ESA is estimated to occur nationally in 1,253 small systems serving an 

estimated population of approximately 1.4 million people. It is also estimated to occur nationally 

in 34 large systems serving an estimated cumulative population of approximately 1.3 million 
EPA-OGWDW Occurrence Data from the UCMR 2

41

people. Metolachlor ESA also occurred in 7 very large systems serving 5.6 million people. These 

findings suggest that an estimated 1,294 PWSs serving more than 8.3 million people nationally 

have metolachlor ESA detections. 

Exhibit 5-14: Metolachlor ESA National Occurrence Measures from UCMR 2 

Screening Survey Data - Summary of System and Population Served Data - All 

Detections

Source Water 

Type UCMR 2 Sample .

Number (and 

Percent) of 

Detections in the 

UCMR 2 Sample

. National Inventory .

National Estimate1 of 

the Number (and 

Percent) of 

Detections

.

. Systems Population Systems Population Systems Population Systems Population

. . . . Small Systems (serving ≤ 10,000 people) . . . . 

Ground Water 240 548,364 5 

(2.08%)

17,540

(3.2%) 57,818 37,685,557 1,205(2.08%)

1,205,412

(3.2%)

Surface Water 240 660,557 3 

(1.25%)

17,498

(2.65%) 3,866 8,928,745 48(1.25%)

236,514

(2.65%)

All Small 

Systems 480 1,208,921 8 (1.67%)

35,038

(2.9%) 61,684 46,614,302 1,253(2.03%)

1,441,926

(3.09%)

. . . . Large Systems (serving 10,001 - 100,000 people) . . . . 

Ground Water 151 6,584,184 1 

(0.66%)

73,993

(1.12%) 1,506 38,870,272 10(0.66%)

436,824

(1.12%)

Surface Water 169 7,444,830 3 

(1.78%)

138,897

(1.87%) 1,366 44,536,172 24(1.78%)

830,904

(1.87%)

All Large 

Systems 320 14,029,015 4 (1.25%)

212,890

(1.52%) 2,872 83,406,444 34(1.19%)

1,267,728

(1.52%)

. . . . Very Large Systems (serving > 100,000 people) -- CENSUS . . . . 

Ground Water 63 17,269,919 1 

(1.59%)

1,045,522

(6.05%) 63 17,269,919 1 (1.59%)

1,045,522

(6.05%)

Surface Water 335 124,711,765 6 

(1.79%)

4,580,535

(3.67%) 335 124,711,765 6 (1.79%)

4,580,535

(3.67%)

All Very Large 

Systems 398 141,981,684 7 (1.76%)

5,626,057

(3.96%) 398 141,981,684 7 (1.76%)

5,626,057

(3.96%)

. . . . All Systems . . . . 

All Water 

Systems 1,198 157,219,620 19(1.59%)

5,873,985

(3.74%) 64,954 272,002,430 1,294(1.99%)

8,335,711

(3.06%)

1 National estimates for the small and large systems are extrapolations generated by multiplying the UCMR 2 national statistical 

sample findings of system/population percentages by the national system/population inventory numbers for PWSs developed from 

EPA’s SDWIS, the CWSS, and UCMR. National estimates for the very large systems are based directly on the UCMR 2 results, 

since this was a census, i.e., all very large systems were required to conduct UCMR 2 Screening Survey. See Section 4.3.3 for a full 

description of national extrapolations. Due to rounding, some calculations may appear to be incorrect. 
EPA-OGWDW Occurrence Data from the UCMR 2

42

Metolachlor ESA was evaluated relative to an HRL of 700 μg/L. None of the metolachlor 

ESA detections exceeded one-half the HRL (350 μg/L) or the full HRL (700 μg/L); thus no 

occurrence tables relative to the HRL are included below. 

5.2.5 Metolachlor OA

As indicated in Appendices A and B, under the UCMR 2 Screening Survey 11,157 

samples of metolachlor OA were collected from 1,198 PWSs. Of these, 3 samples (0.03%) had 

analytical detections of metolachlor OA at or above the MRL of 2 μg/L. The maximum detected 

concentration of metolachlor OA was 3.539 μg/L and the median value was 3.078 μg/L. 

Appendix C includes more detailed occurrence numbers for metolachlor OA, such as summary 

statistics by source water type and system size.

All three metolachlor OA detections occurred in a single very large ground water system 

in the State of New York. This system served a population of approximately 1.05 million people 

or 0.67% of the total population served by UCMR 2 Screening Survey PWSs. The percentage of 

all small, large, and very large UCMR 2 Screening Survey systems with at least one detection of 

metolachlor OA was 0.08%. A summary of the number of systems with detections and the 

population served by them are presented in Exhibit 5-15. 

The design of the UCMR 2 Screening Survey enables extrapolation of national estimates 

of occurrence of contaminants detected in small and large water systems (see Section 4.3.3). 

Occurrence results from the very large systems are already nationally representative so national 

extrapolations are not necessary. These findings suggest that an estimated one PWS serving 1.05 

million people nationally has metolachlor OA detections.

Exhibit 5-15: Metolachlor OA National Occurrence Measures from UCMR 2 

Screening Survey Data - Summary of System and Population Served Data - All 

Detections

Source Water 

Type UCMR 2 Sample .

Number (and 

Percent) of 

Detections in the 

UCMR 2 Sample

. National Inventory .

National Estimate1 of 

the Number (and 

Percent) of 

Detections

.

. Systems Population Systems Population Systems Population Systems Population

. . . . Small Systems (serving ≤ 10,000 people) . . . . 

Ground Water 240 548,364 0 

(0%)

0 

(0%) 57,818 37,685,557 0 (0%)

0 

(0%)

Surface Water 240 660,557 0 

(0%)

0 

(0%) 3,866 8,928,745 0 (0%)

0 

(0%)

All Small 

Systems 480 1,208,921 0 (0%)

0 

(0%) 61,684 46,614,302 0 (0%)

0 

(0%)

. . . . Large Systems (serving 10,001 - 100,000 people) . . . . 

Ground Water 151 6,584,184 0 

(0%)

0 

(0%) 1,506 38,870,272 0 (0%)

0 

(0%)
EPA-OGWDW Occurrence Data from the UCMR 2

43

Source Water 

Type UCMR 2 Sample .

Number (and 

Percent) of 

Detections in the 

UCMR 2 Sample

. National Inventory .

National Estimate1 of 

the Number (and 

Percent) of 

Detections

.

. Systems Population Systems Population Systems Population Systems Population

Surface Water 169 7,444,830 0 

(0%)

0 

(0%) 1,366 44,536,172 0 (0%)

0 

(0%)

All Large 

Systems 320 14,029,015 0 (0%)

0 

(0%) 2,872 83,406,444 0 (0%)

0 

(0%)

. . . . Very Large Systems (serving > 100,000 people) -- CENSUS . . . . 

Ground Water 63 17,269,919 1 

(1.59%)

1,045,522

(6.05%) 63 17,269,919 1 (1.59%)

1,045,522

(6.05%)

Surface Water 335 124,711,765 0 

(0%)

0 

(0%) 335 124,711,765 0 (0%)

0 

(0%)

All Very Large 

Systems 398 141,981,684 1 (0.25%)

1,045,522

(0.74%) 398 141,981,684 1 (0.25%)

1,045,522

(0.74%)

. . . . All Systems . . . . 

All Water 

Systems 1,198 157,219,620 1 (0.08%)

1,045,522

(0.67%) 64,954 272,002,430 1 (0%)

1,045,522

(0.38%)

1 National estimates for the small and large systems are extrapolations generated by multiplying the UCMR 2 national statistical 

sample findings of system/population percentages by the national system/population inventory numbers for PWSs developed from 

EPA’s SDWIS, the CWSS, and UCMR. National estimates for the very large systems are based directly on the UCMR 2 results, 

since this was a census, i.e., all very large systems were required to conduct UCMR 2 Screening Survey. See Section 4.3.3 for a full 

description of national extrapolations. Due to rounding, some calculations may appear to be incorrect. 

Metolachlor OA was evaluated relative to an HRL of 700 μg/L. None of the metolachlor 

OA detections exceeded one-half the HRL (350 μg/L) or the HRL (700 μg/L); thus no 

occurrence tables relative to the HRL are included below. 

5.2.6 NDBA

As indicated in Appendices A and B, under the UCMR 2 Screening Survey 18,101 

samples of NDBA were collected from 1,198 PWSs. Of these, 9 samples (0.05%) had analytical 

detections of NDBA at or above the MRL of 0.004 μg/L. The maximum detected concentration 

of NDBA was 0.02062 μg/L and the median value was 0.00666 μg/L. Appendix C includes more 

detailed occurrence numbers for NDBA, such as summary statistics by source water type and 

system size.

Detections of NDBA occurred in three ground water and two surface water systems in 

four states. These five systems served a cumulative population of approximately 1.7 million 

people or 1.07% of the total population served by UCMR 2 Screening Survey PWSs. The 

percentage of all small, large, and very large UCMR 2 Screening Survey systems with at least 

one detection of NDBA was 0.42%. A summary of the number of systems with detections and 

the population served by them are presented in Exhibit 5-16. 
EPA-OGWDW Occurrence Data from the UCMR 2

44

The design of the UCMR 2 Screening Survey enables extrapolation of national estimates 

of occurrence of contaminants detected in small and large water systems (see Section 4.3.3). 

Occurrence results from the very large systems are already nationally representative so national 

extrapolations are not necessary.

NDBA is estimated to occur nationally in 482 small systems serving approximately 

982,000 people. NDBA also occurred in 3 very large systems serving 1.67 million people. These 

findings suggest that an estimated 485 PWSs serving approximately 2.7 million people 

nationally have NDBA detections. 

Exhibit 5-16: NDBA National Occurrence Measures from UCMR 2 Screening 

Survey Data - Summary of System and Population Served Data - All Detections

Source Water 

Type UCMR 2 Sample .

Number (and 

Percent) of 

Detections in the 

UCMR 2 Sample

. National Inventory .

National Estimate1 of 

the Number (and 

Percent) of 

Detections

.

. Systems Population Systems Population Systems Population Systems Population

. . . . Small Systems (serving ≤ 10,000 people) . . . . 

Ground Water 240 548,364 2 

(0.83%)

14,292

(2.61%) 57,818 37,685,557 482(0.83%)

982,198

(2.61%)

Surface Water 240 660,557 0 

(0%)

0 

(0%) 3,866 8,928,745 0 (0%)

0 

(0%)

All Small 

Systems 480 1,208,921 2 (0.42%)

14,292

(1.18%) 61,684 46,614,302 482(0.78%)

982,198

(2.11%)

. . . . Large Systems (serving 10,001 - 100,000 people) . . . . 

Ground Water 151 6,584,184 0 

(0%)

0 

(0%) 1,506 38,870,272 0 (0%)

0 

(0%)

Surface Water 169 7,444,830 0 

(0%)

0 

(0%) 1,366 44,536,172 0 (0%)

0 

(0%)

All Large 

Systems 320 14,029,015 0 (0%)

0 

(0%) 2,872 83,406,444 0 (0%)

0 

(0%)

. . . . Very Large Systems (serving > 100,000 people) -- CENSUS . . . . 

Ground Water 63 17,269,919 1 

(1.59%)

1,045,522

(6.05%) 63 17,269,919 1 (1.59%)

1,045,522

(6.05%)

Surface Water 335 124,711,765 2 

(0.6%)

626,169

(0.5%) 335 124,711,765 2 (0.6%)

626,169

(0.5%)

All Very Large 

Systems 398 141,981,684 3 (0.75%)

1,671,691

(1.18%) 398 141,981,684 3 (0.75%)

1,671,691

(1.18%)

. . . . All Systems . . . . 

All Water 

Systems 1,198 157,219,620 5 (0.42%)

1,685,983

(1.07%) 64,954 272,002,430 485(0.75%)

2,653,889

(0.98%)

1 National estimates for the small and large systems are extrapolations generated by multiplying the UCMR 2 national statistical 

sample findings of system/population percentages by the national system/population inventory numbers for PWSs developed from 

EPA’s SDWIS, the CWSS, and UCMR. National estimates for the very large systems are based directly on the UCMR 2 results, 

since this was a census, i.e., all very large systems were required to conduct UCMR 2 Screening Survey. See Section 4.3.3 for a full 

description of national extrapolations. Due to rounding, some calculations may appear to be incorrect. 
EPA-OGWDW Occurrence Data from the UCMR 2

45

NDBA was evaluated relative to an HRL of 0.03 μg/L. NDBA was evaluated relative to 

an HRL of 0.03 μg/L. Exhibit 5-17 and Exhibit 5-18 present the number of systems and the 

population they serve with detections greater than one-half the HRL and the HRL, respectively. 

Nationally, NDBA is estimated to exceed one-half the HRL in 241 small systems serving 

approximately 467,000 people. There were no exceedances of the HRL. 

Exhibit 5-17: NDBA National Occurrence Measures from UCMR 2 Screening 

Survey Data - Summary of System and Population Served Data - Detections > 1⁄2 

HRL

Source Water 

Type UCMR 2 Sample .

Number (and 

Percent) of 

Detections > 1/2 

HRL (0.015 μg/L) in 

the UCMR 2 Sample

. National Inventory .

National Estimate1

of the Number (and 

Percent) of 

Detections > 1/2 

HRL (0.015 μg/L)

.

. Systems Population Systems Population Systems Population Systems Population

. . . . Small Systems (serving ≤ 10,000 people) . . . . 

Ground Water 240 548,364 1 

(0.42%)

6,792

(1.24%) 57,818 37,685,557 241(0.42%)

466,771

(1.24%)

Surface Water 240 660,557 0 

(0%)

0 

(0%) 3,866 8,928,745 0 (0%)

0 

(0%)

All Small 

Systems 480 1,208,921 1 (0.21%)

6,792

(0.56%) 61,684 46,614,302 241(0.39%)

466,771

(1%)

. . . . Large Systems (serving 10,001 - 100,000 people) . . . . 

Ground Water 151 6,584,184 0 

(0%)

0 

(0%) 1,506 38,870,272 0 (0%)

0 

(0%)

Surface Water 169 7,444,830 0 

(0%)

0 

(0%) 1,366 44,536,172 0 (0%)

0 

(0%)

All Large 

Systems 320 14,029,015 0 (0%)

0 

(0%) 2,872 83,406,444 0 (0%)

0 

(0%)

. . . . Very Large Systems (serving > 100,000 people) -- CENSUS . . . . 

Ground Water 63 17,269,919 0 

(0%)

0 

(0%) 63 17,269,919 0 (0%)

0 

(0%)

Surface Water 335 124,711,765 0 

(0%)

0 

(0%) 335 124,711,765 0 (0%)

0 

(0%)

All Very 

Large 

Systems

398 141,981,684 0 

(0%)

0 

(0%) 398 141,981,684 0 (0%)

0 

(0%)

. . . . All Systems . . . . 

All Water 

Systems 1,198 157,219,620 1 (0.08%)

6,792

(0.004%) 64,954 272,002,430 241(0.37%)

466,771

(0.17%)

1 National estimates for the small and large systems are extrapolations generated by multiplying the UCMR 2 national statistical 

sample findings of system/population percentages by the national system/population inventory numbers for PWSs developed from 

EPA’s SDWIS, the CWSS, and UCMR. National estimates for the very large systems are based directly on the UCMR 2 results, 

since this was a census, i.e., all very large systems were required to conduct UCMR 2 Screening Survey. See Section 4.3.3 for a full 

description of national extrapolations. Due to rounding, some calculations may appear to be incorrect. 
EPA-OGWDW Occurrence Data from the UCMR 2

46

Exhibit 5-18: NDBA National Occurrence Measures from UCMR 2 Screening 

Survey Data - Summary of System and Population Served Data - Detections > 

HRL

Source Water 

Type UCMR 2 Sample .

Number (and 

Percent) of 

Detections > HRL 

(0.03 μg/L) in the 

UCMR 2 Sample

. National Inventory .

National Estimate1 of 

the Number (and 

Percent) of 

Detections > HRL 

(0.03 μg/L)

.

. Systems Population Systems Population Systems Population Systems Population

. . . . Small Systems (serving ≤ 10,000 people) . . . . 

Ground Water 240 548,364 0 

(0%)

0 

(0%) 57,818 37,685,557 0 (0%)

0 

(0%)

Surface Water 240 660,557 0 

(0%)

0 

(0%) 3,866 8,928,745 0 (0%)

0 

(0%)

All Small 

Systems 480 1,208,921 0 (0%)

0 

(0%) 61,684 46,614,302 0 (0%)

0 

(0%)

. . . . Large Systems (serving 10,001 - 100,000 people) . . . . 

Ground Water 151 6,584,184 0 

(0%)

0 

(0%) 1,506 38,870,272 0 (0%)

0 

(0%)

Surface Water 169 7,444,830 0 

(0%)

0 

(0%) 1,366 44,536,172 0 (0%)

0 

(0%)

All Large 

Systems 320 14,029,015 0 (0%)

0 

(0%) 2,872 83,406,444 0 (0%)

0 

(0%)

. . . . Very Large Systems (serving > 100,000 people) -- CENSUS . . . . 

Ground Water 63 17,269,919 0 

(0%)

0 

(0%) 63 17,269,919 0 (0%)

0 

(0%)

Surface Water 335 124,711,765 0 

(0%)

0 

(0%) 335 124,711,765 0 (0%)

0 

(0%)

All Very Large 

Systems 398 141,981,684 0 (0%)

0 

(0%) 398 141,981,684 0 (0%)

0 

(0%)

. . . . All Systems . . . . 

All Water 

Systems 1,198 157,219,620 0 (0%)

0 

(0%) 64,954 272,002,430 0 (0%)

0 

(0%)

1 National estimates for the small and large systems are extrapolations generated by multiplying the UCMR 2 national statistical 

sample findings of system/population percentages by the national system/population inventory numbers for PWSs developed from 

EPA’s SDWIS, the CWSS, and UCMR. National estimates for the very large systems are based directly on the UCMR 2 results, 

since this was a census, i.e., all very large systems were required to conduct UCMR 2 Screening Survey. See Section 4.3.3 for a full 

description of national extrapolations. Due to rounding, some calculations may appear to be incorrect. 

5.2.7 NDEA

As indicated in Appendices A and B, under the UCMR 2 Screening Survey 18,096 

samples of NDEA were collected from 1,198 PWSs. Of these, 46 (0.25%) samples had analytical 

detections of NDEA at or above the MRL of 0.005 μg/L. The maximum detected concentration 

of NDEA was 0.1 μg/L and the median value was 0.007 μg/L. Appendix C includes more 

detailed occurrence numbers for NDEA, such as summary statistics by source water type and 

system size and the number and percentage of samples with detections exceeding the HRL.
EPA-OGWDW Occurrence Data from the UCMR 2

47

NDEA was detected in seven ground and 19 surface water systems in eight states and one 

territory (Guam). The majority of these detections occurred in very large surface water systems. 

Systems with detections served a cumulative population of approximately 11.2 million people or 

7.14% of the total population served by UCMR 2 Screening Survey PWSs. The percentage of all 

small, large, and very large UCMR 2 Screening Survey systems with at least one detection of 

NDEA was 2.17%. A summary of the number of systems with detections and the population 

served by them are presented in Exhibit 5-19. 

The design of the UCMR 2 Screening Survey enables extrapolation of national estimates 

of occurrence of contaminants detected in small and large water systems (see Section 4.3.3). 

Occurrence results from the very large systems are already nationally representative so national 

extrapolations are not necessary.

NDEA is estimated to occur nationally in 241 small systems serving approximately 

452,000 people. It is also estimated to occur nationally in 34 large systems serving an estimated 

population of approximately 1.4 million people. NDEA also occurred in 21 very large systems 

serving approximately 11.0 million people. These findings suggest that an estimated 296 PWSs 

serving approximately 12.9 million people nationally have NDEA detections. 

Exhibit 5-19: NDEA National Occurrence Measures from UCMR 2 Screening 

Survey Data - Summary of System and Population Served Data - All Detections

Source Water 

Type UCMR 2 Sample .

Number (and 

Percent) of 

Detections in the 

UCMR 2 Sample

. National Inventory .

National Estimate1 of 

the Number (and 

Percent) of 

Detections

.

. Systems Population Systems Population Systems Population Systems Population

. . . . Small Systems (serving ≤ 10,000 people) . . . . 

Ground Water 240 548,364 1 

(0.42%)

6,575

(1.2%) 57,818 37,685,557 241(0.42%)

451,858

(1.2%)

Surface Water 240 660,557 0 

(0%)

0 

(0%) 3,866 8,928,745 0 (0%)

0 

(0%)

All Small 

Systems 480 1,208,921 1 (0.21%)

6,575

(0.54%) 61,684 46,614,302 241(0.39%)

451,858

(0.97%)

. . . . Large Systems (serving 10,001 - 100,000 people) . . . . 

Ground Water 151 6,584,184 1 

(0.66%)

93,660

(1.42%) 1,506 38,870,272 10(0.66%)

552,930

(1.42%)

Surface Water 169 7,444,830 3 

(1.78%)

148,608

(2%) 1,366 44,536,172 24(1.78%)

888,995

(2%)

All Large 

Systems 320 14,029,015 4 (1.25%)

242,268

(1.73%) 2,872 83,406,444 34(1.19%)

1,441,924

(1.73%)

. . . . Very Large Systems (serving > 100,000 people) -- CENSUS . . . . 

Ground Water 63 17,269,919 5 

(7.94%)

668,861

(3.87%) 63 17,269,919 5 (7.94%)

668,861

(3.87%)
EPA-OGWDW Occurrence Data from the UCMR 2

48

Source Water 

Type UCMR 2 Sample .

Number (and 

Percent) of 

Detections in the 

UCMR 2 Sample

. National Inventory .

National Estimate1 of 

the Number (and 

Percent) of 

Detections

.

. Systems Population Systems Population Systems Population Systems Population

Surface Water 335 124,711,765 16

(4.78%)

10,314,490

(8.27%) 335 124,711,765 16(4.78%)

10,314,490

(8.27%)

All Very Large 

Systems 398 141,981,684 21(5.28%)

10,983,351

(7.74%) 398 141,981,684 21(5.28%)

10,983,351

(7.74%)

. . . . All Systems . . . . 

All Water 

Systems 1,198 157,219,620 26(2.17%)

11,232,194

(7.14%) 64,954 272,002,430 296(0.46%)

12,877,133

(4.73%)

1 National estimates for the small and large systems are extrapolations generated by multiplying the UCMR 2 national statistical 

sample findings of system/population percentages by the national system/population inventory numbers for PWSs developed from 

EPA’s SDWIS, the CWSS, and UCMR. National estimates for the very large systems are based directly on the UCMR 2 results, 

since this was a census, i.e., all very large systems were required to conduct UCMR 2 Screening Survey. See Section 4.3.3 for a full 

description of national extrapolations. Due to rounding, some calculations may appear to be incorrect. 

NDEA was evaluated relative to an HRL of 0.0004 μg/L. Exhibit 5-20 and Exhibit 5-21 

present the number of systems and the population they serve with detections greater than onehalf the HRL and the HRL, respectively. Nationally, NDEA is estimated to exceed one-half the 

HRL and the HRL in 241 small systems serving approximately 452,000 people and 34 large 

systems serving an estimated 1.4 million people. NDEA also exceeded one-half the HRL and the 

HRL in 21 very large systems serving approximately 11.0 million people. These findings suggest 

that an estimated 296 PWSs serving approximately 12.9 million people nationally have NDEA 

detections. (Note that since all of the NDEA detections are greater than the HRL of 0.0004 μg/L, 

the estimates of national exceedance of one-half the HRL and the HRL are identical to the 

estimated NDEA national occurrence presented in Exhibit 5-19 above.) 

Exhibit 5-20: NDEA National Occurrence Measures from UCMR 2 Screening 

Survey Data - Summary of System and Population Served Data - Detections > 1⁄2 

HRL

Source Water 

Type UCMR 2 Sample .

Number (and 

Percent) of 

Detections > 1/2 

HRL (0.0002 μg/L) in 

the UCMR 2 Sample

. National Inventory .

National Estimate1 of 

the Number (and 

Percent) of 

Detections > 1/2 HRL 

(0.0002 μg/L)

.

. Systems Population Systems Population Systems Population Systems Population

. . . . Small Systems (serving ≤ 10,000 people) . . . . 

Ground Water 240 548,364 1 

(0.42%)

6,575

(1.2%) 57,818 37,685,557 241(0.42%)

451,858

(1.2%)

Surface Water 240 660,557 0 

(0%)

0 

(0%) 3,866 8,928,745 0 

(0%)

0 

(0%)

All Small 

Systems 480 1,208,921 1 (0.21%)

6,575

(0.54%) 61,684 46,614,302 241(0.39%)

451,858

(0.97%)
EPA-OGWDW Occurrence Data from the UCMR 2

49

Source Water 

Type UCMR 2 Sample .

Number (and 

Percent) of 

Detections > 1/2 

HRL (0.0002 μg/L) in 

the UCMR 2 Sample

. National Inventory .

National Estimate1 of 

the Number (and 

Percent) of 

Detections > 1/2 HRL 

(0.0002 μg/L)

.

. Systems Population Systems Population Systems Population Systems Population

. . . . Large Systems (serving 10,001 - 100,000 people) . . . . 

Ground Water 151 6,584,184 1 

(0.66%)

93,660

(1.42%) 1,506 38,870,272 10(0.66%)

552,930

(1.42%)

Surface Water 169 7,444,830 3 

(1.78%)

148,608

(2%) 1,366 44,536,172 24(1.78%)

888,995

(2%)

All Large 

Systems 320 14,029,015 4 (1.25%)

242,268

(1.73%) 2,872 83,406,444 34(1.19%)

1,441,924

(1.73%)

. . . . Very Large Systems (serving > 100,000 people) -- CENSUS . . . . 

Ground Water 63 17,269,919 5 

(7.94%)

668,861

(3.87%) 63 17,269,919 5 (7.94%)

668,861

(3.87%)

Surface Water 335 124,711,765 16

(4.78%)

10,314,490

(8.27%) 335 124,711,765 16(4.78%)

10,314,490

(8.27%)

All Very Large 

Systems 398 141,981,684 21(5.28%)

10,983,351

(7.74%) 398 141,981,684 21(5.28%)

10,983,351

(7.74%)

. . . . All Systems . . . . 

All Water 

Systems 1,198 157,219,620 26(2.17%)

11,232,194

(7.14%) 64,954 272,002,430 296(0.46%)

12,877,133

(4.73%)

1 National estimates for the small and large systems are extrapolations generated by multiplying the UCMR 2 national statistical 

sample findings of system/population percentages by the national system/population inventory numbers for PWSs developed from 

EPA’s SDWIS, the CWSS, and UCMR. National estimates for the very large systems are based directly on the UCMR 2 results, 

since this was a census, i.e., all very large systems were required to conduct UCMR 2 Screening Survey. See Section 4.3.3 for a full 

description of national extrapolations. Due to rounding, some calculations may appear to be incorrect. 

Exhibit 5-21: NDEA National Occurrence Measures from UCMR 2 Screening 

Survey Data - Summary of System and Population Served Data - Detections > 

HRL

Source Water 

Type UCMR 2 Sample .

Number (and 

Percent) of 

Detections > HRL 

(0.0004 μg/L) in the 

UCMR 2 Sample

. National Inventory .

National Estimate1 of 

the Number (and 

Percent) of 

Detections > HRL 

(0.0004 μg/L)

.

. Systems Population Systems Population Systems Population Systems Population

. . . . Small Systems (serving ≤ 10,000 people) . . . . 

Ground Water 240 548,364 1 

(0.42%)

6,575

(1.2%) 57,818 37,685,557 241(0.42%)

451,858

(1.2%)

Surface Water 240 660,557 0 

(0%)

0 

(0%) 3,866 8,928,745 0 

(0%)

0 

(0%)

All Small 

Systems 480 1,208,921 1 (0.21%)

6,575

(0.54%) 61,684 46,614,302 241(0.39%)

451,858

(0.97%)
EPA-OGWDW Occurrence Data from the UCMR 2

50

Source Water 

Type UCMR 2 Sample .

Number (and 

Percent) of 

Detections > HRL 

(0.0004 μg/L) in the 

UCMR 2 Sample

. National Inventory .

National Estimate1 of 

the Number (and 

Percent) of 

Detections > HRL 

(0.0004 μg/L)

.

. Systems Population Systems Population Systems Population Systems Population

. . . . Large Systems (serving 10,001 - 100,000 people) . . . . 

Ground Water 151 6,584,184 1 

(0.66%)

93,660

(1.42%) 1,506 38,870,272 10(0.66%)

552,930

(1.42%)

Surface Water 169 7,444,830 3 

(1.78%)

148,608

(2%) 1,366 44,536,172 24(1.78%)

888,995

(2%)

All Large 

Systems 320 14,029,015 4 (1.25%)

242,268

(1.73%) 2,872 83,406,444 34(1.19%)

1,441,924

(1.73%)

. . . . Very Large Systems (serving > 100,000 people) -- CENSUS . . . . 

Ground Water 63 17,269,919 5 

(7.94%)

668,861

(3.87%) 63 17,269,919 5 (7.94%)

668,861

(3.87%)

Surface Water 335 124,711,765 16

(4.78%)

10,314,490

(8.27%) 335 124,711,765 16(4.78%)

10,314,490

(8.27%)

All Very Large 

Systems 398 141,981,684 21(5.28%)

10,983,351

(7.74%) 398 141,981,684 21(5.28%)

10,983,351

(7.74%)

. . . . All Systems . . . . 

All Water 

Systems 1,198 157,219,620 26(2.17%)

11,232,194

(7.14%) 64,954 272,002,430 296(0.46%)

12,877,133

(4.73%)

1 National estimates for the small and large systems are extrapolations generated by multiplying the UCMR 2 national statistical 

sample findings of system/population percentages by the national system/population inventory numbers for PWSs developed from 

EPA’s SDWIS, the CWSS, and UCMR. National estimates for the very large systems are based directly on the UCMR 2 results, 

since this was a census, i.e., all very large systems were required to conduct UCMR 2 Screening Survey. See Section 4.3.3 for a full 

description of national extrapolations. Due to rounding, some calculations may appear to be incorrect. 

5.2.8 NDMA

As indicated in Appendices A and B, under the UCMR 2 Screening Survey 18,098 

samples of NDMA were collected from 1,198 PWSs. Of these, 1,861 samples (10.3%) had 

analytical detections of NDMA at or above the MRL of 0.002 μg/L. The maximum detected 

concentration of NDMA was 0.63 μg/L and the median value was 0.004 μg/L. Appendix C 

includes more detailed occurrence numbers for NDMA, such as summary statistics by source 

water type and system size and the number and percentage of samples with detections exceeding 

the HRL.

NDMA was detected in 45 states and two territories (Guam and Puerto Rico). The 

majority of those detections occurred in surface water systems. The 324 systems with detections 

served a cumulative population of approximately 65.3 million people or 41.54% of the total 

population served by UCMR 2 Screening Survey PWSs. The percentage of all small, large, and 

very large UCMR 2 Screening Survey systems with at least one detection of NDMA was 

27.05%. A summary of the number of systems with detections and the population served by 

them are presented in Exhibit 5-22. 
EPA-OGWDW Occurrence Data from the UCMR 2

51

The design of the UCMR 2 Screening Survey enables extrapolation of national estimates 

of occurrence of contaminants detected in small and large water systems (see Section 4.3.3). 

Occurrence results from the very large systems are already nationally representative so national 

extrapolations are not necessary.

NDMA is estimated to occur nationally in 3,601 small water systems serving an 

estimated 5.3 million people. It is also estimated to occur nationally in 598 large water systems 

of serving an estimated 21.1 million people. NDMA also occurred in 169 very large systems 

serving almost 61.5 million people. These findings suggest that an estimated 4,369 PWSs serving 

approximately 87.9 million people nationally have NDMA detections. 

Exhibit 5-22: NDMA National Occurrence Measures from UCMR 2 Screening 

Survey Data - Summary of System and Population Served Data - All Detections

Source Water 

Type UCMR 2 Sample .

Number (and 

Percent) of 

Detections in the 

UCMR 2 Sample

. National Inventory .

National Estimate1 of 

the Number (and 

Percent) of 

Detections

.

. Systems Population Systems Population Systems Population Systems Population

. . . . Small Systems (serving ≤ 10,000 people) . . . . 

Ground Water 240 548,364 10

(4.17%)

26,059

(4.75%) 57,818 37,685,557 2,409(4.17%)

1,790,869

(4.75%)

Surface Water 240 660,557 74

(30.83%)

259,285

(39.25%) 3,866 8,928,745 1,192(30.83%)

3,504,746

(39.25%)

All Small 

Systems 480 1,208,921 84(17.5%)

285,344

(23.6%) 61,684 46,614,302 3,601(5.84%)

5,295,615

(11.36%)

. . . . Large Systems (serving 10,001 - 100,000 people) . . . . 

Ground Water 151 6,584,184 13

(8.61%)

739,206

(11.23%) 1,506 38,870,272 130(8.61%)

4,363,960

(11.23%)

Surface Water 169 7,444,830 58

(34.32%)

2,792,925

(37.51%) 1,366 44,536,172 469(34.32%)

16,707,724

(37.51%)

All Large 

Systems 320 14,029,015 71(22.19%)

3,532,130

(25.18%) 2,872 83,406,444 598(20.84%)

21,071,684

(25.26%)

. . . . Very Large Systems (serving > 100,000 people) -- CENSUS . . . . 

Ground Water 63 17,269,919 15

(23.81%)

5,706,228

(33.04%) 63 17,269,919 15(23.81%)

5,706,228

(33.04%)

Surface Water 335 124,711,765 154

(45.97%)

55,788,062

(44.73%) 335 124,711,765 154(45.97%)

55,788,062

(44.73%)

All Very Large 

Systems 398 141,981,684 169(42.46%)

61,494,290

(43.31%) 398 141,981,684 169(42.46%)

61,494,290

(43.31%)
EPA-OGWDW Occurrence Data from the UCMR 2

52

Source Water 

Type UCMR 2 Sample .

Number (and 

Percent) of 

Detections in the 

UCMR 2 Sample

. National Inventory .

National Estimate1 of 

the Number (and 

Percent) of 

Detections

.

. Systems Population Systems Population Systems Population Systems Population

. . . . All Systems . . . . 

All Water 

Systems 1,198 157,219,620 324(27.05%)

65,311,764

(41.54%) 64,954 272,002,430 4,369(6.73%)

87,861,589

(32.3%)

1 National estimates for the small and large systems are extrapolations generated by multiplying the UCMR 2 national statistical 

sample findings of system/population percentages by the national system/population inventory numbers for PWSs developed from 

EPA’s SDWIS, the CWSS, and UCMR. National estimates for the very large systems are based directly on the UCMR 2 results, 

since this was a census, i.e., all very large systems were required to conduct UCMR 2 Screening Survey. See Section 4.3.3 for a full 

description of national extrapolations. Due to rounding, some calculations may appear to be incorrect. 

NDMA was evaluated relative to an HRL of 0.0006 μg/L. Exhibit 5-23 and Exhibit 5-24 

present the number of systems and the population they serve with detections greater than onehalf the HRL and the HRL, respectively. Nationally, NDMA is estimated to exceed one-half the 

HRL and the HRL in 3,601 small systems serving an estimated 5.3 million people and 598 large 

systems serving an estimated 21.1 million people. NDMA also exceeded one-half the HRL and 

the HRL in 169 very large systems serving approximately 61.5 million people. These findings 

suggest that an estimated 4,369 PWSs serving approximately 87.9 million people nationally have 

NDMA detections. (Note that since all of the NDMA detections are greater than the HRL of 

0.0006 μg/L, the estimates of national exceedance of one-half the HRL and the HRL are 

identical to the estimated NDMA national occurrence presented in Exhibit 5-22 above.) 

Exhibit 5-23: NDMA National Occurrence Measures from UCMR 2 Screening 

Survey Data - Summary of System and Population Served Data - Detections > 1⁄2 

HRL

Source Water 

Type UCMR 2 Sample .

Number (and 

Percent) of 

Detections > 1/2 

HRL (0.0003 μg/L) in 

the UCMR 2 Sample

. National Inventory .

National Estimate1 of 

the Number (and 

Percent) of 

Detections > 1/2 HRL 

(0.0003 μg/L)

.

. Systems Population Systems Population Systems Population Systems Population

. . . . Small Systems (serving ≤ 10,000 people) . . . . 

Ground Water 240 548,364 10

(4.17%)

26,059

(4.75%) 57,818 37,685,557 2,409(4.17%)

1,790,869

(4.75%)

Surface Water 240 660,557 74

(30.83%)

259,285

(39.25%) 3,866 8,928,745 1,192(30.83%)

3,504,746

(39.25%)

All Small 

Systems 480 1,208,921 84(17.5%)

285,344

(23.6%) 61,684 46,614,302 3,601(5.84%)

5,295,615

(11.36%)

. . . . Large Systems (serving 10,001 - 100,000 people) . . . . 

Ground Water 151 6,584,184 13

(8.61%)

739,206

(11.23%) 1,506 38,870,272 130(8.61%)

4,363,960

(11.23%)
EPA-OGWDW Occurrence Data from the UCMR 2

53

Source Water 

Type UCMR 2 Sample .

Number (and 

Percent) of 

Detections > 1/2 

HRL (0.0003 μg/L) in 

the UCMR 2 Sample

. National Inventory .

National Estimate1 of 

the Number (and 

Percent) of 

Detections > 1/2 HRL 

(0.0003 μg/L)

.

. Systems Population Systems Population Systems Population Systems Population

Surface Water 169 7,444,830 58

(34.32%)

2,792,925

(37.51%) 1,366 44,536,172 469(34.32%)

16,707,724

(37.51%)

All Large 

Systems 320 14,029,015 71(22.19%)

3,532,130

(25.18%) 2,872 83,406,444 598(20.84%)

21,071,684

(25.26%)

. . . . Very Large Systems (serving > 100,000 people) -- CENSUS . . . . 

Ground Water 63 17,269,919 15

(23.81%)

5,706,228

(33.04%) 63 17,269,919 15(23.81%)

5,706,228

(33.04%)

Surface Water 335 124,711,765 154

(45.97%)

55,788,062

(44.73%) 335 124,711,765 154(45.97%)

55,788,062

(44.73%)

All Very Large 

Systems 398 141,981,684 169(42.46%)

61,494,290

(43.31%) 398 141,981,684 169(42.46%)

61,494,290

(43.31%)

. . . . All Systems . . . . 

All Water 

Systems 1,198 157,219,620 324(27.05%)

65,311,764

(41.54%) 64,954 272,002,430 4,369(6.73%)

87,861,589

(32.3%)

1 National estimates for the small and large systems are extrapolations generated by multiplying the UCMR 2 national statistical 

sample findings of system/population percentages by the national system/population inventory numbers for PWSs developed from 

EPA’s SDWIS, the CWSS, and UCMR. National estimates for the very large systems are based directly on the UCMR 2 results, 

since this was a census, i.e., all very large systems were required to conduct UCMR 2 Screening Survey. See Section 4.3.3 for a full 

description of national extrapolations. Due to rounding, some calculations may appear to be incorrect. 

Exhibit 5-24: NDMA National Occurrence Measures from UCMR 2 Screening 

Survey Data - Summary of System and Population Served Data - Detections > 

HRL

Source Water 

Type UCMR 2 Sample .

Number (and 

Percent) of 

Detections > HRL 

(0.0006 μg/L) in the 

UCMR 2 Sample

. National Inventory .

National Estimate1 of 

the Number (and 

Percent) of 

Detections > HRL 

(0.0006 μg/L)

.

. Systems Population Systems Population Systems Population Systems Population

. . . . Small Systems (serving ≤ 10,000 people) . . . . 

Ground Water 240 548,364 10

(4.17%)

26,059

(4.75%) 57,818 37,685,557 2,409(4.17%)

1,790,869

(4.75%)

Surface Water 240 660,557 74

(30.83%)

259,285

(39.25%) 3,866 8,928,745 1,192(30.83%)

3,504,746

(39.25%)

All Small 

Systems 480 1,208,921 84(17.5%)

285,344

(23.6%) 61,684 46,614,302 3,601(5.84%)

5,295,615

(11.36%)

. . . . Large Systems (serving .10,001 - 100,000 people) . . . . 

Ground Water 151 6,584,184 13

(8.61%)

739,206

(11.23%) 1,506 38,870,272 130(8.61%)

4,363,960

(11.23%)
EPA-OGWDW Occurrence Data from the UCMR 2

54

Source Water 

Type UCMR 2 Sample .

Number (and 

Percent) of 

Detections > HRL 

(0.0006 μg/L) in the 

UCMR 2 Sample

. National Inventory .

National Estimate1 of 

the Number (and 

Percent) of 

Detections > HRL 

(0.0006 μg/L)

.

. Systems Population Systems Population Systems Population Systems Population

Surface Water 169 7,444,830 58

(34.32%)

2,792,925

(37.51%) 1,366 44,536,172 469(34.32%)

16,707,724

(37.51%)

All Large 

Systems 320 14,029,015 71(22.19%)

3,532,130

(25.18%) 2,872 83,406,444 598(20.84%)

21,071,684

(25.26%)

. . . . Very Large Systems (serving > 100,000 people) -- CENSUS . . . . 

Ground Water 63 17,269,919 15

(23.81%)

5,706,228

(33.04%) 63 17,269,919 15(23.81%)

5,706,228

(33.04%)

Surface Water 335 124,711,765 154

(45.97%)

55,788,062

(44.73%) 335 124,711,765 154(45.97%)

55,788,062

(44.73%)

All Very Large 

Systems 398 141,981,684 169(42.46%)

61,494,290

(43.31%) 398 141,981,684 169(42.46%)

61,494,290

(43.31%)

. . . . All Systems . . . . 

All Water 

Systems 1,198 157,219,620 324(27.05%)

65,311,764

(41.54%) 64,954 272,002,430 4,369(6.73%)

87,861,589

(32.3%)

1 National estimates for the small and large systems are extrapolations generated by multiplying the UCMR 2 national statistical 

sample findings of system/population percentages by the national system/population inventory numbers for PWSs developed from 

EPA’s SDWIS, the CWSS, and UCMR. National estimates for the very large systems are based directly on the UCMR 2 results, 

since this was a census, i.e., all very large systems were required to conduct UCMR 2 Screening Survey. See Section 4.3.3 for a full 

description of national extrapolations. Due to rounding, some calculations may appear to be incorrect. 

5.2.9 NMEA

As indicated in Appendices A and B, under the UCMR 2 Screening Survey 18,101 

samples of NMEA were collected from 1,198 PWSs. Of these, 3 samples (0.02%) had analytical 

detections of NMEA at or above the MRL of 0.003 μg/L. The maximum detected concentration 

of NMEA was 0.0049 μg/L and the median value was also 0.0045 μg/L. Appendix C includes 

more detailed occurrence numbers for NMEA, such as summary statistics by source water type 

and system size and the number and percentage of samples with detections exceeding the HRL.

All three NMEA detections occurred in three small surface water systems in two states 

(Oklahoma and Washington). These systems served a cumulative population of 4,480 people or 

0.003% of the total population served by UCMR 2 Screening Survey PWSs. The percentage of 

all small, large, and very large UCMR 2 Screening Survey systems with at least one detection of 

NMEA was 0.25%. A summary of the number of systems with detections and the population 

served by them are presented in Exhibit 5-25. 

The design of the UCMR 2 Screening Survey enables extrapolation of national estimates 

of occurrence of contaminants detected in small and large water systems (see Section 4.3.3). 

Occurrence results from the very large systems are already nationally representative so national 

extrapolations are not necessary.
EPA-OGWDW Occurrence Data from the UCMR 2

55

NMEA is estimated to occur nationally in 48 small water systems serving approximately 

61,000 people. It is not estimated to occur nationally in any large or very large water systems. 

These findings suggest that an estimated 48 PWSs serving approximately 61,000 people 

nationally have NMEA detections.

Exhibit 5-25: NMEA National Occurrence Measures from UCMR 2 Screening 

Survey Data - Summary of System and Population Served Data - All Detections

Source Water 

Type UCMR 2 Sample .

Number (and 

Percent) of 

Detections in the 

UCMR 2 Sample

. National Inventory .

National Estimate1 of 

the Number (and 

Percent) of 

Detections

.

. Systems Population Systems Population Systems Population Systems Population

. . . . Small Systems (serving ≤ 10,000 people) . . . . 

Ground Water 240 548,364 0 

(0%)

0 

(0%) 57,818 37,685,557 0 (0%)

0 

(0%)

Surface Water 240 660,557 3 

(1.25%)

4,480

(0.68%) 3,866 8,928,745 48(1.25%)

60,556

(0.68%)

All Small 

Systems 480 1,208,921 3 (0.63%)

4,480

(0.37%) 61,684 46,614,302 48(0.08%)

60,556

(0.13%)

. . . . Large Systems (serving 10,001 - 100,000 people) . . . . 

Ground Water 151 6,584,184 0 

(0%)

0 

(0%) 1,506 38,870,272 0 (0%)

0 

(0%)

Surface Water 169 7,444,830 0 

(0%)

0 

(0%) 1,366 44,536,172 0 (0%)

0 

(0%)

All Large 

Systems 320 14,029,015 0 (0%)

0 

(0%) 2,872 83,406,444 0 (0%)

0 

(0%)

. . . . Very Large Systems (serving > 100,000 people) -- CENSUS . . . . 

Ground Water 63 17,269,919 0 

(0%)

0 

(0%) 63 17,269,919 0 (0%)

0 

(0%)

Surface Water 335 124,711,765 0 

(0%)

0 

(0%) 335 124,711,765 0 (0%)

0 

(0%)

All Very Large 

Systems 398 141,981,684 0 (0%)

0 

(0%) 398 141,981,684 0 (0%)

0 

(0%)

. . . . All Systems . . . . 

All Water 

Systems 1,198 157,219,620 3 (0.25%)

4,480

(0.003%) 64,954 272,002,430 48(0.07%)

60,556

(0.02%)

1 National estimates for the small and large systems are extrapolations generated by multiplying the UCMR 2 national statistical 

sample findings of system/population percentages by the national system/population inventory numbers for PWSs developed from 

EPA’s SDWIS, the CWSS, and UCMR. National estimates for the very large systems are based directly on the UCMR 2 results, 

since this was a census, i.e., all very large systems were required to conduct UCMR 2 Screening Survey. See Section 4.3.3 for a full 

description of national extrapolations. Due to rounding, some calculations may appear to be incorrect. 

NMEA was evaluated relative to an HRL of 0.003 μg/L. Exhibit 5-26 and Exhibit 5-27 

present the number of systems and the population they serve with detections greater than one-
EPA-OGWDW Occurrence Data from the UCMR 2

56

half the HRL and the HRL, respectively. Nationally, NMEA is estimated to exceed one-half the 

HRL and the HRL in 48 small systems serving an estimated 61,000 people. NMEA is not 

estimated to occur nationally in any large or very large water systems. These findings suggest 

that an estimated 48 PWSs serving approximately 61,000 people nationally have NMEA 

detections. (Note that since all of the NMEA detections are greater than the HRL of 0.003 μg/L, 

the estimates of national exceedance of one-half the HRL and the HRL are identical to the 

estimated NMEA national occurrence presented in Exhibit 5-25 above.) 

Exhibit 5-26: NMEA National Occurrence Measures from UCMR 2 Screening 

Survey Data - Summary of System and Population Served Data – 

Detections > 1⁄2 HRL

Source Water 

Type UCMR 2 Sample .

Number (and 

Percent) of 

Detections > 1/2 

HRL (0.0015 μg/L) in 

the UCMR 2 Sample

. National Inventory .

National Estimate1 of 

the Number (and 

Percent) of 

Detections > 1/2 HRL 

(0.0015 μg/L)

.

. Systems Population Systems Population Systems Population Systems Population

. . . . Small Systems (serving ≤ 10,000 people) . . . . 

Ground Water 240 548,364 0 

(0%)

0 

(0%) 57,818 37,685,557 0 (0%)

0 

(0%)

Surface Water 240 660,557 3 

(1.25%)

4,480

(0.68%) 3,866 8,928,745 48(1.25%)

60,556

(0.68%)

All Small 

Systems 480 1,208,921 3 (0.63%)

4,480

(0.37%) 61,684 46,614,302 48(0.08%)

60,556

(0.13%)

. . . . Large Systems (serving 10,001 - 100,000 people) . . . . 

Ground Water 151 6,584,184 0 

(0%)

0 

(0%) 1,506 38,870,272 0 (0%)

0 

(0%)

Surface Water 169 7,444,830 0 

(0%)

0 

(0%) 1,366 44,536,172 0 (0%)

0 

(0%)

All Large 

Systems 320 14,029,015 0 (0%)

0 

(0%) 2,872 83,406,444 0 (0%)

0 

(0%)

. . . . Very Large Systems (serving > 100,000 people) -- CENSUS . . . . 

Ground Water 63 17,269,919 0 

(0%)

0 

(0%) 63 17,269,919 0 (0%)

0 

(0%)

Surface Water 335 124,711,765 0 

(0%)

0 

(0%) 335 124,711,765 0 (0%)

0 

(0%)

All Very Large 

Systems 398 141,981,684 0 (0%)

0 

(0%) 398 141,981,684 0 (0%)

0 

(0%)

. . . . All Systems . . . . 

All Water 

Systems 1,198 157,219,620 3 (0.25%)

4,480

(0.003%) 64,954 272,002,430 48(0.07%)

60,556

(0.02%)

1 National estimates for the small and large systems are extrapolations generated by multiplying the UCMR 2 national statistical 

sample findings of system/population percentages by the national system/population inventory numbers for PWSs developed from 

EPA’s SDWIS, the CWSS, and UCMR. National estimates for the very large systems are based directly on the UCMR 2 results, 

since this was a census, i.e., all very large systems were required to conduct UCMR 2 Screening Survey. See Section 4.3.3 for a full 

description of national extrapolations. Due to rounding, some calculations may appear to be incorrect. 
EPA-OGWDW Occurrence Data from the UCMR 2

57

Exhibit 5-27: NMEA National Occurrence Measures from UCMR 2 Screening 

Survey Data - Summary of System and Population Served Data - Detections > 

HRL

Source Water 

Type UCMR 2 Sample .

Number (and 

Percent) of 

Detections > HRL 

(0.003 μg/L) in the 

UCMR 2 Sample

. National Inventory .

National Estimate1 of 

the Number (and 

Percent) of 

Detections > HRL 

(0.003 μg/L)

.

. Systems Population Systems Population Systems Population Systems Population

. . . . Small Systems (serving ≤ 10,000 people) . . . . 

Ground Water 240 548,364 0 

(0%)

0 

(0%) 57,818 37,685,557 0 (0%)

0 

(0%)

Surface Water 240 660,557 3 

(1.25%)

4,480

(0.68%) 3,866 8,928,745 48(1.25%)

60,556

(0.68%)

All Small 

Systems 480 1,208,921 3 (0.63%)

4,480

(0.37%) 61,684 46,614,302 48(0.08%)

60,556

(0.13%)

. . . . Large Systems (serving 10,001 - 100,000 people) . . . . 

Ground Water 151 6,584,184 0 

(0%)

0 

(0%) 1,506 38,870,272 0 (0%)

0 

(0%)

Surface Water 169 7,444,830 0 

(0%)

0 

(0%) 1,366 44,536,172 0 (0%)

0 

(0%)

All Large 

Systems 320 14,029,015 0 (0%)

0 

(0%) 2,872 83,406,444 0 (0%)

0 

(0%)

. . . . Very Large Systems (serving > 100,000 people) -- CENSUS . . . . 

Ground Water 63 17,269,919 0 

(0%)

0 

(0%) 63 17,269,919 0 (0%)

0 

(0%)

Surface Water 335 124,711,765 0 

(0%)

0 

(0%) 335 124,711,765 0 (0%)

0 

(0%)

All Very Large 

Systems 398 141,981,684 0 (0%)

0 

(0%) 398 141,981,684 0 (0%)

0 

(0%)

. . . . All Systems . . . . 

All Water 

Systems 1,198 157,219,620 3 (0.25%)

4,480

(0.003%) 64,954 272,002,430 48(0.07%)

60,556

(0.02%)

1 National estimates for the small and large systems are extrapolations generated by multiplying the UCMR 2 national statistical 

sample findings of system/population percentages by the national system/population inventory numbers for PWSs developed from 

EPA’s SDWIS, the CWSS, and UCMR. National estimates for the very large systems are based directly on the UCMR 2 results, 

since this was a census, i.e., all very large systems were required to conduct UCMR 2 Screening Survey. See Section 4.3.3 for a full 

description of national extrapolations. Due to rounding, some calculations may appear to be incorrect. 
EPA-OGWDW Occurrence Data from the UCMR 2

58

5.2.10 NPYR

As indicated in Appendices A and B, under the UCMR 2 Screening Survey 18,101 

samples of NPYR were collected from 1,198 PWSs. Of these, 41 samples (0.23%) had analytical 

detections of NPYR at or above the MRL of 0.002 μg/L. The maximum detected concentration 

of NPYR was 0.0238 μg/L and the median value was 0.0039 μg/L. Appendix C includes more 

detailed occurrence numbers for NPYR, such as summary statistics by source water type and 

system size and the number and percentage of samples with detections exceeding the HRL.

The 41 NPYR detections occurred in 21 systems in 10 states; all but one of the systems 

were surface water systems. The 21 systems served a cumulative population of approximately 

7.4 million people, or 4.73% of the total population served by UCMR 2 Screening Survey PWSs. 

The percentage of all small, large, and very large UCMR 2 Screening Survey systems with at 

least one detection of NPYR was 1.75%. A summary of the number of systems with detections 

and the population served by them are presented in Exhibit 5-28. 

The design of the UCMR 2 Screening Survey enables extrapolation of national estimates 

of occurrence of contaminants detected in small and large water systems (see Section 4.3.3). 

Occurrence results from the very large systems are already nationally representative so national 

extrapolations are not necessary.

NPYR is estimated to occur nationally in 48 small systems serving approximately 

197,000 people. It is also estimated to occur nationally in 48 large systems serving an estimated 

1.1 million people. NPYR also occurred in 12 very large systems serving about 7.2 million 

people. These findings suggest that an estimated 109 PWSs serving approximately 8.6 million 

people nationally have NPYR detections. 

Exhibit 5-28: NPYR National Occurrence Measures from UCMR 2 Screening 

Survey Data - Summary of System and Population Served Data - All Detections

Source Water 

Type UCMR 2 Sample .

Number (and 

Percent) of 

Detections in the 

UCMR 2 Sample

. National Inventory .

National Estimate1

of the Number (and 

Percent) of 

Detections

.

. Systems Population Systems Population Systems Population Systems Population

. . . . Small Systems (serving ≤ 10,000 people) . . . . 

Ground Water 240 548,364 0 

(0%)

0 

(0%) 57,818 37,685,557 0 (0%)

0 

(0%)

Surface Water 240 660,557 3 

(1.25%)

14,572

(2.21%) 3,866 8,928,745 48(1.25%)

196,970

(2.21%)

All Small 

Systems 480 1,208,921 3 (0.63%)

14,572

(1.21%) 61,684 46,614,302 48(0.08%)

196,970

(0.42%)

. . . . Large Systems (serving 10,001 - 100,000 people) . . . . 

Ground Water 151 6,584,184 0 

(0%)

0 

(0%) 1,506 38,870,272 0 (0%)

0 

(0%)
EPA-OGWDW Occurrence Data from the UCMR 2

59

Source Water 

Type UCMR 2 Sample .

Number (and 

Percent) of 

Detections in the 

UCMR 2 Sample

. National Inventory .

National Estimate1

of the Number (and 

Percent) of 

Detections

.

. Systems Population Systems Population Systems Population Systems Population

Surface Water 169 7,444,830 6 

(3.55%)

188,603

(2.53%) 1,366 44,536,172 48(3.55%)

1,128,251

(2.53%)

All Large 

Systems 320 14,029,015 6 (1.88%)

188,603

(1.34%) 2,872 83,406,444 48(1.69%)

1,128,251

(1.35%)

. . . . Very Large Systems (serving > 100,000 people) -- CENSUS . . . . 

Ground Water 63 17,269,919 1 

(1.59%)

148,137

(0.86%) 63 17,269,919 1 (1.59%)

148,137

(0.86%)

Surface Water 335 124,711,765 11

(3.28%)

7,080,239

(5.68%) 335 124,711,765 11(3.28%)

7,080,239

(5.68%)

All Very Large 

Systems 398 141,981,684 12(3.02%)

7,228,376

(5.09%) 398 141,981,684 12(3.02%)

7,228,376

(5.09%)

. . . . All Systems . . . . 

All Water 

Systems 1,198 157,219,620 21(1.75%)

7,431,551

(4.73%) 64,954 272,002,430 109(0.17%)

8,553,597

(3.14%)

1 National estimates for the small and large systems are extrapolations generated by multiplying the UCMR 2 national statistical 

sample findings of system/population percentages by the national system/population inventory numbers for PWSs developed from 

EPA’s SDWIS, the CWSS, and UCMR. National estimates for the very large systems are based directly on the UCMR 2 results, 

since this was a census, i.e., all very large systems were required to conduct UCMR 2 Screening Survey. See Section 4.3.3 for a full 

description of national extrapolations. Due to rounding, some calculations may appear to be incorrect. 

NPYR was evaluated relative to an HRL of 0.002 μg/L. Exhibit 5-29 and Exhibit 5-30 

present the number of systems with detections greater than one-half the HRL and the HRL, 

respectively as well as the population they serve. NPYR is estimated to occur greater than onehalf the HRL and the HRL in 48 small systems serving approximately 197,000 people nationally. 

It is also estimated to occur nationally greater than one-half the HRL and the HRL in 48 large 

systems serving an estimated 1.1 million people. NPYR also occurred in 12 very large systems 

serving about 7.2 million people. These findings suggest that an estimated 109 PWSs serving 

approximately 8.6 million people nationally have NPYR detections greater than the HRL. (Note 

that since all of the NPYR detections are greater than the HRL of 0.002 μg/L, the estimates of 

national exceedance of one-half the HRL and the HRL are identical to the estimated NPYR 

national occurrence presented in Exhibit 6-27 above.) 
EPA-OGWDW Occurrence Data from the UCMR 2

60

Exhibit 5-29: NPYR National Occurrence Measures from UCMR 2 Screening 

Survey Data - Summary of System and Population Served Data - Detections > 1⁄2 

HRL

Source Water 

Type UCMR 2 Sample .

Number (and 

Percent) of 

Detections > 1/2 

HRL (0.001 μg/L) in 

the UCMR 2 Sample

. National Inventory .

National Estimate1 of 

the Number (and 

Percent) of 

Detections > 1/2 HRL 

(0.001 μg/L)

.

. Systems Population Systems Population Systems Population Systems Population

. . . . Small Systems (serving ≤ 10,000 people) . . . . 

Ground Water 240 548,364 0 

(0%)

0 

(0%) 57,818 37,685,557 0 (0%)

0 

(0%)

Surface Water 240 660,557 3 

(1.25%)

14,572

(2.21%) 3,866 8,928,745 48(1.25%)

196,970

(2.21%)

All Small 

Systems 480 1,208,921 3 (0.63%)

14,572

(1.21%) 61,684 46,614,302 48(0.08%)

196,970

(0.42%)

. . . . Large Systems (serving 10,001 - 100,000 people) . . . . 

Ground Water 151 6,584,184 0 

(0%)

0 

(0%) 1,506 38,870,272 0 (0%)

0 

(0%)

Surface Water 169 7,444,830 6 

(3.55%)

188,603

(2.53%) 1,366 44,536,172 48(3.55%)

1,128,251

(2.53%)

All Large 

Systems 320 14,029,015 6 (1.88%)

188,603

(1.34%) 2,872 83,406,444 48(1.69%)

1,128,251

(1.35%)

. . . . Very Large Systems (serving > 100,000 people) -- CENSUS . . . . 

Ground Water 63 17,269,919 1 

(1.59%)

148,137

(0.86%) 63 17,269,919 1 (1.59%)

148,137

(0.86%)

Surface Water 335 124,711,765 11

(3.28%)

7,080,239

(5.68%) 335 124,711,765 11(3.28%)

7,080,239

(5.68%)

All Very Large 

Systems 398 141,981,684 12(3.02%)

7,228,376

(5.09%) 398 141,981,684 12(3.02%)

7,228,376

(5.09%)

. . . . All Systems . . . . 

All Water 

Systems 1,198 157,219,620 21(1.75%)

7,431,551

(4.73%) 64,954 272,002,430 109(0.17%)

8,553,597

(3.14%)

1 National estimates for the small and large systems are extrapolations generated by multiplying the UCMR 2 national statistical 

sample findings of system/population percentages by the national system/population inventory numbers for PWSs developed from 

EPA’s SDWIS, the CWSS, and UCMR. National estimates for the very large systems are based directly on the UCMR 2 results, 

since this was a census, i.e., all very large systems were required to conduct UCMR 2 Screening Survey. See Section 4.3.3 for a full 

description of national extrapolations. Due to rounding, some calculations may appear to be incorrect. 
EPA-OGWDW Occurrence Data from the UCMR 2

61

Exhibit 5-30: NPYR National Occurrence Measures from UCMR 2 Screening 

Survey Data - Summary of System and Population Served Data - Detections > 

HRL

Source Water 

Type UCMR 2 Sample .

Number (and 

Percent) of 

Detections > HRL 

(0.002 μg/L) in the 

UCMR 2 Sample

. National Inventory .

National Estimate1

of the Number (and 

Percent) of 

Detections > HRL 

(0.002 μg/L)

.

. Systems Population Systems Population Systems Population Systems Population

. . . . Small Systems (serving ≤ 10,000 people) . . . . 

Ground Water 240 548,364 0 

(0%)

0 

(0%) 57,818 37,685,557 0 (0%)

0 

(0%)

Surface Water 240 660,557 3 

(1.25%)

14,572

(2.21%) 3,866 8,928,745 48(1.25%)

196,970

(2.21%)

All Small 

Systems 480 1,208,921 3 (0.63%)

14,572

(1.21%) 61,684 46,614,302 48(0.08%)

196,970

(0.42%)

. . . . Large Systems (serving 10,001 - 100,000 people) . . . . 

Ground Water 151 6,584,184 0 

(0%)

0 

(0%) 1,506 38,870,272 0 (0%)

0 

(0%)

Surface Water 169 7,444,830 6 

(3.55%)

188,603

(2.53%) 1,366 44,536,172 48(3.55%)

1,128,251

(2.53%)

All Large 

Systems 320 14,029,015 6 (1.88%)

188,603

(1.34%) 2,872 83,406,444 48(1.69%)

1,128,251

(1.35%)

. . . . Very Large Systems (serving > 100,000 people) -- CENSUS . . . . 

Ground Water 63 17,269,919 1 

(1.59%)

148,137

(0.86%) 63 17,269,919 1 (1.59%)

148,137

(0.86%)

Surface Water 335 124,711,765 11

(3.28%)

7,080,239

(5.68%) 335 124,711,765 11(3.28%)

7,080,239

(5.68%)

All Very 

Large 

Systems

398 141,981,684 12

(3.02%)

7,228,376

(5.09%) 398 141,981,684 12(3.02%)

7,228,376

(5.09%)

. . . . All Systems . . . . 

All Water 

Systems 1,198 157,219,620 21(1.75%)

7,431,551

(4.73%) 64,954 272,002,430 109(0.17%)

8,553,597

(3.14%)

1 National estimates for the small and large systems are extrapolations generated by multiplying the UCMR 2 national statistical 

sample findings of system/population percentages by the national system/population inventory numbers for PWSs developed from 

EPA’s SDWIS, the CWSS, and UCMR. National estimates for the very large systems are based directly on the UCMR 2 results, 

since this was a census, i.e., all very large systems were required to conduct UCMR 2 Screening Survey. See Section 4.3.3 for a full 

description of national extrapolations. Due to rounding, some calculations may appear to be incorrect. 
EPA-OGWDW Occurrence Data from the UCMR 2

62

6 References

United States Environmental Protection Agency (USEPA). 1999. Revisions to the Unregulated 

Contaminant Monitoring Regulation for Public Water Systems. Federal Register. Vol. 64, no. 

180, p. 50556, September 17, 1999. 

USEPA. 2001. Statistical Design and Sample Selection for the Unregulated Contaminant 

Monitoring Regulation (1999). August 2001. EPA-815-R-01-004, Office of Water. 

USEPA. 2002. Analysis of National Occurrence of the 1998 Contaminant Candidate List (CCL) 

Regulatory Determination Priority Contaminants in Public Water Systems. May 2002. EPA-815-

D-01-002, Office of Water.

USEPA. 2003a. Occurrence Estimation Methodology and Occurrence Findings for Six-Year 

Review of National Primary Drinking Water Regulations. June 2003. EPA-815-R-03-006, Office 

of Water.

USEPA. 2003b. Quality Assurance Project Plan for the Implementation of the Unregulated 

Contaminant Monitoring Regulation. Draft. April 2003. Office of Water.

USEPA. 2005. Unregulated Contaminant Monitoring Regulation (UCMR) for Public Water 

Systems Revisions; Proposed Rule. Federal Register. Vol. 70, no. 161, p. 49093, August 22, 

2005. 

USEPA. 2006. Reference Guide for the Second Cycle of the Unregulated Contaminant 

Monitoring Regulation (UCMR 2). December 2006. EPA-815-R-06-016, Office of Water.

USEPA. 2007. Unregulated Contaminant Monitoring Regulation (UCMR) for Public Water 

Systems Revisions; Final Rule. Federal Register. Vol. 72, no. 2, p. 367, January 4, 2007. 

USEPA. 2008a. The Analysis of Occurrence Data from the Unregulated Contaminant 

Monitoring Program (UCM) and National Inorganics and Radionuclides Survey (NIRS) in 

Support of Regulatory Determinations for the Second Drinking Water Contaminant Candidate 

List (CCL 2). June 2008. EPA-815-R-08-014, Office of Water. 

USEPA. 2008b. The Analysis of Occurrence Data from the First Unregulated Contaminant 

Monitoring Regulation (UCMR 1) in Support of Regulatory Determinations for the Second 

Drinking Water Contaminant Candidate List. June 2008. EPA-815-R-08-013, Office of Water. 

USEPA. 2009. Standard Operating Procedure: NCOD Data Import for Small Systems for the 

Second Cycle of the Unregulated Contaminant Monitoring Regulation. Revision 1.0. December 

2009. SOP TSC UCMR2 004. 

USEPA. 2010. Technical Description of the Statistical Model of Perchlorate Occurrence in 

Drinking Water. Peer Reviewed Draft Report.
EPA-OGWDW Occurrence Data from the UCMR 2

63

USEPA. 2014a. Protocol for the Regulatory Determination 3. Post-expert review final. Including 

Appendices A-F. April 2014. EPA-815-R-14-005. 

USEPA 2014b. Announcement of Preliminary Regulatory Determinations for Contaminants on 

the Third Drinking Water Contaminant Candidate List. Federal Register. Vol. 79, No. 202, pp. 

62715-62750. 

USEPA. 2015. Regulatory Determination 3 Support Document. EPA 815-R-15-014. 
EPA-OGWDW Occurrence Data from the UCMR 2 

List of Appendix Tables

Appendix A. Final UCMR 2 Data: Summary of Occurrence Based on Samples, Systems, and 

Population Served 

Appendix B. Final UCMR 2 Data: Summary of Systems and Population Served by State 

Appendix C. Final UCMR 2 Data: Summary of Samples (Relative to the HRL) and Summary of 

Detected Concentrations
EPA-OGWDW Occurrence Data from the UCMR 2 

Appendix A

Table A1. BDE-47 – Final UCMR 2 Assessment Monitoring Data - Occurrence Based on 

Samples, Systems, and Population Served 

Table A2. BDE-99 - Final UCMR 2 Assessment Monitoring Data - Occurrence Based on 

Samples, Systems, and Population Served 

Table A3. BDE-100 - Final UCMR 2 Assessment Monitoring Data - Occurrence Based on 

Samples, Systems, and Population Served 

Table A4. BDE-153 - Final UCMR 2 Assessment Monitoring Data - Occurrence Based on 

Samples, Systems, and Population Served 

Table A5. Dimethoate - Final UCMR 2 Assessment Monitoring Data - Occurrence Based on 

Samples, Systems, and Population Served 

Table A6. 1,3-Dinitrobenzene - Final UCMR 2 Assessment Monitoring Data - Occurrence Based 

on Samples, Systems, and Population Served 

Table A7. HBB - Final UCMR 2 Assessment Monitoring Data - Occurrence Based on Samples, 

Systems, and Population Served 

Table A8. RDX - Final UCMR 2 Assessment Monitoring Data - Occurrence Based on Samples, 

Systems, and Population Served 

Table A9. Terbufos Sulfone - Final UCMR 2 Assessment Monitoring Data - Occurrence Based 

on Samples, Systems, and Population Served 

Table A10. TNT - Final UCMR 2 Assessment Monitoring Data - Occurrence Based on Samples, 

Systems, and Population Served 

Table A11. Acetochlor - Final UCMR 2 Screening Survey Data - Occurrence Based on Samples, 

Systems, and Population Served 

Table A12. Acetochlor ESA - Final UCMR 2 Screening Survey Data - Occurrence Based on 

Samples, Systems, and Population Served 

Table A13. Acetochlor OA - Final UCMR 2 Screening Survey Data - Occurrence Based on 

Samples, Systems, and Population Served 

Table A14. Alachlor - Final UCMR 2 Screening Survey Data - Occurrence Based on Samples, 

Systems, and Population Served 

Table A15. Alachlor ESA - Final UCMR 2 Screening Survey Data - Occurrence Based on 

Samples, Systems, and Population Served 

Table A16. Alachlor OA - Final UCMR 2 Screening Survey Data - Occurrence Based on 

Samples, Systems, and Population Served 

Table A17. Metolachlor - Final UCMR 2 Screening Survey Data - Occurrence Based on 

Samples, Systems, and Population Served 
EPA-OGWDW Occurrence Data from the UCMR 2 

Table A18. Metolachlor ESA - Final UCMR 2 Screening Survey Data - Occurrence Based on 

Samples, Systems, and Population Served 

Table A19. Metolachlor OA - Final UCMR 2 Screening Survey Data - Occurrence Based on 

Samples, Systems, and Population Served 

Table A20. NDBA - Final UCMR 2 Screening Survey Data - Occurrence Based on Samples, 

Systems, and Population Served 

Table A21. NDEA - Final UCMR 2 Screening Survey Data - Occurrence Based on Samples, 

Systems, and Population Served 

Table A22. NDMA - Final UCMR 2 Screening Survey Data - Occurrence Based on Samples, 

Systems, and Population Served 

Table A23. NDPA - Final UCMR 2 Screening Survey Data - Occurrence Based on Samples, 

Systems, and Population Served 

Table A24. NMEA - Final UCMR 2 Screening Survey Data - Occurrence Based on Samples, 

Systems, and Population Served 

Table A25. NPYR - Final UCMR 2 Screening Survey Data - Occurrence Based on Samples, 

Systems, and Population Served 
EPA-OGWDW

Appendix A. Summary of Occurrence Based on Samples, Systems, and Population Served

Occurrence Data from the UCMR 2

Table A1. BDE-47 - UCMR 2 Assessment Monitoring Data - Occurrence Based on Samples, Systems, and Population Served 

Source Water Type Total Number 

of Samples

Samples with 

Detections: 

Number

Samples with 

Detections: 

Percent

Total Number 

of Systems

Systems with 

Detections: 

Number

Systems with 

Detections: 

Percent

Population 

Served by 

Systems

Population 

Served by 

Systems with 

Detections: 

Number

Population 

Served by 

Systems with 

Detections: 

Percent

Sample of Small Systems (serving ≤ 10,000 people)

Ground Water 2,328 0 0.00% 618 0 0.00% 1,790,743 0 0.00%

Surface Water 920 0 0.00% 182 0 0.00% 878,262 0 0.00%

All Small Systems 3,248 0 0.00% 800 0 0.00% 2,669,004 0 0.00%

Census of Large Systems (serving 10,001 - 100,000 people)

Ground Water 11,760 0 0.00% 1,374 0 0.00% 34,828,693 0 0.00%

Surface Water 10,331 0 0.00% 1,568 0 0.00% 49,758,358 0 0.00%

All Large Systems 22,091 0 0.00% 2,942 0 0.00% 84,587,051 0 0.00%

Census of Very Large Systems (serving > 100,000 people)

Ground Water 2,014 0 0.00% 63 0 0.00% 17,269,919 0 0.00%

Surface Water 4,796 0 0.00% 335 0 0.00% 124,711,765 0 0.00%

All Very Large Systems 6,810 0 0.00% 398 0 0.00% 141,981,684 0 0.00%

All Systems

All Water Systems 32,149 0 0.00% 4,140 0 0.00% 229,237,740 0 0.00%

Page 1 of 25
EPA-OGWDW

Appendix A. Summary of Occurrence Based on Samples, Systems, and Population Served

Occurrence Data from the UCMR 2

Table A2. BDE-99 - UCMR 2 Assessment Monitoring Data - Occurrence Based on Samples, Systems, and Population Served 

Source Water Type Total Number 

of Samples

Samples with 

Detections: 

Number

Samples with 

Detections: 

Percent

Total Number 

of Systems

Systems with 

Detections: 

Number

Systems with 

Detections: 

Percent

Population 

Served by 

Systems

Population 

Served by 

Systems with 

Detections: 

Number

Population 

Served by 

Systems with 

Detections: 

Percent

Sample of Small Systems (serving ≤ 10,000 people)

Ground Water 2,328 0 0.00% 618 0 0.00% 1,790,743 0 0.00%

Surface Water 920 0 0.00% 182 0 0.00% 878,262 0 0.00%

All Small Systems 3,248 0 0.00% 800 0 0.00% 2,669,004 0 0.00%

Census of Large Systems (serving 10,001 - 100,000 people)

Ground Water 11,760 0 0.00% 1,374 0 0.00% 34,828,693 0 0.00%

Surface Water 10,331 0 0.00% 1,568 0 0.00% 49,758,358 0 0.00%

All Large Systems 22,091 0 0.00% 2,942 0 0.00% 84,587,051 0 0.00%

Census of Very Large Systems (serving > 100,000 people)

Ground Water 2,014 0 0.00% 63 0 0.00% 17,269,919 0 0.00%

Surface Water 4,796 0 0.00% 335 0 0.00% 124,711,765 0 0.00%

All Very Large Systems 6,810 0 0.00% 398 0 0.00% 141,981,684 0 0.00%

All Systems

All Water Systems 32,149 0 0.00% 4,140 0 0.00% 229,237,740 0 0.00%

Page 2 of 25
EPA-OGWDW

Appendix A. Summary of Occurrence Based on Samples, Systems, and Population Served

Occurrence Data from the UCMR 2

Table A3. BDE-100 - UCMR 2 Assessment Monitoring Data - Occurrence Based on Samples, Systems, and Population Served 

Source Water Type Total Number 

of Samples

Samples with 

Detections: 

Number

Samples with 

Detections: 

Percent

Total Number 

of Systems

Systems with 

Detections: 

Number

Systems with 

Detections: 

Percent

Population 

Served by 

Systems

Population 

Served by 

Systems with 

Detections: 

Number

Population 

Served by 

Systems with 

Detections: 

Percent

Sample of Small Systems (serving ≤ 10,000 people)

Ground Water 2,328 0 0.00% 618 0 0.00% 1,790,743 0 0.00%

Surface Water 920 0 0.00% 182 0 0.00% 878,262 0 0.00%

All Small Systems 3,248 0 0.00% 800 0 0.00% 2,669,004 0 0.00%

Census of Large Systems (serving 10,001 - 100,000 people)

Ground Water 11,760 0 0.00% 1,374 0 0.00% 34,828,693 0 0.00%

Surface Water 10,331 0 0.00% 1,568 0 0.00% 49,758,358 0 0.00%

All Large Systems 22,091 0 0.00% 2,942 0 0.00% 84,587,051 0 0.00%

Census of Very Large Systems (serving > 100,000 people)

Ground Water 2,014 0 0.00% 63 0 0.00% 17,269,919 0 0.00%

Surface Water 4,796 0 0.00% 335 0 0.00% 124,711,765 0 0.00%

All Very Large Systems 6,810 0 0.00% 398 0 0.00% 141,981,684 0 0.00%

All Systems

All Water Systems 32,149 0 0.00% 4,140 0 0.00% 229,237,740 0 0.00%

Page 3 of 25
EPA-OGWDW

Appendix A. Summary of Occurrence Based on Samples, Systems, and Population Served

Occurrence Data from the UCMR 2

Table A4. BDE-153 - UCMR 2 Assessment Monitoring Data - Occurrence Based on Samples, Systems, and Population Served 

Source Water Type Total Number 

of Samples

Samples with 

Detections: 

Number

Samples with 

Detections: 

Percent

Total Number 

of Systems

Systems with 

Detections: 

Number

Systems with 

Detections: 

Percent

Population 

Served by 

Systems

Population 

Served by 

Systems with 

Detections: 

Number

Population 

Served by 

Systems with 

Detections: 

Percent

Sample of Small Systems (serving ≤ 10,000 people)

Ground Water 2,328 0 0.00% 618 0 0.00% 1,790,743 0 0.00%

Surface Water 920 0 0.00% 182 0 0.00% 878,262 0 0.00%

All Small Systems 3,248 0 0.00% 800 0 0.00% 2,669,004 0 0.00%

Census of Large Systems (serving 10,001 - 100,000 people)

Ground Water 11,759 0 0.00% 1,374 0 0.00% 34,828,693 0 0.00%

Surface Water 10,324 0 0.00% 1,568 0 0.00% 49,758,358 0 0.00%

All Large Systems 22,083 0 0.00% 2,942 0 0.00% 84,587,051 0 0.00%

Census of Very Large Systems (serving > 100,000 people)

Ground Water 2,014 0 0.00% 63 0 0.00% 17,269,919 0 0.00%

Surface Water 4,794 0 0.00% 335 0 0.00% 124,711,765 0 0.00%

All Very Large Systems 6,808 0 0.00% 398 0 0.00% 141,981,684 0 0.00%

All Systems

All Water Systems 32,139 0 0.00% 4,140 0 0.00% 229,237,740 0 0.00%

Page 4 of 25
EPA-OGWDW

Appendix A. Summary of Occurrence Based on Samples, Systems, and Population Served

Occurrence Data from the UCMR 2

Table A5. Dimethoate - UCMR 2 Assessment Monitoring Data - Occurrence Based on Samples, Systems, and Population Served 

Source Water Type Total Number 

of Samples

Samples with 

Detections: 

Number

Samples with 

Detections: 

Percent

Total Number 

of Systems

Systems with 

Detections: 

Number

Systems with 

Detections: 

Percent

Population 

Served by 

Systems

Population 

Served by 

Systems with 

Detections: 

Number

Population 

Served by 

Systems with 

Detections: 

Percent

Sample of Small Systems (serving ≤ 10,000 people)

Ground Water 2,328 0 0.00% 618 0 0.00% 1,790,743 0 0.00%

Surface Water 920 0 0.00% 182 0 0.00% 878,262 0 0.00%

All Small Systems 3,248 0 0.00% 800 0 0.00% 2,669,004 0 0.00%

Census of Large Systems (serving 10,001 - 100,000 people)

Ground Water 11,760 0 0.00% 1,374 0 0.00% 34,828,693 0 0.00%

Surface Water 10,332 0 0.00% 1,568 0 0.00% 49,758,358 0 0.00%

All Large Systems 22,092 0 0.00% 2,942 0 0.00% 84,587,051 0 0.00%

Census of Very Large Systems (serving > 100,000 people)

Ground Water 2,014 0 0.00% 63 0 0.00% 17,269,919 0 0.00%

Surface Water 4,796 0 0.00% 335 0 0.00% 124,711,765 0 0.00%

All Very Large Systems 6,810 0 0.00% 398 0 0.00% 141,981,684 0 0.00%

All Systems

All Water Systems 32,150 0 0.00% 4,140 0 0.00% 229,237,740 0 0.00%

Page 5 of 25
EPA-OGWDW

Appendix A. Summary of Occurrence Based on Samples, Systems, and Population Served

Occurrence Data from the UCMR 2

Table A6. 1,3-Dinitrobenzene - UCMR 2 Assessment Monitoring Data - Occurrence Based on Samples, Systems, and Population Served 

Source Water Type Total Number 

of Samples

Samples with 

Detections: 

Number

Samples with 

Detections: 

Percent

Total Number 

of Systems

Systems with 

Detections: 

Number

Systems with 

Detections: 

Percent

Population 

Served by 

Systems

Population 

Served by 

Systems with 

Detections: 

Number

Population 

Served by 

Systems with 

Detections: 

Percent

Sample of Small Systems (serving ≤ 10,000 people)

Ground Water 2,332 0 0.00% 618 0 0.00% 1,790,743 0 0.00%

Surface Water 919 0 0.00% 182 0 0.00% 878,262 0 0.00%

All Small Systems 3,251 0 0.00% 800 0 0.00% 2,669,004 0 0.00%

Census of Large Systems (serving 10,001 - 100,000 people)

Ground Water 11,761 0 0.00% 1,373 0 0.00% 34,816,693 0 0.00%

Surface Water 10,327 0 0.00% 1,568 0 0.00% 49,758,358 0 0.00%

All Large Systems 22,088 0 0.00% 2,941 0 0.00% 84,575,051 0 0.00%

Census of Very Large Systems (serving > 100,000 people)

Ground Water 2,012 0 0.00% 63 0 0.00% 17,269,919 0 0.00%

Surface Water 4,801 0 0.00% 335 0 0.00% 124,711,765 0 0.00%

All Very Large Systems 6,813 0 0.00% 398 0 0.00% 141,981,684 0 0.00%

All Systems

All Water Systems 32,152 0 0.00% 4,139 0 0.00% 229,225,740 0 0.00%

Page 6 of 25
EPA-OGWDW

Appendix A. Summary of Occurrence Based on Samples, Systems, and Population Served

Occurrence Data from the UCMR 2

Table A7. HBB - UCMR 2 Assessment Monitoring Data - Occurrence Based on Samples, Systems, and Population Served 

Source Water Type Total Number 

of Samples

Samples with 

Detections: 

Number

Samples with 

Detections: 

Percent

Total Number 

of Systems

Systems with 

Detections: 

Number

Systems with 

Detections: 

Percent

Population 

Served by 

Systems

Population 

Served by 

Systems with 

Detections: 

Number

Population 

Served by 

Systems with 

Detections: 

Percent

Sample of Small Systems (serving ≤ 10,000 people)

Ground Water 2,328 0 0.00% 618 0 0.00% 1,790,743 0 0.00%

Surface Water 920 0 0.00% 182 0 0.00% 878,262 0 0.00%

All Small Systems 3,248 0 0.00% 800 0 0.00% 2,669,004 0 0.00%

Census of Large Systems (serving 10,001 - 100,000 people)

Ground Water 11,759 0 0.00% 1,374 0 0.00% 34,828,693 0 0.00%

Surface Water 10,328 0 0.00% 1,568 0 0.00% 49,758,358 0 0.00%

All Large Systems 22,087 0 0.00% 2,942 0 0.00% 84,587,051 0 0.00%

Census of Very Large Systems (serving > 100,000 people)

Ground Water 2,014 0 0.00% 63 0 0.00% 17,269,919 0 0.00%

Surface Water 4,794 0 0.00% 335 0 0.00% 124,711,765 0 0.00%

All Very Large Systems 6,808 0 0.00% 398 0 0.00% 141,981,684 0 0.00%

All Systems

All Water Systems 32,143 0 0.00% 4,140 0 0.00% 229,237,740 0 0.00%

Page 7 of 25
EPA-OGWDW

Appendix A. Summary of Occurrence Based on Samples, Systems, and Population Served

Occurrence Data from the UCMR 2

Table A8. RDX - UCMR 2 Assessment Monitoring Data - Occurrence Based on Samples, Systems, and Population Served 

Source Water Type Total Number 

of Samples

Samples with 

Detections: 

Number

Samples with 

Detections: 

Percent

Total Number 

of Systems

Systems with 

Detections: 

Number

Systems with 

Detections: 

Percent

Population 

Served by 

Systems

Population 

Served by 

Systems with 

Detections: 

Number

Population 

Served by 

Systems with 

Detections: 

Percent

Sample of Small Systems (serving ≤ 10,000 people)

Ground Water 2,332 0 0.00% 618 0 0.00% 1,790,743 0 0.00%

Surface Water 919 0 0.00% 182 0 0.00% 878,262 0 0.00%

All Small Systems 3,251 0 0.00% 800 0 0.00% 2,669,004 0 0.00%

Census of Large Systems (serving 10,001 - 100,000 people)

Ground Water 11,760 0 0.00% 1,373 0 0.00% 34,816,693 0 0.00%

Surface Water 10,327 4 0.04% 1,568 3 0.19% 49,758,358 96,033 0.19%

All Large Systems 22,087 4 0.02% 2,941 3 0.10% 84,575,051 96,033 0.11%

Census of Very Large Systems (serving > 100,000 people)

Ground Water 2,012 0 0.00% 63 0 0.00% 17,269,919 0 0.00%

Surface Water 4,800 0 0.00% 335 0 0.00% 124,711,765 0 0.00%

All Very Large Systems 6,812 0 0.00% 398 0 0.00% 141,981,684 0 0.00%

All Systems

All Water Systems 32,150 4 0.01% 4,139 3 0.07% 229,225,740 96,033 0.04%

Page 8 of 25
EPA-OGWDW

Appendix A. Summary of Occurrence Based on Samples, Systems, and Population Served

Occurrence Data from the UCMR 2

Table A9. Terbufos Sulfone - UCMR 2 Assessment Monitoring Data - Occurrence Based on Samples, Systems, and Population Served 

Source Water Type Total Number 

of Samples

Samples with 

Detections: 

Number

Samples with 

Detections: 

Percent

Total Number 

of Systems

Systems with 

Detections: 

Number

Systems with 

Detections: 

Percent

Population 

Served by 

Systems

Population 

Served by 

Systems with 

Detections: 

Number

Population 

Served by 

Systems with 

Detections: 

Percent

Sample of Small Systems (serving ≤ 10,000 people)

Ground Water 2,328 0 0.00% 618 0 0.00% 1,790,743 0 0.00%

Surface Water 920 0 0.00% 182 0 0.00% 878,262 0 0.00%

All Small Systems 3,248 0 0.00% 800 0 0.00% 2,669,004 0 0.00%

Census of Large Systems (serving 10,001 - 100,000 people)

Ground Water 11,760 1 0.01% 1,374 1 0.07% 34,828,693 44,600 0.13%

Surface Water 10,331 0 0.00% 1,568 0 0.00% 49,758,358 0 0.00%

All Large Systems 22,091 1 0.005% 2,942 1 0.03% 84,587,051 44,600 0.05%

Census of Very Large Systems (serving > 100,000 people)

Ground Water 2,014 0 0.00% 63 0 0.00% 17,269,919 0 0.00%

Surface Water 4,796 0 0.00% 335 0 0.00% 124,711,765 0 0.00%

All Very Large Systems 6,810 0 0.00% 398 0 0.00% 141,981,684 0 0.00%

All Systems

All Water Systems 32,149 1 0.003% 4,140 1 0.02% 229,237,740 44,600 0.02%

Page 9 of 25
EPA-OGWDW

Appendix A. Summary of Occurrence Based on Samples, Systems, and Population Served

Occurrence Data from the UCMR 2

Table A10. TNT - UCMR 2 Assessment Monitoring Data - Occurrence Based on Samples, Systems, and Population Served 

Source Water Type Total Number 

of Samples

Samples with 

Detections: 

Number

Samples with 

Detections: 

Percent

Total Number 

of Systems

Systems with 

Detections: 

Number

Systems with 

Detections: 

Percent

Population 

Served by 

Systems

Population 

Served by 

Systems with 

Detections: 

Number

Population 

Served by 

Systems with 

Detections: 

Percent

Sample of Small Systems (serving ≤ 10,000 people)

Ground Water 2,332 0 0.00% 618 0 0.00% 1,790,743 0 0.00%

Surface Water 919 0 0.00% 182 0 0.00% 878,262 0 0.00%

All Small Systems 3,251 0 0.00% 800 0 0.00% 2,669,004 0 0.00%

Census of Large Systems (serving 10,001 - 100,000 people)

Ground Water 11,760 0 0.00% 1,373 0 0.00% 34,816,693 0 0.00%

Surface Water 10,327 0 0.00% 1,568 0 0.00% 49,758,358 0 0.00%

All Large Systems 22,087 0 0.00% 2,941 0 0.00% 84,575,051 0 0.00%

Census of Very Large Systems (serving > 100,000 people)

Ground Water 2,012 0 0.00% 63 0 0.00% 17,269,919 0 0.00%

Surface Water 4,801 0 0.00% 335 0 0.00% 124,711,765 0 0.00%

All Very Large Systems 6,813 0 0.00% 398 0 0.00% 141,981,684 0 0.00%

All Systems

All Water Systems 32,151 0 0.00% 4,139 0 0.00% 229,225,740 0 0.00%

Page 10 of 25
EPA-OGWDW

Appendix A. Summary of Occurrence Based on Samples, Systems, and Population Served

Occurrence Data from the UCMR 2

Table A11. Acetochlor - UCMR 2 Screening Survey Data - Occurrence Based on Samples, Systems, and Population Served 

Source Water Type Total Number 

of Samples

Samples with 

Detections: 

Number

Samples with 

Detections: 

Percent

Total Number 

of Systems

Systems with 

Detections: 

Number

Systems with 

Detections: 

Percent

Population 

Served by 

Systems

Population 

Served by 

Systems with 

Detections: 

Number

Population 

Served by 

Systems with 

Detections: 

Percent

Sample of Small Systems (serving ≤ 10,000 people)

Ground Water 788 0 0.00% 240 0 0.00% 548,364 0 0.00%

Surface Water 1,040 0 0.00% 240 0 0.00% 660,557 0 0.00%

All Small Systems 1,828 0 0.00% 480 0 0.00% 1,208,921 0 0.00%

Sample of Large Systems (serving 10,001 - 100,000 people)

Ground Water 1,392 0 0.00% 151 0 0.00% 6,584,184 0 0.00%

Surface Water 1,178 0 0.00% 169 0 0.00% 7,444,830 0 0.00%

All Large Systems 2,570 0 0.00% 320 0 0.00% 14,029,015 0 0.00%

Census of Very Large Systems (serving > 100,000 people)

Ground Water 2,010 0 0.00% 63 0 0.00% 17,269,919 0 0.00%

Surface Water 4,785 0 0.00% 335 0 0.00% 124,711,765 0 0.00%

All Very Large Systems 6,795 0 0.00% 398 0 0.00% 141,981,684 0 0.00%

All Systems

All Water Systems 11,193 0 0.00% 1,198 0 0.00% 157,219,620 0 0.00%

Page 11 of 25
EPA-OGWDW

Appendix A. Summary of Occurrence Based on Samples, Systems, and Population Served

Occurrence Data from the UCMR 2

Table A12. Acetochlor ESA - UCMR 2 Screening Survey Data - Occurrence Based on Samples, Systems, and Population Served 

Source Water Type Total Number 

of Samples

Samples with 

Detections: 

Number

Samples with 

Detections: 

Percent

Total Number 

of Systems

Systems with 

Detections: 

Number

Systems with 

Detections: 

Percent

Population 

Served by 

Systems

Population 

Served by 

Systems with 

Detections: 

Number

Population 

Served by 

Systems with 

Detections: 

Percent

Sample of Small Systems (serving ≤ 10,000 people)

Ground Water 786 0 0.00% 240 0 0.00% 548,364 0 0.00%

Surface Water 1,035 1 0.10% 240 1 0.42% 660,557 3,455 0.52%

All Small Systems 1,821 1 0.05% 480 1 0.21% 1,208,921 3,455 0.29%

Sample of Large Systems (serving 10,001 - 100,000 people)

Ground Water 1,381 0 0.00% 151 0 0.00% 6,584,184 0 0.00%

Surface Water 1,170 0 0.00% 169 0 0.00% 7,444,830 0 0.00%

All Large Systems 2,551 0 0.00% 320 0 0.00% 14,029,015 0 0.00%

Census of Very Large Systems (serving > 100,000 people)

Ground Water 1,999 0 0.00% 63 0 0.00% 17,269,919 0 0.00%

Surface Water 4,786 1 0.02% 335 1 0.30% 124,711,765 3,828,700 3.07%

All Very Large Systems 6,785 1 0.01% 398 1 0.25% 141,981,684 3,828,700 2.70%

All Systems

All Water Systems 11,157 2 0.02% 1,198 2 0.17% 157,219,620 3,832,155 2.44%

Page 12 of 25
EPA-OGWDW

Appendix A. Summary of Occurrence Based on Samples, Systems, and Population Served

Occurrence Data from the UCMR 2

Table A13. Acetochlor OA - UCMR 2 Screening Survey Data - Occurrence Based on Samples, Systems, and Population Served 

Source Water Type Total Number 

of Samples

Samples with 

Detections: 

Number

Samples with 

Detections: 

Percent

Total Number 

of Systems

Systems with 

Detections: 

Number

Systems with 

Detections: 

Percent

Population 

Served by 

Systems

Population 

Served by 

Systems with 

Detections: 

Number

Population 

Served by 

Systems with 

Detections: 

Percent

Sample of Small Systems (serving ≤ 10,000 people)

Ground Water 786 0 0.00% 240 0 0.00% 548,364 0 0.00%

Surface Water 1,035 0 0.00% 240 0 0.00% 660,557 0 0.00%

All Small Systems 1,821 0 0.00% 480 0 0.00% 1,208,921 0 0.00%

Sample of Large Systems (serving 10,001 - 100,000 people)

Ground Water 1,381 0 0.00% 151 0 0.00% 6,584,184 0 0.00%

Surface Water 1,170 0 0.00% 169 0 0.00% 7,444,830 0 0.00%

All Large Systems 2,551 0 0.00% 320 0 0.00% 14,029,015 0 0.00%

Census of Very Large Systems (serving > 100,000 people)

Ground Water 1,999 0 0.00% 63 0 0.00% 17,269,919 0 0.00%

Surface Water 4,786 0 0.00% 335 0 0.00% 124,711,765 0 0.00%

All Very Large Systems 6,785 0 0.00% 398 0 0.00% 141,981,684 0 0.00%

All Systems

All Water Systems 11,157 0 0.00% 1,198 0 0.00% 157,219,620 0 0.00%

Page 13 of 25
EPA-OGWDW

Appendix A. Summary of Occurrence Based on Samples, Systems, and Population Served

Occurrence Data from the UCMR 2

Table A14. Alachlor - UCMR 2 Screening Survey Data - Occurrence Based on Samples, Systems, and Population Served 

Source Water Type Total Number 

of Samples

Samples with 

Detections: 

Number

Samples with 

Detections: 

Percent

Total Number 

of Systems

Systems with 

Detections: 

Number

Systems with 

Detections: 

Percent

Population 

Served by 

Systems

Population 

Served by 

Systems with 

Detections: 

Number

Population 

Served by 

Systems with 

Detections: 

Percent

Sample of Small Systems (serving ≤ 10,000 people)

Ground Water 788 0 0.00% 240 0 0.00% 548,364 0 0.00%

Surface Water 1,040 0 0.00% 240 0 0.00% 660,557 0 0.00%

All Small Systems 1,828 0 0.00% 480 0 0.00% 1,208,921 0 0.00%

Sample of Large Systems (serving 10,001 - 100,000 people)

Ground Water 1,392 0 0.00% 151 0 0.00% 6,584,184 0 0.00%

Surface Water 1,178 0 0.00% 169 0 0.00% 7,444,830 0 0.00%

All Large Systems 2,570 0 0.00% 320 0 0.00% 14,029,015 0 0.00%

Census of Very Large Systems (serving > 100,000 people)

Ground Water 2,010 0 0.00% 63 0 0.00% 17,269,919 0 0.00%

Surface Water 4,785 0 0.00% 335 0 0.00% 124,711,765 0 0.00%

All Very Large Systems 6,795 0 0.00% 398 0 0.00% 141,981,684 0 0.00%

All Systems

All Water Systems 11,193 0 0.00% 1,198 0 0.00% 157,219,620 0 0.00%

Page 14 of 25
EPA-OGWDW

Appendix A. Summary of Occurrence Based on Samples, Systems, and Population Served

Occurrence Data from the UCMR 2

Table A15. Alachlor ESA - UCMR 2 Screening Survey Data - Occurrence Based on Samples, Systems, and Population Served 

Source Water Type Total Number 

of Samples

Samples with 

Detections: 

Number

Samples with 

Detections: 

Percent

Total Number 

of Systems

Systems with 

Detections: 

Number

Systems with 

Detections: 

Percent

Population 

Served by 

Systems

Population 

Served by 

Systems with 

Detections: 

Number

Population 

Served by 

Systems with 

Detections: 

Percent

Sample of Small Systems (serving ≤ 10,000 people)

Ground Water 786 0 0.00% 240 0 0.00% 548,364 0 0.00%

Surface Water 1,035 3 0.29% 240 1 0.42% 660,557 7,705 1.17%

All Small Systems 1,821 3 0.16% 480 1 0.21% 1,208,921 7,705 0.64%

Sample of Large Systems (serving 10,001 - 100,000 people)

Ground Water 1,381 1 0.07% 151 1 0.66% 6,584,184 73,993 1.12%

Surface Water 1,170 0 0.00% 169 0 0.00% 7,444,830 0 0.00%

All Large Systems 2,551 1 0.04% 320 1 0.31% 14,029,015 73,993 0.53%

Census of Very Large Systems (serving > 100,000 people)

Ground Water 1,999 0 0.00% 63 0 0.00% 17,269,919 0 0.00%

Surface Water 4,785 1 0.02% 335 1 0.30% 124,711,765 3,828,700 3.07%

All Very Large Systems 6,784 1 0.01% 398 1 0.25% 141,981,684 3,828,700 2.70%

All Systems

All Water Systems 11,156 5 0.04% 1,198 3 0.25% 157,219,620 3,910,398 2.49%

Page 15 of 25
EPA-OGWDW

Appendix A. Summary of Occurrence Based on Samples, Systems, and Population Served

Occurrence Data from the UCMR 2

Table A16. Alachlor OA - UCMR 2 Screening Survey Data - Occurrence Based on Samples, Systems, and Population Served 

Source Water Type Total Number 

of Samples

Samples with 

Detections: 

Number

Samples with 

Detections: 

Percent

Total Number 

of Systems

Systems with 

Detections: 

Number

Systems with 

Detections: 

Percent

Population 

Served by 

Systems

Population 

Served by 

Systems with 

Detections: 

Number

Population 

Served by 

Systems with 

Detections: 

Percent

Sample of Small Systems (serving ≤ 10,000 people)

Ground Water 786 0 0.00% 240 0 0.00% 548,364 0 0.00%

Surface Water 1,035 0 0.00% 240 0 0.00% 660,557 0 0.00%

All Small Systems 1,821 0 0.00% 480 0 0.00% 1,208,921 0 0.00%

Sample of Large Systems (serving 10,001 - 100,000 people)

Ground Water 1,381 0 0.00% 151 0 0.00% 6,584,184 0 0.00%

Surface Water 1,170 0 0.00% 169 0 0.00% 7,444,830 0 0.00%

All Large Systems 2,551 0 0.00% 320 0 0.00% 14,029,015 0 0.00%

Census of Very Large Systems (serving > 100,000 people)

Ground Water 1,999 0 0.00% 63 0 0.00% 17,269,919 0 0.00%

Surface Water 4,786 0 0.00% 335 0 0.00% 124,711,765 0 0.00%

All Very Large Systems 6,785 0 0.00% 398 0 0.00% 141,981,684 0 0.00%

All Systems

All Water Systems 11,157 0 0.00% 1,198 0 0.00% 157,219,620 0 0.00%

Page 16 of 25
EPA-OGWDW

Appendix A. Summary of Occurrence Based on Samples, Systems, and Population Served

Occurrence Data from the UCMR 2

Table A17. Metolachlor - UCMR 2 Screening Survey Data - Occurrence Based on Samples, Systems, and Population Served 

Source Water Type Total Number 

of Samples

Samples with 

Detections: 

Number

Samples with 

Detections: 

Percent

Total Number 

of Systems

Systems with 

Detections: 

Number

Systems with 

Detections: 

Percent

Population 

Served by 

Systems

Population 

Served by 

Systems with 

Detections: 

Number

Population 

Served by 

Systems with 

Detections: 

Percent

Sample of Small Systems (serving ≤ 10,000 people)

Ground Water 788 0 0.00% 240 0 0.00% 548,364 0 0.00%

Surface Water 1,040 2 0.19% 240 2 0.83% 660,557 2,240 0.34%

All Small Systems 1,828 2 0.11% 480 2 0.42% 1,208,921 2,240 0.19%

Sample of Large Systems (serving 10,001 - 100,000 people)

Ground Water 1,392 0 0.00% 151 0 0.00% 6,584,184 0 0.00%

Surface Water 1,178 0 0.00% 169 0 0.00% 7,444,830 0 0.00%

All Large Systems 2,570 0 0.00% 320 0 0.00% 14,029,015 0 0.00%

Census of Very Large Systems (serving > 100,000 people)

Ground Water 2,010 0 0.00% 63 0 0.00% 17,269,919 0 0.00%

Surface Water 4,784 1 0.02% 335 1 0.30% 124,711,765 105,270 0.08%

All Very Large Systems 6,794 1 0.01% 398 1 0.25% 141,981,684 105,270 0.07%

All Systems

All Water Systems 11,192 3 0.03% 1,198 3 0.25% 157,219,620 107,510 0.07%

Page 17 of 25
EPA-OGWDW

Appendix A. Summary of Occurrence Based on Samples, Systems, and Population Served

Occurrence Data from the UCMR 2

Table A18. Metolachlor ESA - UCMR 2 Screening Survey Data - Occurrence Based on Samples, Systems, and Population Served 

Source Water Type Total Number 

of Samples

Samples with 

Detections: 

Number

Samples with 

Detections: 

Percent

Total Number 

of Systems

Systems with 

Detections: 

Number

Systems with 

Detections: 

Percent

Population 

Served by 

Systems

Population 

Served by 

Systems with 

Detections: 

Number

Population 

Served by 

Systems with 

Detections: 

Percent

Sample of Small Systems (serving ≤ 10,000 people)

Ground Water 786 16 2.04% 240 5 2.08% 548,364 17,540 3.20%

Surface Water 1,035 5 0.48% 240 3 1.25% 660,557 17,498 2.65%

All Small Systems 1,821 21 1.15% 480 8 1.67% 1,208,921 35,038 2.90%

Sample of Large Systems (serving 10,001 - 100,000 people)

Ground Water 1,381 4 0.29% 151 1 0.66% 6,584,184 73,993 1.12%

Surface Water 1,170 8 0.68% 169 3 1.78% 7,444,830 138,897 1.87%

All Large Systems 2,551 12 0.47% 320 4 1.25% 14,029,015 212,890 1.52%

Census of Very Large Systems (serving > 100,000 people)

Ground Water 1,999 9 0.45% 63 1 1.59% 17,269,919 1,045,522 6.05%

Surface Water 4,786 10 0.21% 335 6 1.79% 124,711,765 4,580,535 3.67%

All Very Large Systems 6,785 19 0.28% 398 7 1.76% 141,981,684 5,626,057 3.96%

All Systems

All Water Systems 11,157 52 0.47% 1,198 19 1.59% 157,219,620 5,873,985 3.74%

Page 18 of 25
EPA-OGWDW

Appendix A. Summary of Occurrence Based on Samples, Systems, and Population Served

Occurrence Data from the UCMR 2

Table A19. Metolachlor OA - UCMR 2 Screening Survey Data - Occurrence Based on Samples, Systems, and Population Served 

Source Water Type Total Number 

of Samples

Samples with 

Detections: 

Number

Samples with 

Detections: 

Percent

Total Number 

of Systems

Systems with 

Detections: 

Number

Systems with 

Detections: 

Percent

Population 

Served by 

Systems

Population 

Served by 

Systems with 

Detections: 

Number

Population 

Served by 

Systems with 

Detections: 

Percent

Sample of Small Systems (serving ≤ 10,000 people)

Ground Water 786 0 0.00% 240 0 0.00% 548,364 0 0.00%

Surface Water 1,035 0 0.00% 240 0 0.00% 660,557 0 0.00%

All Small Systems 1,821 0 0.00% 480 0 0.00% 1,208,921 0 0.00%

Sample of Large Systems (serving 10,001 - 100,000 people)

Ground Water 1,381 0 0.00% 151 0 0.00% 6,584,184 0 0.00%

Surface Water 1,170 0 0.00% 169 0 0.00% 7,444,830 0 0.00%

All Large Systems 2,551 0 0.00% 320 0 0.00% 14,029,015 0 0.00%

Census of Very Large Systems (serving > 100,000 people)

Ground Water 1,999 3 0.15% 63 1 1.59% 17,269,919 1,045,522 6.05%

Surface Water 4,786 0 0.00% 335 0 0.00% 124,711,765 0 0.00%

All Very Large Systems 6,785 3 0.04% 398 1 0.25% 141,981,684 1,045,522 0.74%

All Systems

All Water Systems 11,157 3 0.03% 1,198 1 0.08% 157,219,620 1,045,522 0.67%

Page 19 of 25
EPA-OGWDW

Appendix A. Summary of Occurrence Based on Samples, Systems, and Population Served

Occurrence Data from the UCMR 2

Table A20. NDBA - UCMR 2 Screening Survey Data - Occurrence Based on Samples, Systems, and Population Served 

Source Water Type Total Number 

of Samples

Samples with 

Detections: 

Number

Samples with 

Detections: 

Percent

Total Number 

of Systems

Systems with 

Detections: 

Number

Systems with 

Detections: 

Percent

Population 

Served by 

Systems

Population 

Served by 

Systems with 

Detections: 

Number

Population 

Served by 

Systems with 

Detections: 

Percent

Sample of Small Systems (serving ≤ 10,000 people)

Ground Water 1,237 3 0.24% 240 2 0.83% 548,364 14,292 2.61%

Surface Water 1,996 0 0.00% 240 0 0.00% 660,557 0 0.00%

All Small Systems 3,233 3 0.09% 480 2 0.42% 1,208,921 14,292 1.18%

Sample of Large Systems (serving 10,001 - 100,000 people)

Ground Water 1,932 0 0.00% 151 0 0.00% 6,584,184 0 0.00%

Surface Water 2,091 0 0.00% 169 0 0.00% 7,444,830 0 0.00%

All Large Systems 4,023 0 0.00% 320 0 0.00% 14,029,015 0 0.00%

Census of Very Large Systems (serving > 100,000 people)

Ground Water 2,966 3 0.10% 63 1 1.59% 17,269,919 1,045,522 6.05%

Surface Water 7,879 3 0.04% 335 2 0.60% 124,711,765 626,169 0.50%

All Very Large Systems 10,845 6 0.06% 398 3 0.75% 141,981,684 1,671,691 1.18%

All Systems

All Water Systems 18,101 9 0.05% 1,198 5 0.42% 157,219,620 1,685,983 1.07%

Page 20 of 25
EPA-OGWDW

Appendix A. Summary of Occurrence Based on Samples, Systems, and Population Served

Occurrence Data from the UCMR 2

Table A21. NDEA - UCMR 2 Screening Survey Data - Occurrence Based on Samples, Systems, and Population Served 

Source Water Type Total Number 

of Samples

Samples with 

Detections: 

Number

Samples with 

Detections: 

Percent

Total Number 

of Systems

Systems with 

Detections: 

Number

Systems with 

Detections: 

Percent

Population 

Served by 

Systems

Population 

Served by 

Systems with 

Detections: 

Number

Population 

Served by 

Systems with 

Detections: 

Percent

Sample of Small Systems (serving ≤ 10,000 people)

Ground Water 1,237 1 0.08% 240 1 0.42% 548,364 6,575 1.20%

Surface Water 1,996 0 0.00% 240 0 0.00% 660,557 0 0.00%

All Small Systems 3,233 1 0.03% 480 1 0.21% 1,208,921 6,575 0.54%

Sample of Large Systems (serving 10,001 - 100,000 people)

Ground Water 1,920 3 0.16% 151 1 0.66% 6,584,184 93,660 1.42%

Surface Water 2,091 6 0.29% 169 3 1.78% 7,444,830 148,608 2.00%

All Large Systems 4,011 9 0.22% 320 4 1.25% 14,029,015 242,268 1.73%

Census of Very Large Systems (serving > 100,000 people)

Ground Water 2,968 7 0.24% 63 5 7.94% 17,269,919 668,861 3.87%

Surface Water 7,884 29 0.37% 335 16 4.78% 124,711,765 10,314,490 8.27%

All Very Large Systems 10,852 36 0.33% 398 21 5.28% 141,981,684 10,983,351 7.74%

All Systems

All Water Systems 18,096 46 0.25% 1,198 26 2.17% 157,219,620 11,232,194 7.14%

Page 21 of 25
EPA-OGWDW

Appendix A. Summary of Occurrence Based on Samples, Systems, and Population Served

Occurrence Data from the UCMR 2

Table A22. NDMA - UCMR 2 Screening Survey Data - Occurrence Based on Samples, Systems, and Population Served 

Source Water Type Total Number 

of Samples

Samples with 

Detections: 

Number

Samples with 

Detections: 

Percent

Total Number 

of Systems

Systems with 

Detections: 

Number

Systems with 

Detections: 

Percent

Population 

Served by 

Systems

Population 

Served by 

Systems with 

Detections: 

Number

Population 

Served by 

Systems with 

Detections: 

Percent

Sample of Small Systems (serving ≤ 10,000 people)

Ground Water 1,237 14 1.13% 240 10 4.17% 548,364 26,059 4.75%

Surface Water 1,996 326 16.33% 240 74 30.83% 660,557 259,285 39.25%

All Small Systems 3,233 340 10.52% 480 84 17.50% 1,208,921 285,344 23.60%

Sample of Large Systems (serving 10,001 - 100,000 people)

Ground Water 1,932 48 2.48% 151 13 8.61% 6,584,184 739,206 11.23%

Surface Water 2,091 305 14.59% 169 58 34.32% 7,444,830 2,792,925 37.51%

All Large Systems 4,023 353 8.77% 320 71 22.19% 14,029,015 3,532,130 25.18%

Census of Very Large Systems (serving > 100,000 people)

Ground Water 2,966 52 1.75% 63 15 23.81% 17,269,919 5,706,228 33.04%

Surface Water 7,876 1,116 14.17% 335 154 45.97% 124,711,765 55,788,062 44.73%

All Very Large Systems 10,842 1,168 10.77% 398 169 42.46% 141,981,684 61,494,290 43.31%

All Systems

All Water Systems 18,098 1,861 10.28% 1,198 324 27.05% 157,219,620 65,311,764 41.54%

Page 22 of 25
EPA-OGWDW

Appendix A. Summary of Occurrence Based on Samples, Systems, and Population Served

Occurrence Data from the UCMR 2

Table A23. NDPA - UCMR 2 Screening Survey Data - Occurrence Based on Samples, Systems, and Population Served 

Source Water Type Total Number 

of Samples

Samples with 

Detections: 

Number

Samples with 

Detections: 

Percent

Total Number 

of Systems

Systems with 

Detections: 

Number

Systems with 

Detections: 

Percent

Population 

Served by 

Systems

Population 

Served by 

Systems with 

Detections: 

Number

Population 

Served by 

Systems with 

Detections: 

Percent

Sample of Small Systems (serving ≤ 10,000 people)

Ground Water 1,237 0 0.00% 240 0 0.00% 548,364 0 0.00%

Surface Water 1,996 0 0.00% 240 0 0.00% 660,557 0 0.00%

All Small Systems 3,233 0 0.00% 480 0 0.00% 1,208,921 0 0.00%

Sample of Large Systems (serving 10,001 - 100,000 people)

Ground Water 1,932 0 0.00% 151 0 0.00% 6,584,184 0 0.00%

Surface Water 2,091 0 0.00% 169 0 0.00% 7,444,830 0 0.00%

All Large Systems 4,023 0 0.00% 320 0 0.00% 14,029,015 0 0.00%

Census of Very Large Systems (serving > 100,000 people)

Ground Water 2,968 0 0.00% 63 0 0.00% 17,269,919 0 0.00%

Surface Water 7,883 0 0.00% 335 0 0.00% 124,711,765 0 0.00%

All Very Large Systems 10,851 0 0.00% 398 0 0.00% 141,981,684 0 0.00%

All Systems

All Water Systems 18,107 0 0.00% 1,198 0 0.00% 157,219,620 0 0.00%

Page 23 of 25
EPA-OGWDW

Appendix A. Summary of Occurrence Based on Samples, Systems, and Population Served

Occurrence Data from the UCMR 2

Table A24. NMEA - UCMR 2 Screening Survey Data - Occurrence Based on Samples, Systems, and Population Served 

Source Water Type Total Number 

of Samples

Samples with 

Detections: 

Number

Samples with 

Detections: 

Percent

Total Number 

of Systems

Systems with 

Detections: 

Number

Systems with 

Detections: 

Percent

Population 

Served by 

Systems

Population 

Served by 

Systems with 

Detections: 

Number

Population 

Served by 

Systems with 

Detections: 

Percent

Sample of Small Systems (serving ≤ 10,000 people)

Ground Water 1,237 0 0.00% 240 0 0.00% 548,364 0 0.00%

Surface Water 1,996 3 0.15% 240 3 1.25% 660,557 4,480 0.68%

All Small Systems 3,233 3 0.09% 480 3 0.63% 1,208,921 4,480 0.37%

Sample of Large Systems (serving 10,001 - 100,000 people)

Ground Water 1,932 0 0.00% 151 0 0.00% 6,584,184 0 0.00%

Surface Water 2,091 0 0.00% 169 0 0.00% 7,444,830 0 0.00%

All Large Systems 4,023 0 0.00% 320 0 0.00% 14,029,015 0 0.00%

Census of Very Large Systems (serving > 100,000 people)

Ground Water 2,966 0 0.00% 63 0 0.00% 17,269,919 0 0.00%

Surface Water 7,879 0 0.00% 335 0 0.00% 124,711,765 0 0.00%

All Very Large Systems 10,845 0 0.00% 398 0 0.00% 141,981,684 0 0.00%

All Systems

All Water Systems 18,101 3 0.02% 1,198 3 0.25% 157,219,620 4,480 0.003%

Page 24 of 25
EPA-OGWDW

Appendix A. Summary of Occurrence Based on Samples, Systems, and Population Served

Occurrence Data from the UCMR 2

Table A25. NPYR - UCMR 2 Screening Survey Data - Occurrence Based on Samples, Systems, and Population Served 

Source Water Type Total Number 

of Samples

Samples with 

Detections: 

Number

Samples with 

Detections: 

Percent

Total Number 

of Systems

Systems with 

Detections: 

Number

Systems with 

Detections: 

Percent

Population 

Served by 

Systems

Population 

Served by 

Systems with 

Detections: 

Number

Population 

Served by 

Systems with 

Detections: 

Percent

Sample of Small Systems (serving ≤ 10,000 people)

Ground Water 1,237 0 0.00% 240 0 0.00% 548,364 0 0.00%

Surface Water 1,996 11 0.55% 240 3 1.25% 660,557 14,572 2.21%

All Small Systems 3,233 11 0.34% 480 3 0.63% 1,208,921 14,572 1.21%

Sample of Large Systems (serving 10,001 - 100,000 people)

Ground Water 1,932 0 0.00% 151 0 0.00% 6,584,184 0 0.00%

Surface Water 2,091 7 0.33% 169 6 3.55% 7,444,830 188,603 2.53%

All Large Systems 4,023 7 0.17% 320 6 1.88% 14,029,015 188,603 1.34%

Census of Very Large Systems (serving > 100,000 people)

Ground Water 2,966 1 0.03% 63 1 1.59% 17,269,919 148,137 0.86%

Surface Water 7,879 22 0.28% 335 11 3.28% 124,711,765 7,080,239 5.68%

All Very Large Systems 10,845 23 0.21% 398 12 3.02% 141,981,684 7,228,376 5.09%

All Systems

All Water Systems 18,101 41 0.23% 1,198 21 1.75% 157,219,620 7,431,551 4.73%

Page 25 of 25
EPA-OGWDW Occurrence Data from the UCMR 2

Appendix B

Table B1. BDE-47 - Final UCMR 2 Assessment Monitoring Data - Number of Systems and 

Population Served by State

Table B2. BDE-99 - Final UCMR 2 Assessment Monitoring Data - Number of Systems and 

Population Served by State 

Table B3. BDE-100 - Final UCMR 2 Assessment Monitoring Data - Number of Systems and 

Population Served by State 

Table B4. BDE-153 - Final UCMR 2 Assessment Monitoring Data - Number of Systems and 

Population Served by State 

Table B5. Dimethoate - Final UCMR 2 Assessment Monitoring Data - Number of Systems and 

Population Served by State 

Table B6. 1,3-Dinitrobenzene - Final UCMR 2 Assessment Monitoring Data - Number of 

Systems and Population Served by State 

Table B7. HBB - Final UCMR 2 Assessment Monitoring Data - Number of Systems and 

Population Served by State 

Table B8. RDX - Final UCMR 2 Assessment Monitoring Data - Number of Systems and 

Population Served by State 

Table B9. Terbufos Sulfone - Final UCMR 2 Assessment Monitoring Data - Number of 

Systems and Population Served by State 

Table B10. TNT - Final UCMR 2 Assessment Monitoring Data - Number of Systems and 

Population Served by State 

Table B11. Acetochlor - Final UCMR 2 Screening Survey Data - Number of Systems and 

Population Served by State 

Table B12. Acetochlor ESA - Final UCMR 2 Screening Survey Data - Number of Systems and 

Population Served by State 

Table B13. Acetochlor OA - Final UCMR 2 Screening Survey Data - Number of Systems and 

Population Served by State 

Table B14. Alachlor - Final UCMR 2 Screening Survey Data - Number of Systems and 

Population Served by State 

Table B15. Alachlor ESA - Final UCMR 2 Screening Survey Data - Number of Systems and 

Population Served by State 

Table B16. Alachlor OA - Final UCMR 2 Screening Survey Data - Number of Systems and 

Population Served by State 

Table B17. Metolachlor - Final UCMR 2 Screening Survey Data - Number of Systems and 

Population Served by State 
EPA-OGWDW Occurrence Data from the UCMR 2 

Table B18. Metolachlor ESA - Final UCMR 2 Screening Survey Data - Number of Systems and 

Population Served by State 

Table B19. Metolachlor OA - Final UCMR 2 Screening Survey Data - Number of Systems and 

Population Served by State

Table B20. NDBA - Final UCMR 2 Screening Survey Data - Number of Systems and 

Population Served by State 

Table B21. NDEA - Final UCMR 2 Screening Survey Data - Number of Systems and 

Population Served by State 

Table B22. NDMA - Final UCMR 2 Screening Survey Data - Number of Systems and 

Population Served by State 

Table B23. NDPA - Final UCMR 2 Screening Survey Data - Number of Systems and 

Population Served by State 

Table B24. NMEA - Final UCMR 2 Screening Survey Data - Number of Systems and 

Population Served by State 

Table B25. NPYR - Final UCMR 2 Screening Survey Data - Number of Systems and Population 

Served by State
EPA-OGWDW

Appendix B. Summary of Systems and Population Served by State

Occurrence Data from the UCMR 2

State 1

Total 

Number of 

Samples

Total 

Number of 

Systems

Number of 

Small Systems 

(serving ≤10,000 

people): Ground 

Water

Number of 

Small Systems 

(serving ≤10,000 

people): 

Surface Water

Number of 

Large Systems 

(serving 10,001-

100,000 people): 

Ground Water

Number of 

Large Systems 

(serving 10,001-

100,000 people): 

Surface Water

Number of Very 

Large Systems 

(serving 

>100,000 

people): Ground 

Water

Number of Very 

Large Systems 

(serving 

>100,000 

people): 

Surface Water

Alabama 946 120 13 3 36 62 0 6

Alaska 49 9 3 2 2 1 0 1

American Samoa 4 1 0 0 0 1 0 0

Arizona 951 69 13 0 41 5 1 9

Arkansas 289 61 9 4 17 28 0 3

California 6,725 393 32 14 123 152 8 64

Colorado 505 68 5 6 13 34 0 10

Connecticut 329 41 5 1 7 23 0 5

Delaware 106 10 4 0 2 1 0 3

District of Columbia 8 1 0 0 0 0 0 1

Florida 1,152 231 28 0 161 7 23 12

Georgia 570 110 14 5 27 51 1 12

Guam 246 3 0 0 0 2 1 0

Hawaii 315 18 3 0 8 5 2 0

Idaho 257 22 7 0 13 1 0 1

Illinois 839 141 22 5 61 42 3 8

Indiana 399 99 16 2 56 18 1 6

Iowa 233 54 14 1 24 12 0 3

Kansas 224 46 7 4 12 17 0 6

Kentucky 433 107 2 4 10 86 1 4

Louisiana 606 92 25 3 36 21 3 4

Maine 89 19 4 2 3 9 0 1

Maryland 180 38 7 2 13 12 1 3

Massachusetts 965 126 9 3 55 50 1 8

Michigan 393 77 21 2 18 29 2 5

Minnesota 356 91 15 1 64 9 0 2

Mississippi 636 78 30 0 46 0 0 2

Missouri 464 75 16 4 31 19 1 4

Montana 112 13 4 2 1 5 0 1

N. Mariana Islands 69 2 1 0 1 0 0 0

Navajo Nation 12 2 1 0 1 0 0 0

Nebraska 238 22 8 0 10 2 0 2

Nevada 184 15 4 1 4 2 0 4

New Hampshire 155 24 5 1 4 13 0 1

New Jersey 1,055 131 14 1 55 49 1 11

New Mexico 331 32 7 1 18 5 1 0

New York 1,542 154 18 11 47 59 5 14

North Carolina 1,032 126 16 5 27 65 1 12

North Dakota 50 12 2 1 3 6 0 0

Ohio 525 153 20 5 59 58 1 10

Oklahoma 422 62 6 8 11 34 0 3

Oregon 365 55 6 4 10 30 0 5

Pennsylvania 1,218 171 24 13 24 92 0 18

Puerto Rico 655 83 6 5 17 47 0 8

Rhode Island 92 13 2 0 4 5 0 2

South Carolina 321 63 6 3 8 41 0 5

South Dakota 87 15 4 1 3 6 0 1

Tennessee 569 121 5 8 16 87 1 4

Texas 2,200 295 63 23 62 122 1 24

Utah 513 54 6 2 14 25 0 7

Vermont 46 11 3 2 0 6 0 0

Virgin Islands 20 4 2 0 0 2 0 0

Virginia 409 73 9 6 4 43 0 11

Washington 834 93 18 3 46 20 2 4

West Virginia 142 36 3 6 3 22 0 2

Wisconsin 561 78 19 1 38 16 1 3

Wyoming 56 11 3 0 1 7 0 0

Tribes - Region 1 4 1 0 0 0 1 0 0

Tribes - Region 5 10 4 3 0 1 0 0 0

Tribes - Region 6 0 0 0 0 0 0 0 0

Tribes - Region 8 6 2 0 1 1 0 0 0

Tribes - Region 9 45 9 6 0 2 1 0 0

Total 32,149 4,140 618 182 1,374 1,568 63 335

1 The UCMR data are not representative at the state-level.

Table B1. BDE-47 - UCMR 2 Assessment Monitoring Data - Number of Systems and Population Served by State

Page 1 of 2
EPA-OGWDW

Appendix B. Summary of Systems and Population Served by State

Occurrence Data from the UCMR 2

State 1 Total Population 

Served

Pop. Served by 

Small Systems 

(serving ≤10,000 

people): Ground 

Water

Pop. Served by 

Small Systems 

(serving ≤10,000 

people): Surface 

Water

Pop. Served by 

Large Systems 

(serving 10,001-

100,000 people): 

Ground Water

Pop. Served by 

Large Systems 

(serving 10,001-

100,000 people): 

Surface Water

Pop. Served by 

Very Large 

Systems (serving 

>100,000 people): 

Ground Water

Pop. Served by 

Very Large 

Systems (serving 

>100,000 people): 

Surface Water

Alabama 4,249,148 64,214 15,859 850,382 1,612,450 0 1,706,245

Alaska 234,237 6,025 9,791 59,290 23,965 0 135,166

American Samoa 45,000 0 0 0 45,000 0 0

Arizona 4,417,574 32,953 0 999,514 110,587 675,445 2,599,075

Arkansas 1,771,814 31,449 19,189 395,797 638,748 0 686,632

California 32,516,672 101,399 70,338 3,738,533 6,626,442 1,088,908 20,891,052

Colorado 4,395,410 12,154 13,190 312,380 1,020,990 0 3,036,696

Connecticut 2,423,307 6,961 7,784 101,145 929,609 0 1,377,809

Delaware 550,332 14,255 0 54,443 36,130 0 445,504

District of Columbia 783,055 0 0 0 0 0 783,055

Florida 15,964,524 85,230 0 5,601,752 190,650 7,266,168 2,820,724

Georgia 6,323,497 30,214 19,473 555,035 1,594,334 163,688 3,960,753

Guam 136,301 0 0 0 36,300 100,001 0

Hawaii 1,168,403 14,938 0 237,807 128,935 786,723 0

Idaho 598,638 20,705 0 377,881 14,052 0 186,000

Illinois 7,910,559 62,240 31,607 1,237,820 1,377,669 405,228 4,795,996

Indiana 3,833,462 53,832 8,150 1,343,907 460,953 113,400 1,853,220

Iowa 1,669,054 34,873 7,782 635,226 435,492 0 555,682

Kansas 1,903,624 14,044 15,781 288,095 327,403 0 1,258,301

Kentucky 4,050,273 6,419 21,540 145,399 2,190,482 85,697 1,600,737

Louisiana 3,411,211 100,823 8,085 762,163 705,285 663,655 1,171,200

Maine 368,811 10,566 8,770 43,690 192,225 0 113,560

Maryland 4,493,237 9,908 6,123 346,418 348,121 249,600 3,533,067

Massachusetts 7,942,671 43,421 14,171 1,317,567 1,768,248 159,180 4,640,084

Michigan 5,866,881 54,175 12,964 366,966 859,317 283,846 4,289,613

Minnesota 3,092,542 38,944 4,960 1,707,947 406,914 0 933,777

Mississippi 1,418,405 86,727 0 988,496 0 0 343,182

Missouri 3,711,957 49,173 19,101 600,252 449,297 223,971 2,370,164

Montana 376,922 8,734 8,778 72,215 183,824 0 103,371

N. Mariana Islands 72,737 1,081 0 71,656 0 0 0

Navajo Nation 19,080 836 0 18,244 0 0 0

Nebraska 998,770 26,423 0 219,594 37,864 0 714,889

Nevada 1,999,825 13,712 8,323 59,000 73,095 0 1,845,695

New Hampshire 562,737 8,516 10,000 86,706 305,451 0 152,064

New Jersey 7,116,424 60,693 3,400 1,156,623 1,666,422 115,378 4,113,907

New Mexico 1,152,067 16,238 8,256 501,653 172,567 453,353 0

New York 14,764,779 35,519 44,587 1,371,569 1,657,155 1,682,822 9,973,127

North Carolina 5,366,551 37,318 18,964 580,495 1,974,056 108,666 2,647,052

North Dakota 350,292 5,414 2,694 78,529 263,655 0 0

Ohio 8,788,460 64,492 31,964 1,498,349 1,822,242 123,850 5,247,564

Oklahoma 2,491,284 10,318 31,117 241,483 950,915 0 1,257,451

Oregon 2,413,155 13,140 24,170 188,470 830,806 0 1,356,569

Pennsylvania 8,692,491 58,224 57,237 425,487 2,978,041 0 5,173,502

Puerto Rico 5,552,363 20,268 20,177 384,807 1,688,215 0 3,438,896

Rhode Island 911,235 1,812 0 107,302 250,585 0 551,536

South Carolina 2,785,309 14,508 19,828 180,888 1,218,197 0 1,351,888

South Dakota 349,953 10,139 1,592 43,056 167,166 0 128,000

Tennessee 4,625,703 22,345 49,153 428,243 2,499,282 687,096 939,584

Texas 18,832,904 189,890 115,111 1,429,442 3,795,822 1,253,442 12,049,197

Utah 2,403,787 20,075 15,000 274,446 934,364 0 1,159,902

Vermont 196,255 5,245 5,830 0 185,180 0 0

Virgin Islands 67,889 2,550 0 0 65,339 0 0

Virginia 4,635,684 11,756 31,277 98,415 1,285,803 0 3,208,433

Washington 4,265,055 47,921 18,679 1,255,343 756,649 374,556 1,811,906

West Virginia 958,526 8,711 26,897 65,669 527,486 0 329,764

Wisconsin 2,806,236 59,710 8,550 842,048 620,506 205,247 1,070,175

Wyoming 296,668 6,591 0 24,999 265,078 0 0

Tribes - Region 1 41,000 0 0 0 41,000 0 0

Tribes - Region 5 18,788 4,068 0 14,720 0 0 0

Tribes - Region 6 0 0 0 0 0 0 0

Tribes - Region 8 12,160 0 2,020 10,140 0 0 0

Tribes - Region 9 62,055 18,855 0 31,200 12,000 0 0

Total 229,237,740 1,790,743 878,262 34,828,693 49,758,358 17,269,919 124,711,765

1 The UCMR data are not representative at the state-level.

Table B1. BDE-47 - UCMR 2 Assessment Monitoring Data - Number of Systems and Population Served by State

Page 2 of 2
EPA-OGWDW

Appendix B. Summary of Systems and Population Served by State

Occurrence Data from the UCMR 2

Table B2. BDE-99 - UCMR 2 Assessment Monitoring Data - Number of Systems and Population Served by State

State 1

Total 

Number of 

Samples

Total 

Number of 

Systems

Number of 

Small Systems 

(serving ≤10,000 

people): Ground 

Water

Number of 

Small Systems 

(serving ≤10,000 

people): 

Surface Water

Number of 

Large Systems 

(serving 10,001-

100,000 people): 

Ground Water

Number of 

Large Systems 

(serving 10,001-

100,000 people): 

Surface Water

Number of Very 

Large Systems 

(serving 

>100,000 

people): Ground 

Water

Number of Very 

Large Systems 

(serving 

>100,000 

people): 

Surface Water

Alabama 946 120 13 3 36 62 0 6

Alaska 49 9 3 2 2 1 0 1

American Samoa 4 1 0 0 0 1 0 0

Arizona 951 69 13 0 41 5 1 9

Arkansas 289 61 9 4 17 28 0 3

California 6,725 393 32 14 123 152 8 64

Colorado 505 68 5 6 13 34 0 10

Connecticut 329 41 5 1 7 23 0 5

Delaware 106 10 4 0 2 1 0 3

District of Columbia 8 1 0 0 0 0 0 1

Florida 1,152 231 28 0 161 7 23 12

Georgia 570 110 14 5 27 51 1 12

Guam 246 3 0 0 0 2 1 0

Hawaii 315 18 3 0 8 5 2 0

Idaho 257 22 7 0 13 1 0 1

Illinois 839 141 22 5 61 42 3 8

Indiana 399 99 16 2 56 18 1 6

Iowa 233 54 14 1 24 12 0 3

Kansas 224 46 7 4 12 17 0 6

Kentucky 433 107 2 4 10 86 1 4

Louisiana 606 92 25 3 36 21 3 4

Maine 89 19 4 2 3 9 0 1

Maryland 180 38 7 2 13 12 1 3

Massachusetts 965 126 9 3 55 50 1 8

Michigan 393 77 21 2 18 29 2 5

Minnesota 356 91 15 1 64 9 0 2

Mississippi 636 78 30 0 46 0 0 2

Missouri 464 75 16 4 31 19 1 4

Montana 112 13 4 2 1 5 0 1

N. Mariana Islands 69 2 1 0 1 0 0 0

Navajo Nation 12 2 1 0 1 0 0 0

Nebraska 238 22 8 0 10 2 0 2

Nevada 184 15 4 1 4 2 0 4

New Hampshire 155 24 5 1 4 13 0 1

New Jersey 1,055 131 14 1 55 49 1 11

New Mexico 331 32 7 1 18 5 1 0

New York 1,542 154 18 11 47 59 5 14

North Carolina 1,032 126 16 5 27 65 1 12

North Dakota 50 12 2 1 3 6 0 0

Ohio 525 153 20 5 59 58 1 10

Oklahoma 422 62 6 8 11 34 0 3

Oregon 365 55 6 4 10 30 0 5

Pennsylvania 1,218 171 24 13 24 92 0 18

Puerto Rico 655 83 6 5 17 47 0 8

Rhode Island 92 13 2 0 4 5 0 2

South Carolina 321 63 6 3 8 41 0 5

South Dakota 87 15 4 1 3 6 0 1

Tennessee 569 121 5 8 16 87 1 4

Texas 2,200 295 63 23 62 122 1 24

Utah 513 54 6 2 14 25 0 7

Vermont 46 11 3 2 0 6 0 0

Virgin Islands 20 4 2 0 0 2 0 0

Virginia 409 73 9 6 4 43 0 11

Washington 834 93 18 3 46 20 2 4

West Virginia 142 36 3 6 3 22 0 2

Wisconsin 561 78 19 1 38 16 1 3

Wyoming 56 11 3 0 1 7 0 0

Tribes - Region 1 4 1 0 0 0 1 0 0

Tribes - Region 5 10 4 3 0 1 0 0 0

Tribes - Region 6 0 0 0 0 0 0 0 0

Tribes - Region 8 6 2 0 1 1 0 0 0

Tribes - Region 9 45 9 6 0 2 1 0 0

Total 32,149 4,140 618 182 1,374 1,568 63 335

1

 The UCMR data are not representative at the state-level.

Page 1 of 2
EPA-OGWDW

Appendix B. Summary of Systems and Population Served by State

Occurrence Data from the UCMR 2

Table B2. BDE-99 - UCMR 2 Assessment Monitoring Data - Number of Systems and Population Served by State

State 1

Total 

Population 

Served

Pop. Served by 

Small Systems 

(serving ≤10,000 

people): Ground 

Water

Pop. Served by 

Small Systems 

(serving ≤10,000 

people): 

Surface Water

Pop. Served by 

Large Systems 

(serving 10,001-

100,000 people): 

Ground Water

Pop. Served by 

Large Systems 

(serving 10,001-

100,000 people): 

Surface Water

Pop. Served by 

Very Large 

Systems (serving 

>100,000 people): 

Ground Water

Pop. Served by 

Very Large 

Systems (serving 

>100,000 people): 

Surface Water

Alabama 4,249,148 64,214 15,859 850,382 1,612,450 0 1,706,245

Alaska 234,237 6,025 9,791 59,290 23,965 0 135,166

American Samoa 45,000 0 0 0 45,000 0 0

Arizona 4,417,574 32,953 0 999,514 110,587 675,445 2,599,075

Arkansas 1,771,814 31,449 19,189 395,797 638,748 0 686,632

California 32,516,672 101,399 70,338 3,738,533 6,626,442 1,088,908 20,891,052

Colorado 4,395,410 12,154 13,190 312,380 1,020,990 0 3,036,696

Connecticut 2,423,307 6,961 7,784 101,145 929,609 0 1,377,809

Delaware 550,332 14,255 0 54,443 36,130 0 445,504

District of Columbia 783,055 0 0 0 0 0 783,055

Florida 15,964,524 85,230 0 5,601,752 190,650 7,266,168 2,820,724

Georgia 6,323,497 30,214 19,473 555,035 1,594,334 163,688 3,960,753

Guam 136,301 0 0 0 36,300 100,001 0

Hawaii 1,168,403 14,938 0 237,807 128,935 786,723 0

Idaho 598,638 20,705 0 377,881 14,052 0 186,000

Illinois 7,910,559 62,240 31,607 1,237,820 1,377,669 405,228 4,795,996

Indiana 3,833,462 53,832 8,150 1,343,907 460,953 113,400 1,853,220

Iowa 1,669,054 34,873 7,782 635,226 435,492 0 555,682

Kansas 1,903,624 14,044 15,781 288,095 327,403 0 1,258,301

Kentucky 4,050,273 6,419 21,540 145,399 2,190,482 85,697 1,600,737

Louisiana 3,411,211 100,823 8,085 762,163 705,285 663,655 1,171,200

Maine 368,811 10,566 8,770 43,690 192,225 0 113,560

Maryland 4,493,237 9,908 6,123 346,418 348,121 249,600 3,533,067

Massachusetts 7,942,671 43,421 14,171 1,317,567 1,768,248 159,180 4,640,084

Michigan 5,866,881 54,175 12,964 366,966 859,317 283,846 4,289,613

Minnesota 3,092,542 38,944 4,960 1,707,947 406,914 0 933,777

Mississippi 1,418,405 86,727 0 988,496 0 0 343,182

Missouri 3,711,957 49,173 19,101 600,252 449,297 223,971 2,370,164

Montana 376,922 8,734 8,778 72,215 183,824 0 103,371

N. Mariana Islands 72,737 1,081 0 71,656 0 0 0

Navajo Nation 19,080 836 0 18,244 0 0 0

Nebraska 998,770 26,423 0 219,594 37,864 0 714,889

Nevada 1,999,825 13,712 8,323 59,000 73,095 0 1,845,695

New Hampshire 562,737 8,516 10,000 86,706 305,451 0 152,064

New Jersey 7,116,424 60,693 3,400 1,156,623 1,666,422 115,378 4,113,907

New Mexico 1,152,067 16,238 8,256 501,653 172,567 453,353 0

New York 14,764,779 35,519 44,587 1,371,569 1,657,155 1,682,822 9,973,127

North Carolina 5,366,551 37,318 18,964 580,495 1,974,056 108,666 2,647,052

North Dakota 350,292 5,414 2,694 78,529 263,655 0 0

Ohio 8,788,460 64,492 31,964 1,498,349 1,822,242 123,850 5,247,564

Oklahoma 2,491,284 10,318 31,117 241,483 950,915 0 1,257,451

Oregon 2,413,155 13,140 24,170 188,470 830,806 0 1,356,569

Pennsylvania 8,692,491 58,224 57,237 425,487 2,978,041 0 5,173,502

Puerto Rico 5,552,363 20,268 20,177 384,807 1,688,215 0 3,438,896

Rhode Island 911,235 1,812 0 107,302 250,585 0 551,536

South Carolina 2,785,309 14,508 19,828 180,888 1,218,197 0 1,351,888

South Dakota 349,953 10,139 1,592 43,056 167,166 0 128,000

Tennessee 4,625,703 22,345 49,153 428,243 2,499,282 687,096 939,584

Texas 18,832,904 189,890 115,111 1,429,442 3,795,822 1,253,442 12,049,197

Utah 2,403,787 20,075 15,000 274,446 934,364 0 1,159,902

Vermont 196,255 5,245 5,830 0 185,180 0 0

Virgin Islands 67,889 2,550 0 0 65,339 0 0

Virginia 4,635,684 11,756 31,277 98,415 1,285,803 0 3,208,433

Washington 4,265,055 47,921 18,679 1,255,343 756,649 374,556 1,811,906

West Virginia 958,526 8,711 26,897 65,669 527,486 0 329,764

Wisconsin 2,806,236 59,710 8,550 842,048 620,506 205,247 1,070,175

Wyoming 296,668 6,591 0 24,999 265,078 0 0

Tribes - Region 1 41,000 0 0 0 41,000 0 0

Tribes - Region 5 18,788 4,068 0 14,720 0 0 0

Tribes - Region 6 0 0 0 0 0 0 0

Tribes - Region 8 12,160 0 2,020 10,140 0 0 0

Tribes - Region 9 62,055 18,855 0 31,200 12,000 0 0

Total 229,237,740 1,790,743 878,262 34,828,693 49,758,358 17,269,919 124,711,765

1

 The UCMR data are not representative at the state-level.

Page 2 of 2
EPA-OGWDW

Appendix B. Summary of Systems and Population Served by State

Occurrence Data from the UCMR 2

Table B3. BDE-100 - UCMR 2 Assessment Monitoring Data - Number of Systems and Population Served by State

State 1

Total 

Number of 

Samples

Total 

Number of 

Systems

Number of 

Small Systems 

(serving ≤10,000 

people): Ground 

Water

Number of 

Small Systems 

(serving ≤10,000 

people): 

Surface Water

Number of 

Large Systems 

(serving 10,001-

100,000 people): 

Ground Water

Number of 

Large Systems 

(serving 10,001-

100,000 people): 

Surface Water

Number of Very 

Large Systems 

(serving 

>100,000 

people): Ground 

Water

Number of Very 

Large Systems 

(serving 

>100,000 

people): 

Surface Water

Alabama 946 120 13 3 36 62 0 6

Alaska 49 9 3 2 2 1 0 1

American Samoa 4 1 0 0 0 1 0 0

Arizona 951 69 13 0 41 5 1 9

Arkansas 289 61 9 4 17 28 0 3

California 6,725 393 32 14 123 152 8 64

Colorado 505 68 5 6 13 34 0 10

Connecticut 329 41 5 1 7 23 0 5

Delaware 106 10 4 0 2 1 0 3

District of Columbia 8 1 0 0 0 0 0 1

Florida 1,152 231 28 0 161 7 23 12

Georgia 570 110 14 5 27 51 1 12

Guam 246 3 0 0 0 2 1 0

Hawaii 315 18 3 0 8 5 2 0

Idaho 257 22 7 0 13 1 0 1

Illinois 839 141 22 5 61 42 3 8

Indiana 399 99 16 2 56 18 1 6

Iowa 233 54 14 1 24 12 0 3

Kansas 224 46 7 4 12 17 0 6

Kentucky 433 107 2 4 10 86 1 4

Louisiana 606 92 25 3 36 21 3 4

Maine 89 19 4 2 3 9 0 1

Maryland 180 38 7 2 13 12 1 3

Massachusetts 965 126 9 3 55 50 1 8

Michigan 393 77 21 2 18 29 2 5

Minnesota 356 91 15 1 64 9 0 2

Mississippi 636 78 30 0 46 0 0 2

Missouri 464 75 16 4 31 19 1 4

Montana 112 13 4 2 1 5 0 1

N. Mariana Islands 69 2 1 0 1 0 0 0

Navajo Nation 12 2 1 0 1 0 0 0

Nebraska 238 22 8 0 10 2 0 2

Nevada 184 15 4 1 4 2 0 4

New Hampshire 155 24 5 1 4 13 0 1

New Jersey 1,055 131 14 1 55 49 1 11

New Mexico 331 32 7 1 18 5 1 0

New York 1,542 154 18 11 47 59 5 14

North Carolina 1,032 126 16 5 27 65 1 12

North Dakota 50 12 2 1 3 6 0 0

Ohio 525 153 20 5 59 58 1 10

Oklahoma 422 62 6 8 11 34 0 3

Oregon 365 55 6 4 10 30 0 5

Pennsylvania 1,218 171 24 13 24 92 0 18

Puerto Rico 655 83 6 5 17 47 0 8

Rhode Island 92 13 2 0 4 5 0 2

South Carolina 321 63 6 3 8 41 0 5

South Dakota 87 15 4 1 3 6 0 1

Tennessee 569 121 5 8 16 87 1 4

Texas 2,200 295 63 23 62 122 1 24

Utah 513 54 6 2 14 25 0 7

Vermont 46 11 3 2 0 6 0 0

Virgin Islands 20 4 2 0 0 2 0 0

Virginia 409 73 9 6 4 43 0 11

Washington 834 93 18 3 46 20 2 4

West Virginia 142 36 3 6 3 22 0 2

Wisconsin 561 78 19 1 38 16 1 3

Wyoming 56 11 3 0 1 7 0 0

Tribes - Region 1 4 1 0 0 0 1 0 0

Tribes - Region 5 10 4 3 0 1 0 0 0

Tribes - Region 6 0 0 0 0 0 0 0 0

Tribes - Region 8 6 2 0 1 1 0 0 0

Tribes - Region 9 45 9 6 0 2 1 0 0

Total 32,149 4,140 618 182 1,374 1,568 63 335

1

 The UCMR data are not representative at the state-level.

Page 1 of 2
EPA-OGWDW

Appendix B. Summary of Systems and Population Served by State

Occurrence Data from the UCMR 2

Table B3. BDE-100 - UCMR 2 Assessment Monitoring Data - Number of Systems and Population Served by State

State 1

Total 

Population 

Served

Pop. Served by 

Small Systems 

(serving ≤10,000 

people): Ground 

Water

Pop. Served by 

Small Systems 

(serving ≤10,000 

people): 

Surface Water

Pop. Served by 

Large Systems 

(serving 10,001-

100,000 people): 

Ground Water

Pop. Served by 

Large Systems 

(serving 10,001-

100,000 people): 

Surface Water

Pop. Served by 

Very Large 

Systems (serving 

>100,000 people): 

Ground Water

Pop. Served by 

Very Large 

Systems (serving 

>100,000 people): 

Surface Water

Alabama 4,249,148 64,214 15,859 850,382 1,612,450 0 1,706,245

Alaska 234,237 6,025 9,791 59,290 23,965 0 135,166

American Samoa 45,000 0 0 0 45,000 0 0

Arizona 4,417,574 32,953 0 999,514 110,587 675,445 2,599,075

Arkansas 1,771,814 31,449 19,189 395,797 638,748 0 686,632

California 32,516,672 101,399 70,338 3,738,533 6,626,442 1,088,908 20,891,052

Colorado 4,395,410 12,154 13,190 312,380 1,020,990 0 3,036,696

Connecticut 2,423,307 6,961 7,784 101,145 929,609 0 1,377,809

Delaware 550,332 14,255 0 54,443 36,130 0 445,504

District of Columbia 783,055 0 0 0 0 0 783,055

Florida 15,964,524 85,230 0 5,601,752 190,650 7,266,168 2,820,724

Georgia 6,323,497 30,214 19,473 555,035 1,594,334 163,688 3,960,753

Guam 136,301 0 0 0 36,300 100,001 0

Hawaii 1,168,403 14,938 0 237,807 128,935 786,723 0

Idaho 598,638 20,705 0 377,881 14,052 0 186,000

Illinois 7,910,559 62,240 31,607 1,237,820 1,377,669 405,228 4,795,996

Indiana 3,833,462 53,832 8,150 1,343,907 460,953 113,400 1,853,220

Iowa 1,669,054 34,873 7,782 635,226 435,492 0 555,682

Kansas 1,903,624 14,044 15,781 288,095 327,403 0 1,258,301

Kentucky 4,050,273 6,419 21,540 145,399 2,190,482 85,697 1,600,737

Louisiana 3,411,211 100,823 8,085 762,163 705,285 663,655 1,171,200

Maine 368,811 10,566 8,770 43,690 192,225 0 113,560

Maryland 4,493,237 9,908 6,123 346,418 348,121 249,600 3,533,067

Massachusetts 7,942,671 43,421 14,171 1,317,567 1,768,248 159,180 4,640,084

Michigan 5,866,881 54,175 12,964 366,966 859,317 283,846 4,289,613

Minnesota 3,092,542 38,944 4,960 1,707,947 406,914 0 933,777

Mississippi 1,418,405 86,727 0 988,496 0 0 343,182

Missouri 3,711,957 49,173 19,101 600,252 449,297 223,971 2,370,164

Montana 376,922 8,734 8,778 72,215 183,824 0 103,371

N. Mariana Islands 72,737 1,081 0 71,656 0 0 0

Navajo Nation 19,080 836 0 18,244 0 0 0

Nebraska 998,770 26,423 0 219,594 37,864 0 714,889

Nevada 1,999,825 13,712 8,323 59,000 73,095 0 1,845,695

New Hampshire 562,737 8,516 10,000 86,706 305,451 0 152,064

New Jersey 7,116,424 60,693 3,400 1,156,623 1,666,422 115,378 4,113,907

New Mexico 1,152,067 16,238 8,256 501,653 172,567 453,353 0

New York 14,764,779 35,519 44,587 1,371,569 1,657,155 1,682,822 9,973,127

North Carolina 5,366,551 37,318 18,964 580,495 1,974,056 108,666 2,647,052

North Dakota 350,292 5,414 2,694 78,529 263,655 0 0

Ohio 8,788,460 64,492 31,964 1,498,349 1,822,242 123,850 5,247,564

Oklahoma 2,491,284 10,318 31,117 241,483 950,915 0 1,257,451

Oregon 2,413,155 13,140 24,170 188,470 830,806 0 1,356,569

Pennsylvania 8,692,491 58,224 57,237 425,487 2,978,041 0 5,173,502

Puerto Rico 5,552,363 20,268 20,177 384,807 1,688,215 0 3,438,896

Rhode Island 911,235 1,812 0 107,302 250,585 0 551,536

South Carolina 2,785,309 14,508 19,828 180,888 1,218,197 0 1,351,888

South Dakota 349,953 10,139 1,592 43,056 167,166 0 128,000

Tennessee 4,625,703 22,345 49,153 428,243 2,499,282 687,096 939,584

Texas 18,832,904 189,890 115,111 1,429,442 3,795,822 1,253,442 12,049,197

Utah 2,403,787 20,075 15,000 274,446 934,364 0 1,159,902

Vermont 196,255 5,245 5,830 0 185,180 0 0

Virgin Islands 67,889 2,550 0 0 65,339 0 0

Virginia 4,635,684 11,756 31,277 98,415 1,285,803 0 3,208,433

Washington 4,265,055 47,921 18,679 1,255,343 756,649 374,556 1,811,906

West Virginia 958,526 8,711 26,897 65,669 527,486 0 329,764

Wisconsin 2,806,236 59,710 8,550 842,048 620,506 205,247 1,070,175

Wyoming 296,668 6,591 0 24,999 265,078 0 0

Tribes - Region 1 41,000 0 0 0 41,000 0 0

Tribes - Region 5 18,788 4,068 0 14,720 0 0 0

Tribes - Region 6 0 0 0 0 0 0 0

Tribes - Region 8 12,160 0 2,020 10,140 0 0 0

Tribes - Region 9 62,055 18,855 0 31,200 12,000 0 0

Total 229,237,740 1,790,743 878,262 34,828,693 49,758,358 17,269,919 124,711,765

1

 The UCMR data are not representative at the state-level.

Page 2 of 2
EPA-OGWDW

Appendix B. Summary of Systems and Population Served by State

Occurrence Data from the UCMR 2

Table B4. BDE-153 - UCMR 2 Assessment Monitoring Data - Number of Systems and Population Served by State

State 1

Total 

Number of 

Samples

Total 

Number of 

Systems

Number of 

Small Systems 

(serving ≤10,000 

people): Ground 

Water

Number of 

Small Systems 

(serving ≤10,000 

people): 

Surface Water

Number of 

Large Systems 

(serving 10,001-

100,000 people): 

Ground Water

Number of 

Large Systems 

(serving 10,001-

100,000 people): 

Surface Water

Number of Very 

Large Systems 

(serving 

>100,000 

people): Ground 

Water

Number of Very 

Large Systems 

(serving 

>100,000 

people): 

Surface Water

Alabama 946 120 13 3 36 62 0 6

Alaska 49 9 3 2 2 1 0 1

American Samoa 4 1 0 0 0 1 0 0

Arizona 951 69 13 0 41 5 1 9

Arkansas 289 61 9 4 17 28 0 3

California 6,725 393 32 14 123 152 8 64

Colorado 505 68 5 6 13 34 0 10

Connecticut 329 41 5 1 7 23 0 5

Delaware 106 10 4 0 2 1 0 3

District of Columbia 8 1 0 0 0 0 0 1

Florida 1,152 231 28 0 161 7 23 12

Georgia 570 110 14 5 27 51 1 12

Guam 246 3 0 0 0 2 1 0

Hawaii 315 18 3 0 8 5 2 0

Idaho 257 22 7 0 13 1 0 1

Illinois 839 141 22 5 61 42 3 8

Indiana 399 99 16 2 56 18 1 6

Iowa 233 54 14 1 24 12 0 3

Kansas 224 46 7 4 12 17 0 6

Kentucky 433 107 2 4 10 86 1 4

Louisiana 606 92 25 3 36 21 3 4

Maine 89 19 4 2 3 9 0 1

Maryland 180 38 7 2 13 12 1 3

Massachusetts 965 126 9 3 55 50 1 8

Michigan 393 77 21 2 18 29 2 5

Minnesota 356 91 15 1 64 9 0 2

Mississippi 636 78 30 0 46 0 0 2

Missouri 464 75 16 4 31 19 1 4

Montana 112 13 4 2 1 5 0 1

N. Mariana Islands 69 2 1 0 1 0 0 0

Navajo Nation 12 2 1 0 1 0 0 0

Nebraska 238 22 8 0 10 2 0 2

Nevada 184 15 4 1 4 2 0 4

New Hampshire 155 24 5 1 4 13 0 1

New Jersey 1,055 131 14 1 55 49 1 11

New Mexico 331 32 7 1 18 5 1 0

New York 1,542 154 18 11 47 59 5 14

North Carolina 1,032 126 16 5 27 65 1 12

North Dakota 50 12 2 1 3 6 0 0

Ohio 525 153 20 5 59 58 1 10

Oklahoma 422 62 6 8 11 34 0 3

Oregon 365 55 6 4 10 30 0 5

Pennsylvania 1,218 171 24 13 24 92 0 18

Puerto Rico 655 83 6 5 17 47 0 8

Rhode Island 92 13 2 0 4 5 0 2

South Carolina 321 63 6 3 8 41 0 5

South Dakota 87 15 4 1 3 6 0 1

Tennessee 569 121 5 8 16 87 1 4

Texas 2,190 295 63 23 62 122 1 24

Utah 513 54 6 2 14 25 0 7

Vermont 46 11 3 2 0 6 0 0

Virgin Islands 20 4 2 0 0 2 0 0

Virginia 409 73 9 6 4 43 0 11

Washington 834 93 18 3 46 20 2 4

West Virginia 142 36 3 6 3 22 0 2

Wisconsin 561 78 19 1 38 16 1 3

Wyoming 56 11 3 0 1 7 0 0

Tribes - Region 1 4 1 0 0 0 1 0 0

Tribes - Region 5 10 4 3 0 1 0 0 0

Tribes - Region 6 0 0 0 0 0 0 0 0

Tribes - Region 8 6 2 0 1 1 0 0 0

Tribes - Region 9 45 9 6 0 2 1 0 0

Total 32,139 4,140 618 182 1,374 1,568 63 335

1

 The UCMR data are not representative at the state-level.

Page 1 of 2
EPA-OGWDW

Appendix B. Summary of Systems and Population Served by State

Occurrence Data from the UCMR 2

Table B4. BDE-153 - UCMR 2 Assessment Monitoring Data - Number of Systems and Population Served by State

State 1

Total 

Population 

Served

Pop. Served by 

Small Systems 

(serving ≤10,000 

people): Ground 

Water

Pop. Served by 

Small Systems 

(serving ≤10,000 

people): 

Surface Water

Pop. Served by 

Large Systems 

(serving 10,001-

100,000 people): 

Ground Water

Pop. Served by 

Large Systems 

(serving 10,001-

100,000 people): 

Surface Water

Pop. Served by 

Very Large 

Systems (serving 

>100,000 people): 

Ground Water

Pop. Served by 

Very Large 

Systems (serving 

>100,000 people): 

Surface Water

Alabama 4,249,148 64,214 15,859 850,382 1,612,450 0 1,706,245

Alaska 234,237 6,025 9,791 59,290 23,965 0 135,166

American Samoa 45,000 0 0 0 45,000 0 0

Arizona 4,417,574 32,953 0 999,514 110,587 675,445 2,599,075

Arkansas 1,771,814 31,449 19,189 395,797 638,748 0 686,632

California 32,516,672 101,399 70,338 3,738,533 6,626,442 1,088,908 20,891,052

Colorado 4,395,410 12,154 13,190 312,380 1,020,990 0 3,036,696

Connecticut 2,423,307 6,961 7,784 101,145 929,609 0 1,377,809

Delaware 550,332 14,255 0 54,443 36,130 0 445,504

District of Columbia 783,055 0 0 0 0 0 783,055

Florida 15,964,524 85,230 0 5,601,752 190,650 7,266,168 2,820,724

Georgia 6,323,497 30,214 19,473 555,035 1,594,334 163,688 3,960,753

Guam 136,301 0 0 0 36,300 100,001 0

Hawaii 1,168,403 14,938 0 237,807 128,935 786,723 0

Idaho 598,638 20,705 0 377,881 14,052 0 186,000

Illinois 7,910,559 62,240 31,607 1,237,820 1,377,669 405,228 4,795,996

Indiana 3,833,462 53,832 8,150 1,343,907 460,953 113,400 1,853,220

Iowa 1,669,054 34,873 7,782 635,226 435,492 0 555,682

Kansas 1,903,624 14,044 15,781 288,095 327,403 0 1,258,301

Kentucky 4,050,273 6,419 21,540 145,399 2,190,482 85,697 1,600,737

Louisiana 3,411,211 100,823 8,085 762,163 705,285 663,655 1,171,200

Maine 368,811 10,566 8,770 43,690 192,225 0 113,560

Maryland 4,493,237 9,908 6,123 346,418 348,121 249,600 3,533,067

Massachusetts 7,942,671 43,421 14,171 1,317,567 1,768,248 159,180 4,640,084

Michigan 5,866,881 54,175 12,964 366,966 859,317 283,846 4,289,613

Minnesota 3,092,542 38,944 4,960 1,707,947 406,914 0 933,777

Mississippi 1,418,405 86,727 0 988,496 0 0 343,182

Missouri 3,711,957 49,173 19,101 600,252 449,297 223,971 2,370,164

Montana 376,922 8,734 8,778 72,215 183,824 0 103,371

N. Mariana Islands 72,737 1,081 0 71,656 0 0 0

Navajo Nation 19,080 836 0 18,244 0 0 0

Nebraska 998,770 26,423 0 219,594 37,864 0 714,889

Nevada 1,999,825 13,712 8,323 59,000 73,095 0 1,845,695

New Hampshire 562,737 8,516 10,000 86,706 305,451 0 152,064

New Jersey 7,116,424 60,693 3,400 1,156,623 1,666,422 115,378 4,113,907

New Mexico 1,152,067 16,238 8,256 501,653 172,567 453,353 0

New York 14,764,779 35,519 44,587 1,371,569 1,657,155 1,682,822 9,973,127

North Carolina 5,366,551 37,318 18,964 580,495 1,974,056 108,666 2,647,052

North Dakota 350,292 5,414 2,694 78,529 263,655 0 0

Ohio 8,788,460 64,492 31,964 1,498,349 1,822,242 123,850 5,247,564

Oklahoma 2,491,284 10,318 31,117 241,483 950,915 0 1,257,451

Oregon 2,413,155 13,140 24,170 188,470 830,806 0 1,356,569

Pennsylvania 8,692,491 58,224 57,237 425,487 2,978,041 0 5,173,502

Puerto Rico 5,552,363 20,268 20,177 384,807 1,688,215 0 3,438,896

Rhode Island 911,235 1,812 0 107,302 250,585 0 551,536

South Carolina 2,785,309 14,508 19,828 180,888 1,218,197 0 1,351,888

South Dakota 349,953 10,139 1,592 43,056 167,166 0 128,000

Tennessee 4,625,703 22,345 49,153 428,243 2,499,282 687,096 939,584

Texas 18,832,904 189,890 115,111 1,429,442 3,795,822 1,253,442 12,049,197

Utah 2,403,787 20,075 15,000 274,446 934,364 0 1,159,902

Vermont 196,255 5,245 5,830 0 185,180 0 0

Virgin Islands 67,889 2,550 0 0 65,339 0 0

Virginia 4,635,684 11,756 31,277 98,415 1,285,803 0 3,208,433

Washington 4,265,055 47,921 18,679 1,255,343 756,649 374,556 1,811,906

West Virginia 958,526 8,711 26,897 65,669 527,486 0 329,764

Wisconsin 2,806,236 59,710 8,550 842,048 620,506 205,247 1,070,175

Wyoming 296,668 6,591 0 24,999 265,078 0 0

Tribes - Region 1 41,000 0 0 0 41,000 0 0

Tribes - Region 5 18,788 4,068 0 14,720 0 0 0

Tribes - Region 6 0 0 0 0 0 0 0

Tribes - Region 8 12,160 0 2,020 10,140 0 0 0

Tribes - Region 9 62,055 18,855 0 31,200 12,000 0 0

Total 229,237,740 1,790,743 878,262 34,828,693 49,758,358 17,269,919 124,711,765

1

 The UCMR data are not representative at the state-level.

Page 2 of 2
EPA-OGWDW

Appendix B. Summary of Systems and Population Served by State

Occurrence Data from the UCMR 2

Table B5. Dimethoate - UCMR 2 Assessment Monitoring Data - Number of Systems and Population Served by State

State 1

Total 

Number of 

Samples

Total 

Number of 

Systems

Number of 

Small Systems 

(serving ≤10,000 

people): Ground 

Water

Number of 

Small Systems 

(serving ≤10,000 

people): 

Surface Water

Number of 

Large Systems 

(serving 10,001-

100,000 people): 

Ground Water

Number of 

Large Systems 

(serving 10,001-

100,000 people): 

Surface Water

Number of Very 

Large Systems 

(serving 

>100,000 

people): Ground 

Water

Number of Very 

Large Systems 

(serving 

>100,000 

people): 

Surface Water

Alabama 946 120 13 3 36 62 0 6

Alaska 49 9 3 2 2 1 0 1

American Samoa 4 1 0 0 0 1 0 0

Arizona 951 69 13 0 41 5 1 9

Arkansas 289 61 9 4 17 28 0 3

California 6,725 393 32 14 123 152 8 64

Colorado 505 68 5 6 13 34 0 10

Connecticut 329 41 5 1 7 23 0 5

Delaware 106 10 4 0 2 1 0 3

District of Columbia 8 1 0 0 0 0 0 1

Florida 1,152 231 28 0 161 7 23 12

Georgia 570 110 14 5 27 51 1 12

Guam 246 3 0 0 0 2 1 0

Hawaii 315 18 3 0 8 5 2 0

Idaho 257 22 7 0 13 1 0 1

Illinois 839 141 22 5 61 42 3 8

Indiana 399 99 16 2 56 18 1 6

Iowa 233 54 14 1 24 12 0 3

Kansas 224 46 7 4 12 17 0 6

Kentucky 433 107 2 4 10 86 1 4

Louisiana 607 92 25 3 36 21 3 4

Maine 89 19 4 2 3 9 0 1

Maryland 180 38 7 2 13 12 1 3

Massachusetts 965 126 9 3 55 50 1 8

Michigan 393 77 21 2 18 29 2 5

Minnesota 356 91 15 1 64 9 0 2

Mississippi 636 78 30 0 46 0 0 2

Missouri 464 75 16 4 31 19 1 4

Montana 112 13 4 2 1 5 0 1

N. Mariana Islands 69 2 1 0 1 0 0 0

Navajo Nation 12 2 1 0 1 0 0 0

Nebraska 238 22 8 0 10 2 0 2

Nevada 184 15 4 1 4 2 0 4

New Hampshire 155 24 5 1 4 13 0 1

New Jersey 1,055 131 14 1 55 49 1 11

New Mexico 331 32 7 1 18 5 1 0

New York 1,542 154 18 11 47 59 5 14

North Carolina 1,032 126 16 5 27 65 1 12

North Dakota 50 12 2 1 3 6 0 0

Ohio 525 153 20 5 59 58 1 10

Oklahoma 422 62 6 8 11 34 0 3

Oregon 365 55 6 4 10 30 0 5

Pennsylvania 1,218 171 24 13 24 92 0 18

Puerto Rico 655 83 6 5 17 47 0 8

Rhode Island 92 13 2 0 4 5 0 2

South Carolina 321 63 6 3 8 41 0 5

South Dakota 87 15 4 1 3 6 0 1

Tennessee 569 121 5 8 16 87 1 4

Texas 2,200 295 63 23 62 122 1 24

Utah 513 54 6 2 14 25 0 7

Vermont 46 11 3 2 0 6 0 0

Virgin Islands 20 4 2 0 0 2 0 0

Virginia 409 73 9 6 4 43 0 11

Washington 834 93 18 3 46 20 2 4

West Virginia 142 36 3 6 3 22 0 2

Wisconsin 561 78 19 1 38 16 1 3

Wyoming 56 11 3 0 1 7 0 0

Tribes - Region 1 4 1 0 0 0 1 0 0

Tribes - Region 5 10 4 3 0 1 0 0 0

Tribes - Region 6 0 0 0 0 0 0 0 0

Tribes - Region 8 6 2 0 1 1 0 0 0

Tribes - Region 9 45 9 6 0 2 1 0 0

Total 32,150 4,140 618 182 1,374 1,568 63 335

1

 The UCMR data are not representative at the state-level.

Page 1 of 2
EPA-OGWDW

Appendix B. Summary of Systems and Population Served by State

Occurrence Data from the UCMR 2

Table B5. Dimethoate - UCMR 2 Assessment Monitoring Data - Number of Systems and Population Served by State

State 1

Total 

Population 

Served

Pop. Served by 

Small Systems 

(serving ≤10,000 

people): Ground 

Water

Pop. Served by 

Small Systems 

(serving ≤10,000 

people): 

Surface Water

Pop. Served by 

Large Systems 

(serving 10,001-

100,000 people): 

Ground Water

Pop. Served by 

Large Systems 

(serving 10,001-

100,000 people): 

Surface Water

Pop. Served by 

Very Large 

Systems (serving 

>100,000 people): 

Ground Water

Pop. Served by 

Very Large 

Systems (serving 

>100,000 people): 

Surface Water

Alabama 4,249,148 64,214 15,859 850,382 1,612,450 0 1,706,245

Alaska 234,237 6,025 9,791 59,290 23,965 0 135,166

American Samoa 45,000 0 0 0 45,000 0 0

Arizona 4,417,574 32,953 0 999,514 110,587 675,445 2,599,075

Arkansas 1,771,814 31,449 19,189 395,797 638,748 0 686,632

California 32,516,672 101,399 70,338 3,738,533 6,626,442 1,088,908 20,891,052

Colorado 4,395,410 12,154 13,190 312,380 1,020,990 0 3,036,696

Connecticut 2,423,307 6,961 7,784 101,145 929,609 0 1,377,809

Delaware 550,332 14,255 0 54,443 36,130 0 445,504

District of Columbia 783,055 0 0 0 0 0 783,055

Florida 15,964,524 85,230 0 5,601,752 190,650 7,266,168 2,820,724

Georgia 6,323,497 30,214 19,473 555,035 1,594,334 163,688 3,960,753

Guam 136,301 0 0 0 36,300 100,001 0

Hawaii 1,168,403 14,938 0 237,807 128,935 786,723 0

Idaho 598,638 20,705 0 377,881 14,052 0 186,000

Illinois 7,910,559 62,240 31,607 1,237,820 1,377,669 405,228 4,795,996

Indiana 3,833,462 53,832 8,150 1,343,907 460,953 113,400 1,853,220

Iowa 1,669,054 34,873 7,782 635,226 435,492 0 555,682

Kansas 1,903,624 14,044 15,781 288,095 327,403 0 1,258,301

Kentucky 4,050,273 6,419 21,540 145,399 2,190,482 85,697 1,600,737

Louisiana 3,411,211 100,823 8,085 762,163 705,285 663,655 1,171,200

Maine 368,811 10,566 8,770 43,690 192,225 0 113,560

Maryland 4,493,237 9,908 6,123 346,418 348,121 249,600 3,533,067

Massachusetts 7,942,671 43,421 14,171 1,317,567 1,768,248 159,180 4,640,084

Michigan 5,866,881 54,175 12,964 366,966 859,317 283,846 4,289,613

Minnesota 3,092,542 38,944 4,960 1,707,947 406,914 0 933,777

Mississippi 1,418,405 86,727 0 988,496 0 0 343,182

Missouri 3,711,957 49,173 19,101 600,252 449,297 223,971 2,370,164

Montana 376,922 8,734 8,778 72,215 183,824 0 103,371

N. Mariana Islands 72,737 1,081 0 71,656 0 0 0

Navajo Nation 19,080 836 0 18,244 0 0 0

Nebraska 998,770 26,423 0 219,594 37,864 0 714,889

Nevada 1,999,825 13,712 8,323 59,000 73,095 0 1,845,695

New Hampshire 562,737 8,516 10,000 86,706 305,451 0 152,064

New Jersey 7,116,424 60,693 3,400 1,156,623 1,666,422 115,378 4,113,907

New Mexico 1,152,067 16,238 8,256 501,653 172,567 453,353 0

New York 14,764,779 35,519 44,587 1,371,569 1,657,155 1,682,822 9,973,127

North Carolina 5,366,551 37,318 18,964 580,495 1,974,056 108,666 2,647,052

North Dakota 350,292 5,414 2,694 78,529 263,655 0 0

Ohio 8,788,460 64,492 31,964 1,498,349 1,822,242 123,850 5,247,564

Oklahoma 2,491,284 10,318 31,117 241,483 950,915 0 1,257,451

Oregon 2,413,155 13,140 24,170 188,470 830,806 0 1,356,569

Pennsylvania 8,692,491 58,224 57,237 425,487 2,978,041 0 5,173,502

Puerto Rico 5,552,363 20,268 20,177 384,807 1,688,215 0 3,438,896

Rhode Island 911,235 1,812 0 107,302 250,585 0 551,536

South Carolina 2,785,309 14,508 19,828 180,888 1,218,197 0 1,351,888

South Dakota 349,953 10,139 1,592 43,056 167,166 0 128,000

Tennessee 4,625,703 22,345 49,153 428,243 2,499,282 687,096 939,584

Texas 18,832,904 189,890 115,111 1,429,442 3,795,822 1,253,442 12,049,197

Utah 2,403,787 20,075 15,000 274,446 934,364 0 1,159,902

Vermont 196,255 5,245 5,830 0 185,180 0 0

Virgin Islands 67,889 2,550 0 0 65,339 0 0

Virginia 4,635,684 11,756 31,277 98,415 1,285,803 0 3,208,433

Washington 4,265,055 47,921 18,679 1,255,343 756,649 374,556 1,811,906

West Virginia 958,526 8,711 26,897 65,669 527,486 0 329,764

Wisconsin 2,806,236 59,710 8,550 842,048 620,506 205,247 1,070,175

Wyoming 296,668 6,591 0 24,999 265,078 0 0

Tribes - Region 1 41,000 0 0 0 41,000 0 0

Tribes - Region 5 18,788 4,068 0 14,720 0 0 0

Tribes - Region 6 0 0 0 0 0 0 0

Tribes - Region 8 12,160 0 2,020 10,140 0 0 0

Tribes - Region 9 62,055 18,855 0 31,200 12,000 0 0

Total 229,237,740 1,790,743 878,262 34,828,693 49,758,358 17,269,919 124,711,765

1

 The UCMR data are not representative at the state-level.

Page 2 of 2
EPA-OGWDW

Appendix B. Summary of Systems and Population Served by State

Occurrence Data from the UCMR 2

Table B6. 1,3-Dinitrobenzene - UCMR 2 Assessment Monitoring Data - Number of Systems and Population Served by State

State 1

Total 

Number of 

Samples

Total 

Number of 

Systems

Number of 

Small Systems 

(serving ≤10,000 

people): Ground 

Water

Number of 

Small Systems 

(serving ≤10,000 

people): 

Surface Water

Number of 

Large Systems 

(serving 10,001-

100,000 people): 

Ground Water

Number of 

Large Systems 

(serving 10,001-

100,000 people): 

Surface Water

Number of Very 

Large Systems 

(serving 

>100,000 

people): Ground 

Water

Number of Very 

Large Systems 

(serving 

>100,000 

people): 

Surface Water

Alabama 946 120 13 3 36 62 0 6

Alaska 48 8 3 2 1 1 0 1

American Samoa 4 1 0 0 0 1 0 0

Arizona 952 69 13 0 41 5 1 9

Arkansas 290 61 9 4 17 28 0 3

California 6,724 393 32 14 123 152 8 64

Colorado 503 68 5 6 13 34 0 10

Connecticut 329 41 5 1 7 23 0 5

Delaware 106 10 4 0 2 1 0 3

District of Columbia 8 1 0 0 0 0 0 1

Florida 1,155 231 28 0 161 7 23 12

Georgia 570 110 14 5 27 51 1 12

Guam 245 3 0 0 0 2 1 0

Hawaii 313 18 3 0 8 5 2 0

Idaho 256 22 7 0 13 1 0 1

Illinois 839 141 22 5 61 42 3 8

Indiana 399 99 16 2 56 18 1 6

Iowa 234 54 14 1 24 12 0 3

Kansas 226 46 7 4 12 17 0 6

Kentucky 432 107 2 4 10 86 1 4

Louisiana 606 92 25 3 36 21 3 4

Maine 89 19 4 2 3 9 0 1

Maryland 180 38 7 2 13 12 1 3

Massachusetts 965 126 9 3 55 50 1 8

Michigan 393 77 21 2 18 29 2 5

Minnesota 356 91 15 1 64 9 0 2

Mississippi 635 78 30 0 46 0 0 2

Missouri 463 75 16 4 31 19 1 4

Montana 111 13 4 2 1 5 0 1

N. Mariana Islands 68 2 1 0 1 0 0 0

Navajo Nation 12 2 1 0 1 0 0 0

Nebraska 238 22 8 0 10 2 0 2

Nevada 184 15 4 1 4 2 0 4

New Hampshire 155 24 5 1 4 13 0 1

New Jersey 1,058 131 14 1 55 49 1 11

New Mexico 331 32 7 1 18 5 1 0

New York 1,538 154 18 11 47 59 5 14

North Carolina 1,029 126 16 5 27 65 1 12

North Dakota 50 12 2 1 3 6 0 0

Ohio 525 153 20 5 59 58 1 10

Oklahoma 434 62 6 8 11 34 0 3

Oregon 365 55 6 4 10 30 0 5

Pennsylvania 1,218 171 24 13 24 92 0 18

Puerto Rico 645 83 6 5 17 47 0 8

Rhode Island 91 13 2 0 4 5 0 2

South Carolina 321 63 6 3 8 41 0 5

South Dakota 87 15 4 1 3 6 0 1

Tennessee 569 121 5 8 16 87 1 4

Texas 2,199 295 63 23 62 122 1 24

Utah 514 54 6 2 14 25 0 7

Vermont 46 11 3 2 0 6 0 0

Virgin Islands 20 4 2 0 0 2 0 0

Virginia 409 73 9 6 4 43 0 11

Washington 844 93 18 3 46 20 2 4

West Virginia 142 36 3 6 3 22 0 2

Wisconsin 561 78 19 1 38 16 1 3

Wyoming 57 11 3 0 1 7 0 0

Tribes - Region 1 4 1 0 0 0 1 0 0

Tribes - Region 5 10 4 3 0 1 0 0 0

Tribes - Region 6 0 0 0 0 0 0 0 0

Tribes - Region 8 6 2 0 1 1 0 0 0

Tribes - Region 9 45 9 6 0 2 1 0 0

Total 32,152 4,139 618 182 1,373 1,568 63 335

1

 The UCMR data are not representative at the state-level.

Page 1 of 2
EPA-OGWDW

Appendix B. Summary of Systems and Population Served by State

Occurrence Data from the UCMR 2

State 1

Total 

Population 

Served

Pop. Served by 

Small Systems 

(serving ≤10,000 

people): Ground 

Water

Pop. Served by 

Small Systems 

(serving ≤10,000 

people): 

Surface Water

Pop. Served by 

Large Systems 

(serving 10,001-

100,000 people): 

Ground Water

Pop. Served by 

Large Systems 

(serving 10,001-

100,000 people): 

Surface Water

Pop. Served by 

Very Large 

Systems (serving 

>100,000 people): 

Ground Water

Pop. Served by 

Very Large 

Systems (serving 

>100,000 people): 

Surface Water

Alabama 4,249,148 64,214 15,859 850,382 1,612,450 0 1,706,245

Alaska 222,237 6,025 9,791 47,290 23,965 0 135,166

American Samoa 45,000 0 0 0 45,000 0 0

Arizona 4,417,574 32,953 0 999,514 110,587 675,445 2,599,075

Arkansas 1,771,814 31,449 19,189 395,797 638,748 0 686,632

California 32,516,672 101,399 70,338 3,738,533 6,626,442 1,088,908 20,891,052

Colorado 4,395,410 12,154 13,190 312,380 1,020,990 0 3,036,696

Connecticut 2,423,307 6,961 7,784 101,145 929,609 0 1,377,809

Delaware 550,332 14,255 0 54,443 36,130 0 445,504

District of Columbia 783,055 0 0 0 0 0 783,055

Florida 15,964,524 85,230 0 5,601,752 190,650 7,266,168 2,820,724

Georgia 6,323,497 30,214 19,473 555,035 1,594,334 163,688 3,960,753

Guam 136,301 0 0 0 36,300 100,001 0

Hawaii 1,168,403 14,938 0 237,807 128,935 786,723 0

Idaho 598,638 20,705 0 377,881 14,052 0 186,000

Illinois 7,910,559 62,240 31,607 1,237,820 1,377,669 405,228 4,795,996

Indiana 3,833,462 53,832 8,150 1,343,907 460,953 113,400 1,853,220

Iowa 1,669,054 34,873 7,782 635,226 435,492 0 555,682

Kansas 1,903,624 14,044 15,781 288,095 327,403 0 1,258,301

Kentucky 4,050,273 6,419 21,540 145,399 2,190,482 85,697 1,600,737

Louisiana 3,411,211 100,823 8,085 762,163 705,285 663,655 1,171,200

Maine 368,811 10,566 8,770 43,690 192,225 0 113,560

Maryland 4,493,237 9,908 6,123 346,418 348,121 249,600 3,533,067

Massachusetts 7,942,671 43,421 14,171 1,317,567 1,768,248 159,180 4,640,084

Michigan 5,866,881 54,175 12,964 366,966 859,317 283,846 4,289,613

Minnesota 3,092,542 38,944 4,960 1,707,947 406,914 0 933,777

Mississippi 1,418,405 86,727 0 988,496 0 0 343,182

Missouri 3,711,957 49,173 19,101 600,252 449,297 223,971 2,370,164

Montana 376,922 8,734 8,778 72,215 183,824 0 103,371

N. Mariana Islands 72,737 1,081 0 71,656 0 0 0

Navajo Nation 19,080 836 0 18,244 0 0 0

Nebraska 998,770 26,423 0 219,594 37,864 0 714,889

Nevada 1,999,825 13,712 8,323 59,000 73,095 0 1,845,695

New Hampshire 562,737 8,516 10,000 86,706 305,451 0 152,064

New Jersey 7,116,424 60,693 3,400 1,156,623 1,666,422 115,378 4,113,907

New Mexico 1,152,067 16,238 8,256 501,653 172,567 453,353 0

New York 14,764,779 35,519 44,587 1,371,569 1,657,155 1,682,822 9,973,127

North Carolina 5,366,551 37,318 18,964 580,495 1,974,056 108,666 2,647,052

North Dakota 350,292 5,414 2,694 78,529 263,655 0 0

Ohio 8,788,460 64,492 31,964 1,498,349 1,822,242 123,850 5,247,564

Oklahoma 2,491,284 10,318 31,117 241,483 950,915 0 1,257,451

Oregon 2,413,155 13,140 24,170 188,470 830,806 0 1,356,569

Pennsylvania 8,692,491 58,224 57,237 425,487 2,978,041 0 5,173,502

Puerto Rico 5,552,363 20,268 20,177 384,807 1,688,215 0 3,438,896

Rhode Island 911,235 1,812 0 107,302 250,585 0 551,536

South Carolina 2,785,309 14,508 19,828 180,888 1,218,197 0 1,351,888

South Dakota 349,953 10,139 1,592 43,056 167,166 0 128,000

Tennessee 4,625,703 22,345 49,153 428,243 2,499,282 687,096 939,584

Texas 18,832,904 189,890 115,111 1,429,442 3,795,822 1,253,442 12,049,197

Utah 2,403,787 20,075 15,000 274,446 934,364 0 1,159,902

Vermont 196,255 5,245 5,830 0 185,180 0 0

Virgin Islands 67,889 2,550 0 0 65,339 0 0

Virginia 4,635,684 11,756 31,277 98,415 1,285,803 0 3,208,433

Washington 4,265,055 47,921 18,679 1,255,343 756,649 374,556 1,811,906

West Virginia 958,526 8,711 26,897 65,669 527,486 0 329,764

Wisconsin 2,806,236 59,710 8,550 842,048 620,506 205,247 1,070,175

Wyoming 296,668 6,591 0 24,999 265,078 0 0

Tribes - Region 1 41,000 0 0 0 41,000 0 0

Tribes - Region 5 18,788 4,068 0 14,720 0 0 0

Tribes - Region 6 0 0 0 0 0 0 0

Tribes - Region 8 12,160 0 2,020 10,140 0 0 0

Tribes - Region 9 62,055 18,855 0 31,200 12,000 0 0

Total 229,225,740 1,790,743 878,262 34,816,693 49,758,358 17,269,919 124,711,765

1

 The UCMR data are not representative at the state-level.

Table B6. 1,3-Dinitrobenzene - UCMR 2 Assessment Monitoring Data - Number of Systems and Population Served by 

Page 2 of 2
EPA-OGWDW

Appendix B. Summary of Systems and Population Served by State

Occurrence Data from the UCMR 2

Table B7. HBB - UCMR 2 Assessment Monitoring Data - Number of Systems and Population Served by State

State 1

Total 

Number of 

Samples

Total 

Number of 

Systems

Number of 

Small Systems 

(serving ≤10,000 

people): Ground 

Water

Number of 

Small Systems 

(serving ≤10,000 

people): 

Surface Water

Number of 

Large Systems 

(serving 10,001-

100,000 people): 

Ground Water

Number of 

Large Systems 

(serving 10,001-

100,000 people): 

Surface Water

Number of Very 

Large Systems 

(serving 

>100,000 

people): Ground 

Water

Number of Very 

Large Systems 

(serving 

>100,000 

people): 

Surface Water

Alabama 946 120 13 3 36 62 0 6

Alaska 49 9 3 2 2 1 0 1

American Samoa 4 1 0 0 0 1 0 0

Arizona 951 69 13 0 41 5 1 9

Arkansas 289 61 9 4 17 28 0 3

California 6,725 393 32 14 123 152 8 64

Colorado 505 68 5 6 13 34 0 10

Connecticut 329 41 5 1 7 23 0 5

Delaware 106 10 4 0 2 1 0 3

District of Columbia 8 1 0 0 0 0 0 1

Florida 1,152 231 28 0 161 7 23 12

Georgia 570 110 14 5 27 51 1 12

Guam 246 3 0 0 0 2 1 0

Hawaii 315 18 3 0 8 5 2 0

Idaho 257 22 7 0 13 1 0 1

Illinois 839 141 22 5 61 42 3 8

Indiana 399 99 16 2 56 18 1 6

Iowa 233 54 14 1 24 12 0 3

Kansas 224 46 7 4 12 17 0 6

Kentucky 433 107 2 4 10 86 1 4

Louisiana 606 92 25 3 36 21 3 4

Maine 89 19 4 2 3 9 0 1

Maryland 180 38 7 2 13 12 1 3

Massachusetts 965 126 9 3 55 50 1 8

Michigan 393 77 21 2 18 29 2 5

Minnesota 356 91 15 1 64 9 0 2

Mississippi 636 78 30 0 46 0 0 2

Missouri 464 75 16 4 31 19 1 4

Montana 112 13 4 2 1 5 0 1

N. Mariana Islands 69 2 1 0 1 0 0 0

Navajo Nation 12 2 1 0 1 0 0 0

Nebraska 238 22 8 0 10 2 0 2

Nevada 184 15 4 1 4 2 0 4

New Hampshire 155 24 5 1 4 13 0 1

New Jersey 1,055 131 14 1 55 49 1 11

New Mexico 331 32 7 1 18 5 1 0

New York 1,542 154 18 11 47 59 5 14

North Carolina 1,032 126 16 5 27 65 1 12

North Dakota 50 12 2 1 3 6 0 0

Ohio 525 153 20 5 59 58 1 10

Oklahoma 422 62 6 8 11 34 0 3

Oregon 365 55 6 4 10 30 0 5

Pennsylvania 1,218 171 24 13 24 92 0 18

Puerto Rico 655 83 6 5 17 47 0 8

Rhode Island 92 13 2 0 4 5 0 2

South Carolina 321 63 6 3 8 41 0 5

South Dakota 87 15 4 1 3 6 0 1

Tennessee 569 121 5 8 16 87 1 4

Texas 2,194 295 63 23 62 122 1 24

Utah 513 54 6 2 14 25 0 7

Vermont 46 11 3 2 0 6 0 0

Virgin Islands 20 4 2 0 0 2 0 0

Virginia 409 73 9 6 4 43 0 11

Washington 834 93 18 3 46 20 2 4

West Virginia 142 36 3 6 3 22 0 2

Wisconsin 561 78 19 1 38 16 1 3

Wyoming 56 11 3 0 1 7 0 0

Tribes - Region 1 4 1 0 0 0 1 0 0

Tribes - Region 5 10 4 3 0 1 0 0 0

Tribes - Region 6 0 0 0 0 0 0 0 0

Tribes - Region 8 6 2 0 1 1 0 0 0

Tribes - Region 9 45 9 6 0 2 1 0 0

Total 32,143 4,140 618 182 1,374 1,568 63 335

1

 The UCMR data are not representative at the state-level.

Page 1 of 2
EPA-OGWDW

Appendix B. Summary of Systems and Population Served by State

Occurrence Data from the UCMR 2

Table B7. HBB - UCMR 2 Assessment Monitoring Data - Number of Systems and Population Served by State

State 1

Total 

Population 

Served

Pop. Served by 

Small Systems 

(serving ≤10,000 

people): Ground 

Water

Pop. Served by 

Small Systems 

(serving ≤10,000 

people): 

Surface Water

Pop. Served by 

Large Systems 

(serving 10,001-

100,000 people): 

Ground Water

Pop. Served by 

Large Systems 

(serving 10,001-

100,000 people): 

Surface Water

Pop. Served by 

Very Large 

Systems (serving 

>100,000 people): 

Ground Water

Pop. Served by 

Very Large 

Systems (serving 

>100,000 people): 

Surface Water

Alabama 4,249,148 64,214 15,859 850,382 1,612,450 0 1,706,245

Alaska 234,237 6,025 9,791 59,290 23,965 0 135,166

American Samoa 45,000 0 0 0 45,000 0 0

Arizona 4,417,574 32,953 0 999,514 110,587 675,445 2,599,075

Arkansas 1,771,814 31,449 19,189 395,797 638,748 0 686,632

California 32,516,672 101,399 70,338 3,738,533 6,626,442 1,088,908 20,891,052

Colorado 4,395,410 12,154 13,190 312,380 1,020,990 0 3,036,696

Connecticut 2,423,307 6,961 7,784 101,145 929,609 0 1,377,809

Delaware 550,332 14,255 0 54,443 36,130 0 445,504

District of Columbia 783,055 0 0 0 0 0 783,055

Florida 15,964,524 85,230 0 5,601,752 190,650 7,266,168 2,820,724

Georgia 6,323,497 30,214 19,473 555,035 1,594,334 163,688 3,960,753

Guam 136,301 0 0 0 36,300 100,001 0

Hawaii 1,168,403 14,938 0 237,807 128,935 786,723 0

Idaho 598,638 20,705 0 377,881 14,052 0 186,000

Illinois 7,910,559 62,240 31,607 1,237,820 1,377,669 405,228 4,795,996

Indiana 3,833,462 53,832 8,150 1,343,907 460,953 113,400 1,853,220

Iowa 1,669,054 34,873 7,782 635,226 435,492 0 555,682

Kansas 1,903,624 14,044 15,781 288,095 327,403 0 1,258,301

Kentucky 4,050,273 6,419 21,540 145,399 2,190,482 85,697 1,600,737

Louisiana 3,411,211 100,823 8,085 762,163 705,285 663,655 1,171,200

Maine 368,811 10,566 8,770 43,690 192,225 0 113,560

Maryland 4,493,237 9,908 6,123 346,418 348,121 249,600 3,533,067

Massachusetts 7,942,671 43,421 14,171 1,317,567 1,768,248 159,180 4,640,084

Michigan 5,866,881 54,175 12,964 366,966 859,317 283,846 4,289,613

Minnesota 3,092,542 38,944 4,960 1,707,947 406,914 0 933,777

Mississippi 1,418,405 86,727 0 988,496 0 0 343,182

Missouri 3,711,957 49,173 19,101 600,252 449,297 223,971 2,370,164

Montana 376,922 8,734 8,778 72,215 183,824 0 103,371

N. Mariana Islands 72,737 1,081 0 71,656 0 0 0

Navajo Nation 19,080 836 0 18,244 0 0 0

Nebraska 998,770 26,423 0 219,594 37,864 0 714,889

Nevada 1,999,825 13,712 8,323 59,000 73,095 0 1,845,695

New Hampshire 562,737 8,516 10,000 86,706 305,451 0 152,064

New Jersey 7,116,424 60,693 3,400 1,156,623 1,666,422 115,378 4,113,907

New Mexico 1,152,067 16,238 8,256 501,653 172,567 453,353 0

New York 14,764,779 35,519 44,587 1,371,569 1,657,155 1,682,822 9,973,127

North Carolina 5,366,551 37,318 18,964 580,495 1,974,056 108,666 2,647,052

North Dakota 350,292 5,414 2,694 78,529 263,655 0 0

Ohio 8,788,460 64,492 31,964 1,498,349 1,822,242 123,850 5,247,564

Oklahoma 2,491,284 10,318 31,117 241,483 950,915 0 1,257,451

Oregon 2,413,155 13,140 24,170 188,470 830,806 0 1,356,569

Pennsylvania 8,692,491 58,224 57,237 425,487 2,978,041 0 5,173,502

Puerto Rico 5,552,363 20,268 20,177 384,807 1,688,215 0 3,438,896

Rhode Island 911,235 1,812 0 107,302 250,585 0 551,536

South Carolina 2,785,309 14,508 19,828 180,888 1,218,197 0 1,351,888

South Dakota 349,953 10,139 1,592 43,056 167,166 0 128,000

Tennessee 4,625,703 22,345 49,153 428,243 2,499,282 687,096 939,584

Texas 18,832,904 189,890 115,111 1,429,442 3,795,822 1,253,442 12,049,197

Utah 2,403,787 20,075 15,000 274,446 934,364 0 1,159,902

Vermont 196,255 5,245 5,830 0 185,180 0 0

Virgin Islands 67,889 2,550 0 0 65,339 0 0

Virginia 4,635,684 11,756 31,277 98,415 1,285,803 0 3,208,433

Washington 4,265,055 47,921 18,679 1,255,343 756,649 374,556 1,811,906

West Virginia 958,526 8,711 26,897 65,669 527,486 0 329,764

Wisconsin 2,806,236 59,710 8,550 842,048 620,506 205,247 1,070,175

Wyoming 296,668 6,591 0 24,999 265,078 0 0

Tribes - Region 1 41,000 0 0 0 41,000 0 0

Tribes - Region 5 18,788 4,068 0 14,720 0 0 0

Tribes - Region 6 0 0 0 0 0 0 0

Tribes - Region 8 12,160 0 2,020 10,140 0 0 0

Tribes - Region 9 62,055 18,855 0 31,200 12,000 0 0

Total 229,237,740 1,790,743 878,262 34,828,693 49,758,358 17,269,919 124,711,765

1

 The UCMR data are not representative at the state-level.

Page 2 of 2
EPA-OGWDW

Appendix B. Summary of Systems and Population Served by State

Occurrence Data from the UCMR 2

Table B8. RDX - UCMR 2 Assessment Monitoring Data - Number of Systems and Population Served by State

State 1

Total 

Number of 

Samples

Total 

Number of 

Systems

Number of 

Small Systems 

(serving ≤10,000 

people): Ground 

Water

Number of 

Small Systems 

(serving ≤10,000 

people): 

Surface Water

Number of 

Large Systems 

(serving 10,001-

100,000 people): 

Ground Water

Number of 

Large Systems 

(serving 10,001-

100,000 people): 

Surface Water

Number of Very 

Large Systems 

(serving 

>100,000 

people): Ground 

Water

Number of Very 

Large Systems 

(serving 

>100,000 

people): 

Surface Water

Alabama 946 120 13 3 36 62 0 6

Alaska 48 8 3 2 1 1 0 1

American Samoa 4 1 0 0 0 1 0 0

Arizona 952 69 13 0 41 5 1 9

Arkansas 290 61 9 4 17 28 0 3

California 6,724 393 32 14 123 152 8 64

Colorado 503 68 5 6 13 34 0 10

Connecticut 329 41 5 1 7 23 0 5

Delaware 106 10 4 0 2 1 0 3

District of Columbia 8 1 0 0 0 0 0 1

Florida 1,155 231 28 0 161 7 23 12

Georgia 570 110 14 5 27 51 1 12

Guam 245 3 0 0 0 2 1 0

Hawaii 313 18 3 0 8 5 2 0

Idaho 256 22 7 0 13 1 0 1

Illinois 839 141 22 5 61 42 3 8

Indiana 399 99 16 2 56 18 1 6

Iowa 234 54 14 1 24 12 0 3

Kansas 226 46 7 4 12 17 0 6

Kentucky 432 107 2 4 10 86 1 4

Louisiana 606 92 25 3 36 21 3 4

Maine 89 19 4 2 3 9 0 1

Maryland 180 38 7 2 13 12 1 3

Massachusetts 965 126 9 3 55 50 1 8

Michigan 393 77 21 2 18 29 2 5

Minnesota 356 91 15 1 64 9 0 2

Mississippi 635 78 30 0 46 0 0 2

Missouri 463 75 16 4 31 19 1 4

Montana 111 13 4 2 1 5 0 1

N. Mariana Islands 68 2 1 0 1 0 0 0

Navajo Nation 12 2 1 0 1 0 0 0

Nebraska 238 22 8 0 10 2 0 2

Nevada 184 15 4 1 4 2 0 4

New Hampshire 155 24 5 1 4 13 0 1

New Jersey 1,058 131 14 1 55 49 1 11

New Mexico 331 32 7 1 18 5 1 0

New York 1,538 154 18 11 47 59 5 14

North Carolina 1,029 126 16 5 27 65 1 12

North Dakota 50 12 2 1 3 6 0 0

Ohio 525 153 20 5 59 58 1 10

Oklahoma 434 62 6 8 11 34 0 3

Oregon 365 55 6 4 10 30 0 5

Pennsylvania 1,218 171 24 13 24 92 0 18

Puerto Rico 645 83 6 5 17 47 0 8

Rhode Island 91 13 2 0 4 5 0 2

South Carolina 321 63 6 3 8 41 0 5

South Dakota 87 15 4 1 3 6 0 1

Tennessee 569 121 5 8 16 87 1 4

Texas 2,198 295 63 23 62 122 1 24

Utah 514 54 6 2 14 25 0 7

Vermont 46 11 3 2 0 6 0 0

Virgin Islands 20 4 2 0 0 2 0 0

Virginia 409 73 9 6 4 43 0 11

Washington 843 93 18 3 46 20 2 4

West Virginia 142 36 3 6 3 22 0 2

Wisconsin 561 78 19 1 38 16 1 3

Wyoming 57 11 3 0 1 7 0 0

Tribes - Region 1 4 1 0 0 0 1 0 0

Tribes - Region 5 10 4 3 0 1 0 0 0

Tribes - Region 6 0 0 0 0 0 0 0 0

Tribes - Region 8 6 2 0 1 1 0 0 0

Tribes - Region 9 45 9 6 0 2 1 0 0

Total 32,150 4,139 618 182 1,373 1,568 63 335

1

 The UCMR data are not representative at the state-level.

Page 1 of 2
EPA-OGWDW

Appendix B. Summary of Systems and Population Served by State

Occurrence Data from the UCMR 2

Table B8. RDX - UCMR 2 Assessment Monitoring Data - Number of Systems and Population Served by State

State 1

Total 

Population 

Served

Pop. Served by 

Small Systems 

(serving ≤10,000 

people): Ground 

Water

Pop. Served by 

Small Systems 

(serving ≤10,000 

people): 

Surface Water

Pop. Served by 

Large Systems 

(serving 10,001-

100,000 people): 

Ground Water

Pop. Served by 

Large Systems 

(serving 10,001-

100,000 people): 

Surface Water

Pop. Served by 

Very Large 

Systems (serving 

>100,000 people): 

Ground Water

Pop. Served by 

Very Large 

Systems (serving 

>100,000 people): 

Surface Water

Alabama 4,249,148 64,214 15,859 850,382 1,612,450 0 1,706,245

Alaska 222,237 6,025 9,791 47,290 23,965 0 135,166

American Samoa 45,000 0 0 0 45,000 0 0

Arizona 4,417,574 32,953 0 999,514 110,587 675,445 2,599,075

Arkansas 1,771,814 31,449 19,189 395,797 638,748 0 686,632

California 32,516,672 101,399 70,338 3,738,533 6,626,442 1,088,908 20,891,052

Colorado 4,395,410 12,154 13,190 312,380 1,020,990 0 3,036,696

Connecticut 2,423,307 6,961 7,784 101,145 929,609 0 1,377,809

Delaware 550,332 14,255 0 54,443 36,130 0 445,504

District of Columbia 783,055 0 0 0 0 0 783,055

Florida 15,964,524 85,230 0 5,601,752 190,650 7,266,168 2,820,724

Georgia 6,323,497 30,214 19,473 555,035 1,594,334 163,688 3,960,753

Guam 136,301 0 0 0 36,300 100,001 0

Hawaii 1,168,403 14,938 0 237,807 128,935 786,723 0

Idaho 598,638 20,705 0 377,881 14,052 0 186,000

Illinois 7,910,559 62,240 31,607 1,237,820 1,377,669 405,228 4,795,996

Indiana 3,833,462 53,832 8,150 1,343,907 460,953 113,400 1,853,220

Iowa 1,669,054 34,873 7,782 635,226 435,492 0 555,682

Kansas 1,903,624 14,044 15,781 288,095 327,403 0 1,258,301

Kentucky 4,050,273 6,419 21,540 145,399 2,190,482 85,697 1,600,737

Louisiana 3,411,211 100,823 8,085 762,163 705,285 663,655 1,171,200

Maine 368,811 10,566 8,770 43,690 192,225 0 113,560

Maryland 4,493,237 9,908 6,123 346,418 348,121 249,600 3,533,067

Massachusetts 7,942,671 43,421 14,171 1,317,567 1,768,248 159,180 4,640,084

Michigan 5,866,881 54,175 12,964 366,966 859,317 283,846 4,289,613

Minnesota 3,092,542 38,944 4,960 1,707,947 406,914 0 933,777

Mississippi 1,418,405 86,727 0 988,496 0 0 343,182

Missouri 3,711,957 49,173 19,101 600,252 449,297 223,971 2,370,164

Montana 376,922 8,734 8,778 72,215 183,824 0 103,371

N. Mariana Islands 72,737 1,081 0 71,656 0 0 0

Navajo Nation 19,080 836 0 18,244 0 0 0

Nebraska 998,770 26,423 0 219,594 37,864 0 714,889

Nevada 1,999,825 13,712 8,323 59,000 73,095 0 1,845,695

New Hampshire 562,737 8,516 10,000 86,706 305,451 0 152,064

New Jersey 7,116,424 60,693 3,400 1,156,623 1,666,422 115,378 4,113,907

New Mexico 1,152,067 16,238 8,256 501,653 172,567 453,353 0

New York 14,764,779 35,519 44,587 1,371,569 1,657,155 1,682,822 9,973,127

North Carolina 5,366,551 37,318 18,964 580,495 1,974,056 108,666 2,647,052

North Dakota 350,292 5,414 2,694 78,529 263,655 0 0

Ohio 8,788,460 64,492 31,964 1,498,349 1,822,242 123,850 5,247,564

Oklahoma 2,491,284 10,318 31,117 241,483 950,915 0 1,257,451

Oregon 2,413,155 13,140 24,170 188,470 830,806 0 1,356,569

Pennsylvania 8,692,491 58,224 57,237 425,487 2,978,041 0 5,173,502

Puerto Rico 5,552,363 20,268 20,177 384,807 1,688,215 0 3,438,896

Rhode Island 911,235 1,812 0 107,302 250,585 0 551,536

South Carolina 2,785,309 14,508 19,828 180,888 1,218,197 0 1,351,888

South Dakota 349,953 10,139 1,592 43,056 167,166 0 128,000

Tennessee 4,625,703 22,345 49,153 428,243 2,499,282 687,096 939,584

Texas 18,832,904 189,890 115,111 1,429,442 3,795,822 1,253,442 12,049,197

Utah 2,403,787 20,075 15,000 274,446 934,364 0 1,159,902

Vermont 196,255 5,245 5,830 0 185,180 0 0

Virgin Islands 67,889 2,550 0 0 65,339 0 0

Virginia 4,635,684 11,756 31,277 98,415 1,285,803 0 3,208,433

Washington 4,265,055 47,921 18,679 1,255,343 756,649 374,556 1,811,906

West Virginia 958,526 8,711 26,897 65,669 527,486 0 329,764

Wisconsin 2,806,236 59,710 8,550 842,048 620,506 205,247 1,070,175

Wyoming 296,668 6,591 0 24,999 265,078 0 0

Tribes - Region 1 41,000 0 0 0 41,000 0 0

Tribes - Region 5 18,788 4,068 0 14,720 0 0 0

Tribes - Region 6 0 0 0 0 0 0 0

Tribes - Region 8 12,160 0 2,020 10,140 0 0 0

Tribes - Region 9 62,055 18,855 0 31,200 12,000 0 0

Total 229,225,740 1,790,743 878,262 34,816,693 49,758,358 17,269,919 124,711,765

1

 The UCMR data are not representative at the state-level.

Page 2 of 2
EPA-OGWDW

Appendix B. Summary of Systems and Population Served by State

Occurrence Data from the UCMR 2

Table B9. Terbufos Sulfone - UCMR 2 Assessment Monitoring Data - Number of Systems and Population Served by State

State 1

Total 

Number of 

Samples

Total 

Number of 

Systems

Number of 

Small Systems 

(serving ≤10,000 

people): Ground 

Water

Number of 

Small Systems 

(serving ≤10,000 

people): 

Surface Water

Number of 

Large Systems 

(serving 10,001-

100,000 people): 

Ground Water

Number of 

Large Systems 

(serving 10,001-

100,000 people): 

Surface Water

Number of Very 

Large Systems 

(serving 

>100,000 

people): Ground 

Water

Number of Very 

Large Systems 

(serving 

>100,000 

people): 

Surface Water

Alabama 946 120 13 3 36 62 0 6

Alaska 49 9 3 2 2 1 0 1

American Samoa 4 1 0 0 0 1 0 0

Arizona 951 69 13 0 41 5 1 9

Arkansas 289 61 9 4 17 28 0 3

California 6,725 393 32 14 123 152 8 64

Colorado 505 68 5 6 13 34 0 10

Connecticut 329 41 5 1 7 23 0 5

Delaware 106 10 4 0 2 1 0 3

District of Columbia 8 1 0 0 0 0 0 1

Florida 1,152 231 28 0 161 7 23 12

Georgia 570 110 14 5 27 51 1 12

Guam 246 3 0 0 0 2 1 0

Hawaii 315 18 3 0 8 5 2 0

Idaho 257 22 7 0 13 1 0 1

Illinois 839 141 22 5 61 42 3 8

Indiana 399 99 16 2 56 18 1 6

Iowa 233 54 14 1 24 12 0 3

Kansas 224 46 7 4 12 17 0 6

Kentucky 433 107 2 4 10 86 1 4

Louisiana 606 92 25 3 36 21 3 4

Maine 89 19 4 2 3 9 0 1

Maryland 180 38 7 2 13 12 1 3

Massachusetts 965 126 9 3 55 50 1 8

Michigan 393 77 21 2 18 29 2 5

Minnesota 356 91 15 1 64 9 0 2

Mississippi 636 78 30 0 46 0 0 2

Missouri 464 75 16 4 31 19 1 4

Montana 112 13 4 2 1 5 0 1

N. Mariana Islands 69 2 1 0 1 0 0 0

Navajo Nation 12 2 1 0 1 0 0 0

Nebraska 238 22 8 0 10 2 0 2

Nevada 184 15 4 1 4 2 0 4

New Hampshire 155 24 5 1 4 13 0 1

New Jersey 1,055 131 14 1 55 49 1 11

New Mexico 331 32 7 1 18 5 1 0

New York 1,542 154 18 11 47 59 5 14

North Carolina 1,032 126 16 5 27 65 1 12

North Dakota 50 12 2 1 3 6 0 0

Ohio 525 153 20 5 59 58 1 10

Oklahoma 422 62 6 8 11 34 0 3

Oregon 365 55 6 4 10 30 0 5

Pennsylvania 1,218 171 24 13 24 92 0 18

Puerto Rico 655 83 6 5 17 47 0 8

Rhode Island 92 13 2 0 4 5 0 2

South Carolina 321 63 6 3 8 41 0 5

South Dakota 87 15 4 1 3 6 0 1

Tennessee 569 121 5 8 16 87 1 4

Texas 2,200 295 63 23 62 122 1 24

Utah 513 54 6 2 14 25 0 7

Vermont 46 11 3 2 0 6 0 0

Virgin Islands 20 4 2 0 0 2 0 0

Virginia 409 73 9 6 4 43 0 11

Washington 834 93 18 3 46 20 2 4

West Virginia 142 36 3 6 3 22 0 2

Wisconsin 561 78 19 1 38 16 1 3

Wyoming 56 11 3 0 1 7 0 0

Tribes - Region 1 4 1 0 0 0 1 0 0

Tribes - Region 5 10 4 3 0 1 0 0 0

Tribes - Region 6 0 0 0 0 0 0 0 0

Tribes - Region 8 6 2 0 1 1 0 0 0

Tribes - Region 9 45 9 6 0 2 1 0 0

Total 32,149 4,140 618 182 1,374 1,568 63 335

1

 The UCMR data are not representative at the state-level.

Page 1 of 2
EPA-OGWDW

Appendix B. Summary of Systems and Population Served by State

Occurrence Data from the UCMR 2

State 1

Total 

Population 

Served

Pop. Served by 

Small Systems 

(serving ≤10,000 

people): Ground 

Water

Pop. Served by 

Small Systems 

(serving ≤10,000 

people): 

Surface Water

Pop. Served by 

Large Systems 

(serving 10,001-

100,000 people): 

Ground Water

Pop. Served by 

Large Systems 

(serving 10,001-

100,000 people): 

Surface Water

Pop. Served by 

Very Large 

Systems (serving 

>100,000 people): 

Ground Water

Pop. Served by 

Very Large 

Systems (serving 

>100,000 people): 

Surface Water

Alabama 4,249,148 64,214 15,859 850,382 1,612,450 0 1,706,245

Alaska 234,237 6,025 9,791 59,290 23,965 0 135,166

American Samoa 45,000 0 0 0 45,000 0 0

Arizona 4,417,574 32,953 0 999,514 110,587 675,445 2,599,075

Arkansas 1,771,814 31,449 19,189 395,797 638,748 0 686,632

California 32,516,672 101,399 70,338 3,738,533 6,626,442 1,088,908 20,891,052

Colorado 4,395,410 12,154 13,190 312,380 1,020,990 0 3,036,696

Connecticut 2,423,307 6,961 7,784 101,145 929,609 0 1,377,809

Delaware 550,332 14,255 0 54,443 36,130 0 445,504

District of Columbia 783,055 0 0 0 0 0 783,055

Florida 15,964,524 85,230 0 5,601,752 190,650 7,266,168 2,820,724

Georgia 6,323,497 30,214 19,473 555,035 1,594,334 163,688 3,960,753

Guam 136,301 0 0 0 36,300 100,001 0

Hawaii 1,168,403 14,938 0 237,807 128,935 786,723 0

Idaho 598,638 20,705 0 377,881 14,052 0 186,000

Illinois 7,910,559 62,240 31,607 1,237,820 1,377,669 405,228 4,795,996

Indiana 3,833,462 53,832 8,150 1,343,907 460,953 113,400 1,853,220

Iowa 1,669,054 34,873 7,782 635,226 435,492 0 555,682

Kansas 1,903,624 14,044 15,781 288,095 327,403 0 1,258,301

Kentucky 4,050,273 6,419 21,540 145,399 2,190,482 85,697 1,600,737

Louisiana 3,411,211 100,823 8,085 762,163 705,285 663,655 1,171,200

Maine 368,811 10,566 8,770 43,690 192,225 0 113,560

Maryland 4,493,237 9,908 6,123 346,418 348,121 249,600 3,533,067

Massachusetts 7,942,671 43,421 14,171 1,317,567 1,768,248 159,180 4,640,084

Michigan 5,866,881 54,175 12,964 366,966 859,317 283,846 4,289,613

Minnesota 3,092,542 38,944 4,960 1,707,947 406,914 0 933,777

Mississippi 1,418,405 86,727 0 988,496 0 0 343,182

Missouri 3,711,957 49,173 19,101 600,252 449,297 223,971 2,370,164

Montana 376,922 8,734 8,778 72,215 183,824 0 103,371

N. Mariana Islands 72,737 1,081 0 71,656 0 0 0

Navajo Nation 19,080 836 0 18,244 0 0 0

Nebraska 998,770 26,423 0 219,594 37,864 0 714,889

Nevada 1,999,825 13,712 8,323 59,000 73,095 0 1,845,695

New Hampshire 562,737 8,516 10,000 86,706 305,451 0 152,064

New Jersey 7,116,424 60,693 3,400 1,156,623 1,666,422 115,378 4,113,907

New Mexico 1,152,067 16,238 8,256 501,653 172,567 453,353 0

New York 14,764,779 35,519 44,587 1,371,569 1,657,155 1,682,822 9,973,127

North Carolina 5,366,551 37,318 18,964 580,495 1,974,056 108,666 2,647,052

North Dakota 350,292 5,414 2,694 78,529 263,655 0 0

Ohio 8,788,460 64,492 31,964 1,498,349 1,822,242 123,850 5,247,564

Oklahoma 2,491,284 10,318 31,117 241,483 950,915 0 1,257,451

Oregon 2,413,155 13,140 24,170 188,470 830,806 0 1,356,569

Pennsylvania 8,692,491 58,224 57,237 425,487 2,978,041 0 5,173,502

Puerto Rico 5,552,363 20,268 20,177 384,807 1,688,215 0 3,438,896

Rhode Island 911,235 1,812 0 107,302 250,585 0 551,536

South Carolina 2,785,309 14,508 19,828 180,888 1,218,197 0 1,351,888

South Dakota 349,953 10,139 1,592 43,056 167,166 0 128,000

Tennessee 4,625,703 22,345 49,153 428,243 2,499,282 687,096 939,584

Texas 18,832,904 189,890 115,111 1,429,442 3,795,822 1,253,442 12,049,197

Utah 2,403,787 20,075 15,000 274,446 934,364 0 1,159,902

Vermont 196,255 5,245 5,830 0 185,180 0 0

Virgin Islands 67,889 2,550 0 0 65,339 0 0

Virginia 4,635,684 11,756 31,277 98,415 1,285,803 0 3,208,433

Washington 4,265,055 47,921 18,679 1,255,343 756,649 374,556 1,811,906

West Virginia 958,526 8,711 26,897 65,669 527,486 0 329,764

Wisconsin 2,806,236 59,710 8,550 842,048 620,506 205,247 1,070,175

Wyoming 296,668 6,591 0 24,999 265,078 0 0

Tribes - Region 1 41,000 0 0 0 41,000 0 0

Tribes - Region 5 18,788 4,068 0 14,720 0 0 0

Tribes - Region 6 0 0 0 0 0 0 0

Tribes - Region 8 12,160 0 2,020 10,140 0 0 0

Tribes - Region 9 62,055 18,855 0 31,200 12,000 0 0

Total 229,237,740 1,790,743 878,262 34,828,693 49,758,358 17,269,919 124,711,765

1

 The UCMR data are not representative at the state-level.

Table B9. Terbufos Sulfone - UCMR 2 Assessment Monitoring Data - Number of Systems and Population Served by 

Page 2 of 2
EPA-OGWDW

Appendix B. Summary of Systems and Population Served by State

Occurrence Data from the UCMR 2

Table B10. TNT - UCMR 2 Assessment Monitoring Data - Number of Systems and Population Served by State

State 1

Total 

Number of 

Samples

Total 

Number of 

Systems

Number of 

Small Systems 

(serving ≤10,000 

people): Ground 

Water

Number of 

Small Systems 

(serving ≤10,000 

people): 

Surface Water

Number of 

Large Systems 

(serving 10,001-

100,000 people): 

Ground Water

Number of 

Large Systems 

(serving 10,001-

100,000 people): 

Surface Water

Number of Very 

Large Systems 

(serving 

>100,000 

people): Ground 

Water

Number of Very 

Large Systems 

(serving 

>100,000 

people): 

Surface Water

Alabama 946 120 13 3 36 62 0 6

Alaska 48 8 3 2 1 1 0 1

American Samoa 4 1 0 0 0 1 0 0

Arizona 952 69 13 0 41 5 1 9

Arkansas 290 61 9 4 17 28 0 3

California 6,724 393 32 14 123 152 8 64

Colorado 503 68 5 6 13 34 0 10

Connecticut 329 41 5 1 7 23 0 5

Delaware 106 10 4 0 2 1 0 3

District of Columbia 8 1 0 0 0 0 0 1

Florida 1,155 231 28 0 161 7 23 12

Georgia 570 110 14 5 27 51 1 12

Guam 245 3 0 0 0 2 1 0

Hawaii 313 18 3 0 8 5 2 0

Idaho 256 22 7 0 13 1 0 1

Illinois 839 141 22 5 61 42 3 8

Indiana 399 99 16 2 56 18 1 6

Iowa 234 54 14 1 24 12 0 3

Kansas 226 46 7 4 12 17 0 6

Kentucky 432 107 2 4 10 86 1 4

Louisiana 606 92 25 3 36 21 3 4

Maine 89 19 4 2 3 9 0 1

Maryland 180 38 7 2 13 12 1 3

Massachusetts 965 126 9 3 55 50 1 8

Michigan 393 77 21 2 18 29 2 5

Minnesota 356 91 15 1 64 9 0 2

Mississippi 635 78 30 0 46 0 0 2

Missouri 463 75 16 4 31 19 1 4

Montana 111 13 4 2 1 5 0 1

N. Mariana Islands 68 2 1 0 1 0 0 0

Navajo Nation 12 2 1 0 1 0 0 0

Nebraska 238 22 8 0 10 2 0 2

Nevada 184 15 4 1 4 2 0 4

New Hampshire 155 24 5 1 4 13 0 1

New Jersey 1,058 131 14 1 55 49 1 11

New Mexico 331 32 7 1 18 5 1 0

New York 1,538 154 18 11 47 59 5 14

North Carolina 1,029 126 16 5 27 65 1 12

North Dakota 50 12 2 1 3 6 0 0

Ohio 525 153 20 5 59 58 1 10

Oklahoma 434 62 6 8 11 34 0 3

Oregon 365 55 6 4 10 30 0 5

Pennsylvania 1,218 171 24 13 24 92 0 18

Puerto Rico 645 83 6 5 17 47 0 8

Rhode Island 91 13 2 0 4 5 0 2

South Carolina 321 63 6 3 8 41 0 5

South Dakota 87 15 4 1 3 6 0 1

Tennessee 569 121 5 8 16 87 1 4

Texas 2,199 295 63 23 62 122 1 24

Utah 514 54 6 2 14 25 0 7

Vermont 46 11 3 2 0 6 0 0

Virgin Islands 20 4 2 0 0 2 0 0

Virginia 409 73 9 6 4 43 0 11

Washington 843 93 18 3 46 20 2 4

West Virginia 142 36 3 6 3 22 0 2

Wisconsin 561 78 19 1 38 16 1 3

Wyoming 57 11 3 0 1 7 0 0

Tribes - Region 1 4 1 0 0 0 1 0 0

Tribes - Region 5 10 4 3 0 1 0 0 0

Tribes - Region 6 0 0 0 0 0 0 0 0

Tribes - Region 8 6 2 0 1 1 0 0 0

Tribes - Region 9 45 9 6 0 2 1 0 0

Total 32,151 4,139 618 182 1,373 1,568 63 335

1

 The UCMR data are not representative at the state-level.

Page 1 of 2
EPA-OGWDW

Appendix B. Summary of Systems and Population Served by State

Occurrence Data from the UCMR 2

Table B10. TNT - UCMR 2 Assessment Monitoring Data - Number of Systems and Population Served by State

State 1

Total 

Population 

Served

Pop. Served by 

Small Systems 

(serving ≤10,000 

people): Ground 

Water

Pop. Served by 

Small Systems 

(serving ≤10,000 

people): 

Surface Water

Pop. Served by 

Large Systems 

(serving 10,001-

100,000 people): 

Ground Water

Pop. Served by 

Large Systems 

(serving 10,001-

100,000 people): 

Surface Water

Pop. Served by 

Very Large 

Systems (serving 

>100,000 people): 

Ground Water

Pop. Served by 

Very Large 

Systems (serving 

>100,000 people): 

Surface Water

Alabama 4,249,148 64,214 15,859 850,382 1,612,450 0 1,706,245

Alaska 222,237 6,025 9,791 47,290 23,965 0 135,166

American Samoa 45,000 0 0 0 45,000 0 0

Arizona 4,417,574 32,953 0 999,514 110,587 675,445 2,599,075

Arkansas 1,771,814 31,449 19,189 395,797 638,748 0 686,632

California 32,516,672 101,399 70,338 3,738,533 6,626,442 1,088,908 20,891,052

Colorado 4,395,410 12,154 13,190 312,380 1,020,990 0 3,036,696

Connecticut 2,423,307 6,961 7,784 101,145 929,609 0 1,377,809

Delaware 550,332 14,255 0 54,443 36,130 0 445,504

District of Columbia 783,055 0 0 0 0 0 783,055

Florida 15,964,524 85,230 0 5,601,752 190,650 7,266,168 2,820,724

Georgia 6,323,497 30,214 19,473 555,035 1,594,334 163,688 3,960,753

Guam 136,301 0 0 0 36,300 100,001 0

Hawaii 1,168,403 14,938 0 237,807 128,935 786,723 0

Idaho 598,638 20,705 0 377,881 14,052 0 186,000

Illinois 7,910,559 62,240 31,607 1,237,820 1,377,669 405,228 4,795,996

Indiana 3,833,462 53,832 8,150 1,343,907 460,953 113,400 1,853,220

Iowa 1,669,054 34,873 7,782 635,226 435,492 0 555,682

Kansas 1,903,624 14,044 15,781 288,095 327,403 0 1,258,301

Kentucky 4,050,273 6,419 21,540 145,399 2,190,482 85,697 1,600,737

Louisiana 3,411,211 100,823 8,085 762,163 705,285 663,655 1,171,200

Maine 368,811 10,566 8,770 43,690 192,225 0 113,560

Maryland 4,493,237 9,908 6,123 346,418 348,121 249,600 3,533,067

Massachusetts 7,942,671 43,421 14,171 1,317,567 1,768,248 159,180 4,640,084

Michigan 5,866,881 54,175 12,964 366,966 859,317 283,846 4,289,613

Minnesota 3,092,542 38,944 4,960 1,707,947 406,914 0 933,777

Mississippi 1,418,405 86,727 0 988,496 0 0 343,182

Missouri 3,711,957 49,173 19,101 600,252 449,297 223,971 2,370,164

Montana 376,922 8,734 8,778 72,215 183,824 0 103,371

N. Mariana Islands 72,737 1,081 0 71,656 0 0 0

Navajo Nation 19,080 836 0 18,244 0 0 0

Nebraska 998,770 26,423 0 219,594 37,864 0 714,889

Nevada 1,999,825 13,712 8,323 59,000 73,095 0 1,845,695

New Hampshire 562,737 8,516 10,000 86,706 305,451 0 152,064

New Jersey 7,116,424 60,693 3,400 1,156,623 1,666,422 115,378 4,113,907

New Mexico 1,152,067 16,238 8,256 501,653 172,567 453,353 0

New York 14,764,779 35,519 44,587 1,371,569 1,657,155 1,682,822 9,973,127

North Carolina 5,366,551 37,318 18,964 580,495 1,974,056 108,666 2,647,052

North Dakota 350,292 5,414 2,694 78,529 263,655 0 0

Ohio 8,788,460 64,492 31,964 1,498,349 1,822,242 123,850 5,247,564

Oklahoma 2,491,284 10,318 31,117 241,483 950,915 0 1,257,451

Oregon 2,413,155 13,140 24,170 188,470 830,806 0 1,356,569

Pennsylvania 8,692,491 58,224 57,237 425,487 2,978,041 0 5,173,502

Puerto Rico 5,552,363 20,268 20,177 384,807 1,688,215 0 3,438,896

Rhode Island 911,235 1,812 0 107,302 250,585 0 551,536

South Carolina 2,785,309 14,508 19,828 180,888 1,218,197 0 1,351,888

South Dakota 349,953 10,139 1,592 43,056 167,166 0 128,000

Tennessee 4,625,703 22,345 49,153 428,243 2,499,282 687,096 939,584

Texas 18,832,904 189,890 115,111 1,429,442 3,795,822 1,253,442 12,049,197

Utah 2,403,787 20,075 15,000 274,446 934,364 0 1,159,902

Vermont 196,255 5,245 5,830 0 185,180 0 0

Virgin Islands 67,889 2,550 0 0 65,339 0 0

Virginia 4,635,684 11,756 31,277 98,415 1,285,803 0 3,208,433

Washington 4,265,055 47,921 18,679 1,255,343 756,649 374,556 1,811,906

West Virginia 958,526 8,711 26,897 65,669 527,486 0 329,764

Wisconsin 2,806,236 59,710 8,550 842,048 620,506 205,247 1,070,175

Wyoming 296,668 6,591 0 24,999 265,078 0 0

Tribes - Region 1 41,000 0 0 0 41,000 0 0

Tribes - Region 5 18,788 4,068 0 14,720 0 0 0

Tribes - Region 6 0 0 0 0 0 0 0

Tribes - Region 8 12,160 0 2,020 10,140 0 0 0

Tribes - Region 9 62,055 18,855 0 31,200 12,000 0 0

Total 229,225,740 1,790,743 878,262 34,816,693 49,758,358 17,269,919 124,711,765

1

 The UCMR data are not representative at the state-level.

Page 2 of 2
EPA-OGWDW

Appendix B. Summary of Systems and Population Served by State

Occurrence Data from the UCMR 2

Table B11. Acetochlor - UCMR 2 Screening Survey Data - Number of Systems and Population Served by State

State 1

Total 

Number of 

Samples

Total 

Number of 

Systems

Number of 

Small Systems 

(serving ≤10,000 

people): Ground 

Water

Number of 

Small Systems 

(serving ≤10,000 

people): 

Surface Water

Number of 

Large Systems 

(serving 10,001-

100,000 people): 

Ground Water

Number of 

Large Systems 

(serving 10,001-

100,000 people): 

Surface Water

Number of Very 

Large Systems 

(serving 

>100,000 

people): Ground 

Water

Number of Very 

Large Systems 

(serving 

>100,000 

people): 

Surface Water

Alabama 147 20 4 2 3 5 0 6

Alaska 58 9 1 7 0 0 0 1

American Samoa 0 0 0 0 0 0 0 0

Arizona 382 19 4 2 3 0 1 9

Arkansas 68 13 3 3 2 2 0 3

California 3,347 154 13 28 19 22 8 64

Colorado 159 26 3 9 1 3 0 10

Connecticut 84 12 3 1 1 2 0 5

Delaware 83 5 1 0 1 0 0 3

District of Columbia 8 1 0 0 0 0 0 1

Florida 433 79 11 1 31 1 23 12

Georgia 170 31 6 5 2 5 1 12

Guam 219 1 0 0 0 0 1 0

Hawaii 140 4 1 0 1 0 2 0

Idaho 67 9 3 3 2 0 0 1

Illinois 270 35 7 5 4 8 3 8

Indiana 109 21 5 2 5 2 1 6

Iowa 82 15 5 2 3 2 0 3

Kansas 76 16 3 5 1 1 0 6

Kentucky 83 17 0 4 0 8 1 4

Louisiana 212 22 8 2 3 2 3 4

Maine 22 6 2 2 0 1 0 1

Maryland 60 13 3 3 2 1 1 3

Massachusetts 141 24 4 2 4 5 1 8

Michigan 146 23 9 2 2 3 2 5

Minnesota 59 18 6 1 7 2 0 2

Mississippi 82 15 10 0 3 0 0 2

Missouri 96 20 6 4 3 2 1 4

Montana 24 7 2 4 0 0 0 1

N. Mariana Islands 0 0 0 0 0 0 0 0

Navajo Nation 14 3 2 0 1 0 0 0

Nebraska 45 7 3 1 1 0 0 2

Nevada 98 8 2 1 0 1 0 4

New Hampshire 17 6 3 1 0 1 0 1

New Jersey 257 26 6 0 4 4 1 11

New Mexico 110 8 3 2 2 0 1 0

New York 857 53 8 14 6 6 5 14

North Carolina 210 35 7 5 3 7 1 12

North Dakota 14 4 1 2 0 1 0 0

Ohio 152 36 7 5 7 6 1 10

Oklahoma 83 19 3 9 1 3 0 3

Oregon 84 17 3 6 0 3 0 5

Pennsylvania 333 51 10 14 0 9 0 18

Puerto Rico 275 27 2 10 2 5 0 8

Rhode Island 18 4 1 0 0 1 0 2

South Carolina 70 16 3 3 1 4 0 5

South Dakota 32 9 2 5 0 1 0 1

Tennessee 114 23 1 7 2 8 1 4

Texas 779 96 23 27 6 15 1 24

Utah 142 16 2 3 1 3 0 7

Vermont 18 5 1 3 0 1 0 0

Virgin Islands 2 1 1 0 0 0 0 0

Virginia 158 27 4 7 0 5 0 11

Washington 253 29 8 4 8 3 2 4

West Virginia 46 12 1 7 0 2 0 2

Wisconsin 149 17 8 0 3 2 1 3

Wyoming 16 4 0 3 0 1 0 0

Tribes - Region 1 0 0 0 0 0 0 0 0

Tribes - Region 5 0 0 0 0 0 0 0 0

Tribes - Region 6 4 2 2 0 0 0 0 0

Tribes - Region 8 0 0 0 0 0 0 0 0

Tribes - Region 9 16 2 0 2 0 0 0 0

Total 11,193 1,198 240 240 151 169 63 335

1

 The UCMR data are not representative at the state-level.

Page 1 of 2
EPA-OGWDW

Appendix B. Summary of Systems and Population Served by State

Occurrence Data from the UCMR 2

Table B11. Acetochlor - UCMR 2 Screening Survey Data - Number of Systems and Population Served by State

State 1

Total 

Population 

Served

Pop. Served by 

Small Systems 

(serving ≤10,000 

people): Ground 

Water

Pop. Served by 

Small Systems 

(serving ≤10,000 

people): 

Surface Water

Pop. Served by 

Large Systems 

(serving 10,001-

100,000 people): 

Ground Water

Pop. Served by 

Large Systems 

(serving 10,001-

100,000 people): 

Surface Water

Pop. Served by 

Very Large 

Systems (serving 

>100,000 people): 

Ground Water

Pop. Served by 

Very Large 

Systems (serving 

>100,000 people): 

Surface Water

Alabama 2,040,600 17,259 9,693 103,109 204,295 0 1,706,245

Alaska 143,305 90 8,049 0 0 0 135,166

American Samoa 0 0 0 0 0 0 0

Arizona 3,403,868 14,319 1,729 113,300 0 675,445 2,599,075

Arkansas 845,459 11,365 8,930 85,674 52,858 0 686,632

California 24,372,007 29,816 49,813 1,008,796 1,303,622 1,088,908 20,891,052

Colorado 3,219,993 8,226 15,710 31,000 128,361 0 3,036,696

Connecticut 1,497,295 1,004 6,620 17,500 94,362 0 1,377,809

Delaware 484,765 4,383 0 34,878 0 0 445,504

District of Columbia 783,055 0 0 0 0 0 783,055

Florida 11,889,692 31,802 7,075 1,732,771 31,152 7,266,168 2,820,724

Georgia 4,397,366 9,885 12,463 39,543 211,034 163,688 3,960,753

Guam 100,001 0 0 0 0 100,001 0

Hawaii 854,836 4,958 0 63,155 0 786,723 0

Idaho 280,917 5,329 1,237 88,351 0 0 186,000

Illinois 5,680,520 22,938 20,358 71,451 364,550 405,228 4,795,996

Indiana 2,277,440 14,331 9,489 216,877 70,123 113,400 1,853,220

Iowa 805,109 14,756 7,369 146,216 81,086 0 555,682

Kansas 1,331,673 6,004 14,995 41,348 11,025 0 1,258,301

Kentucky 1,962,150 0 17,056 0 258,661 85,697 1,600,737

Louisiana 2,049,851 22,928 7,429 115,495 69,144 663,655 1,171,200

Maine 132,909 724 7,600 0 11,025 0 113,560

Maryland 3,874,592 6,534 7,390 64,801 13,200 249,600 3,533,067

Massachusetts 5,202,826 10,300 12,914 130,449 249,899 159,180 4,640,084

Michigan 4,826,722 12,746 12,269 97,711 130,537 283,846 4,289,613

Minnesota 1,400,744 10,862 7,501 300,404 148,200 0 933,777

Mississippi 424,022 31,538 0 49,302 0 0 343,182

Missouri 2,793,981 11,698 13,341 97,715 77,092 223,971 2,370,164

Montana 112,643 3,104 6,168 0 0 0 103,371

N. Mariana Islands 0 0 0 0 0 0 0

Navajo Nation 21,873 3,629 0 18,244 0 0 0

Nebraska 743,335 4,946 2,500 21,000 0 0 714,889

Nevada 1,908,764 6,832 237 0 56,000 0 1,845,695

New Hampshire 165,859 950 1,595 0 11,250 0 152,064

New Jersey 4,449,920 10,749 0 91,759 118,127 115,378 4,113,907

New Mexico 568,968 7,769 2,846 105,000 0 453,353 0

New York 12,173,772 8,634 35,158 248,594 225,437 1,682,822 9,973,127

North Carolina 3,220,020 15,311 26,493 111,438 311,061 108,666 2,647,052

North Dakota 92,952 1,099 1,254 0 90,599 0 0

Ohio 5,968,446 21,415 12,060 300,293 263,264 123,850 5,247,564

Oklahoma 1,432,777 6,402 25,003 15,435 128,486 0 1,257,451

Oregon 1,505,465 7,740 18,036 0 123,120 0 1,356,569

Pennsylvania 5,612,428 14,708 33,537 0 390,681 0 5,173,502

Puerto Rico 3,794,459 4,955 17,083 112,793 220,732 0 3,438,896

Rhode Island 613,600 355 0 0 61,709 0 551,536

South Carolina 1,604,882 8,549 10,201 53,122 181,122 0 1,351,888

South Dakota 152,210 811 3,162 0 20,237 0 128,000

Tennessee 2,104,138 8,587 31,013 66,568 371,290 687,096 939,584

Texas 14,372,970 60,963 89,693 228,445 691,230 1,253,442 12,049,197

Utah 1,362,703 8,500 9,345 24,000 160,956 0 1,159,902

Vermont 63,618 298 11,570 0 51,750 0 0

Virgin Islands 50 50 0 0 0 0 0

Virginia 3,377,005 3,451 21,232 0 143,889 0 3,208,433

Washington 2,706,556 15,667 6,360 404,649 93,417 374,556 1,811,906

West Virginia 434,635 424 26,216 0 78,231 0 329,764

Wisconsin 1,507,678 17,221 0 133,000 82,035 205,247 1,070,175

Wyoming 68,027 0 8,043 0 59,984 0 0

Tribes - Region 1 0 0 0 0 0 0 0

Tribes - Region 5 0 0 0 0 0 0 0

Tribes - Region 6 1,450 1,450 0 0 0 0 0

Tribes - Region 8 0 0 0 0 0 0 0

Tribes - Region 9 2,722 0 2,722 0 0 0 0

Total 157,219,620 548,364 660,557 6,584,184 7,444,830 17,269,919 124,711,765

1

 The UCMR data are not representative at the state-level.

Page 2 of 2
EPA-OGWDW

Appendix B. Summary of Systems and Population Served by State

Occurrence Data from the UCMR 2

Table B12. Acetochlor ESA - UCMR 2 Screening Survey Data - Number of Systems and Population Served by State

State 1

Total 

Number of 

Samples

Total 

Number of 

Systems

Number of 

Small Systems 

(serving ≤10,000 

people): Ground 

Water

Number of 

Small Systems 

(serving ≤10,000 

people): 

Surface Water

Number of 

Large Systems 

(serving 10,001-

100,000 people): 

Ground Water

Number of 

Large Systems 

(serving 10,001-

100,000 people): 

Surface Water

Number of Very 

Large Systems 

(serving 

>100,000 

people): Ground 

Water

Number of Very 

Large Systems 

(serving 

>100,000 

people): 

Surface Water

Alabama 147 20 4 2 3 5 0 6

Alaska 58 9 1 7 0 0 0 1

American Samoa 0 0 0 0 0 0 0 0

Arizona 382 19 4 2 3 0 1 9

Arkansas 68 13 3 3 2 2 0 3

California 3,351 154 13 28 19 22 8 64

Colorado 158 26 3 9 1 3 0 10

Connecticut 83 12 3 1 1 2 0 5

Delaware 83 5 1 0 1 0 0 3

District of Columbia 8 1 0 0 0 0 0 1

Florida 432 79 11 1 31 1 23 12

Georgia 169 31 6 5 2 5 1 12

Guam 220 1 0 0 0 0 1 0

Hawaii 140 4 1 0 1 0 2 0

Idaho 67 9 3 3 2 0 0 1

Illinois 270 35 7 5 4 8 3 8

Indiana 109 21 5 2 5 2 1 6

Iowa 82 15 5 2 3 2 0 3

Kansas 76 16 3 5 1 1 0 6

Kentucky 83 17 0 4 0 8 1 4

Louisiana 209 22 8 2 3 2 3 4

Maine 22 6 2 2 0 1 0 1

Maryland 60 13 3 3 2 1 1 3

Massachusetts 135 24 4 2 4 5 1 8

Michigan 145 23 9 2 2 3 2 5

Minnesota 59 18 6 1 7 2 0 2

Mississippi 82 15 10 0 3 0 0 2

Missouri 95 20 6 4 3 2 1 4

Montana 24 7 2 4 0 0 0 1

N. Mariana Islands 0 0 0 0 0 0 0 0

Navajo Nation 14 3 2 0 1 0 0 0

Nebraska 45 7 3 1 1 0 0 2

Nevada 98 8 2 1 0 1 0 4

New Hampshire 17 6 3 1 0 1 0 1

New Jersey 257 26 6 0 4 4 1 11

New Mexico 110 8 3 2 2 0 1 0

New York 848 53 8 14 6 6 5 14

North Carolina 209 35 7 5 3 7 1 12

North Dakota 14 4 1 2 0 1 0 0

Ohio 152 36 7 5 7 6 1 10

Oklahoma 83 19 3 9 1 3 0 3

Oregon 84 17 3 6 0 3 0 5

Pennsylvania 334 51 10 14 0 9 0 18

Puerto Rico 275 27 2 10 2 5 0 8

Rhode Island 18 4 1 0 0 1 0 2

South Carolina 70 16 3 3 1 4 0 5

South Dakota 32 9 2 5 0 1 0 1

Tennessee 114 23 1 7 2 8 1 4

Texas 776 96 23 27 6 15 1 24

Utah 142 16 2 3 1 3 0 7

Vermont 17 5 1 3 0 1 0 0

Virgin Islands 2 1 1 0 0 0 0 0

Virginia 158 27 4 7 0 5 0 11

Washington 241 29 8 4 8 3 2 4

West Virginia 46 12 1 7 0 2 0 2

Wisconsin 149 17 8 0 3 2 1 3

Wyoming 16 4 0 3 0 1 0 0

Tribes - Region 1 0 0 0 0 0 0 0 0

Tribes - Region 5 0 0 0 0 0 0 0 0

Tribes - Region 6 3 2 2 0 0 0 0 0

Tribes - Region 8 0 0 0 0 0 0 0 0

Tribes - Region 9 16 2 0 2 0 0 0 0

Total 11,157 1,198 240 240 151 169 63 335

1

 The UCMR data are not representative at the state-level.

Page 1 of 2
EPA-OGWDW

Appendix B. Summary of Systems and Population Served by State

Occurrence Data from the UCMR 2

Table B12. Acetochlor ESA - UCMR 2 Screening Survey Data - Number of Systems and Population Served by State

State 1

Total 

Population 

Served

Pop. Served by 

Small Systems 

(serving ≤10,000 

people): Ground 

Water

Pop. Served by 

Small Systems 

(serving ≤10,000 

people): 

Surface Water

Pop. Served by 

Large Systems 

(serving 10,001-

100,000 people): 

Ground Water

Pop. Served by 

Large Systems 

(serving 10,001-

100,000 people): 

Surface Water

Pop. Served by 

Very Large 

Systems (serving 

>100,000 people): 

Ground Water

Pop. Served by 

Very Large 

Systems (serving 

>100,000 people): 

Surface Water

Alabama 2,040,600 17,259 9,693 103,109 204,295 0 1,706,245

Alaska 143,305 90 8,049 0 0 0 135,166

American Samoa 0 0 0 0 0 0 0

Arizona 3,403,868 14,319 1,729 113,300 0 675,445 2,599,075

Arkansas 845,459 11,365 8,930 85,674 52,858 0 686,632

California 24,372,007 29,816 49,813 1,008,796 1,303,622 1,088,908 20,891,052

Colorado 3,219,993 8,226 15,710 31,000 128,361 0 3,036,696

Connecticut 1,497,295 1,004 6,620 17,500 94,362 0 1,377,809

Delaware 484,765 4,383 0 34,878 0 0 445,504

District of Columbia 783,055 0 0 0 0 0 783,055

Florida 11,889,692 31,802 7,075 1,732,771 31,152 7,266,168 2,820,724

Georgia 4,397,366 9,885 12,463 39,543 211,034 163,688 3,960,753

Guam 100,001 0 0 0 0 100,001 0

Hawaii 854,836 4,958 0 63,155 0 786,723 0

Idaho 280,917 5,329 1,237 88,351 0 0 186,000

Illinois 5,680,520 22,938 20,358 71,451 364,550 405,228 4,795,996

Indiana 2,277,440 14,331 9,489 216,877 70,123 113,400 1,853,220

Iowa 805,109 14,756 7,369 146,216 81,086 0 555,682

Kansas 1,331,673 6,004 14,995 41,348 11,025 0 1,258,301

Kentucky 1,962,150 0 17,056 0 258,661 85,697 1,600,737

Louisiana 2,049,851 22,928 7,429 115,495 69,144 663,655 1,171,200

Maine 132,909 724 7,600 0 11,025 0 113,560

Maryland 3,874,592 6,534 7,390 64,801 13,200 249,600 3,533,067

Massachusetts 5,202,826 10,300 12,914 130,449 249,899 159,180 4,640,084

Michigan 4,826,722 12,746 12,269 97,711 130,537 283,846 4,289,613

Minnesota 1,400,744 10,862 7,501 300,404 148,200 0 933,777

Mississippi 424,022 31,538 0 49,302 0 0 343,182

Missouri 2,793,981 11,698 13,341 97,715 77,092 223,971 2,370,164

Montana 112,643 3,104 6,168 0 0 0 103,371

N. Mariana Islands 0 0 0 0 0 0 0

Navajo Nation 21,873 3,629 0 18,244 0 0 0

Nebraska 743,335 4,946 2,500 21,000 0 0 714,889

Nevada 1,908,764 6,832 237 0 56,000 0 1,845,695

New Hampshire 165,859 950 1,595 0 11,250 0 152,064

New Jersey 4,449,920 10,749 0 91,759 118,127 115,378 4,113,907

New Mexico 568,968 7,769 2,846 105,000 0 453,353 0

New York 12,173,772 8,634 35,158 248,594 225,437 1,682,822 9,973,127

North Carolina 3,220,020 15,311 26,493 111,438 311,061 108,666 2,647,052

North Dakota 92,952 1,099 1,254 0 90,599 0 0

Ohio 5,968,446 21,415 12,060 300,293 263,264 123,850 5,247,564

Oklahoma 1,432,777 6,402 25,003 15,435 128,486 0 1,257,451

Oregon 1,505,465 7,740 18,036 0 123,120 0 1,356,569

Pennsylvania 5,612,428 14,708 33,537 0 390,681 0 5,173,502

Puerto Rico 3,794,459 4,955 17,083 112,793 220,732 0 3,438,896

Rhode Island 613,600 355 0 0 61,709 0 551,536

South Carolina 1,604,882 8,549 10,201 53,122 181,122 0 1,351,888

South Dakota 152,210 811 3,162 0 20,237 0 128,000

Tennessee 2,104,138 8,587 31,013 66,568 371,290 687,096 939,584

Texas 14,372,970 60,963 89,693 228,445 691,230 1,253,442 12,049,197

Utah 1,362,703 8,500 9,345 24,000 160,956 0 1,159,902

Vermont 63,618 298 11,570 0 51,750 0 0

Virgin Islands 50 50 0 0 0 0 0

Virginia 3,377,005 3,451 21,232 0 143,889 0 3,208,433

Washington 2,706,556 15,667 6,360 404,649 93,417 374,556 1,811,906

West Virginia 434,635 424 26,216 0 78,231 0 329,764

Wisconsin 1,507,678 17,221 0 133,000 82,035 205,247 1,070,175

Wyoming 68,027 0 8,043 0 59,984 0 0

Tribes - Region 1 0 0 0 0 0 0 0

Tribes - Region 5 0 0 0 0 0 0 0

Tribes - Region 6 1,450 1,450 0 0 0 0 0

Tribes - Region 8 0 0 0 0 0 0 0

Tribes - Region 9 2,722 0 2,722 0 0 0 0

Total 157,219,620 548,364 660,557 6,584,184 7,444,830 17,269,919 124,711,765

1

 The UCMR data are not representative at the state-level.

Page 2 of 2
EPA-OGWDW

Appendix B. Summary of Systems and Population Served by State

Occurrence Data from the UCMR 2

Table B13. Acetochlor OA - UCMR 2 Screening Survey Data - Number of Systems and Population Served by State

State 1

Total 

Number of 

Samples

Total 

Number of 

Systems

Number of 

Small Systems 

(serving ≤10,000 

people): Ground 

Water

Number of 

Small Systems 

(serving ≤10,000 

people): 

Surface Water

Number of 

Large Systems 

(serving 10,001-

100,000 people): 

Ground Water

Number of 

Large Systems 

(serving 10,001-

100,000 people): 

Surface Water

Number of Very 

Large Systems 

(serving 

>100,000 

people): Ground 

Water

Number of Very 

Large Systems 

(serving 

>100,000 

people): 

Surface Water

Alabama 147 20 4 2 3 5 0 6

Alaska 58 9 1 7 0 0 0 1

American Samoa 0 0 0 0 0 0 0 0

Arizona 382 19 4 2 3 0 1 9

Arkansas 68 13 3 3 2 2 0 3

California 3,351 154 13 28 19 22 8 64

Colorado 158 26 3 9 1 3 0 10

Connecticut 83 12 3 1 1 2 0 5

Delaware 83 5 1 0 1 0 0 3

District of Columbia 8 1 0 0 0 0 0 1

Florida 432 79 11 1 31 1 23 12

Georgia 169 31 6 5 2 5 1 12

Guam 220 1 0 0 0 0 1 0

Hawaii 140 4 1 0 1 0 2 0

Idaho 67 9 3 3 2 0 0 1

Illinois 270 35 7 5 4 8 3 8

Indiana 109 21 5 2 5 2 1 6

Iowa 82 15 5 2 3 2 0 3

Kansas 76 16 3 5 1 1 0 6

Kentucky 83 17 0 4 0 8 1 4

Louisiana 209 22 8 2 3 2 3 4

Maine 22 6 2 2 0 1 0 1

Maryland 60 13 3 3 2 1 1 3

Massachusetts 135 24 4 2 4 5 1 8

Michigan 145 23 9 2 2 3 2 5

Minnesota 59 18 6 1 7 2 0 2

Mississippi 82 15 10 0 3 0 0 2

Missouri 95 20 6 4 3 2 1 4

Montana 24 7 2 4 0 0 0 1

N. Mariana Islands 0 0 0 0 0 0 0 0

Navajo Nation 14 3 2 0 1 0 0 0

Nebraska 45 7 3 1 1 0 0 2

Nevada 98 8 2 1 0 1 0 4

New Hampshire 17 6 3 1 0 1 0 1

New Jersey 257 26 6 0 4 4 1 11

New Mexico 110 8 3 2 2 0 1 0

New York 848 53 8 14 6 6 5 14

North Carolina 209 35 7 5 3 7 1 12

North Dakota 14 4 1 2 0 1 0 0

Ohio 152 36 7 5 7 6 1 10

Oklahoma 83 19 3 9 1 3 0 3

Oregon 84 17 3 6 0 3 0 5

Pennsylvania 334 51 10 14 0 9 0 18

Puerto Rico 275 27 2 10 2 5 0 8

Rhode Island 18 4 1 0 0 1 0 2

South Carolina 70 16 3 3 1 4 0 5

South Dakota 32 9 2 5 0 1 0 1

Tennessee 114 23 1 7 2 8 1 4

Texas 776 96 23 27 6 15 1 24

Utah 142 16 2 3 1 3 0 7

Vermont 17 5 1 3 0 1 0 0

Virgin Islands 2 1 1 0 0 0 0 0

Virginia 158 27 4 7 0 5 0 11

Washington 241 29 8 4 8 3 2 4

West Virginia 46 12 1 7 0 2 0 2

Wisconsin 149 17 8 0 3 2 1 3

Wyoming 16 4 0 3 0 1 0 0

Tribes - Region 1 0 0 0 0 0 0 0 0

Tribes - Region 5 0 0 0 0 0 0 0 0

Tribes - Region 6 3 2 2 0 0 0 0 0

Tribes - Region 8 0 0 0 0 0 0 0 0

Tribes - Region 9 16 2 0 2 0 0 0 0

Total 11,157 1,198 240 240 151 169 63 335

1

 The UCMR data are not representative at the state-level.

Page 1 of 2
EPA-OGWDW

Appendix B. Summary of Systems and Population Served by State

Occurrence Data from the UCMR 2

Table B13. Acetochlor OA - UCMR 2 Screening Survey Data - Number of Systems and Population Served by State

State 1

Total 

Population 

Served

Pop. Served by 

Small Systems 

(serving ≤10,000 

people): Ground 

Water

Pop. Served by 

Small Systems 

(serving ≤10,000 

people): 

Surface Water

Pop. Served by 

Large Systems 

(serving 10,001-

100,000 people): 

Ground Water

Pop. Served by 

Large Systems 

(serving 10,001-

100,000 people): 

Surface Water

Pop. Served by 

Very Large 

Systems (serving 

>100,000 people): 

Ground Water

Pop. Served by 

Very Large 

Systems (serving 

>100,000 people): 

Surface Water

Alabama 2,040,600 17,259 9,693 103,109 204,295 0 1,706,245

Alaska 143,305 90 8,049 0 0 0 135,166

American Samoa 0 0 0 0 0 0 0

Arizona 3,403,868 14,319 1,729 113,300 0 675,445 2,599,075

Arkansas 845,459 11,365 8,930 85,674 52,858 0 686,632

California 24,372,007 29,816 49,813 1,008,796 1,303,622 1,088,908 20,891,052

Colorado 3,219,993 8,226 15,710 31,000 128,361 0 3,036,696

Connecticut 1,497,295 1,004 6,620 17,500 94,362 0 1,377,809

Delaware 484,765 4,383 0 34,878 0 0 445,504

District of Columbia 783,055 0 0 0 0 0 783,055

Florida 11,889,692 31,802 7,075 1,732,771 31,152 7,266,168 2,820,724

Georgia 4,397,366 9,885 12,463 39,543 211,034 163,688 3,960,753

Guam 100,001 0 0 0 0 100,001 0

Hawaii 854,836 4,958 0 63,155 0 786,723 0

Idaho 280,917 5,329 1,237 88,351 0 0 186,000

Illinois 5,680,520 22,938 20,358 71,451 364,550 405,228 4,795,996

Indiana 2,277,440 14,331 9,489 216,877 70,123 113,400 1,853,220

Iowa 805,109 14,756 7,369 146,216 81,086 0 555,682

Kansas 1,331,673 6,004 14,995 41,348 11,025 0 1,258,301

Kentucky 1,962,150 0 17,056 0 258,661 85,697 1,600,737

Louisiana 2,049,851 22,928 7,429 115,495 69,144 663,655 1,171,200

Maine 132,909 724 7,600 0 11,025 0 113,560

Maryland 3,874,592 6,534 7,390 64,801 13,200 249,600 3,533,067

Massachusetts 5,202,826 10,300 12,914 130,449 249,899 159,180 4,640,084

Michigan 4,826,722 12,746 12,269 97,711 130,537 283,846 4,289,613

Minnesota 1,400,744 10,862 7,501 300,404 148,200 0 933,777

Mississippi 424,022 31,538 0 49,302 0 0 343,182

Missouri 2,793,981 11,698 13,341 97,715 77,092 223,971 2,370,164

Montana 112,643 3,104 6,168 0 0 0 103,371

N. Mariana Islands 0 0 0 0 0 0 0

Navajo Nation 21,873 3,629 0 18,244 0 0 0

Nebraska 743,335 4,946 2,500 21,000 0 0 714,889

Nevada 1,908,764 6,832 237 0 56,000 0 1,845,695

New Hampshire 165,859 950 1,595 0 11,250 0 152,064

New Jersey 4,449,920 10,749 0 91,759 118,127 115,378 4,113,907

New Mexico 568,968 7,769 2,846 105,000 0 453,353 0

New York 12,173,772 8,634 35,158 248,594 225,437 1,682,822 9,973,127

North Carolina 3,220,020 15,311 26,493 111,438 311,061 108,666 2,647,052

North Dakota 92,952 1,099 1,254 0 90,599 0 0

Ohio 5,968,446 21,415 12,060 300,293 263,264 123,850 5,247,564

Oklahoma 1,432,777 6,402 25,003 15,435 128,486 0 1,257,451

Oregon 1,505,465 7,740 18,036 0 123,120 0 1,356,569

Pennsylvania 5,612,428 14,708 33,537 0 390,681 0 5,173,502

Puerto Rico 3,794,459 4,955 17,083 112,793 220,732 0 3,438,896

Rhode Island 613,600 355 0 0 61,709 0 551,536

South Carolina 1,604,882 8,549 10,201 53,122 181,122 0 1,351,888

South Dakota 152,210 811 3,162 0 20,237 0 128,000

Tennessee 2,104,138 8,587 31,013 66,568 371,290 687,096 939,584

Texas 14,372,970 60,963 89,693 228,445 691,230 1,253,442 12,049,197

Utah 1,362,703 8,500 9,345 24,000 160,956 0 1,159,902

Vermont 63,618 298 11,570 0 51,750 0 0

Virgin Islands 50 50 0 0 0 0 0

Virginia 3,377,005 3,451 21,232 0 143,889 0 3,208,433

Washington 2,706,556 15,667 6,360 404,649 93,417 374,556 1,811,906

West Virginia 434,635 424 26,216 0 78,231 0 329,764

Wisconsin 1,507,678 17,221 0 133,000 82,035 205,247 1,070,175

Wyoming 68,027 0 8,043 0 59,984 0 0

Tribes - Region 1 0 0 0 0 0 0 0

Tribes - Region 5 0 0 0 0 0 0 0

Tribes - Region 6 1,450 1,450 0 0 0 0 0

Tribes - Region 8 0 0 0 0 0 0 0

Tribes - Region 9 2,722 0 2,722 0 0 0 0

Total 157,219,620 548,364 660,557 6,584,184 7,444,830 17,269,919 124,711,765

1

 The UCMR data are not representative at the state-level.

Page 2 of 2
EPA-OGWDW

Appendix B. Summary of Systems and Population Served by State

Occurrence Data from the UCMR 2

Table B14. Alachlor - UCMR 2 Screening Survey Data - Number of Systems and Population Served by State

State 1

Total 

Number of 

Samples

Total 

Number of 

Systems

Number of 

Small Systems 

(serving ≤10,000 

people): Ground 

Water

Number of 

Small Systems 

(serving ≤10,000 

people): 

Surface Water

Number of 

Large Systems 

(serving 10,001-

100,000 people): 

Ground Water

Number of 

Large Systems 

(serving 10,001-

100,000 people): 

Surface Water

Number of Very 

Large Systems 

(serving 

>100,000 

people): Ground 

Water

Number of Very 

Large Systems 

(serving 

>100,000 

people): 

Surface Water

Alabama 147 20 4 2 3 5 0 6

Alaska 58 9 1 7 0 0 0 1

American Samoa 0 0 0 0 0 0 0 0

Arizona 382 19 4 2 3 0 1 9

Arkansas 68 13 3 3 2 2 0 3

California 3,347 154 13 28 19 22 8 64

Colorado 159 26 3 9 1 3 0 10

Connecticut 84 12 3 1 1 2 0 5

Delaware 83 5 1 0 1 0 0 3

District of Columbia 8 1 0 0 0 0 0 1

Florida 433 79 11 1 31 1 23 12

Georgia 170 31 6 5 2 5 1 12

Guam 219 1 0 0 0 0 1 0

Hawaii 140 4 1 0 1 0 2 0

Idaho 67 9 3 3 2 0 0 1

Illinois 270 35 7 5 4 8 3 8

Indiana 109 21 5 2 5 2 1 6

Iowa 82 15 5 2 3 2 0 3

Kansas 76 16 3 5 1 1 0 6

Kentucky 83 17 0 4 0 8 1 4

Louisiana 212 22 8 2 3 2 3 4

Maine 22 6 2 2 0 1 0 1

Maryland 60 13 3 3 2 1 1 3

Massachusetts 141 24 4 2 4 5 1 8

Michigan 146 23 9 2 2 3 2 5

Minnesota 59 18 6 1 7 2 0 2

Mississippi 82 15 10 0 3 0 0 2

Missouri 96 20 6 4 3 2 1 4

Montana 24 7 2 4 0 0 0 1

N. Mariana Islands 0 0 0 0 0 0 0 0

Navajo Nation 14 3 2 0 1 0 0 0

Nebraska 45 7 3 1 1 0 0 2

Nevada 98 8 2 1 0 1 0 4

New Hampshire 17 6 3 1 0 1 0 1

New Jersey 257 26 6 0 4 4 1 11

New Mexico 110 8 3 2 2 0 1 0

New York 857 53 8 14 6 6 5 14

North Carolina 210 35 7 5 3 7 1 12

North Dakota 14 4 1 2 0 1 0 0

Ohio 152 36 7 5 7 6 1 10

Oklahoma 83 19 3 9 1 3 0 3

Oregon 84 17 3 6 0 3 0 5

Pennsylvania 333 51 10 14 0 9 0 18

Puerto Rico 275 27 2 10 2 5 0 8

Rhode Island 18 4 1 0 0 1 0 2

South Carolina 70 16 3 3 1 4 0 5

South Dakota 32 9 2 5 0 1 0 1

Tennessee 114 23 1 7 2 8 1 4

Texas 779 96 23 27 6 15 1 24

Utah 142 16 2 3 1 3 0 7

Vermont 18 5 1 3 0 1 0 0

Virgin Islands 2 1 1 0 0 0 0 0

Virginia 158 27 4 7 0 5 0 11

Washington 253 29 8 4 8 3 2 4

West Virginia 46 12 1 7 0 2 0 2

Wisconsin 149 17 8 0 3 2 1 3

Wyoming 16 4 0 3 0 1 0 0

Tribes - Region 1 0 0 0 0 0 0 0 0

Tribes - Region 5 0 0 0 0 0 0 0 0

Tribes - Region 6 4 2 2 0 0 0 0 0

Tribes - Region 8 0 0 0 0 0 0 0 0

Tribes - Region 9 16 2 0 2 0 0 0 0

Total 11,193 1,198 240 240 151 169 63 335

1

 The UCMR data are not representative at the state-level.

Page 1 of 2
EPA-OGWDW

Appendix B. Summary of Systems and Population Served by State

Occurrence Data from the UCMR 2

Table B14. Alachlor - UCMR 2 Screening Survey Data - Number of Systems and Population Served by State

State 1

Total 

Population 

Served

Pop. Served by 

Small Systems 

(serving ≤10,000 

people): Ground 

Water

Pop. Served by 

Small Systems 

(serving ≤10,000 

people): 

Surface Water

Pop. Served by 

Large Systems 

(serving 10,001-

100,000 people): 

Ground Water

Pop. Served by 

Large Systems 

(serving 10,001-

100,000 people): 

Surface Water

Pop. Served by 

Very Large 

Systems (serving 

>100,000 people): 

Ground Water

Pop. Served by 

Very Large 

Systems (serving 

>100,000 people): 

Surface Water

Alabama 2,040,600 17,259 9,693 103,109 204,295 0 1,706,245

Alaska 143,305 90 8,049 0 0 0 135,166

American Samoa 0 0 0 0 0 0 0

Arizona 3,403,868 14,319 1,729 113,300 0 675,445 2,599,075

Arkansas 845,459 11,365 8,930 85,674 52,858 0 686,632

California 24,372,007 29,816 49,813 1,008,796 1,303,622 1,088,908 20,891,052

Colorado 3,219,993 8,226 15,710 31,000 128,361 0 3,036,696

Connecticut 1,497,295 1,004 6,620 17,500 94,362 0 1,377,809

Delaware 484,765 4,383 0 34,878 0 0 445,504

District of Columbia 783,055 0 0 0 0 0 783,055

Florida 11,889,692 31,802 7,075 1,732,771 31,152 7,266,168 2,820,724

Georgia 4,397,366 9,885 12,463 39,543 211,034 163,688 3,960,753

Guam 100,001 0 0 0 0 100,001 0

Hawaii 854,836 4,958 0 63,155 0 786,723 0

Idaho 280,917 5,329 1,237 88,351 0 0 186,000

Illinois 5,680,520 22,938 20,358 71,451 364,550 405,228 4,795,996

Indiana 2,277,440 14,331 9,489 216,877 70,123 113,400 1,853,220

Iowa 805,109 14,756 7,369 146,216 81,086 0 555,682

Kansas 1,331,673 6,004 14,995 41,348 11,025 0 1,258,301

Kentucky 1,962,150 0 17,056 0 258,661 85,697 1,600,737

Louisiana 2,049,851 22,928 7,429 115,495 69,144 663,655 1,171,200

Maine 132,909 724 7,600 0 11,025 0 113,560

Maryland 3,874,592 6,534 7,390 64,801 13,200 249,600 3,533,067

Massachusetts 5,202,826 10,300 12,914 130,449 249,899 159,180 4,640,084

Michigan 4,826,722 12,746 12,269 97,711 130,537 283,846 4,289,613

Minnesota 1,400,744 10,862 7,501 300,404 148,200 0 933,777

Mississippi 424,022 31,538 0 49,302 0 0 343,182

Missouri 2,793,981 11,698 13,341 97,715 77,092 223,971 2,370,164

Montana 112,643 3,104 6,168 0 0 0 103,371

N. Mariana Islands 0 0 0 0 0 0 0

Navajo Nation 21,873 3,629 0 18,244 0 0 0

Nebraska 743,335 4,946 2,500 21,000 0 0 714,889

Nevada 1,908,764 6,832 237 0 56,000 0 1,845,695

New Hampshire 165,859 950 1,595 0 11,250 0 152,064

New Jersey 4,449,920 10,749 0 91,759 118,127 115,378 4,113,907

New Mexico 568,968 7,769 2,846 105,000 0 453,353 0

New York 12,173,772 8,634 35,158 248,594 225,437 1,682,822 9,973,127

North Carolina 3,220,020 15,311 26,493 111,438 311,061 108,666 2,647,052

North Dakota 92,952 1,099 1,254 0 90,599 0 0

Ohio 5,968,446 21,415 12,060 300,293 263,264 123,850 5,247,564

Oklahoma 1,432,777 6,402 25,003 15,435 128,486 0 1,257,451

Oregon 1,505,465 7,740 18,036 0 123,120 0 1,356,569

Pennsylvania 5,612,428 14,708 33,537 0 390,681 0 5,173,502

Puerto Rico 3,794,459 4,955 17,083 112,793 220,732 0 3,438,896

Rhode Island 613,600 355 0 0 61,709 0 551,536

South Carolina 1,604,882 8,549 10,201 53,122 181,122 0 1,351,888

South Dakota 152,210 811 3,162 0 20,237 0 128,000

Tennessee 2,104,138 8,587 31,013 66,568 371,290 687,096 939,584

Texas 14,372,970 60,963 89,693 228,445 691,230 1,253,442 12,049,197

Utah 1,362,703 8,500 9,345 24,000 160,956 0 1,159,902

Vermont 63,618 298 11,570 0 51,750 0 0

Virgin Islands 50 50 0 0 0 0 0

Virginia 3,377,005 3,451 21,232 0 143,889 0 3,208,433

Washington 2,706,556 15,667 6,360 404,649 93,417 374,556 1,811,906

West Virginia 434,635 424 26,216 0 78,231 0 329,764

Wisconsin 1,507,678 17,221 0 133,000 82,035 205,247 1,070,175

Wyoming 68,027 0 8,043 0 59,984 0 0

Tribes - Region 1 0 0 0 0 0 0 0

Tribes - Region 5 0 0 0 0 0 0 0

Tribes - Region 6 1,450 1,450 0 0 0 0 0

Tribes - Region 8 0 0 0 0 0 0 0

Tribes - Region 9 2,722 0 2,722 0 0 0 0

Total 157,219,620 548,364 660,557 6,584,184 7,444,830 17,269,919 124,711,765

1

 The UCMR data are not representative at the state-level.

Page 2 of 2
EPA-OGWDW

Appendix B. Summary of Systems and Population Served by State

Occurrence Data from the UCMR 2

Table B15. Alachlor ESA - UCMR 2 Screening Survey Data - Number of Systems and Population Served by State

State 1

Total 

Number of 

Samples

Total 

Number of 

Systems

Number of 

Small Systems 

(serving ≤10,000 

people): Ground 

Water

Number of 

Small Systems 

(serving ≤10,000 

people): 

Surface Water

Number of 

Large Systems 

(serving 10,001-

100,000 people): 

Ground Water

Number of 

Large Systems 

(serving 10,001-

100,000 people): 

Surface Water

Number of Very 

Large Systems 

(serving 

>100,000 

people): Ground 

Water

Number of Very 

Large Systems 

(serving 

>100,000 

people): 

Surface Water

Alabama 147 20 4 2 3 5 0 6

Alaska 58 9 1 7 0 0 0 1

American Samoa 0 0 0 0 0 0 0 0

Arizona 382 19 4 2 3 0 1 9

Arkansas 68 13 3 3 2 2 0 3

California 3,350 154 13 28 19 22 8 64

Colorado 158 26 3 9 1 3 0 10

Connecticut 83 12 3 1 1 2 0 5

Delaware 83 5 1 0 1 0 0 3

District of Columbia 8 1 0 0 0 0 0 1

Florida 432 79 11 1 31 1 23 12

Georgia 169 31 6 5 2 5 1 12

Guam 220 1 0 0 0 0 1 0

Hawaii 140 4 1 0 1 0 2 0

Idaho 67 9 3 3 2 0 0 1

Illinois 270 35 7 5 4 8 3 8

Indiana 109 21 5 2 5 2 1 6

Iowa 82 15 5 2 3 2 0 3

Kansas 76 16 3 5 1 1 0 6

Kentucky 83 17 0 4 0 8 1 4

Louisiana 209 22 8 2 3 2 3 4

Maine 22 6 2 2 0 1 0 1

Maryland 60 13 3 3 2 1 1 3

Massachusetts 135 24 4 2 4 5 1 8

Michigan 145 23 9 2 2 3 2 5

Minnesota 59 18 6 1 7 2 0 2

Mississippi 82 15 10 0 3 0 0 2

Missouri 95 20 6 4 3 2 1 4

Montana 24 7 2 4 0 0 0 1

N. Mariana Islands 0 0 0 0 0 0 0 0

Navajo Nation 14 3 2 0 1 0 0 0

Nebraska 45 7 3 1 1 0 0 2

Nevada 98 8 2 1 0 1 0 4

New Hampshire 17 6 3 1 0 1 0 1

New Jersey 257 26 6 0 4 4 1 11

New Mexico 110 8 3 2 2 0 1 0

New York 848 53 8 14 6 6 5 14

North Carolina 209 35 7 5 3 7 1 12

North Dakota 14 4 1 2 0 1 0 0

Ohio 152 36 7 5 7 6 1 10

Oklahoma 83 19 3 9 1 3 0 3

Oregon 84 17 3 6 0 3 0 5

Pennsylvania 334 51 10 14 0 9 0 18

Puerto Rico 275 27 2 10 2 5 0 8

Rhode Island 18 4 1 0 0 1 0 2

South Carolina 70 16 3 3 1 4 0 5

South Dakota 32 9 2 5 0 1 0 1

Tennessee 114 23 1 7 2 8 1 4

Texas 776 96 23 27 6 15 1 24

Utah 142 16 2 3 1 3 0 7

Vermont 17 5 1 3 0 1 0 0

Virgin Islands 2 1 1 0 0 0 0 0

Virginia 158 27 4 7 0 5 0 11

Washington 241 29 8 4 8 3 2 4

West Virginia 46 12 1 7 0 2 0 2

Wisconsin 149 17 8 0 3 2 1 3

Wyoming 16 4 0 3 0 1 0 0

Tribes - Region 1 0 0 0 0 0 0 0 0

Tribes - Region 5 0 0 0 0 0 0 0 0

Tribes - Region 6 3 2 2 0 0 0 0 0

Tribes - Region 8 0 0 0 0 0 0 0 0

Tribes - Region 9 16 2 0 2 0 0 0 0

Total 11,156 1,198 240 240 151 169 63 335

1

 The UCMR data are not representative at the state-level.

Page 1 of 2
EPA-OGWDW

Appendix B. Summary of Systems and Population Served by State

Occurrence Data from the UCMR 2

Table B15. Alachlor ESA - UCMR 2 Screening Survey Data - Number of Systems and Population Served by State

State 1

Total 

Population 

Served

Pop. Served by 

Small Systems 

(serving ≤10,000 

people): Ground 

Water

Pop. Served by 

Small Systems 

(serving ≤10,000 

people): 

Surface Water

Pop. Served by 

Large Systems 

(serving 10,001-

100,000 people): 

Ground Water

Pop. Served by 

Large Systems 

(serving 10,001-

100,000 people): 

Surface Water

Pop. Served by 

Very Large 

Systems (serving 

>100,000 people): 

Ground Water

Pop. Served by 

Very Large 

Systems (serving 

>100,000 people): 

Surface Water

Alabama 2,040,600 17,259 9,693 103,109 204,295 0 1,706,245

Alaska 143,305 90 8,049 0 0 0 135,166

American Samoa 0 0 0 0 0 0 0

Arizona 3,403,868 14,319 1,729 113,300 0 675,445 2,599,075

Arkansas 845,459 11,365 8,930 85,674 52,858 0 686,632

California 24,372,007 29,816 49,813 1,008,796 1,303,622 1,088,908 20,891,052

Colorado 3,219,993 8,226 15,710 31,000 128,361 0 3,036,696

Connecticut 1,497,295 1,004 6,620 17,500 94,362 0 1,377,809

Delaware 484,765 4,383 0 34,878 0 0 445,504

District of Columbia 783,055 0 0 0 0 0 783,055

Florida 11,889,692 31,802 7,075 1,732,771 31,152 7,266,168 2,820,724

Georgia 4,397,366 9,885 12,463 39,543 211,034 163,688 3,960,753

Guam 100,001 0 0 0 0 100,001 0

Hawaii 854,836 4,958 0 63,155 0 786,723 0

Idaho 280,917 5,329 1,237 88,351 0 0 186,000

Illinois 5,680,520 22,938 20,358 71,451 364,550 405,228 4,795,996

Indiana 2,277,440 14,331 9,489 216,877 70,123 113,400 1,853,220

Iowa 805,109 14,756 7,369 146,216 81,086 0 555,682

Kansas 1,331,673 6,004 14,995 41,348 11,025 0 1,258,301

Kentucky 1,962,150 0 17,056 0 258,661 85,697 1,600,737

Louisiana 2,049,851 22,928 7,429 115,495 69,144 663,655 1,171,200

Maine 132,909 724 7,600 0 11,025 0 113,560

Maryland 3,874,592 6,534 7,390 64,801 13,200 249,600 3,533,067

Massachusetts 5,202,826 10,300 12,914 130,449 249,899 159,180 4,640,084

Michigan 4,826,722 12,746 12,269 97,711 130,537 283,846 4,289,613

Minnesota 1,400,744 10,862 7,501 300,404 148,200 0 933,777

Mississippi 424,022 31,538 0 49,302 0 0 343,182

Missouri 2,793,981 11,698 13,341 97,715 77,092 223,971 2,370,164

Montana 112,643 3,104 6,168 0 0 0 103,371

N. Mariana Islands 0 0 0 0 0 0 0

Navajo Nation 21,873 3,629 0 18,244 0 0 0

Nebraska 743,335 4,946 2,500 21,000 0 0 714,889

Nevada 1,908,764 6,832 237 0 56,000 0 1,845,695

New Hampshire 165,859 950 1,595 0 11,250 0 152,064

New Jersey 4,449,920 10,749 0 91,759 118,127 115,378 4,113,907

New Mexico 568,968 7,769 2,846 105,000 0 453,353 0

New York 12,173,772 8,634 35,158 248,594 225,437 1,682,822 9,973,127

North Carolina 3,220,020 15,311 26,493 111,438 311,061 108,666 2,647,052

North Dakota 92,952 1,099 1,254 0 90,599 0 0

Ohio 5,968,446 21,415 12,060 300,293 263,264 123,850 5,247,564

Oklahoma 1,432,777 6,402 25,003 15,435 128,486 0 1,257,451

Oregon 1,505,465 7,740 18,036 0 123,120 0 1,356,569

Pennsylvania 5,612,428 14,708 33,537 0 390,681 0 5,173,502

Puerto Rico 3,794,459 4,955 17,083 112,793 220,732 0 3,438,896

Rhode Island 613,600 355 0 0 61,709 0 551,536

South Carolina 1,604,882 8,549 10,201 53,122 181,122 0 1,351,888

South Dakota 152,210 811 3,162 0 20,237 0 128,000

Tennessee 2,104,138 8,587 31,013 66,568 371,290 687,096 939,584

Texas 14,372,970 60,963 89,693 228,445 691,230 1,253,442 12,049,197

Utah 1,362,703 8,500 9,345 24,000 160,956 0 1,159,902

Vermont 63,618 298 11,570 0 51,750 0 0

Virgin Islands 50 50 0 0 0 0 0

Virginia 3,377,005 3,451 21,232 0 143,889 0 3,208,433

Washington 2,706,556 15,667 6,360 404,649 93,417 374,556 1,811,906

West Virginia 434,635 424 26,216 0 78,231 0 329,764

Wisconsin 1,507,678 17,221 0 133,000 82,035 205,247 1,070,175

Wyoming 68,027 0 8,043 0 59,984 0 0

Tribes - Region 1 0 0 0 0 0 0 0

Tribes - Region 5 0 0 0 0 0 0 0

Tribes - Region 6 1,450 1,450 0 0 0 0 0

Tribes - Region 8 0 0 0 0 0 0 0

Tribes - Region 9 2,722 0 2,722 0 0 0 0

Total 157,219,620 548,364 660,557 6,584,184 7,444,830 17,269,919 124,711,765

1

 The UCMR data are not representative at the state-level.

Page 2 of 2
EPA-OGWDW

Appendix B. Summary of Systems and Population Served by State

Occurrence Data from the UCMR 2

Table B16. Alachlor OA - UCMR 2 Screening Survey Data - Number of Systems and Population Served by State

State 1

Total 

Number of 

Samples

Total 

Number of 

Systems

Number of 

Small Systems 

(serving ≤10,000 

people): Ground 

Water

Number of 

Small Systems 

(serving ≤10,000 

people): 

Surface Water

Number of 

Large Systems 

(serving 10,001-

100,000 people): 

Ground Water

Number of 

Large Systems 

(serving 10,001-

100,000 people): 

Surface Water

Number of Very 

Large Systems 

(serving 

>100,000 

people): Ground 

Water

Number of Very 

Large Systems 

(serving 

>100,000 

people): 

Surface Water

Alabama 147 20 4 2 3 5 0 6

Alaska 58 9 1 7 0 0 0 1

American Samoa 0 0 0 0 0 0 0 0

Arizona 382 19 4 2 3 0 1 9

Arkansas 68 13 3 3 2 2 0 3

California 3,351 154 13 28 19 22 8 64

Colorado 158 26 3 9 1 3 0 10

Connecticut 83 12 3 1 1 2 0 5

Delaware 83 5 1 0 1 0 0 3

District of Columbia 8 1 0 0 0 0 0 1

Florida 432 79 11 1 31 1 23 12

Georgia 169 31 6 5 2 5 1 12

Guam 220 1 0 0 0 0 1 0

Hawaii 140 4 1 0 1 0 2 0

Idaho 67 9 3 3 2 0 0 1

Illinois 270 35 7 5 4 8 3 8

Indiana 109 21 5 2 5 2 1 6

Iowa 82 15 5 2 3 2 0 3

Kansas 76 16 3 5 1 1 0 6

Kentucky 83 17 0 4 0 8 1 4

Louisiana 209 22 8 2 3 2 3 4

Maine 22 6 2 2 0 1 0 1

Maryland 60 13 3 3 2 1 1 3

Massachusetts 135 24 4 2 4 5 1 8

Michigan 145 23 9 2 2 3 2 5

Minnesota 59 18 6 1 7 2 0 2

Mississippi 82 15 10 0 3 0 0 2

Missouri 95 20 6 4 3 2 1 4

Montana 24 7 2 4 0 0 0 1

N. Mariana Islands 0 0 0 0 0 0 0 0

Navajo Nation 14 3 2 0 1 0 0 0

Nebraska 45 7 3 1 1 0 0 2

Nevada 98 8 2 1 0 1 0 4

New Hampshire 17 6 3 1 0 1 0 1

New Jersey 257 26 6 0 4 4 1 11

New Mexico 110 8 3 2 2 0 1 0

New York 848 53 8 14 6 6 5 14

North Carolina 209 35 7 5 3 7 1 12

North Dakota 14 4 1 2 0 1 0 0

Ohio 152 36 7 5 7 6 1 10

Oklahoma 83 19 3 9 1 3 0 3

Oregon 84 17 3 6 0 3 0 5

Pennsylvania 334 51 10 14 0 9 0 18

Puerto Rico 275 27 2 10 2 5 0 8

Rhode Island 18 4 1 0 0 1 0 2

South Carolina 70 16 3 3 1 4 0 5

South Dakota 32 9 2 5 0 1 0 1

Tennessee 114 23 1 7 2 8 1 4

Texas 776 96 23 27 6 15 1 24

Utah 142 16 2 3 1 3 0 7

Vermont 17 5 1 3 0 1 0 0

Virgin Islands 2 1 1 0 0 0 0 0

Virginia 158 27 4 7 0 5 0 11

Washington 241 29 8 4 8 3 2 4

West Virginia 46 12 1 7 0 2 0 2

Wisconsin 149 17 8 0 3 2 1 3

Wyoming 16 4 0 3 0 1 0 0

Tribes - Region 1 0 0 0 0 0 0 0 0

Tribes - Region 5 0 0 0 0 0 0 0 0

Tribes - Region 6 3 2 2 0 0 0 0 0

Tribes - Region 8 0 0 0 0 0 0 0 0

Tribes - Region 9 16 2 0 2 0 0 0 0

Total 11,157 1,198 240 240 151 169 63 335

1

 The UCMR data are not representative at the state-level.

Page 1 of 2
EPA-OGWDW

Appendix B. Summary of Systems and Population Served by State

Occurrence Data from the UCMR 2

Table B16. Alachlor OA - UCMR 2 Screening Survey Data - Number of Systems and Population Served by State

State 1

Total 

Population 

Served

Pop. Served by 

Small Systems 

(serving ≤10,000 

people): Ground 

Water

Pop. Served by 

Small Systems 

(serving ≤10,000 

people): 

Surface Water

Pop. Served by 

Large Systems 

(serving 10,001-

100,000 people): 

Ground Water

Pop. Served by 

Large Systems 

(serving 10,001-

100,000 people): 

Surface Water

Pop. Served by 

Very Large 

Systems (serving 

>100,000 people): 

Ground Water

Pop. Served by 

Very Large 

Systems (serving 

>100,000 people): 

Surface Water

Alabama 2,040,600 17,259 9,693 103,109 204,295 0 1,706,245

Alaska 143,305 90 8,049 0 0 0 135,166

American Samoa 0 0 0 0 0 0 0

Arizona 3,403,868 14,319 1,729 113,300 0 675,445 2,599,075

Arkansas 845,459 11,365 8,930 85,674 52,858 0 686,632

California 24,372,007 29,816 49,813 1,008,796 1,303,622 1,088,908 20,891,052

Colorado 3,219,993 8,226 15,710 31,000 128,361 0 3,036,696

Connecticut 1,497,295 1,004 6,620 17,500 94,362 0 1,377,809

Delaware 484,765 4,383 0 34,878 0 0 445,504

District of Columbia 783,055 0 0 0 0 0 783,055

Florida 11,889,692 31,802 7,075 1,732,771 31,152 7,266,168 2,820,724

Georgia 4,397,366 9,885 12,463 39,543 211,034 163,688 3,960,753

Guam 100,001 0 0 0 0 100,001 0

Hawaii 854,836 4,958 0 63,155 0 786,723 0

Idaho 280,917 5,329 1,237 88,351 0 0 186,000

Illinois 5,680,520 22,938 20,358 71,451 364,550 405,228 4,795,996

Indiana 2,277,440 14,331 9,489 216,877 70,123 113,400 1,853,220

Iowa 805,109 14,756 7,369 146,216 81,086 0 555,682

Kansas 1,331,673 6,004 14,995 41,348 11,025 0 1,258,301

Kentucky 1,962,150 0 17,056 0 258,661 85,697 1,600,737

Louisiana 2,049,851 22,928 7,429 115,495 69,144 663,655 1,171,200

Maine 132,909 724 7,600 0 11,025 0 113,560

Maryland 3,874,592 6,534 7,390 64,801 13,200 249,600 3,533,067

Massachusetts 5,202,826 10,300 12,914 130,449 249,899 159,180 4,640,084

Michigan 4,826,722 12,746 12,269 97,711 130,537 283,846 4,289,613

Minnesota 1,400,744 10,862 7,501 300,404 148,200 0 933,777

Mississippi 424,022 31,538 0 49,302 0 0 343,182

Missouri 2,793,981 11,698 13,341 97,715 77,092 223,971 2,370,164

Montana 112,643 3,104 6,168 0 0 0 103,371

N. Mariana Islands 0 0 0 0 0 0 0

Navajo Nation 21,873 3,629 0 18,244 0 0 0

Nebraska 743,335 4,946 2,500 21,000 0 0 714,889

Nevada 1,908,764 6,832 237 0 56,000 0 1,845,695

New Hampshire 165,859 950 1,595 0 11,250 0 152,064

New Jersey 4,449,920 10,749 0 91,759 118,127 115,378 4,113,907

New Mexico 568,968 7,769 2,846 105,000 0 453,353 0

New York 12,173,772 8,634 35,158 248,594 225,437 1,682,822 9,973,127

North Carolina 3,220,020 15,311 26,493 111,438 311,061 108,666 2,647,052

North Dakota 92,952 1,099 1,254 0 90,599 0 0

Ohio 5,968,446 21,415 12,060 300,293 263,264 123,850 5,247,564

Oklahoma 1,432,777 6,402 25,003 15,435 128,486 0 1,257,451

Oregon 1,505,465 7,740 18,036 0 123,120 0 1,356,569

Pennsylvania 5,612,428 14,708 33,537 0 390,681 0 5,173,502

Puerto Rico 3,794,459 4,955 17,083 112,793 220,732 0 3,438,896

Rhode Island 613,600 355 0 0 61,709 0 551,536

South Carolina 1,604,882 8,549 10,201 53,122 181,122 0 1,351,888

South Dakota 152,210 811 3,162 0 20,237 0 128,000

Tennessee 2,104,138 8,587 31,013 66,568 371,290 687,096 939,584

Texas 14,372,970 60,963 89,693 228,445 691,230 1,253,442 12,049,197

Utah 1,362,703 8,500 9,345 24,000 160,956 0 1,159,902

Vermont 63,618 298 11,570 0 51,750 0 0

Virgin Islands 50 50 0 0 0 0 0

Virginia 3,377,005 3,451 21,232 0 143,889 0 3,208,433

Washington 2,706,556 15,667 6,360 404,649 93,417 374,556 1,811,906

West Virginia 434,635 424 26,216 0 78,231 0 329,764

Wisconsin 1,507,678 17,221 0 133,000 82,035 205,247 1,070,175

Wyoming 68,027 0 8,043 0 59,984 0 0

Tribes - Region 1 0 0 0 0 0 0 0

Tribes - Region 5 0 0 0 0 0 0 0

Tribes - Region 6 1,450 1,450 0 0 0 0 0

Tribes - Region 8 0 0 0 0 0 0 0

Tribes - Region 9 2,722 0 2,722 0 0 0 0

Total 157,219,620 548,364 660,557 6,584,184 7,444,830 17,269,919 124,711,765

1

 The UCMR data are not representative at the state-level.

Page 2 of 2
EPA-OGWDW

Appendix B. Summary of Systems and Population Served by State

Occurrence Data from the UCMR 2

Table B17. Metolachlor - UCMR 2 Screening Survey Data - Number of Systems and Population Served by State

State 1

Total 

Number of 

Samples

Total 

Number of 

Systems

Number of 

Small Systems 

(serving ≤10,000 

people): Ground 

Water

Number of 

Small Systems 

(serving ≤10,000 

people): 

Surface Water

Number of 

Large Systems 

(serving 10,001-

100,000 people): 

Ground Water

Number of 

Large Systems 

(serving 10,001-

100,000 people): 

Surface Water

Number of Very 

Large Systems 

(serving 

>100,000 

people): Ground 

Water

Number of Very 

Large Systems 

(serving 

>100,000 

people): 

Surface Water

Alabama 147 20 4 2 3 5 0 6

Alaska 58 9 1 7 0 0 0 1

American Samoa 0 0 0 0 0 0 0 0

Arizona 382 19 4 2 3 0 1 9

Arkansas 68 13 3 3 2 2 0 3

California 3,347 154 13 28 19 22 8 64

Colorado 159 26 3 9 1 3 0 10

Connecticut 83 12 3 1 1 2 0 5

Delaware 83 5 1 0 1 0 0 3

District of Columbia 8 1 0 0 0 0 0 1

Florida 433 79 11 1 31 1 23 12

Georgia 170 31 6 5 2 5 1 12

Guam 219 1 0 0 0 0 1 0

Hawaii 140 4 1 0 1 0 2 0

Idaho 67 9 3 3 2 0 0 1

Illinois 270 35 7 5 4 8 3 8

Indiana 109 21 5 2 5 2 1 6

Iowa 82 15 5 2 3 2 0 3

Kansas 76 16 3 5 1 1 0 6

Kentucky 83 17 0 4 0 8 1 4

Louisiana 212 22 8 2 3 2 3 4

Maine 22 6 2 2 0 1 0 1

Maryland 60 13 3 3 2 1 1 3

Massachusetts 141 24 4 2 4 5 1 8

Michigan 146 23 9 2 2 3 2 5

Minnesota 59 18 6 1 7 2 0 2

Mississippi 82 15 10 0 3 0 0 2

Missouri 96 20 6 4 3 2 1 4

Montana 24 7 2 4 0 0 0 1

N. Mariana Islands 0 0 0 0 0 0 0 0

Navajo Nation 14 3 2 0 1 0 0 0

Nebraska 45 7 3 1 1 0 0 2

Nevada 98 8 2 1 0 1 0 4

New Hampshire 17 6 3 1 0 1 0 1

New Jersey 257 26 6 0 4 4 1 11

New Mexico 110 8 3 2 2 0 1 0

New York 857 53 8 14 6 6 5 14

North Carolina 210 35 7 5 3 7 1 12

North Dakota 14 4 1 2 0 1 0 0

Ohio 152 36 7 5 7 6 1 10

Oklahoma 83 19 3 9 1 3 0 3

Oregon 84 17 3 6 0 3 0 5

Pennsylvania 333 51 10 14 0 9 0 18

Puerto Rico 275 27 2 10 2 5 0 8

Rhode Island 18 4 1 0 0 1 0 2

South Carolina 70 16 3 3 1 4 0 5

South Dakota 32 9 2 5 0 1 0 1

Tennessee 114 23 1 7 2 8 1 4

Texas 779 96 23 27 6 15 1 24

Utah 142 16 2 3 1 3 0 7

Vermont 18 5 1 3 0 1 0 0

Virgin Islands 2 1 1 0 0 0 0 0

Virginia 158 27 4 7 0 5 0 11

Washington 253 29 8 4 8 3 2 4

West Virginia 46 12 1 7 0 2 0 2

Wisconsin 149 17 8 0 3 2 1 3

Wyoming 16 4 0 3 0 1 0 0

Tribes - Region 1 0 0 0 0 0 0 0 0

Tribes - Region 5 0 0 0 0 0 0 0 0

Tribes - Region 6 4 2 2 0 0 0 0 0

Tribes - Region 8 0 0 0 0 0 0 0 0

Tribes - Region 9 16 2 0 2 0 0 0 0

Total 11,192 1,198 240 240 151 169 63 335

1

 The UCMR data are not representative at the state-level.

Page 1 of 2
EPA-OGWDW

Appendix B. Summary of Systems and Population Served by State

Occurrence Data from the UCMR 2

Table B17. Metolachlor - UCMR 2 Screening Survey Data - Number of Systems and Population Served by State

State 1

Total 

Population 

Served

Pop. Served by 

Small Systems 

(serving ≤10,000 

people): Ground 

Water

Pop. Served by 

Small Systems 

(serving ≤10,000 

people): 

Surface Water

Pop. Served by 

Large Systems 

(serving 10,001-

100,000 people): 

Ground Water

Pop. Served by 

Large Systems 

(serving 10,001-

100,000 people): 

Surface Water

Pop. Served by 

Very Large 

Systems (serving 

>100,000 people): 

Ground Water

Pop. Served by 

Very Large 

Systems (serving 

>100,000 people): 

Surface Water

Alabama 2,040,600 17,259 9,693 103,109 204,295 0 1,706,245

Alaska 143,305 90 8,049 0 0 0 135,166

American Samoa 0 0 0 0 0 0 0

Arizona 3,403,868 14,319 1,729 113,300 0 675,445 2,599,075

Arkansas 845,459 11,365 8,930 85,674 52,858 0 686,632

California 24,372,007 29,816 49,813 1,008,796 1,303,622 1,088,908 20,891,052

Colorado 3,219,993 8,226 15,710 31,000 128,361 0 3,036,696

Connecticut 1,497,295 1,004 6,620 17,500 94,362 0 1,377,809

Delaware 484,765 4,383 0 34,878 0 0 445,504

District of Columbia 783,055 0 0 0 0 0 783,055

Florida 11,889,692 31,802 7,075 1,732,771 31,152 7,266,168 2,820,724

Georgia 4,397,366 9,885 12,463 39,543 211,034 163,688 3,960,753

Guam 100,001 0 0 0 0 100,001 0

Hawaii 854,836 4,958 0 63,155 0 786,723 0

Idaho 280,917 5,329 1,237 88,351 0 0 186,000

Illinois 5,680,520 22,938 20,358 71,451 364,550 405,228 4,795,996

Indiana 2,277,440 14,331 9,489 216,877 70,123 113,400 1,853,220

Iowa 805,109 14,756 7,369 146,216 81,086 0 555,682

Kansas 1,331,673 6,004 14,995 41,348 11,025 0 1,258,301

Kentucky 1,962,150 0 17,056 0 258,661 85,697 1,600,737

Louisiana 2,049,851 22,928 7,429 115,495 69,144 663,655 1,171,200

Maine 132,909 724 7,600 0 11,025 0 113,560

Maryland 3,874,592 6,534 7,390 64,801 13,200 249,600 3,533,067

Massachusetts 5,202,826 10,300 12,914 130,449 249,899 159,180 4,640,084

Michigan 4,826,722 12,746 12,269 97,711 130,537 283,846 4,289,613

Minnesota 1,400,744 10,862 7,501 300,404 148,200 0 933,777

Mississippi 424,022 31,538 0 49,302 0 0 343,182

Missouri 2,793,981 11,698 13,341 97,715 77,092 223,971 2,370,164

Montana 112,643 3,104 6,168 0 0 0 103,371

N. Mariana Islands 0 0 0 0 0 0 0

Navajo Nation 21,873 3,629 0 18,244 0 0 0

Nebraska 743,335 4,946 2,500 21,000 0 0 714,889

Nevada 1,908,764 6,832 237 0 56,000 0 1,845,695

New Hampshire 165,859 950 1,595 0 11,250 0 152,064

New Jersey 4,449,920 10,749 0 91,759 118,127 115,378 4,113,907

New Mexico 568,968 7,769 2,846 105,000 0 453,353 0

New York 12,173,772 8,634 35,158 248,594 225,437 1,682,822 9,973,127

North Carolina 3,220,020 15,311 26,493 111,438 311,061 108,666 2,647,052

North Dakota 92,952 1,099 1,254 0 90,599 0 0

Ohio 5,968,446 21,415 12,060 300,293 263,264 123,850 5,247,564

Oklahoma 1,432,777 6,402 25,003 15,435 128,486 0 1,257,451

Oregon 1,505,465 7,740 18,036 0 123,120 0 1,356,569

Pennsylvania 5,612,428 14,708 33,537 0 390,681 0 5,173,502

Puerto Rico 3,794,459 4,955 17,083 112,793 220,732 0 3,438,896

Rhode Island 613,600 355 0 0 61,709 0 551,536

South Carolina 1,604,882 8,549 10,201 53,122 181,122 0 1,351,888

South Dakota 152,210 811 3,162 0 20,237 0 128,000

Tennessee 2,104,138 8,587 31,013 66,568 371,290 687,096 939,584

Texas 14,372,970 60,963 89,693 228,445 691,230 1,253,442 12,049,197

Utah 1,362,703 8,500 9,345 24,000 160,956 0 1,159,902

Vermont 63,618 298 11,570 0 51,750 0 0

Virgin Islands 50 50 0 0 0 0 0

Virginia 3,377,005 3,451 21,232 0 143,889 0 3,208,433

Washington 2,706,556 15,667 6,360 404,649 93,417 374,556 1,811,906

West Virginia 434,635 424 26,216 0 78,231 0 329,764

Wisconsin 1,507,678 17,221 0 133,000 82,035 205,247 1,070,175

Wyoming 68,027 0 8,043 0 59,984 0 0

Tribes - Region 1 0 0 0 0 0 0 0

Tribes - Region 5 0 0 0 0 0 0 0

Tribes - Region 6 1,450 1,450 0 0 0 0 0

Tribes - Region 8 0 0 0 0 0 0 0

Tribes - Region 9 2,722 0 2,722 0 0 0 0

Total 157,219,620 548,364 660,557 6,584,184 7,444,830 17,269,919 124,711,765

1

 The UCMR data are not representative at the state-level.

Page 2 of 2
EPA-OGWDW

Appendix B. Summary of Systems and Population Served by State

Occurrence Data from the UCMR 2

Table B18. Metolachlor ESA - UCMR 2 Screening Survey Data - Number of Systems and Population Served by State

State 1

Total 

Number of 

Samples

Total 

Number of 

Systems

Number of 

Small Systems 

(serving ≤10,000 

people): Ground 

Water

Number of 

Small Systems 

(serving ≤10,000 

people): 

Surface Water

Number of 

Large Systems 

(serving 10,001-

100,000 people): 

Ground Water

Number of 

Large Systems 

(serving 10,001-

100,000 people): 

Surface Water

Number of Very 

Large Systems 

(serving 

>100,000 

people): Ground 

Water

Number of Very 

Large Systems 

(serving 

>100,000 

people): 

Surface Water

Alabama 147 20 4 2 3 5 0 6

Alaska 58 9 1 7 0 0 0 1

American Samoa 0 0 0 0 0 0 0 0

Arizona 382 19 4 2 3 0 1 9

Arkansas 68 13 3 3 2 2 0 3

California 3,351 154 13 28 19 22 8 64

Colorado 158 26 3 9 1 3 0 10

Connecticut 83 12 3 1 1 2 0 5

Delaware 83 5 1 0 1 0 0 3

District of Columbia 8 1 0 0 0 0 0 1

Florida 432 79 11 1 31 1 23 12

Georgia 169 31 6 5 2 5 1 12

Guam 220 1 0 0 0 0 1 0

Hawaii 140 4 1 0 1 0 2 0

Idaho 67 9 3 3 2 0 0 1

Illinois 270 35 7 5 4 8 3 8

Indiana 109 21 5 2 5 2 1 6

Iowa 82 15 5 2 3 2 0 3

Kansas 76 16 3 5 1 1 0 6

Kentucky 83 17 0 4 0 8 1 4

Louisiana 209 22 8 2 3 2 3 4

Maine 22 6 2 2 0 1 0 1

Maryland 60 13 3 3 2 1 1 3

Massachusetts 135 24 4 2 4 5 1 8

Michigan 145 23 9 2 2 3 2 5

Minnesota 59 18 6 1 7 2 0 2

Mississippi 82 15 10 0 3 0 0 2

Missouri 95 20 6 4 3 2 1 4

Montana 24 7 2 4 0 0 0 1

N. Mariana Islands 0 0 0 0 0 0 0 0

Navajo Nation 14 3 2 0 1 0 0 0

Nebraska 45 7 3 1 1 0 0 2

Nevada 98 8 2 1 0 1 0 4

New Hampshire 17 6 3 1 0 1 0 1

New Jersey 257 26 6 0 4 4 1 11

New Mexico 110 8 3 2 2 0 1 0

New York 848 53 8 14 6 6 5 14

North Carolina 209 35 7 5 3 7 1 12

North Dakota 14 4 1 2 0 1 0 0

Ohio 152 36 7 5 7 6 1 10

Oklahoma 83 19 3 9 1 3 0 3

Oregon 84 17 3 6 0 3 0 5

Pennsylvania 334 51 10 14 0 9 0 18

Puerto Rico 275 27 2 10 2 5 0 8

Rhode Island 18 4 1 0 0 1 0 2

South Carolina 70 16 3 3 1 4 0 5

South Dakota 32 9 2 5 0 1 0 1

Tennessee 114 23 1 7 2 8 1 4

Texas 776 96 23 27 6 15 1 24

Utah 142 16 2 3 1 3 0 7

Vermont 17 5 1 3 0 1 0 0

Virgin Islands 2 1 1 0 0 0 0 0

Virginia 158 27 4 7 0 5 0 11

Washington 241 29 8 4 8 3 2 4

West Virginia 46 12 1 7 0 2 0 2

Wisconsin 149 17 8 0 3 2 1 3

Wyoming 16 4 0 3 0 1 0 0

Tribes - Region 1 0 0 0 0 0 0 0 0

Tribes - Region 5 0 0 0 0 0 0 0 0

Tribes - Region 6 3 2 2 0 0 0 0 0

Tribes - Region 8 0 0 0 0 0 0 0 0

Tribes - Region 9 16 2 0 2 0 0 0 0

Total 11,157 1,198 240 240 151 169 63 335

1

 The UCMR data are not representative at the state-level.

Page 1 of 2
EPA-OGWDW

Appendix B. Summary of Systems and Population Served by State

Occurrence Data from the UCMR 2

Table B18. Metolachlor ESA - UCMR 2 Screening Survey Data - Number of Systems and Population Served by State

State 1

Total 

Population 

Served

Pop. Served by 

Small Systems 

(serving ≤10,000 

people): Ground 

Water

Pop. Served by 

Small Systems 

(serving ≤10,000 

people): 

Surface Water

Pop. Served by 

Large Systems 

(serving 10,001-

100,000 people): 

Ground Water

Pop. Served by 

Large Systems 

(serving 10,001-

100,000 people): 

Surface Water

Pop. Served by 

Very Large 

Systems (serving 

>100,000 people): 

Ground Water

Pop. Served by 

Very Large 

Systems (serving 

>100,000 people): 

Surface Water

Alabama 2,040,600 17,259 9,693 103,109 204,295 0 1,706,245

Alaska 143,305 90 8,049 0 0 0 135,166

American Samoa 0 0 0 0 0 0 0

Arizona 3,403,868 14,319 1,729 113,300 0 675,445 2,599,075

Arkansas 845,459 11,365 8,930 85,674 52,858 0 686,632

California 24,372,007 29,816 49,813 1,008,796 1,303,622 1,088,908 20,891,052

Colorado 3,219,993 8,226 15,710 31,000 128,361 0 3,036,696

Connecticut 1,497,295 1,004 6,620 17,500 94,362 0 1,377,809

Delaware 484,765 4,383 0 34,878 0 0 445,504

District of Columbia 783,055 0 0 0 0 0 783,055

Florida 11,889,692 31,802 7,075 1,732,771 31,152 7,266,168 2,820,724

Georgia 4,397,366 9,885 12,463 39,543 211,034 163,688 3,960,753

Guam 100,001 0 0 0 0 100,001 0

Hawaii 854,836 4,958 0 63,155 0 786,723 0

Idaho 280,917 5,329 1,237 88,351 0 0 186,000

Illinois 5,680,520 22,938 20,358 71,451 364,550 405,228 4,795,996

Indiana 2,277,440 14,331 9,489 216,877 70,123 113,400 1,853,220

Iowa 805,109 14,756 7,369 146,216 81,086 0 555,682

Kansas 1,331,673 6,004 14,995 41,348 11,025 0 1,258,301

Kentucky 1,962,150 0 17,056 0 258,661 85,697 1,600,737

Louisiana 2,049,851 22,928 7,429 115,495 69,144 663,655 1,171,200

Maine 132,909 724 7,600 0 11,025 0 113,560

Maryland 3,874,592 6,534 7,390 64,801 13,200 249,600 3,533,067

Massachusetts 5,202,826 10,300 12,914 130,449 249,899 159,180 4,640,084

Michigan 4,826,722 12,746 12,269 97,711 130,537 283,846 4,289,613

Minnesota 1,400,744 10,862 7,501 300,404 148,200 0 933,777

Mississippi 424,022 31,538 0 49,302 0 0 343,182

Missouri 2,793,981 11,698 13,341 97,715 77,092 223,971 2,370,164

Montana 112,643 3,104 6,168 0 0 0 103,371

N. Mariana Islands 0 0 0 0 0 0 0

Navajo Nation 21,873 3,629 0 18,244 0 0 0

Nebraska 743,335 4,946 2,500 21,000 0 0 714,889

Nevada 1,908,764 6,832 237 0 56,000 0 1,845,695

New Hampshire 165,859 950 1,595 0 11,250 0 152,064

New Jersey 4,449,920 10,749 0 91,759 118,127 115,378 4,113,907

New Mexico 568,968 7,769 2,846 105,000 0 453,353 0

New York 12,173,772 8,634 35,158 248,594 225,437 1,682,822 9,973,127

North Carolina 3,220,020 15,311 26,493 111,438 311,061 108,666 2,647,052

North Dakota 92,952 1,099 1,254 0 90,599 0 0

Ohio 5,968,446 21,415 12,060 300,293 263,264 123,850 5,247,564

Oklahoma 1,432,777 6,402 25,003 15,435 128,486 0 1,257,451

Oregon 1,505,465 7,740 18,036 0 123,120 0 1,356,569

Pennsylvania 5,612,428 14,708 33,537 0 390,681 0 5,173,502

Puerto Rico 3,794,459 4,955 17,083 112,793 220,732 0 3,438,896

Rhode Island 613,600 355 0 0 61,709 0 551,536

South Carolina 1,604,882 8,549 10,201 53,122 181,122 0 1,351,888

South Dakota 152,210 811 3,162 0 20,237 0 128,000

Tennessee 2,104,138 8,587 31,013 66,568 371,290 687,096 939,584

Texas 14,372,970 60,963 89,693 228,445 691,230 1,253,442 12,049,197

Utah 1,362,703 8,500 9,345 24,000 160,956 0 1,159,902

Vermont 63,618 298 11,570 0 51,750 0 0

Virgin Islands 50 50 0 0 0 0 0

Virginia 3,377,005 3,451 21,232 0 143,889 0 3,208,433

Washington 2,706,556 15,667 6,360 404,649 93,417 374,556 1,811,906

West Virginia 434,635 424 26,216 0 78,231 0 329,764

Wisconsin 1,507,678 17,221 0 133,000 82,035 205,247 1,070,175

Wyoming 68,027 0 8,043 0 59,984 0 0

Tribes - Region 1 0 0 0 0 0 0 0

Tribes - Region 5 0 0 0 0 0 0 0

Tribes - Region 6 1,450 1,450 0 0 0 0 0

Tribes - Region 8 0 0 0 0 0 0 0

Tribes - Region 9 2,722 0 2,722 0 0 0 0

Total 157,219,620 548,364 660,557 6,584,184 7,444,830 17,269,919 124,711,765

1

 The UCMR data are not representative at the state-level.

Page 2 of 2
EPA-OGWDW

Appendix B. Summary of Systems and Population Served by State

Occurrence Data from the UCMR 2

Table B19. Metolachlor OA - UCMR 2 Screening Survey Data - Number of Systems and Population Served by State

State 1

Total 

Number of 

Samples

Total 

Number of 

Systems

Number of 

Small Systems 

(serving ≤10,000 

people): Ground 

Water

Number of 

Small Systems 

(serving ≤10,000 

people): 

Surface Water

Number of 

Large Systems 

(serving 10,001-

100,000 people): 

Ground Water

Number of 

Large Systems 

(serving 10,001-

100,000 people): 

Surface Water

Number of Very 

Large Systems 

(serving 

>100,000 

people): Ground 

Water

Number of Very 

Large Systems 

(serving 

>100,000 

people): 

Surface Water

Alabama 147 20 4 2 3 5 0 6

Alaska 58 9 1 7 0 0 0 1

American Samoa 0 0 0 0 0 0 0 0

Arizona 382 19 4 2 3 0 1 9

Arkansas 68 13 3 3 2 2 0 3

California 3,351 154 13 28 19 22 8 64

Colorado 158 26 3 9 1 3 0 10

Connecticut 83 12 3 1 1 2 0 5

Delaware 83 5 1 0 1 0 0 3

District of Columbia 8 1 0 0 0 0 0 1

Florida 432 79 11 1 31 1 23 12

Georgia 169 31 6 5 2 5 1 12

Guam 220 1 0 0 0 0 1 0

Hawaii 140 4 1 0 1 0 2 0

Idaho 67 9 3 3 2 0 0 1

Illinois 270 35 7 5 4 8 3 8

Indiana 109 21 5 2 5 2 1 6

Iowa 82 15 5 2 3 2 0 3

Kansas 76 16 3 5 1 1 0 6

Kentucky 83 17 0 4 0 8 1 4

Louisiana 209 22 8 2 3 2 3 4

Maine 22 6 2 2 0 1 0 1

Maryland 60 13 3 3 2 1 1 3

Massachusetts 135 24 4 2 4 5 1 8

Michigan 145 23 9 2 2 3 2 5

Minnesota 59 18 6 1 7 2 0 2

Mississippi 82 15 10 0 3 0 0 2

Missouri 95 20 6 4 3 2 1 4

Montana 24 7 2 4 0 0 0 1

N. Mariana Islands 0 0 0 0 0 0 0 0

Navajo Nation 14 3 2 0 1 0 0 0

Nebraska 45 7 3 1 1 0 0 2

Nevada 98 8 2 1 0 1 0 4

New Hampshire 17 6 3 1 0 1 0 1

New Jersey 257 26 6 0 4 4 1 11

New Mexico 110 8 3 2 2 0 1 0

New York 848 53 8 14 6 6 5 14

North Carolina 209 35 7 5 3 7 1 12

North Dakota 14 4 1 2 0 1 0 0

Ohio 152 36 7 5 7 6 1 10

Oklahoma 83 19 3 9 1 3 0 3

Oregon 84 17 3 6 0 3 0 5

Pennsylvania 334 51 10 14 0 9 0 18

Puerto Rico 275 27 2 10 2 5 0 8

Rhode Island 18 4 1 0 0 1 0 2

South Carolina 70 16 3 3 1 4 0 5

South Dakota 32 9 2 5 0 1 0 1

Tennessee 114 23 1 7 2 8 1 4

Texas 776 96 23 27 6 15 1 24

Utah 142 16 2 3 1 3 0 7

Vermont 17 5 1 3 0 1 0 0

Virgin Islands 2 1 1 0 0 0 0 0

Virginia 158 27 4 7 0 5 0 11

Washington 241 29 8 4 8 3 2 4

West Virginia 46 12 1 7 0 2 0 2

Wisconsin 149 17 8 0 3 2 1 3

Wyoming 16 4 0 3 0 1 0 0

Tribes - Region 1 0 0 0 0 0 0 0 0

Tribes - Region 5 0 0 0 0 0 0 0 0

Tribes - Region 6 3 2 2 0 0 0 0 0

Tribes - Region 8 0 0 0 0 0 0 0 0

Tribes - Region 9 16 2 0 2 0 0 0 0

Total 11,157 1,198 240 240 151 169 63 335

1

 The UCMR data are not representative at the state-level.

Page 1 of 2
EPA-OGWDW

Appendix B. Summary of Systems and Population Served by State

Occurrence Data from the UCMR 2

Table B19. Metolachlor OA - UCMR 2 Screening Survey Data - Number of Systems and Population Served by State

State 1

Total 

Population 

Served

Pop. Served by 

Small Systems 

(serving ≤10,000 

people): Ground 

Water

Pop. Served by 

Small Systems 

(serving ≤10,000 

people): 

Surface Water

Pop. Served by 

Large Systems 

(serving 10,001-

100,000 people): 

Ground Water

Pop. Served by 

Large Systems 

(serving 10,001-

100,000 people): 

Surface Water

Pop. Served by 

Very Large 

Systems (serving 

>100,000 people): 

Ground Water

Pop. Served by 

Very Large 

Systems (serving 

>100,000 people): 

Surface Water

Alabama 2,040,600 17,259 9,693 103,109 204,295 0 1,706,245

Alaska 143,305 90 8,049 0 0 0 135,166

American Samoa 0 0 0 0 0 0 0

Arizona 3,403,868 14,319 1,729 113,300 0 675,445 2,599,075

Arkansas 845,459 11,365 8,930 85,674 52,858 0 686,632

California 24,372,007 29,816 49,813 1,008,796 1,303,622 1,088,908 20,891,052

Colorado 3,219,993 8,226 15,710 31,000 128,361 0 3,036,696

Connecticut 1,497,295 1,004 6,620 17,500 94,362 0 1,377,809

Delaware 484,765 4,383 0 34,878 0 0 445,504

District of Columbia 783,055 0 0 0 0 0 783,055

Florida 11,889,692 31,802 7,075 1,732,771 31,152 7,266,168 2,820,724

Georgia 4,397,366 9,885 12,463 39,543 211,034 163,688 3,960,753

Guam 100,001 0 0 0 0 100,001 0

Hawaii 854,836 4,958 0 63,155 0 786,723 0

Idaho 280,917 5,329 1,237 88,351 0 0 186,000

Illinois 5,680,520 22,938 20,358 71,451 364,550 405,228 4,795,996

Indiana 2,277,440 14,331 9,489 216,877 70,123 113,400 1,853,220

Iowa 805,109 14,756 7,369 146,216 81,086 0 555,682

Kansas 1,331,673 6,004 14,995 41,348 11,025 0 1,258,301

Kentucky 1,962,150 0 17,056 0 258,661 85,697 1,600,737

Louisiana 2,049,851 22,928 7,429 115,495 69,144 663,655 1,171,200

Maine 132,909 724 7,600 0 11,025 0 113,560

Maryland 3,874,592 6,534 7,390 64,801 13,200 249,600 3,533,067

Massachusetts 5,202,826 10,300 12,914 130,449 249,899 159,180 4,640,084

Michigan 4,826,722 12,746 12,269 97,711 130,537 283,846 4,289,613

Minnesota 1,400,744 10,862 7,501 300,404 148,200 0 933,777

Mississippi 424,022 31,538 0 49,302 0 0 343,182

Missouri 2,793,981 11,698 13,341 97,715 77,092 223,971 2,370,164

Montana 112,643 3,104 6,168 0 0 0 103,371

N. Mariana Islands 0 0 0 0 0 0 0

Navajo Nation 21,873 3,629 0 18,244 0 0 0

Nebraska 743,335 4,946 2,500 21,000 0 0 714,889

Nevada 1,908,764 6,832 237 0 56,000 0 1,845,695

New Hampshire 165,859 950 1,595 0 11,250 0 152,064

New Jersey 4,449,920 10,749 0 91,759 118,127 115,378 4,113,907

New Mexico 568,968 7,769 2,846 105,000 0 453,353 0

New York 12,173,772 8,634 35,158 248,594 225,437 1,682,822 9,973,127

North Carolina 3,220,020 15,311 26,493 111,438 311,061 108,666 2,647,052

North Dakota 92,952 1,099 1,254 0 90,599 0 0

Ohio 5,968,446 21,415 12,060 300,293 263,264 123,850 5,247,564

Oklahoma 1,432,777 6,402 25,003 15,435 128,486 0 1,257,451

Oregon 1,505,465 7,740 18,036 0 123,120 0 1,356,569

Pennsylvania 5,612,428 14,708 33,537 0 390,681 0 5,173,502

Puerto Rico 3,794,459 4,955 17,083 112,793 220,732 0 3,438,896

Rhode Island 613,600 355 0 0 61,709 0 551,536

South Carolina 1,604,882 8,549 10,201 53,122 181,122 0 1,351,888

South Dakota 152,210 811 3,162 0 20,237 0 128,000

Tennessee 2,104,138 8,587 31,013 66,568 371,290 687,096 939,584

Texas 14,372,970 60,963 89,693 228,445 691,230 1,253,442 12,049,197

Utah 1,362,703 8,500 9,345 24,000 160,956 0 1,159,902

Vermont 63,618 298 11,570 0 51,750 0 0

Virgin Islands 50 50 0 0 0 0 0

Virginia 3,377,005 3,451 21,232 0 143,889 0 3,208,433

Washington 2,706,556 15,667 6,360 404,649 93,417 374,556 1,811,906

West Virginia 434,635 424 26,216 0 78,231 0 329,764

Wisconsin 1,507,678 17,221 0 133,000 82,035 205,247 1,070,175

Wyoming 68,027 0 8,043 0 59,984 0 0

Tribes - Region 1 0 0 0 0 0 0 0

Tribes - Region 5 0 0 0 0 0 0 0

Tribes - Region 6 1,450 1,450 0 0 0 0 0

Tribes - Region 8 0 0 0 0 0 0 0

Tribes - Region 9 2,722 0 2,722 0 0 0 0

Total 157,219,620 548,364 660,557 6,584,184 7,444,830 17,269,919 124,711,765

1

 The UCMR data are not representative at the state-level.

Page 2 of 2
EPA-OGWDW

Appendix B. Summary of Systems and Population Served by State

Occurrence Data from the UCMR 2

Table B20. NDBA - UCMR 2 Screening Survey Data - Number of Systems and Population Served by State

State 1

Total 

Number of 

Samples

Total 

Number of 

Systems

Number of 

Small Systems 

(serving ≤10,000 

people): Ground 

Water

Number of 

Small Systems 

(serving ≤10,000 

people): 

Surface Water

Number of 

Large Systems 

(serving 10,001-

100,000 people): 

Ground Water

Number of 

Large Systems 

(serving 10,001-

100,000 people): 

Surface Water

Number of Very 

Large Systems 

(serving 

>100,000 

people): Ground 

Water

Number of Very 

Large Systems 

(serving 

>100,000 

people): 

Surface Water

Alabama 270 20 4 2 3 5 0 6

Alaska 97 9 1 7 0 0 0 1

American Samoa 0 0 0 0 0 0 0 0

Arizona 753 19 4 2 3 0 1 9

Arkansas 116 13 3 3 2 2 0 3

California 4,394 154 13 28 19 22 8 64

Colorado 319 26 3 9 1 3 0 10

Connecticut 165 12 3 1 1 2 0 5

Delaware 117 5 1 0 1 0 0 3

District of Columbia 8 1 0 0 0 0 0 1

Florida 793 79 11 1 31 1 23 12

Georgia 315 31 6 5 2 5 1 12

Guam 233 1 0 0 0 0 1 0

Hawaii 161 4 1 0 1 0 2 0

Idaho 109 9 3 3 2 0 0 1

Illinois 392 35 7 5 4 8 3 8

Indiana 203 21 5 2 5 2 1 6

Iowa 130 15 5 2 3 2 0 3

Kansas 140 16 3 5 1 1 0 6

Kentucky 156 17 0 4 0 8 1 4

Louisiana 302 22 8 2 3 2 3 4

Maine 39 6 2 2 0 1 0 1

Maryland 120 13 3 3 2 1 1 3

Massachusetts 221 24 4 2 4 5 1 8

Michigan 255 23 9 2 2 3 2 5

Minnesota 103 18 6 1 7 2 0 2

Mississippi 114 15 10 0 3 0 0 2

Missouri 167 20 6 4 3 2 1 4

Montana 48 7 2 4 0 0 0 1

N. Mariana Islands 0 0 0 0 0 0 0 0

Navajo Nation 30 3 2 0 1 0 0 0

Nebraska 71 7 3 1 1 0 0 2

Nevada 147 8 2 1 0 1 0 4

New Hampshire 31 6 3 1 0 1 0 1

New Jersey 375 26 6 0 4 4 1 11

New Mexico 132 8 3 2 2 0 1 0

New York 1,540 53 8 14 6 6 5 14

North Carolina 355 35 7 5 3 7 1 12

North Dakota 28 4 1 2 0 1 0 0

Ohio 297 36 7 5 7 6 1 10

Oklahoma 158 19 3 9 1 3 0 3

Oregon 147 17 3 6 0 3 0 5

Pennsylvania 656 51 10 14 0 9 0 18

Puerto Rico 569 27 2 10 2 5 0 8

Rhode Island 30 4 1 0 0 1 0 2

South Carolina 140 16 3 3 1 4 0 5

South Dakota 62 9 2 5 0 1 0 1

Tennessee 226 23 1 7 2 8 1 4

Texas 1,627 96 23 27 6 15 1 24

Utah 200 16 2 3 1 3 0 7

Vermont 36 5 1 3 0 1 0 0

Virgin Islands 4 1 1 0 0 0 0 0

Virginia 285 27 4 7 0 5 0 11

Washington 350 29 8 4 8 3 2 4

West Virginia 86 12 1 7 0 2 0 2

Wisconsin 214 17 8 0 3 2 1 3

Wyoming 33 4 0 3 0 1 0 0

Tribes - Region 1 0 0 0 0 0 0 0 0

Tribes - Region 5 0 0 0 0 0 0 0 0

Tribes - Region 6 8 2 2 0 0 0 0 0

Tribes - Region 8 0 0 0 0 0 0 0 0

Tribes - Region 9 24 2 0 2 0 0 0 0

Total 18,101 1,198 240 240 151 169 63 335

1

 The UCMR data are not representative at the state-level.

Page 1 of 2
EPA-OGWDW

Appendix B. Summary of Systems and Population Served by State

Occurrence Data from the UCMR 2

Table B20. NDBA - UCMR 2 Screening Survey Data - Number of Systems and Population Served by State

State 1

Total 

Population 

Served

Pop. Served by 

Small Systems 

(serving ≤10,000 

people): Ground 

Water

Pop. Served by 

Small Systems 

(serving ≤10,000 

people): 

Surface Water

Pop. Served by 

Large Systems 

(serving 10,001-

100,000 people): 

Ground Water

Pop. Served by 

Large Systems 

(serving 10,001-

100,000 people): 

Surface Water

Pop. Served by 

Very Large 

Systems (serving 

>100,000 people): 

Ground Water

Pop. Served by 

Very Large 

Systems (serving 

>100,000 people): 

Surface Water

Alabama 2,040,600 17,259 9,693 103,109 204,295 0 1,706,245

Alaska 143,305 90 8,049 0 0 0 135,166

American Samoa 0 0 0 0 0 0 0

Arizona 3,403,868 14,319 1,729 113,300 0 675,445 2,599,075

Arkansas 845,459 11,365 8,930 85,674 52,858 0 686,632

California 24,372,007 29,816 49,813 1,008,796 1,303,622 1,088,908 20,891,052

Colorado 3,219,993 8,226 15,710 31,000 128,361 0 3,036,696

Connecticut 1,497,295 1,004 6,620 17,500 94,362 0 1,377,809

Delaware 484,765 4,383 0 34,878 0 0 445,504

District of Columbia 783,055 0 0 0 0 0 783,055

Florida 11,889,692 31,802 7,075 1,732,771 31,152 7,266,168 2,820,724

Georgia 4,397,366 9,885 12,463 39,543 211,034 163,688 3,960,753

Guam 100,001 0 0 0 0 100,001 0

Hawaii 854,836 4,958 0 63,155 0 786,723 0

Idaho 280,917 5,329 1,237 88,351 0 0 186,000

Illinois 5,680,520 22,938 20,358 71,451 364,550 405,228 4,795,996

Indiana 2,277,440 14,331 9,489 216,877 70,123 113,400 1,853,220

Iowa 805,109 14,756 7,369 146,216 81,086 0 555,682

Kansas 1,331,673 6,004 14,995 41,348 11,025 0 1,258,301

Kentucky 1,962,150 0 17,056 0 258,661 85,697 1,600,737

Louisiana 2,049,851 22,928 7,429 115,495 69,144 663,655 1,171,200

Maine 132,909 724 7,600 0 11,025 0 113,560

Maryland 3,874,592 6,534 7,390 64,801 13,200 249,600 3,533,067

Massachusetts 5,202,826 10,300 12,914 130,449 249,899 159,180 4,640,084

Michigan 4,826,722 12,746 12,269 97,711 130,537 283,846 4,289,613

Minnesota 1,400,744 10,862 7,501 300,404 148,200 0 933,777

Mississippi 424,022 31,538 0 49,302 0 0 343,182

Missouri 2,793,981 11,698 13,341 97,715 77,092 223,971 2,370,164

Montana 112,643 3,104 6,168 0 0 0 103,371

N. Mariana Islands 0 0 0 0 0 0 0

Navajo Nation 21,873 3,629 0 18,244 0 0 0

Nebraska 743,335 4,946 2,500 21,000 0 0 714,889

Nevada 1,908,764 6,832 237 0 56,000 0 1,845,695

New Hampshire 165,859 950 1,595 0 11,250 0 152,064

New Jersey 4,449,920 10,749 0 91,759 118,127 115,378 4,113,907

New Mexico 568,968 7,769 2,846 105,000 0 453,353 0

New York 12,173,772 8,634 35,158 248,594 225,437 1,682,822 9,973,127

North Carolina 3,220,020 15,311 26,493 111,438 311,061 108,666 2,647,052

North Dakota 92,952 1,099 1,254 0 90,599 0 0

Ohio 5,968,446 21,415 12,060 300,293 263,264 123,850 5,247,564

Oklahoma 1,432,777 6,402 25,003 15,435 128,486 0 1,257,451

Oregon 1,505,465 7,740 18,036 0 123,120 0 1,356,569

Pennsylvania 5,612,428 14,708 33,537 0 390,681 0 5,173,502

Puerto Rico 3,794,459 4,955 17,083 112,793 220,732 0 3,438,896

Rhode Island 613,600 355 0 0 61,709 0 551,536

South Carolina 1,604,882 8,549 10,201 53,122 181,122 0 1,351,888

South Dakota 152,210 811 3,162 0 20,237 0 128,000

Tennessee 2,104,138 8,587 31,013 66,568 371,290 687,096 939,584

Texas 14,372,970 60,963 89,693 228,445 691,230 1,253,442 12,049,197

Utah 1,362,703 8,500 9,345 24,000 160,956 0 1,159,902

Vermont 63,618 298 11,570 0 51,750 0 0

Virgin Islands 50 50 0 0 0 0 0

Virginia 3,377,005 3,451 21,232 0 143,889 0 3,208,433

Washington 2,706,556 15,667 6,360 404,649 93,417 374,556 1,811,906

West Virginia 434,635 424 26,216 0 78,231 0 329,764

Wisconsin 1,507,678 17,221 0 133,000 82,035 205,247 1,070,175

Wyoming 68,027 0 8,043 0 59,984 0 0

Tribes - Region 1 0 0 0 0 0 0 0

Tribes - Region 5 0 0 0 0 0 0 0

Tribes - Region 6 1,450 1,450 0 0 0 0 0

Tribes - Region 8 0 0 0 0 0 0 0

Tribes - Region 9 2,722 0 2,722 0 0 0 0

Total 157,219,620 548,364 660,557 6,584,184 7,444,830 17,269,919 124,711,765

1

 The UCMR data are not representative at the state-level.

Page 2 of 2
EPA-OGWDW

Appendix B. Summary of Systems and Population Served by State

Occurrence Data from the UCMR 2

Table B21. NDEA - UCMR 2 Screening Survey Data - Number of Systems and Population Served by State

State 1

Total 

Number of 

Samples

Total 

Number of 

Systems

Number of 

Small Systems 

(serving ≤10,000 

people): Ground 

Water

Number of 

Small Systems 

(serving ≤10,000 

people): 

Surface Water

Number of 

Large Systems 

(serving 10,001-

100,000 people): 

Ground Water

Number of 

Large Systems 

(serving 10,001-

100,000 people): 

Surface Water

Number of Very 

Large Systems 

(serving 

>100,000 

people): Ground 

Water

Number of Very 

Large Systems 

(serving 

>100,000 

people): 

Surface Water

Alabama 270 20 4 2 3 5 0 6

Alaska 97 9 1 7 0 0 0 1

American Samoa 0 0 0 0 0 0 0 0

Arizona 753 19 4 2 3 0 1 9

Arkansas 116 13 3 3 2 2 0 3

California 4,382 154 13 28 19 22 8 64

Colorado 319 26 3 9 1 3 0 10

Connecticut 165 12 3 1 1 2 0 5

Delaware 117 5 1 0 1 0 0 3

District of Columbia 8 1 0 0 0 0 0 1

Florida 793 79 11 1 31 1 23 12

Georgia 315 31 6 5 2 5 1 12

Guam 233 1 0 0 0 0 1 0

Hawaii 161 4 1 0 1 0 2 0

Idaho 109 9 3 3 2 0 0 1

Illinois 392 35 7 5 4 8 3 8

Indiana 203 21 5 2 5 2 1 6

Iowa 130 15 5 2 3 2 0 3

Kansas 140 16 3 5 1 1 0 6

Kentucky 156 17 0 4 0 8 1 4

Louisiana 302 22 8 2 3 2 3 4

Maine 39 6 2 2 0 1 0 1

Maryland 120 13 3 3 2 1 1 3

Massachusetts 221 24 4 2 4 5 1 8

Michigan 255 23 9 2 2 3 2 5

Minnesota 103 18 6 1 7 2 0 2

Mississippi 114 15 10 0 3 0 0 2

Missouri 167 20 6 4 3 2 1 4

Montana 48 7 2 4 0 0 0 1

N. Mariana Islands 0 0 0 0 0 0 0 0

Navajo Nation 30 3 2 0 1 0 0 0

Nebraska 71 7 3 1 1 0 0 2

Nevada 147 8 2 1 0 1 0 4

New Hampshire 31 6 3 1 0 1 0 1

New Jersey 375 26 6 0 4 4 1 11

New Mexico 132 8 3 2 2 0 1 0

New York 1,540 53 8 14 6 6 5 14

North Carolina 355 35 7 5 3 7 1 12

North Dakota 28 4 1 2 0 1 0 0

Ohio 297 36 7 5 7 6 1 10

Oklahoma 158 19 3 9 1 3 0 3

Oregon 147 17 3 6 0 3 0 5

Pennsylvania 656 51 10 14 0 9 0 18

Puerto Rico 569 27 2 10 2 5 0 8

Rhode Island 30 4 1 0 0 1 0 2

South Carolina 140 16 3 3 1 4 0 5

South Dakota 62 9 2 5 0 1 0 1

Tennessee 226 23 1 7 2 8 1 4

Texas 1,634 96 23 27 6 15 1 24

Utah 200 16 2 3 1 3 0 7

Vermont 36 5 1 3 0 1 0 0

Virgin Islands 4 1 1 0 0 0 0 0

Virginia 285 27 4 7 0 5 0 11

Washington 350 29 8 4 8 3 2 4

West Virginia 86 12 1 7 0 2 0 2

Wisconsin 214 17 8 0 3 2 1 3

Wyoming 33 4 0 3 0 1 0 0

Tribes - Region 1 0 0 0 0 0 0 0 0

Tribes - Region 5 0 0 0 0 0 0 0 0

Tribes - Region 6 8 2 2 0 0 0 0 0

Tribes - Region 8 0 0 0 0 0 0 0 0

Tribes - Region 9 24 2 0 2 0 0 0 0

Total 18,096 1,198 240 240 151 169 63 335

1

 The UCMR data are not representative at the state-level.

Page 1 of 2
EPA-OGWDW

Appendix B. Summary of Systems and Population Served by State

Occurrence Data from the UCMR 2

Table B21. NDEA - UCMR 2 Screening Survey Data - Number of Systems and Population Served by State

State 1

Total 

Population 

Served

Pop. Served by 

Small Systems 

(serving ≤10,000 

people): Ground 

Water

Pop. Served by 

Small Systems 

(serving ≤10,000 

people): 

Surface Water

Pop. Served by 

Large Systems 

(serving 10,001-

100,000 people): 

Ground Water

Pop. Served by 

Large Systems 

(serving 10,001-

100,000 people): 

Surface Water

Pop. Served by 

Very Large 

Systems (serving 

>100,000 people): 

Ground Water

Pop. Served by 

Very Large 

Systems (serving 

>100,000 people): 

Surface Water

Alabama 2,040,600 17,259 9,693 103,109 204,295 0 1,706,245

Alaska 143,305 90 8,049 0 0 0 135,166

American Samoa 0 0 0 0 0 0 0

Arizona 3,403,868 14,319 1,729 113,300 0 675,445 2,599,075

Arkansas 845,459 11,365 8,930 85,674 52,858 0 686,632

California 24,372,007 29,816 49,813 1,008,796 1,303,622 1,088,908 20,891,052

Colorado 3,219,993 8,226 15,710 31,000 128,361 0 3,036,696

Connecticut 1,497,295 1,004 6,620 17,500 94,362 0 1,377,809

Delaware 484,765 4,383 0 34,878 0 0 445,504

District of Columbia 783,055 0 0 0 0 0 783,055

Florida 11,889,692 31,802 7,075 1,732,771 31,152 7,266,168 2,820,724

Georgia 4,397,366 9,885 12,463 39,543 211,034 163,688 3,960,753

Guam 100,001 0 0 0 0 100,001 0

Hawaii 854,836 4,958 0 63,155 0 786,723 0

Idaho 280,917 5,329 1,237 88,351 0 0 186,000

Illinois 5,680,520 22,938 20,358 71,451 364,550 405,228 4,795,996

Indiana 2,277,440 14,331 9,489 216,877 70,123 113,400 1,853,220

Iowa 805,109 14,756 7,369 146,216 81,086 0 555,682

Kansas 1,331,673 6,004 14,995 41,348 11,025 0 1,258,301

Kentucky 1,962,150 0 17,056 0 258,661 85,697 1,600,737

Louisiana 2,049,851 22,928 7,429 115,495 69,144 663,655 1,171,200

Maine 132,909 724 7,600 0 11,025 0 113,560

Maryland 3,874,592 6,534 7,390 64,801 13,200 249,600 3,533,067

Massachusetts 5,202,826 10,300 12,914 130,449 249,899 159,180 4,640,084

Michigan 4,826,722 12,746 12,269 97,711 130,537 283,846 4,289,613

Minnesota 1,400,744 10,862 7,501 300,404 148,200 0 933,777

Mississippi 424,022 31,538 0 49,302 0 0 343,182

Missouri 2,793,981 11,698 13,341 97,715 77,092 223,971 2,370,164

Montana 112,643 3,104 6,168 0 0 0 103,371

N. Mariana Islands 0 0 0 0 0 0 0

Navajo Nation 21,873 3,629 0 18,244 0 0 0

Nebraska 743,335 4,946 2,500 21,000 0 0 714,889

Nevada 1,908,764 6,832 237 0 56,000 0 1,845,695

New Hampshire 165,859 950 1,595 0 11,250 0 152,064

New Jersey 4,449,920 10,749 0 91,759 118,127 115,378 4,113,907

New Mexico 568,968 7,769 2,846 105,000 0 453,353 0

New York 12,173,772 8,634 35,158 248,594 225,437 1,682,822 9,973,127

North Carolina 3,220,020 15,311 26,493 111,438 311,061 108,666 2,647,052

North Dakota 92,952 1,099 1,254 0 90,599 0 0

Ohio 5,968,446 21,415 12,060 300,293 263,264 123,850 5,247,564

Oklahoma 1,432,777 6,402 25,003 15,435 128,486 0 1,257,451

Oregon 1,505,465 7,740 18,036 0 123,120 0 1,356,569

Pennsylvania 5,612,428 14,708 33,537 0 390,681 0 5,173,502

Puerto Rico 3,794,459 4,955 17,083 112,793 220,732 0 3,438,896

Rhode Island 613,600 355 0 0 61,709 0 551,536

South Carolina 1,604,882 8,549 10,201 53,122 181,122 0 1,351,888

South Dakota 152,210 811 3,162 0 20,237 0 128,000

Tennessee 2,104,138 8,587 31,013 66,568 371,290 687,096 939,584

Texas 14,372,970 60,963 89,693 228,445 691,230 1,253,442 12,049,197

Utah 1,362,703 8,500 9,345 24,000 160,956 0 1,159,902

Vermont 63,618 298 11,570 0 51,750 0 0

Virgin Islands 50 50 0 0 0 0 0

Virginia 3,377,005 3,451 21,232 0 143,889 0 3,208,433

Washington 2,706,556 15,667 6,360 404,649 93,417 374,556 1,811,906

West Virginia 434,635 424 26,216 0 78,231 0 329,764

Wisconsin 1,507,678 17,221 0 133,000 82,035 205,247 1,070,175

Wyoming 68,027 0 8,043 0 59,984 0 0

Tribes - Region 1 0 0 0 0 0 0 0

Tribes - Region 5 0 0 0 0 0 0 0

Tribes - Region 6 1,450 1,450 0 0 0 0 0

Tribes - Region 8 0 0 0 0 0 0 0

Tribes - Region 9 2,722 0 2,722 0 0 0 0

Total 157,219,620 548,364 660,557 6,584,184 7,444,830 17,269,919 124,711,765

1

 The UCMR data are not representative at the state-level.

Page 2 of 2
EPA-OGWDW

Appendix B. Summary of Systems and Population Served by State

Occurrence Data from the UCMR 2

Table B22. NDMA - UCMR 2 Screening Survey Data - Number of Systems and Population Served by State

State 1

Total 

Number of 

Samples

Total 

Number of 

Systems

Number of 

Small Systems 

(serving ≤10,000 

people): Ground 

Water

Number of 

Small Systems 

(serving ≤10,000 

people): 

Surface Water

Number of 

Large Systems 

(serving 10,001-

100,000 people): 

Ground Water

Number of 

Large Systems 

(serving 10,001-

100,000 people): 

Surface Water

Number of Very 

Large Systems 

(serving 

>100,000 

people): Ground 

Water

Number of Very 

Large Systems 

(serving 

>100,000 

people): 

Surface Water

Alabama 270 20 4 2 3 5 0 6

Alaska 97 9 1 7 0 0 0 1

American Samoa 0 0 0 0 0 0 0 0

Arizona 753 19 4 2 3 0 1 9

Arkansas 116 13 3 3 2 2 0 3

California 4,392 154 13 28 19 22 8 64

Colorado 319 26 3 9 1 3 0 10

Connecticut 165 12 3 1 1 2 0 5

Delaware 117 5 1 0 1 0 0 3

District of Columbia 8 1 0 0 0 0 0 1

Florida 793 79 11 1 31 1 23 12

Georgia 315 31 6 5 2 5 1 12

Guam 233 1 0 0 0 0 1 0

Hawaii 161 4 1 0 1 0 2 0

Idaho 109 9 3 3 2 0 0 1

Illinois 392 35 7 5 4 8 3 8

Indiana 203 21 5 2 5 2 1 6

Iowa 130 15 5 2 3 2 0 3

Kansas 140 16 3 5 1 1 0 6

Kentucky 156 17 0 4 0 8 1 4

Louisiana 302 22 8 2 3 2 3 4

Maine 39 6 2 2 0 1 0 1

Maryland 120 13 3 3 2 1 1 3

Massachusetts 220 24 4 2 4 5 1 8

Michigan 255 23 9 2 2 3 2 5

Minnesota 103 18 6 1 7 2 0 2

Mississippi 114 15 10 0 3 0 0 2

Missouri 167 20 6 4 3 2 1 4

Montana 48 7 2 4 0 0 0 1

N. Mariana Islands 0 0 0 0 0 0 0 0

Navajo Nation 30 3 2 0 1 0 0 0

Nebraska 71 7 3 1 1 0 0 2

Nevada 147 8 2 1 0 1 0 4

New Hampshire 31 6 3 1 0 1 0 1

New Jersey 375 26 6 0 4 4 1 11

New Mexico 132 8 3 2 2 0 1 0

New York 1,540 53 8 14 6 6 5 14

North Carolina 355 35 7 5 3 7 1 12

North Dakota 28 4 1 2 0 1 0 0

Ohio 297 36 7 5 7 6 1 10

Oklahoma 158 19 3 9 1 3 0 3

Oregon 147 17 3 6 0 3 0 5

Pennsylvania 656 51 10 14 0 9 0 18

Puerto Rico 569 27 2 10 2 5 0 8

Rhode Island 30 4 1 0 0 1 0 2

South Carolina 140 16 3 3 1 4 0 5

South Dakota 62 9 2 5 0 1 0 1

Tennessee 226 23 1 7 2 8 1 4

Texas 1,627 96 23 27 6 15 1 24

Utah 200 16 2 3 1 3 0 7

Vermont 36 5 1 3 0 1 0 0

Virgin Islands 4 1 1 0 0 0 0 0

Virginia 285 27 4 7 0 5 0 11

Washington 350 29 8 4 8 3 2 4

West Virginia 86 12 1 7 0 2 0 2

Wisconsin 214 17 8 0 3 2 1 3

Wyoming 33 4 0 3 0 1 0 0

Tribes - Region 1 0 0 0 0 0 0 0 0

Tribes - Region 5 0 0 0 0 0 0 0 0

Tribes - Region 6 8 2 2 0 0 0 0 0

Tribes - Region 8 0 0 0 0 0 0 0 0

Tribes - Region 9 24 2 0 2 0 0 0 0

Total 18,098 1,198 240 240 151 169 63 335

1

 The UCMR data are not representative at the state-level.

Page 1 of 2
EPA-OGWDW

Appendix B. Summary of Systems and Population Served by State

Occurrence Data from the UCMR 2

Table B22. NDMA - UCMR 2 Screening Survey Data - Number of Systems and Population Served by State

State 1

Total 

Population 

Served

Pop. Served by 

Small Systems 

(serving ≤10,000 

people): Ground 

Water

Pop. Served by 

Small Systems 

(serving ≤10,000 

people): 

Surface Water

Pop. Served by 

Large Systems 

(serving 10,001-

100,000 people): 

Ground Water

Pop. Served by 

Large Systems 

(serving 10,001-

100,000 people): 

Surface Water

Pop. Served by 

Very Large 

Systems (serving 

>100,000 people): 

Ground Water

Pop. Served by 

Very Large 

Systems (serving 

>100,000 people): 

Surface Water

Alabama 2,040,600 17,259 9,693 103,109 204,295 0 1,706,245

Alaska 143,305 90 8,049 0 0 0 135,166

American Samoa 0 0 0 0 0 0 0

Arizona 3,403,868 14,319 1,729 113,300 0 675,445 2,599,075

Arkansas 845,459 11,365 8,930 85,674 52,858 0 686,632

California 24,372,007 29,816 49,813 1,008,796 1,303,622 1,088,908 20,891,052

Colorado 3,219,993 8,226 15,710 31,000 128,361 0 3,036,696

Connecticut 1,497,295 1,004 6,620 17,500 94,362 0 1,377,809

Delaware 484,765 4,383 0 34,878 0 0 445,504

District of Columbia 783,055 0 0 0 0 0 783,055

Florida 11,889,692 31,802 7,075 1,732,771 31,152 7,266,168 2,820,724

Georgia 4,397,366 9,885 12,463 39,543 211,034 163,688 3,960,753

Guam 100,001 0 0 0 0 100,001 0

Hawaii 854,836 4,958 0 63,155 0 786,723 0

Idaho 280,917 5,329 1,237 88,351 0 0 186,000

Illinois 5,680,520 22,938 20,358 71,451 364,550 405,228 4,795,996

Indiana 2,277,440 14,331 9,489 216,877 70,123 113,400 1,853,220

Iowa 805,109 14,756 7,369 146,216 81,086 0 555,682

Kansas 1,331,673 6,004 14,995 41,348 11,025 0 1,258,301

Kentucky 1,962,150 0 17,056 0 258,661 85,697 1,600,737

Louisiana 2,049,851 22,928 7,429 115,495 69,144 663,655 1,171,200

Maine 132,909 724 7,600 0 11,025 0 113,560

Maryland 3,874,592 6,534 7,390 64,801 13,200 249,600 3,533,067

Massachusetts 5,202,826 10,300 12,914 130,449 249,899 159,180 4,640,084

Michigan 4,826,722 12,746 12,269 97,711 130,537 283,846 4,289,613

Minnesota 1,400,744 10,862 7,501 300,404 148,200 0 933,777

Mississippi 424,022 31,538 0 49,302 0 0 343,182

Missouri 2,793,981 11,698 13,341 97,715 77,092 223,971 2,370,164

Montana 112,643 3,104 6,168 0 0 0 103,371

N. Mariana Islands 0 0 0 0 0 0 0

Navajo Nation 21,873 3,629 0 18,244 0 0 0

Nebraska 743,335 4,946 2,500 21,000 0 0 714,889

Nevada 1,908,764 6,832 237 0 56,000 0 1,845,695

New Hampshire 165,859 950 1,595 0 11,250 0 152,064

New Jersey 4,449,920 10,749 0 91,759 118,127 115,378 4,113,907

New Mexico 568,968 7,769 2,846 105,000 0 453,353 0

New York 12,173,772 8,634 35,158 248,594 225,437 1,682,822 9,973,127

North Carolina 3,220,020 15,311 26,493 111,438 311,061 108,666 2,647,052

North Dakota 92,952 1,099 1,254 0 90,599 0 0

Ohio 5,968,446 21,415 12,060 300,293 263,264 123,850 5,247,564

Oklahoma 1,432,777 6,402 25,003 15,435 128,486 0 1,257,451

Oregon 1,505,465 7,740 18,036 0 123,120 0 1,356,569

Pennsylvania 5,612,428 14,708 33,537 0 390,681 0 5,173,502

Puerto Rico 3,794,459 4,955 17,083 112,793 220,732 0 3,438,896

Rhode Island 613,600 355 0 0 61,709 0 551,536

South Carolina 1,604,882 8,549 10,201 53,122 181,122 0 1,351,888

South Dakota 152,210 811 3,162 0 20,237 0 128,000

Tennessee 2,104,138 8,587 31,013 66,568 371,290 687,096 939,584

Texas 14,372,970 60,963 89,693 228,445 691,230 1,253,442 12,049,197

Utah 1,362,703 8,500 9,345 24,000 160,956 0 1,159,902

Vermont 63,618 298 11,570 0 51,750 0 0

Virgin Islands 50 50 0 0 0 0 0

Virginia 3,377,005 3,451 21,232 0 143,889 0 3,208,433

Washington 2,706,556 15,667 6,360 404,649 93,417 374,556 1,811,906

West Virginia 434,635 424 26,216 0 78,231 0 329,764

Wisconsin 1,507,678 17,221 0 133,000 82,035 205,247 1,070,175

Wyoming 68,027 0 8,043 0 59,984 0 0

Tribes - Region 1 0 0 0 0 0 0 0

Tribes - Region 5 0 0 0 0 0 0 0

Tribes - Region 6 1,450 1,450 0 0 0 0 0

Tribes - Region 8 0 0 0 0 0 0 0

Tribes - Region 9 2,722 0 2,722 0 0 0 0

Total 157,219,620 548,364 660,557 6,584,184 7,444,830 17,269,919 124,711,765

1

 The UCMR data are not representative at the state-level.

Page 2 of 2
EPA-OGWDW

Appendix B. Summary of Systems and Population Served by State

Occurrence Data from the UCMR 2

Table B23. NDPA - UCMR 2 Screening Survey Data - Number of Systems and Population Served by State

State 1

Total 

Number of 

Samples

Total 

Number of 

Systems

Number of 

Small Systems 

(serving ≤10,000 

people): Ground 

Water

Number of 

Small Systems 

(serving ≤10,000 

people): 

Surface Water

Number of 

Large Systems 

(serving 10,001-

100,000 people): 

Ground Water

Number of 

Large Systems 

(serving 10,001-

100,000 people): 

Surface Water

Number of Very 

Large Systems 

(serving 

>100,000 

people): Ground 

Water

Number of Very 

Large Systems 

(serving 

>100,000 

people): 

Surface Water

Alabama 270 20 4 2 3 5 0 6

Alaska 97 9 1 7 0 0 0 1

American Samoa 0 0 0 0 0 0 0 0

Arizona 753 19 4 2 3 0 1 9

Arkansas 116 13 3 3 2 2 0 3

California 4,394 154 13 28 19 22 8 64

Colorado 319 26 3 9 1 3 0 10

Connecticut 165 12 3 1 1 2 0 5

Delaware 117 5 1 0 1 0 0 3

District of Columbia 8 1 0 0 0 0 0 1

Florida 793 79 11 1 31 1 23 12

Georgia 315 31 6 5 2 5 1 12

Guam 233 1 0 0 0 0 1 0

Hawaii 161 4 1 0 1 0 2 0

Idaho 109 9 3 3 2 0 0 1

Illinois 392 35 7 5 4 8 3 8

Indiana 203 21 5 2 5 2 1 6

Iowa 130 15 5 2 3 2 0 3

Kansas 140 16 3 5 1 1 0 6

Kentucky 156 17 0 4 0 8 1 4

Louisiana 302 22 8 2 3 2 3 4

Maine 39 6 2 2 0 1 0 1

Maryland 120 13 3 3 2 1 1 3

Massachusetts 221 24 4 2 4 5 1 8

Michigan 255 23 9 2 2 3 2 5

Minnesota 103 18 6 1 7 2 0 2

Mississippi 114 15 10 0 3 0 0 2

Missouri 167 20 6 4 3 2 1 4

Montana 48 7 2 4 0 0 0 1

N. Mariana Islands 0 0 0 0 0 0 0 0

Navajo Nation 30 3 2 0 1 0 0 0

Nebraska 71 7 3 1 1 0 0 2

Nevada 147 8 2 1 0 1 0 4

New Hampshire 31 6 3 1 0 1 0 1

New Jersey 375 26 6 0 4 4 1 11

New Mexico 132 8 3 2 2 0 1 0

New York 1,540 53 8 14 6 6 5 14

North Carolina 355 35 7 5 3 7 1 12

North Dakota 28 4 1 2 0 1 0 0

Ohio 297 36 7 5 7 6 1 10

Oklahoma 158 19 3 9 1 3 0 3

Oregon 147 17 3 6 0 3 0 5

Pennsylvania 656 51 10 14 0 9 0 18

Puerto Rico 569 27 2 10 2 5 0 8

Rhode Island 30 4 1 0 0 1 0 2

South Carolina 140 16 3 3 1 4 0 5

South Dakota 62 9 2 5 0 1 0 1

Tennessee 226 23 1 7 2 8 1 4

Texas 1,633 96 23 27 6 15 1 24

Utah 200 16 2 3 1 3 0 7

Vermont 36 5 1 3 0 1 0 0

Virgin Islands 4 1 1 0 0 0 0 0

Virginia 285 27 4 7 0 5 0 11

Washington 350 29 8 4 8 3 2 4

West Virginia 86 12 1 7 0 2 0 2

Wisconsin 214 17 8 0 3 2 1 3

Wyoming 33 4 0 3 0 1 0 0

Tribes - Region 1 0 0 0 0 0 0 0 0

Tribes - Region 5 0 0 0 0 0 0 0 0

Tribes - Region 6 8 2 2 0 0 0 0 0

Tribes - Region 8 0 0 0 0 0 0 0 0

Tribes - Region 9 24 2 0 2 0 0 0 0

Total 18,107 1,198 240 240 151 169 63 335

1

 The UCMR data are not representative at the state-level.

Page 1 of 2
EPA-OGWDW

Appendix B. Summary of Systems and Population Served by State

Occurrence Data from the UCMR 2

Table B23. NDPA - UCMR 2 Screening Survey Data - Number of Systems and Population Served by State

State 1

Total 

Population 

Served

Pop. Served by 

Small Systems 

(serving ≤10,000 

people): Ground 

Water

Pop. Served by 

Small Systems 

(serving ≤10,000 

people): 

Surface Water

Pop. Served by 

Large Systems 

(serving 10,001-

100,000 people): 

Ground Water

Pop. Served by 

Large Systems 

(serving 10,001-

100,000 people): 

Surface Water

Pop. Served by 

Very Large 

Systems (serving 

>100,000 people): 

Ground Water

Pop. Served by 

Very Large 

Systems (serving 

>100,000 people): 

Surface Water

Alabama 2,040,600 17,259 9,693 103,109 204,295 0 1,706,245

Alaska 143,305 90 8,049 0 0 0 135,166

American Samoa 0 0 0 0 0 0 0

Arizona 3,403,868 14,319 1,729 113,300 0 675,445 2,599,075

Arkansas 845,459 11,365 8,930 85,674 52,858 0 686,632

California 24,372,007 29,816 49,813 1,008,796 1,303,622 1,088,908 20,891,052

Colorado 3,219,993 8,226 15,710 31,000 128,361 0 3,036,696

Connecticut 1,497,295 1,004 6,620 17,500 94,362 0 1,377,809

Delaware 484,765 4,383 0 34,878 0 0 445,504

District of Columbia 783,055 0 0 0 0 0 783,055

Florida 11,889,692 31,802 7,075 1,732,771 31,152 7,266,168 2,820,724

Georgia 4,397,366 9,885 12,463 39,543 211,034 163,688 3,960,753

Guam 100,001 0 0 0 0 100,001 0

Hawaii 854,836 4,958 0 63,155 0 786,723 0

Idaho 280,917 5,329 1,237 88,351 0 0 186,000

Illinois 5,680,520 22,938 20,358 71,451 364,550 405,228 4,795,996

Indiana 2,277,440 14,331 9,489 216,877 70,123 113,400 1,853,220

Iowa 805,109 14,756 7,369 146,216 81,086 0 555,682

Kansas 1,331,673 6,004 14,995 41,348 11,025 0 1,258,301

Kentucky 1,962,150 0 17,056 0 258,661 85,697 1,600,737

Louisiana 2,049,851 22,928 7,429 115,495 69,144 663,655 1,171,200

Maine 132,909 724 7,600 0 11,025 0 113,560

Maryland 3,874,592 6,534 7,390 64,801 13,200 249,600 3,533,067

Massachusetts 5,202,826 10,300 12,914 130,449 249,899 159,180 4,640,084

Michigan 4,826,722 12,746 12,269 97,711 130,537 283,846 4,289,613

Minnesota 1,400,744 10,862 7,501 300,404 148,200 0 933,777

Mississippi 424,022 31,538 0 49,302 0 0 343,182

Missouri 2,793,981 11,698 13,341 97,715 77,092 223,971 2,370,164

Montana 112,643 3,104 6,168 0 0 0 103,371

N. Mariana Islands 0 0 0 0 0 0 0

Navajo Nation 21,873 3,629 0 18,244 0 0 0

Nebraska 743,335 4,946 2,500 21,000 0 0 714,889

Nevada 1,908,764 6,832 237 0 56,000 0 1,845,695

New Hampshire 165,859 950 1,595 0 11,250 0 152,064

New Jersey 4,449,920 10,749 0 91,759 118,127 115,378 4,113,907

New Mexico 568,968 7,769 2,846 105,000 0 453,353 0

New York 12,173,772 8,634 35,158 248,594 225,437 1,682,822 9,973,127

North Carolina 3,220,020 15,311 26,493 111,438 311,061 108,666 2,647,052

North Dakota 92,952 1,099 1,254 0 90,599 0 0

Ohio 5,968,446 21,415 12,060 300,293 263,264 123,850 5,247,564

Oklahoma 1,432,777 6,402 25,003 15,435 128,486 0 1,257,451

Oregon 1,505,465 7,740 18,036 0 123,120 0 1,356,569

Pennsylvania 5,612,428 14,708 33,537 0 390,681 0 5,173,502

Puerto Rico 3,794,459 4,955 17,083 112,793 220,732 0 3,438,896

Rhode Island 613,600 355 0 0 61,709 0 551,536

South Carolina 1,604,882 8,549 10,201 53,122 181,122 0 1,351,888

South Dakota 152,210 811 3,162 0 20,237 0 128,000

Tennessee 2,104,138 8,587 31,013 66,568 371,290 687,096 939,584

Texas 14,372,970 60,963 89,693 228,445 691,230 1,253,442 12,049,197

Utah 1,362,703 8,500 9,345 24,000 160,956 0 1,159,902

Vermont 63,618 298 11,570 0 51,750 0 0

Virgin Islands 50 50 0 0 0 0 0

Virginia 3,377,005 3,451 21,232 0 143,889 0 3,208,433

Washington 2,706,556 15,667 6,360 404,649 93,417 374,556 1,811,906

West Virginia 434,635 424 26,216 0 78,231 0 329,764

Wisconsin 1,507,678 17,221 0 133,000 82,035 205,247 1,070,175

Wyoming 68,027 0 8,043 0 59,984 0 0

Tribes - Region 1 0 0 0 0 0 0 0

Tribes - Region 5 0 0 0 0 0 0 0

Tribes - Region 6 1,450 1,450 0 0 0 0 0

Tribes - Region 8 0 0 0 0 0 0 0

Tribes - Region 9 2,722 0 2,722 0 0 0 0

Total 157,219,620 548,364 660,557 6,584,184 7,444,830 17,269,919 124,711,765

1

 The UCMR data are not representative at the state-level.

Page 2 of 2
EPA-OGWDW

Appendix B. Summary of Systems and Population Served by State

Occurrence Data from the UCMR 2

Table B24. NMEA - UCMR 2 Screening Survey Data - Number of Systems and Population Served by State

State 1

Total 

Number of 

Samples

Total 

Number of 

Systems

Number of 

Small Systems 

(serving ≤10,000 

people): Ground 

Water

Number of 

Small Systems 

(serving ≤10,000 

people): 

Surface Water

Number of 

Large Systems 

(serving 10,001-

100,000 people): 

Ground Water

Number of 

Large Systems 

(serving 10,001-

100,000 people): 

Surface Water

Number of Very 

Large Systems 

(serving 

>100,000 

people): Ground 

Water

Number of Very 

Large Systems 

(serving 

>100,000 

people): 

Surface Water

Alabama 270 20 4 2 3 5 0 6

Alaska 97 9 1 7 0 0 0 1

American Samoa 0 0 0 0 0 0 0 0

Arizona 753 19 4 2 3 0 1 9

Arkansas 116 13 3 3 2 2 0 3

California 4,394 154 13 28 19 22 8 64

Colorado 319 26 3 9 1 3 0 10

Connecticut 165 12 3 1 1 2 0 5

Delaware 117 5 1 0 1 0 0 3

District of Columbia 8 1 0 0 0 0 0 1

Florida 793 79 11 1 31 1 23 12

Georgia 315 31 6 5 2 5 1 12

Guam 233 1 0 0 0 0 1 0

Hawaii 161 4 1 0 1 0 2 0

Idaho 109 9 3 3 2 0 0 1

Illinois 392 35 7 5 4 8 3 8

Indiana 203 21 5 2 5 2 1 6

Iowa 130 15 5 2 3 2 0 3

Kansas 140 16 3 5 1 1 0 6

Kentucky 156 17 0 4 0 8 1 4

Louisiana 302 22 8 2 3 2 3 4

Maine 39 6 2 2 0 1 0 1

Maryland 120 13 3 3 2 1 1 3

Massachusetts 221 24 4 2 4 5 1 8

Michigan 255 23 9 2 2 3 2 5

Minnesota 103 18 6 1 7 2 0 2

Mississippi 114 15 10 0 3 0 0 2

Missouri 167 20 6 4 3 2 1 4

Montana 48 7 2 4 0 0 0 1

N. Mariana Islands 0 0 0 0 0 0 0 0

Navajo Nation 30 3 2 0 1 0 0 0

Nebraska 71 7 3 1 1 0 0 2

Nevada 147 8 2 1 0 1 0 4

New Hampshire 31 6 3 1 0 1 0 1

New Jersey 375 26 6 0 4 4 1 11

New Mexico 132 8 3 2 2 0 1 0

New York 1,540 53 8 14 6 6 5 14

North Carolina 355 35 7 5 3 7 1 12

North Dakota 28 4 1 2 0 1 0 0

Ohio 297 36 7 5 7 6 1 10

Oklahoma 158 19 3 9 1 3 0 3

Oregon 147 17 3 6 0 3 0 5

Pennsylvania 656 51 10 14 0 9 0 18

Puerto Rico 569 27 2 10 2 5 0 8

Rhode Island 30 4 1 0 0 1 0 2

South Carolina 140 16 3 3 1 4 0 5

South Dakota 62 9 2 5 0 1 0 1

Tennessee 226 23 1 7 2 8 1 4

Texas 1,627 96 23 27 6 15 1 24

Utah 200 16 2 3 1 3 0 7

Vermont 36 5 1 3 0 1 0 0

Virgin Islands 4 1 1 0 0 0 0 0

Virginia 285 27 4 7 0 5 0 11

Washington 350 29 8 4 8 3 2 4

West Virginia 86 12 1 7 0 2 0 2

Wisconsin 214 17 8 0 3 2 1 3

Wyoming 33 4 0 3 0 1 0 0

Tribes - Region 1 0 0 0 0 0 0 0 0

Tribes - Region 5 0 0 0 0 0 0 0 0

Tribes - Region 6 8 2 2 0 0 0 0 0

Tribes - Region 8 0 0 0 0 0 0 0 0

Tribes - Region 9 24 2 0 2 0 0 0 0

Total 18,101 1,198 240 240 151 169 63 335

1

 The UCMR data are not representative at the state-level.

Page 1 of 2
EPA-OGWDW

Appendix B. Summary of Systems and Population Served by State

Occurrence Data from the UCMR 2

Table B24. NMEA - UCMR 2 Screening Survey Data - Number of Systems and Population Served by State

State 1

Total 

Population 

Served

Pop. Served by 

Small Systems 

(serving ≤10,000 

people): Ground 

Water

Pop. Served by 

Small Systems 

(serving ≤10,000 

people): 

Surface Water

Pop. Served by 

Large Systems 

(serving 10,001-

100,000 people): 

Ground Water

Pop. Served by 

Large Systems 

(serving 10,001-

100,000 people): 

Surface Water

Pop. Served by 

Very Large 

Systems (serving 

>100,000 people): 

Ground Water

Pop. Served by 

Very Large 

Systems (serving 

>100,000 people): 

Surface Water

Alabama 2,040,600 17,259 9,693 103,109 204,295 0 1,706,245

Alaska 143,305 90 8,049 0 0 0 135,166

American Samoa 0 0 0 0 0 0 0

Arizona 3,403,868 14,319 1,729 113,300 0 675,445 2,599,075

Arkansas 845,459 11,365 8,930 85,674 52,858 0 686,632

California 24,372,007 29,816 49,813 1,008,796 1,303,622 1,088,908 20,891,052

Colorado 3,219,993 8,226 15,710 31,000 128,361 0 3,036,696

Connecticut 1,497,295 1,004 6,620 17,500 94,362 0 1,377,809

Delaware 484,765 4,383 0 34,878 0 0 445,504

District of Columbia 783,055 0 0 0 0 0 783,055

Florida 11,889,692 31,802 7,075 1,732,771 31,152 7,266,168 2,820,724

Georgia 4,397,366 9,885 12,463 39,543 211,034 163,688 3,960,753

Guam 100,001 0 0 0 0 100,001 0

Hawaii 854,836 4,958 0 63,155 0 786,723 0

Idaho 280,917 5,329 1,237 88,351 0 0 186,000

Illinois 5,680,520 22,938 20,358 71,451 364,550 405,228 4,795,996

Indiana 2,277,440 14,331 9,489 216,877 70,123 113,400 1,853,220

Iowa 805,109 14,756 7,369 146,216 81,086 0 555,682

Kansas 1,331,673 6,004 14,995 41,348 11,025 0 1,258,301

Kentucky 1,962,150 0 17,056 0 258,661 85,697 1,600,737

Louisiana 2,049,851 22,928 7,429 115,495 69,144 663,655 1,171,200

Maine 132,909 724 7,600 0 11,025 0 113,560

Maryland 3,874,592 6,534 7,390 64,801 13,200 249,600 3,533,067

Massachusetts 5,202,826 10,300 12,914 130,449 249,899 159,180 4,640,084

Michigan 4,826,722 12,746 12,269 97,711 130,537 283,846 4,289,613

Minnesota 1,400,744 10,862 7,501 300,404 148,200 0 933,777

Mississippi 424,022 31,538 0 49,302 0 0 343,182

Missouri 2,793,981 11,698 13,341 97,715 77,092 223,971 2,370,164

Montana 112,643 3,104 6,168 0 0 0 103,371

N. Mariana Islands 0 0 0 0 0 0 0

Navajo Nation 21,873 3,629 0 18,244 0 0 0

Nebraska 743,335 4,946 2,500 21,000 0 0 714,889

Nevada 1,908,764 6,832 237 0 56,000 0 1,845,695

New Hampshire 165,859 950 1,595 0 11,250 0 152,064

New Jersey 4,449,920 10,749 0 91,759 118,127 115,378 4,113,907

New Mexico 568,968 7,769 2,846 105,000 0 453,353 0

New York 12,173,772 8,634 35,158 248,594 225,437 1,682,822 9,973,127

North Carolina 3,220,020 15,311 26,493 111,438 311,061 108,666 2,647,052

North Dakota 92,952 1,099 1,254 0 90,599 0 0

Ohio 5,968,446 21,415 12,060 300,293 263,264 123,850 5,247,564

Oklahoma 1,432,777 6,402 25,003 15,435 128,486 0 1,257,451

Oregon 1,505,465 7,740 18,036 0 123,120 0 1,356,569

Pennsylvania 5,612,428 14,708 33,537 0 390,681 0 5,173,502

Puerto Rico 3,794,459 4,955 17,083 112,793 220,732 0 3,438,896

Rhode Island 613,600 355 0 0 61,709 0 551,536

South Carolina 1,604,882 8,549 10,201 53,122 181,122 0 1,351,888

South Dakota 152,210 811 3,162 0 20,237 0 128,000

Tennessee 2,104,138 8,587 31,013 66,568 371,290 687,096 939,584

Texas 14,372,970 60,963 89,693 228,445 691,230 1,253,442 12,049,197

Utah 1,362,703 8,500 9,345 24,000 160,956 0 1,159,902

Vermont 63,618 298 11,570 0 51,750 0 0

Virgin Islands 50 50 0 0 0 0 0

Virginia 3,377,005 3,451 21,232 0 143,889 0 3,208,433

Washington 2,706,556 15,667 6,360 404,649 93,417 374,556 1,811,906

West Virginia 434,635 424 26,216 0 78,231 0 329,764

Wisconsin 1,507,678 17,221 0 133,000 82,035 205,247 1,070,175

Wyoming 68,027 0 8,043 0 59,984 0 0

Tribes - Region 1 0 0 0 0 0 0 0

Tribes - Region 5 0 0 0 0 0 0 0

Tribes - Region 6 1,450 1,450 0 0 0 0 0

Tribes - Region 8 0 0 0 0 0 0 0

Tribes - Region 9 2,722 0 2,722 0 0 0 0

Total 157,219,620 548,364 660,557 6,584,184 7,444,830 17,269,919 124,711,765

1

 The UCMR data are not representative at the state-level.

Page 2 of 2
EPA-OGWDW

Appendix B. Summary of Systems and Population Served by State

Occurrence Data from the UCMR 2

Table B25. NPYR - UCMR 2 Screening Survey Data - Number of Systems and Population Served by State

State 1

Total 

Number of 

Samples

Total 

Number of 

Systems

Number of 

Small Systems 

(serving ≤10,000 

people): Ground 

Water

Number of 

Small Systems 

(serving ≤10,000 

people): 

Surface Water

Number of 

Large Systems 

(serving 10,001-

100,000 people): 

Ground Water

Number of 

Large Systems 

(serving 10,001-

100,000 people): 

Surface Water

Number of Very 

Large Systems 

(serving 

>100,000 

people): Ground 

Water

Number of Very 

Large Systems 

(serving 

>100,000 

people): 

Surface Water

Alabama 270 20 4 2 3 5 0 6

Alaska 97 9 1 7 0 0 0 1

American Samoa 0 0 0 0 0 0 0 0

Arizona 753 19 4 2 3 0 1 9

Arkansas 116 13 3 3 2 2 0 3

California 4,394 154 13 28 19 22 8 64

Colorado 319 26 3 9 1 3 0 10

Connecticut 165 12 3 1 1 2 0 5

Delaware 117 5 1 0 1 0 0 3

District of Columbia 8 1 0 0 0 0 0 1

Florida 793 79 11 1 31 1 23 12

Georgia 315 31 6 5 2 5 1 12

Guam 233 1 0 0 0 0 1 0

Hawaii 161 4 1 0 1 0 2 0

Idaho 109 9 3 3 2 0 0 1

Illinois 392 35 7 5 4 8 3 8

Indiana 203 21 5 2 5 2 1 6

Iowa 130 15 5 2 3 2 0 3

Kansas 140 16 3 5 1 1 0 6

Kentucky 156 17 0 4 0 8 1 4

Louisiana 302 22 8 2 3 2 3 4

Maine 39 6 2 2 0 1 0 1

Maryland 120 13 3 3 2 1 1 3

Massachusetts 221 24 4 2 4 5 1 8

Michigan 255 23 9 2 2 3 2 5

Minnesota 103 18 6 1 7 2 0 2

Mississippi 114 15 10 0 3 0 0 2

Missouri 167 20 6 4 3 2 1 4

Montana 48 7 2 4 0 0 0 1

N. Mariana Islands 0 0 0 0 0 0 0 0

Navajo Nation 30 3 2 0 1 0 0 0

Nebraska 71 7 3 1 1 0 0 2

Nevada 147 8 2 1 0 1 0 4

New Hampshire 31 6 3 1 0 1 0 1

New Jersey 375 26 6 0 4 4 1 11

New Mexico 132 8 3 2 2 0 1 0

New York 1,540 53 8 14 6 6 5 14

North Carolina 355 35 7 5 3 7 1 12

North Dakota 28 4 1 2 0 1 0 0

Ohio 297 36 7 5 7 6 1 10

Oklahoma 158 19 3 9 1 3 0 3

Oregon 147 17 3 6 0 3 0 5

Pennsylvania 656 51 10 14 0 9 0 18

Puerto Rico 569 27 2 10 2 5 0 8

Rhode Island 30 4 1 0 0 1 0 2

South Carolina 140 16 3 3 1 4 0 5

South Dakota 62 9 2 5 0 1 0 1

Tennessee 226 23 1 7 2 8 1 4

Texas 1,627 96 23 27 6 15 1 24

Utah 200 16 2 3 1 3 0 7

Vermont 36 5 1 3 0 1 0 0

Virgin Islands 4 1 1 0 0 0 0 0

Virginia 285 27 4 7 0 5 0 11

Washington 350 29 8 4 8 3 2 4

West Virginia 86 12 1 7 0 2 0 2

Wisconsin 214 17 8 0 3 2 1 3

Wyoming 33 4 0 3 0 1 0 0

Tribes - Region 1 0 0 0 0 0 0 0 0

Tribes - Region 5 0 0 0 0 0 0 0 0

Tribes - Region 6 8 2 2 0 0 0 0 0

Tribes - Region 8 0 0 0 0 0 0 0 0

Tribes - Region 9 24 2 0 2 0 0 0 0

Total 18,101 1,198 240 240 151 169 63 335

1

 The UCMR data are not representative at the state-level.

Page 1 of 2
EPA-OGWDW

Appendix B. Summary of Systems and Population Served by State

Occurrence Data from the UCMR 2

Table B25. NPYR - UCMR 2 Screening Survey Data - Number of Systems and Population Served by State

State 1

Total 

Population 

Served

Pop. Served by 

Small Systems 

(serving ≤10,000 

people): Ground 

Water

Pop. Served by 

Small Systems 

(serving ≤10,000 

people): 

Surface Water

Pop. Served by 

Large Systems 

(serving 10,001-

100,000 people): 

Ground Water

Pop. Served by 

Large Systems 

(serving 10,001-

100,000 people): 

Surface Water

Pop. Served by 

Very Large 

Systems (serving 

>100,000 people): 

Ground Water

Pop. Served by 

Very Large 

Systems (serving 

>100,000 people): 

Surface Water

Alabama 2,040,600 17,259 9,693 103,109 204,295 0 1,706,245

Alaska 143,305 90 8,049 0 0 0 135,166

American Samoa 0 0 0 0 0 0 0

Arizona 3,403,868 14,319 1,729 113,300 0 675,445 2,599,075

Arkansas 845,459 11,365 8,930 85,674 52,858 0 686,632

California 24,372,007 29,816 49,813 1,008,796 1,303,622 1,088,908 20,891,052

Colorado 3,219,993 8,226 15,710 31,000 128,361 0 3,036,696

Connecticut 1,497,295 1,004 6,620 17,500 94,362 0 1,377,809

Delaware 484,765 4,383 0 34,878 0 0 445,504

District of Columbia 783,055 0 0 0 0 0 783,055

Florida 11,889,692 31,802 7,075 1,732,771 31,152 7,266,168 2,820,724

Georgia 4,397,366 9,885 12,463 39,543 211,034 163,688 3,960,753

Guam 100,001 0 0 0 0 100,001 0

Hawaii 854,836 4,958 0 63,155 0 786,723 0

Idaho 280,917 5,329 1,237 88,351 0 0 186,000

Illinois 5,680,520 22,938 20,358 71,451 364,550 405,228 4,795,996

Indiana 2,277,440 14,331 9,489 216,877 70,123 113,400 1,853,220

Iowa 805,109 14,756 7,369 146,216 81,086 0 555,682

Kansas 1,331,673 6,004 14,995 41,348 11,025 0 1,258,301

Kentucky 1,962,150 0 17,056 0 258,661 85,697 1,600,737

Louisiana 2,049,851 22,928 7,429 115,495 69,144 663,655 1,171,200

Maine 132,909 724 7,600 0 11,025 0 113,560

Maryland 3,874,592 6,534 7,390 64,801 13,200 249,600 3,533,067

Massachusetts 5,202,826 10,300 12,914 130,449 249,899 159,180 4,640,084

Michigan 4,826,722 12,746 12,269 97,711 130,537 283,846 4,289,613

Minnesota 1,400,744 10,862 7,501 300,404 148,200 0 933,777

Mississippi 424,022 31,538 0 49,302 0 0 343,182

Missouri 2,793,981 11,698 13,341 97,715 77,092 223,971 2,370,164

Montana 112,643 3,104 6,168 0 0 0 103,371

N. Mariana Islands 0 0 0 0 0 0 0

Navajo Nation 21,873 3,629 0 18,244 0 0 0

Nebraska 743,335 4,946 2,500 21,000 0 0 714,889

Nevada 1,908,764 6,832 237 0 56,000 0 1,845,695

New Hampshire 165,859 950 1,595 0 11,250 0 152,064

New Jersey 4,449,920 10,749 0 91,759 118,127 115,378 4,113,907

New Mexico 568,968 7,769 2,846 105,000 0 453,353 0

New York 12,173,772 8,634 35,158 248,594 225,437 1,682,822 9,973,127

North Carolina 3,220,020 15,311 26,493 111,438 311,061 108,666 2,647,052

North Dakota 92,952 1,099 1,254 0 90,599 0 0

Ohio 5,968,446 21,415 12,060 300,293 263,264 123,850 5,247,564

Oklahoma 1,432,777 6,402 25,003 15,435 128,486 0 1,257,451

Oregon 1,505,465 7,740 18,036 0 123,120 0 1,356,569

Pennsylvania 5,612,428 14,708 33,537 0 390,681 0 5,173,502

Puerto Rico 3,794,459 4,955 17,083 112,793 220,732 0 3,438,896

Rhode Island 613,600 355 0 0 61,709 0 551,536

South Carolina 1,604,882 8,549 10,201 53,122 181,122 0 1,351,888

South Dakota 152,210 811 3,162 0 20,237 0 128,000

Tennessee 2,104,138 8,587 31,013 66,568 371,290 687,096 939,584

Texas 14,372,970 60,963 89,693 228,445 691,230 1,253,442 12,049,197

Utah 1,362,703 8,500 9,345 24,000 160,956 0 1,159,902

Vermont 63,618 298 11,570 0 51,750 0 0

Virgin Islands 50 50 0 0 0 0 0

Virginia 3,377,005 3,451 21,232 0 143,889 0 3,208,433

Washington 2,706,556 15,667 6,360 404,649 93,417 374,556 1,811,906

West Virginia 434,635 424 26,216 0 78,231 0 329,764

Wisconsin 1,507,678 17,221 0 133,000 82,035 205,247 1,070,175

Wyoming 68,027 0 8,043 0 59,984 0 0

Tribes - Region 1 0 0 0 0 0 0 0

Tribes - Region 5 0 0 0 0 0 0 0

Tribes - Region 6 1,450 1,450 0 0 0 0 0

Tribes - Region 8 0 0 0 0 0 0 0

Tribes - Region 9 2,722 0 2,722 0 0 0 0

Total 157,219,620 548,364 660,557 6,584,184 7,444,830 17,269,919 124,711,765

1

 The UCMR data are not representative at the state-level.

Page 2 of 2
EPA-OGWDW Occurrence Data from the UCMR 2 

Appendix C

Table C1. RDX – Final UCMR 2 Assessment Monitoring Data – Summary of Samples and 

Detected Concentrations

Table C2. Terbufos Sulfone – Final UCMR 2 Assessment Monitoring Data – Summary of 

Samples and Detected Concentrations

Table C3. Acetochlor ESA – Final UCMR 2 Screening Survey Data – Summary of Samples and 

Detected Concentrations

Table C4. Alachlor ESA – Final UCMR 2 Screening Survey Data – Summary of Samples and 

Detected Concentrations

Table C5. Metolachlor – Final UCMR 2 Screening Survey Data – Summary of Samples and 

Detected Concentrations

Table C6. Metolachlor ESA – Final UCMR 2 Screening Survey Data – Summary of Samples and 

Detected Concentrations

Table C7. Metolachlor OA – Final UCMR 2 Screening Survey Data – Summary of Samples and 

Detected Concentrations

Table C8. NDBA – Final UCMR 2 Screening Survey Data – Summary of Samples and Detected 

Concentrations 

Table C9. NDEA – Final UCMR 2 Screening Survey Data – Summary of Samples and Detected 

Concentrations 

Table C10. NDMA – Final UCMR 2 Screening Survey Data – Summary of Samples and 

Detected Concentrations

Table C11. NMEA – Final UCMR 2 Screening Survey Data – Summary of Samples and 

Detected Concentrations

Table C12. NPYR – Final UCMR 2 Screening Survey Data – Summary of Samples and Detected 

Concentrations 
EPA-OGWDW

Appendix C. Summary of Samples (Relative to the HRL)

Occurrence Data from the UCMR 2

Table C1a. RDX – UCMR 2 Assessment Monitoring Data – Summary of Samples

Source Water Type Total Number 

of Samples

Samples with 

Detections: 

Number

Samples with 

Detections: 

Percent

Samples with 

Detections > 1⁄2 

HRL (10.5 

μg/L): Number

Samples with 

Detections > 1⁄2 

HRL (10.5 

μg/L): Percent

Samples with 

Detections > 

HRL (21 μg/L): 

Number

Samples with 

Detections > 

HRL (21 μg/L): 

Percent

Sample of Small Systems (serving ≤ 10,000 people)

Ground Water 2,332 0 0.00% 0 0.00% 0 0.00%

Surface Water 919 0 0.00% 0 0.00% 0 0.00%

All Small Systems 3,251 0 0.00% 0 0.00% 0 0.00%

Census of Large Systems (serving 10,001 - 100,000 people)

Ground Water 11,760 0 0.00% 0 0.00% 0 0.00%

Surface Water 10,327 4 0.04% 0 0.00% 0 0.00%

All Large Systems 22,087 4 0.02% 0 0.00% 0 0.00%

Census of Very Large Systems (serving > 100,000 people)

Ground Water 2,012 0 0.00% 0 0.00% 0 0.00%

Surface Water 4,800 0 0.00% 0 0.00% 0 0.00%

All Very Large Systems 6,812 0 0.00% 0 0.00% 0 0.00%

All Systems

All Water Systems 32,150 4 0.01% 0 0.00% 0 0.00%

Page 1 of 2
EPA-OGWDW

Appendix C. Summary of Samples (Relative to the HRL)

Occurrence Data from the UCMR 2

Table C1b. RDX – UCMR 2 Assessment Monitoring Data – Summary of Detected Concentrations

Source Water Type

Concentration 

Value of 

Detections (μg/L): 

Minimum

Concentration 

Value of 

Detections (μg/L): 

Median

Concentration 

Value of 

Detections (μg/L): 

90th Percentile

Concentration 

Value of 

Detections (μg/L): 

99th Percentile

Concentration 

Value of 

Detections (μg/L): 

Maximum

Sample of Small Systems (serving ≤ 10,000 people)

Ground Water ND ND ND ND ND

Surface Water ND ND ND ND ND

All Small Systems ND ND ND ND ND

Census of Large Systems (serving 10,001 - 100,000 people)

Ground Water ND ND ND ND ND

Surface Water 1 1.1 1.1 1.1 1.1

All Large Systems 1 1.1 1.1 1.1 1.1

Census of Very Large Systems (serving > 100,000 people)

Ground Water ND ND ND ND ND

Surface Water ND ND ND ND ND

All Very Large Systems ND ND ND ND ND

All Systems

All Water Systems 1 1.1 1.1 1.1 1.1

ND = No detection

Page 2 of 2
EPA-OGWDW

Appendix C. Summary of Samples (Relative to the HRL)

Occurrence Data from the UCMR 2

Table C2a. Terbufos Sulfone – UCMR 2 Assessment Monitoring Data – Summary of Samples

Source Water Type Total Number 

of Samples

Samples with 

Detections: 

Number

Samples with 

Detections: 

Percent

Samples with 

Detections > 1⁄2 

HRL (10.5 

μg/L): Number

Samples with 

Detections > 1⁄2 

HRL (10.5 

μg/L): Percent

Samples with 

Detections > 

HRL (21 μg/L): 

Number

Samples with 

Detections > 

HRL (21 μg/L): 

Percent

Sample of Small Systems (serving ≤ 10,000 people)

Ground Water 2,328 0 0.00% 0 0.00% 0 0.00%

Surface Water 920 0 0.00% 0 0.00% 0 0.00%

All Small Systems 3,248 0 0.00% 0 0.00% 0 0.00%

Census of Large Systems (serving 10,001 - 100,000 people)

Ground Water 11,760 1 0.01% 1 0.01% 1 0.01%

Surface Water 10,331 0 0.00% 0 0.00% 0 0.00%

All Large Systems 22,091 1 0.005% 1 0.005% 1 0.005%

Census of Very Large Systems (serving > 100,000 people)

Ground Water 2,014 0 0.00% 0 0.00% 0 0.00%

Surface Water 4,796 0 0.00% 0 0.00% 0 0.00%

All Very Large Systems 6,810 0 0.00% 0 0.00% 0 0.00%

All Systems

All Water Systems 32,149 1 0.003% 1 0.003% 1 0.003%

D = No detection

Page 1 of 2
EPA-OGWDW

Appendix C. Summary of Samples (Relative to the HRL)

Occurrence Data from the UCMR 2

Table C2b. Terbufos Sulfone – UCMR 2 Assessment Monitoring Data – Summary of Detected Concentrations

Source Water Type

Concentration 

Value of 

Detections (μg/L): 

Minimum

Concentration 

Value of 

Detections (μg/L): 

Median

Concentration 

Value of 

Detections (μg/L): 

90th Percentile

Concentration 

Value of 

Detections (μg/L): 

99th Percentile

Concentration 

Value of 

Detections (μg/L): 

Maximum

Sample of Small Systems (serving ≤ 10,000 people)

Ground Water ND ND ND ND ND

Surface Water ND ND ND ND ND

All Small Systems ND ND ND ND ND

Census of Large Systems (serving 10,001 - 100,000 people)

Ground Water 0.42 0.42 0.42 0.42 0.42

Surface Water ND ND ND ND ND

All Large Systems 0.42 0.42 0.42 0.42 0.42

Census of Very Large Systems (serving > 100,000 people)

Ground Water ND ND ND ND ND

Surface Water ND ND ND ND ND

All Very Large Systems ND ND ND ND ND

All Systems

All Water Systems 0.42 0.42 0.42 0.42 0.42

ND = No detection

Page 2 of 2
EPA-OGWDW

Appendix C. Summary of Samples (Relative to the HRL)

Occurrence Data from the UCMR 2

Table C3a. Acetochlor ESA – UCMR 2 Screening Survey Data – Summary of Samples

Source Water Type Total Number 

of Samples

Samples with 

Detections: 

Number

Samples with 

Detections: 

Percent

Samples with 

Detections > 1⁄2 

HRL (10.5 

μg/L): Number

Samples with 

Detections > 1⁄2 

HRL (10.5 

μg/L): Percent

Samples with 

Detections > 

HRL (21 μg/L): 

Number

Samples with 

Detections > 

HRL (21 μg/L): 

Percent

Sample of Small Systems (serving ≤ 10,000 people)

Ground Water 786 0 0.00% 0 0.00% 0 0.00%

Surface Water 1,035 1 0.10% 1 0.10% 1 0.10%

All Small Systems 1,821 1 0.05% 1 0.05% 1 0.05%

Sample of Large Systems (serving 10,001 - 100,000 people)

Ground Water 1,381 0 0.00% 0 0.00% 0 0.00%

Surface Water 1,170 0 0.00% 0 0.00% 0 0.00%

All Large Systems 2,551 0 0.00% 0 0.00% 0 0.00%

Census of Very Large Systems (serving > 100,000 people)

Ground Water 1,999 0 0.00% 0 0.00% 0 0.00%

Surface Water 4,786 1 0.02% 1 0.02% 1 0.02%

All Very Large Systems 6,785 1 0.01% 1 0.01% 1 0.01%

All Systems

All Water Systems 11,157 2 0.02% 2 0.02% 2 0.02%

Page 1 of 2
EPA-OGWDW

Appendix C. Summary of Samples (Relative to the HRL)

Occurrence Data from the UCMR 2

Table C3b. Acetochlor ESA – UCMR 2 Screening Survey Data – Summary of Detected Concentrations

Source Water Type

Concentration 

Value of 

Detections (μg/L): 

Minimum

Concentration 

Value of 

Detections (μg/L): 

Median

Concentration 

Value of 

Detections (μg/L): 

90th Percentile

Concentration 

Value of 

Detections (μg/L): 

99th Percentile

Concentration 

Value of 

Detections (μg/L): 

Maximum

Sample of Small Systems (serving ≤ 10,000 people)

Ground Water ND ND ND ND ND

Surface Water 1.10526 1.10526 1.10526 1.10526 1.10526

All Small Systems 1.10526 1.10526 1.10526 1.10526 1.10526

Sample of Large Systems (serving 10,001 - 100,000 people)

Ground Water ND ND ND ND ND

Surface Water ND ND ND ND ND

All Large Systems ND ND ND ND ND

Census of Very Large Systems (serving > 100,000 people)

Ground Water ND ND ND ND ND

Surface Water 1.2 1.2 1.2 1.2 1.2

All Very Large Systems 1.2 1.2 1.2 1.2 1.2

All Systems

All Water Systems 1.10526 1.15263 1.19053 1.19905 1.2

ND = No detection

Page 2 of 2
EPA-OGWDW

Appendix C. Summary of Samples (Relative to the HRL)

Occurrence Data from the UCMR 2

Table C4a. Alachlor ESA – UCMR 2 Screening Survey Data – Summary of Samples

Source Water Type Total Number 

of Samples

Samples with 

Detections: 

Number

Samples with 

Detections: 

Percent

Samples with 

Detections > 1⁄2 

HRL (10.5 

μg/L): Number

Samples with 

Detections > 1⁄2 

HRL (10.5 

μg/L): Percent

Samples with 

Detections > 

HRL (21 μg/L): 

Number

Samples with 

Detections > 

HRL (21 μg/L): 

Percent

Sample of Small Systems (serving ≤ 10,000 people)

Ground Water 786 0 0.00% 0 0.00% 0 0.00%

Surface Water 1,035 3 0.29% 3 0.29% 3 0.29%

All Small Systems 1,821 3 0.16% 3 0.16% 3 0.16%

Sample of Large Systems (serving 10,001 - 100,000 people)

Ground Water 1,381 1 0.07% 1 0.07% 1 0.07%

Surface Water 1,170 0 0.00% 0 0.00% 0 0.00%

All Large Systems 2,551 1 0.04% 1 0.04% 1 0.04%

Census of Very Large Systems (serving > 100,000 people)

Ground Water 1,999 0 0.00% 0 0.00% 0 0.00%

Surface Water 4,785 1 0.02% 1 0.02% 1 0.02%

All Very Large Systems 6,784 1 0.01% 1 0.01% 1 0.01%

All Systems

All Water Systems 11,156 5 0.04% 5 0.04% 5 0.04%

Page 1 of 2
EPA-OGWDW

Appendix C. Summary of Samples (Relative to the HRL)

Occurrence Data from the UCMR 2

Table C4b. Alachlor ESA – UCMR 2 Screening Survey Data – Summary of Detected Concentrations

Source Water Type

Concentration 

Value of 

Detections (μg/L): 

Minimum

Concentration 

Value of 

Detections (μg/L): 

Median

Concentration 

Value of 

Detections (μg/L): 

90th Percentile

Concentration 

Value of 

Detections (μg/L): 

99th Percentile

Concentration 

Value of 

Detections (μg/L): 

Maximum

Sample of Small Systems (serving ≤ 10,000 people)

Ground Water ND ND ND ND ND

Surface Water 1 1.2 1.2 1.2 1.2

All Small Systems 1 1.2 1.2 1.2 1.2

Sample of Large Systems (serving 10,001 - 100,000 people)

Ground Water 1.06364 1.06364 1.06364 1.06364 1.06364

Surface Water ND ND ND ND ND

All Large Systems 1.06364 1.06364 1.06364 1.06364 1.06364

Census of Very Large Systems (serving > 100,000 people)

Ground Water ND ND ND ND ND

Surface Water 1.3 1.3 1.3 1.3 1.3

All Very Large Systems 1.3 1.3 1.3 1.3 1.3

All Systems

All Water Systems 1 1.2 1.3 1.3 1.3

ND = No detection

Page 2 of 2
EPA-OGWDW

Appendix C. Summary of Samples (Relative to the HRL)

Occurrence Data from the UCMR 2

Table C5a. Metolachlor – UCMR 2 Screening Survey Data – Summary of Samples

Source Water Type Total Number 

of Samples

Samples with 

Detections: 

Number

Samples with 

Detections: 

Percent

Samples with 

Detections > 1⁄2 

HRL (10.5 

μg/L): Number

Samples with 

Detections > 1⁄2 

HRL (10.5 

μg/L): Percent

Samples with 

Detections > 

HRL (21 μg/L): 

Number

Samples with 

Detections > 

HRL (21 μg/L): 

Percent

Sample of Small Systems (serving ≤ 10,000 people)

Ground Water 788 0 0.00% 0 0.00% 0 0.00%

Surface Water 1,040 2 0.19% 0 0.00% 0 0.00%

All Small Systems 1,828 2 0.11% 0 0.00% 0 0.00%

Sample of Large Systems (serving 10,001 - 100,000 people)

Ground Water 1,392 0 0.00% 0 0.00% 0 0.00%

Surface Water 1,178 0 0.00% 0 0.00% 0 0.00%

All Large Systems 2,570 0 0.00% 0 0.00% 0 0.00%

Census of Very Large Systems (serving > 100,000 people)

Ground Water 2,010 0 0.00% 0 0.00% 0 0.00%

Surface Water 4,784 1 0.02% 0 0.00% 0 0.00%

All Very Large Systems 6,794 1 0.01% 0 0.00% 0 0.00%

All Systems

All Water Systems 11,192 3 0.03% 0 0.00% 0 0.00%

ND = No detection

Page 1 of 2
EPA-OGWDW

Appendix C. Summary of Samples (Relative to the HRL)

Occurrence Data from the UCMR 2

Table C5b. Metolachlor – UCMR 2 Screening Survey Data – Summary of Detected Concentrations

Source Water Type

Concentration 

Value of 

Detections (μg/L): 

Minimum

Concentration 

Value of 

Detections (μg/L): 

Median

Concentration 

Value of 

Detections (μg/L): 

90th Percentile

Concentration 

Value of 

Detections (μg/L): 

99th Percentile

Concentration 

Value of 

Detections (μg/L): 

Maximum

Sample of Small Systems (serving ≤ 10,000 people)

Ground Water ND ND ND ND ND

Surface Water 1.152 1.94218 2.57432 2.71655 2.73235

All Small Systems 1.152 1.94218 2.57432 2.71655 2.73235

Sample of Large Systems (serving 10,001 - 100,000 people)

Ground Water ND ND ND ND ND

Surface Water ND ND ND ND ND

All Large Systems ND ND ND ND ND

Census of Very Large Systems (serving > 100,000 people)

Ground Water ND ND ND ND ND

Surface Water 1.4 1.4 1.4 1.4 1.4

All Very Large Systems 1.4 1.4 1.4 1.4 1.4

All Systems

All Water Systems 1.152 1.4 2.46588 2.7057 2.73235

ND = No detection

Page 2 of 2
EPA-OGWDW

Appendix C. Summary of Samples (Relative to the HRL)

Occurrence Data from the UCMR 2

Table C6a. Metolachlor ESA – UCMR 2 Screening Survey Data – Summary of Samples

Source Water Type Total Number 

of Samples

Samples with 

Detections: 

Number

Samples with 

Detections: 

Percent

Samples with 

Detections > 1⁄2 

HRL (10.5 

μg/L): Number

Samples with 

Detections > 1⁄2 

HRL (10.5 

μg/L): Percent

Samples with 

Detections > 

HRL (21 μg/L): 

Number

Samples with 

Detections > 

HRL (21 μg/L): 

Percent

Sample of Small Systems (serving ≤ 10,000 people)

Ground Water 786 16 2.04% 0 0.00% 0 0.00%

Surface Water 1,035 5 0.48% 0 0.00% 0 0.00%

All Small Systems 1,821 21 1.15% 0 0.00% 0 0.00%

Sample of Large Systems (serving 10,001 - 100,000 people)

Ground Water 1,381 4 0.29% 0 0.00% 0 0.00%

Surface Water 1,170 8 0.68% 0 0.00% 0 0.00%

All Large Systems 2,551 12 0.47% 0 0.00% 0 0.00%

Census of Very Large Systems (serving > 100,000 people)

Ground Water 1,999 9 0.45% 0 0.00% 0 0.00%

Surface Water 4,786 10 0.21% 0 0.00% 0 0.00%

All Very Large Systems 6,785 19 0.28% 0 0.00% 0 0.00%

All Systems

All Water Systems 11,157 52 0.47% 0 0.00% 0 0.00%

Page 1 of 2
EPA-OGWDW

Appendix C. Summary of Samples (Relative to the HRL)

Occurrence Data from the UCMR 2

Table C6b. Metolachlor ESA – UCMR 2 Screening Survey Data – Summary of Detected Concentrations

Source Water Type

Concentration 

Value of 

Detections (μg/L): 

Minimum

Concentration 

Value of 

Detections (μg/L): 

Median

Concentration 

Value of 

Detections (μg/L): 

90th Percentile

Concentration 

Value of 

Detections (μg/L): 

99th Percentile

Concentration 

Value of 

Detections (μg/L): 

Maximum

Sample of Small Systems (serving ≤ 10,000 people)

Ground Water 1.16 1.95 2.71137 3.78137 3.95455

Surface Water 1.02381 1.11739 1.4 1.4 1.4

All Small Systems 1.02381 1.8375 2.62273 3.72364 3.95455

Sample of Large Systems (serving 10,001 - 100,000 people)

Ground Water 1.48261 1.87095 2.13864 2.20614 2.21364

Surface Water 1 1.1 1.3 1.3 1.3

All Large Systems 1 1.25 1.9451 2.18614 2.21364

Census of Very Large Systems (serving > 100,000 people)

Ground Water 1.03 1.168 3.024 3.296 3.326

Surface Water 1.1 1.2 2.0 2.2 2.2

All Very Large Systems 1.03 1.188 2.711 3.258 3.326

All Systems

All Water Systems 1 1.44131 2.61986 3.63399 3.95455

Page 2 of 2
EPA-OGWDW

Appendix C. Summary of Samples (Relative to the HRL)

Occurrence Data from the UCMR 2

Table C7a. Metolachlor OA – UCMR 2 Screening Survey Data – Summary of Samples

Source Water Type Total Number 

of Samples

Samples with 

Detections: 

Number

Samples with 

Detections: 

Percent

Samples with 

Detections > 1⁄2 

HRL (10.5 

μg/L): Number

Samples with 

Detections > 1⁄2 

HRL (10.5 

μg/L): Percent

Samples with 

Detections > 

HRL (21 μg/L): 

Number

Samples with 

Detections > 

HRL (21 μg/L): 

Percent

Sample of Small Systems (serving ≤ 10,000 people)

Ground Water 786 0 0.00% 0 0.00% 0 0.00%

Surface Water 1,035 0 0.00% 0 0.00% 0 0.00%

All Small Systems 1,821 0 0.00% 0 0.00% 0 0.00%

Sample of Large Systems (serving 10,001 - 100,000 people)

Ground Water 1,381 0 0.00% 0 0.00% 0 0.00%

Surface Water 1,170 0 0.00% 0 0.00% 0 0.00%

All Large Systems 2,551 0 0.00% 0 0.00% 0 0.00%

Census of Very Large Systems (serving > 100,000 people)

Ground Water 1,999 3 0.15% 0 0.00% 0 0.00%

Surface Water 4,786 0 0.00% 0 0.00% 0 0.00%

All Very Large Systems 6,785 3 0.04% 0 0.00% 0 0.00%

All Systems

All Water Systems 11,157 3 0.03% 0 0.00% 0 0.00%

Page 1 of 2
EPA-OGWDW

Appendix C. Summary of Samples (Relative to the HRL)

Occurrence Data from the UCMR 2

Table C7b. Metolachlor OA – UCMR 2 Screening Survey Data – Summary of Detected Concentrations

Source Water Type

Concentration 

Value of 

Detections (μg/L): 

Minimum

Concentration 

Value of 

Detections (μg/L): 

Median

Concentration 

Value of 

Detections (μg/L): 

90th Percentile

Concentration 

Value of 

Detections (μg/L): 

99th Percentile

Concentration 

Value of 

Detections (μg/L): 

Maximum

Sample of Small Systems (serving ≤ 10,000 people)

Ground Water ND ND ND ND ND

Surface Water ND ND ND ND ND

All Small Systems ND ND ND ND ND

Sample of Large Systems (serving 10,001 - 100,000 people)

Ground Water ND ND ND ND ND

Surface Water ND ND ND ND ND

All Large Systems ND ND ND ND ND

Census of Very Large Systems (serving > 100,000 people)

Ground Water 2.502 3.078 3.447 3.53 3.539

Surface Water ND ND ND ND ND

All Very Large Systems 2.502 3.078 3.447 3.53 3.539

All Systems

All Water Systems 2.502 3.078 3.447 3.53 3.539

ND = No detection

Page 2 of 2
EPA-OGWDW

Appendix C. Summary of Samples (Relative to the HRL)

Occurrence Data from the UCMR 2

Table C8a. NDBA – UCMR 2 Screening Survey Data – Summary of Samples

Source Water Type Total Number 

of Samples

Samples with 

Detections: 

Number

Samples with 

Detections: 

Percent

Samples with 

Detections > 1⁄2 

HRL (10.5 

μg/L): Number

Samples with 

Detections > 1⁄2 

HRL (10.5 

μg/L): Percent

Samples with 

Detections > 

HRL (21 μg/L): 

Number

Samples with 

Detections > 

HRL (21 μg/L): 

Percent

Sample of Large Systems (serving 10,001 - 100,000 people)

Ground Water 1,237 3 0.24% 1 0.08% 0 0.00%

Surface Water 1,996 0 0.00% 0 0.00% 0 0.00%

All Small Systems 3,233 3 0.09% 1 0.03% 0 0.00%

Sample of Large Systems (serving 10,001 - 100,000 people)

Ground Water 1,932 0 0.00% 0 0.00% 0 0.00%

Surface Water 2,091 0 0.00% 0 0.00% 0 0.00%

All Large Systems 4,023 0 0.00% 0 0.00% 0 0.00%

Census of Very Large Systems (serving > 100,000 people)

Ground Water 2,966 3 0.10% 0 0.00% 0 0.00%

Surface Water 7,879 3 0.04% 0 0.00% 0 0.00%

All Very Large Systems 10,845 6 0.06% 0 0.00% 0 0.00%

All Systems

All Water Systems 18,101 9 0.05% 1 0.01% 0 0.00%

ND = No detection

Page 1 of 2
EPA-OGWDW

Appendix C. Summary of Samples (Relative to the HRL)

Occurrence Data from the UCMR 2

Table C8b. NDBA – UCMR 2 Screening Survey Data – Summary of Detected Concentrations

Source Water Type

Concentration 

Value of 

Detections (μg/L): 

Minimum

Concentration 

Value of 

Detections (μg/L): 

Median

Concentration 

Value of 

Detections (μg/L): 

90th Percentile

Concentration 

Value of 

Detections (μg/L): 

99th Percentile

Concentration 

Value of 

Detections (μg/L): 

Maximum

Sample of Small Systems (serving ≤ 10,000 people)

Ground Water 0.004 0.00629 0.01775 0.02033 0.02062

Surface Water ND ND ND ND ND

All Small Systems 0.004 0.00629 0.01775 0.02033 0.02062

Sample of Large Systems (serving 10,001 - 100,000 people)

Ground Water ND ND ND ND ND

Surface Water ND ND ND ND ND

All Large Systems ND ND ND ND ND

Census of Very Large Systems (serving > 100,000 people)

Ground Water 0.00442 0.00666 0.00877 0.00925 0.0093

Surface Water 0.0048 0.0092 0.0098 0.01 0.01

All Very Large Systems 0.00442 0.00793 0.00965 0.00997 0.01

All Systems

All Water Systems 0.004 0.00666 0.01212 0.01977 0.02062

ND = No detection

Page 2 of 2
EPA-OGWDW

Appendix C. Summary of Samples (Relative to the HRL)

Occurrence Data from the UCMR 2

Table C9a. NDEA – UCMR 2 Screening Survey Data – Summary of Samples

Source Water Type Total Number 

of Samples

Samples with 

Detections: 

Number

Samples with 

Detections: 

Percent

Samples with 

Detections > 1⁄2 

HRL (10.5 

μg/L): Number

Samples with 

Detections > 1⁄2 

HRL (10.5 

μg/L): Percent

Samples with 

Detections > 

HRL (21 μg/L): 

Number

Samples with 

Detections > 

HRL (21 μg/L): 

Percent

Sample of Small Systems (serving ≤ 10,000 people)

Ground Water 1,237 1 0.08% 1 0.08% 1 0.08%

Surface Water 1,996 0 0.00% 0 0.00% 0 0.00%

All Small Systems 3,233 1 0.03% 1 0.03% 1 0.03%

Sample of Large Systems (serving 10,001 - 100,000 people)

Ground Water 1,920 3 0.16% 3 0.16% 3 0.16%

Surface Water 2,091 6 0.29% 6 0.29% 6 0.29%

All Large Systems 4,011 9 0.22% 9 0.22% 9 0.22%

Census of Very Large Systems (serving > 100,000 people)

Ground Water 2,968 7 0.24% 7 0.24% 7 0.24%

Surface Water 7,884 29 0.37% 29 0.37% 29 0.37%

All Very Large Systems 10,852 36 0.33% 36 0.33% 36 0.33%

All Systems

All Water Systems 18,096 46 0.25% 46 0.25% 46 0.25%

ND = No detection

Page 1 of 2
EPA-OGWDW

Appendix C. Summary of Samples (Relative to the HRL)

Occurrence Data from the UCMR 2

Table C9b. NDEA – UCMR 2 Screening Survey Data – Summary of Detected Concentrations

Source Water Type

Concentration 

Value of 

Detections (μg/L): 

Minimum

Concentration 

Value of 

Detections (μg/L): 

Median

Concentration 

Value of 

Detections (μg/L): 

90th Percentile

Concentration 

Value of 

Detections (μg/L): 

99th Percentile

Concentration 

Value of 

Detections (μg/L): 

Maximum

Sample of Small Systems (serving ≤ 10,000 people)

Ground Water 0.009 0.009 0.009 0.009 0.009

Surface Water ND ND ND ND ND

All Small Systems 0.009 0.009 0.009 0.009 0.009

Sample of Large Systems (serving 10,001 - 100,000 people)

Ground Water 0.0051 0.0052 0.0061 0.0063 0.0063

Surface Water 0.0057 0.012 0.0435 0.0494 0.05

All Large Systems 0.0051 0.0086 0.0396 0.049 0.05

Census of Very Large Systems (serving > 100,000 people)

Ground Water 0.0053 0.0061 0.0126 0.0211 0.022

Surface Water 0.005 0.008 0.029 0.096 0.1

All Very Large Systems 0.005 0.007 0.027 0.095 0.1

All Systems

All Water Systems 0.005 0.007 0.031 0.093 0.1

ND = No detection

Page 2 of 2
EPA-OGWDW

Appendix C. Summary of Samples (Relative to the HRL)

Occurrence Data from the UCMR 2

Table C10a. NDMA – UCMR 2 Screening Survey Data – Summary of Samples

Source Water Type Total Number 

of Samples

Samples with 

Detections: 

Number

Samples with 

Detections: 

Percent

Samples with 

Detections > 1⁄2 

HRL (10.5 

μg/L): Number

Samples with 

Detections > 1⁄2 

HRL (10.5 

μg/L): Percent

Samples with 

Detections > 

HRL (21 μg/L): 

Number

Samples with 

Detections > 

HRL (21 μg/L): 

Percent

Sample of Small Systems (serving ≤ 10,000 people)

Ground Water 1,237 14 1.13% 14 1.13% 14 1.13%

Surface Water 1,996 326 16.33% 326 16.33% 326 16.33%

All Small Systems 3,233 340 10.52% 340 10.52% 340 10.52%

Sample of Large Systems (serving 10,001 - 100,000 people)

Ground Water 1,932 48 2.48% 48 2.48% 48 2.48%

Surface Water 2,091 305 14.59% 305 14.59% 305 14.59%

All Large Systems 4,023 353 8.77% 353 8.77% 353 8.77%

Census of Very Large Systems (serving > 100,000 people)

Ground Water 2,966 52 1.75% 52 1.75% 52 1.75%

Surface Water 7,876 1,116 14.17% 1,116 14.17% 1,116 14.17%

All Very Large Systems 10,842 1,168 10.77% 1,168 10.77% 1,168 10.77%

All Systems

All Water Systems 18,098 1,861 10.28% 1,861 10.28% 1,861 10.28%

Page 1 of 2
EPA-OGWDW

Appendix C. Summary of Samples (Relative to the HRL)

Occurrence Data from the UCMR 2

Table C10b. NDMA – UCMR 2 Screening Survey Data – Summary of Detected Concentrations

Source Water Type

Concentration 

Value of 

Detections (μg/L): 

Minimum

Concentration 

Value of 

Detections (μg/L): 

Median

Concentration 

Value of 

Detections (μg/L): 

90th Percentile

Concentration 

Value of 

Detections (μg/L): 

99th Percentile

Concentration 

Value of 

Detections (μg/L): 

Maximum

Sample of Small Systems (serving ≤ 10,000 people)

Ground Water 0.002 0.0036 0.0075 0.0092 0.0094

Surface Water 0.002 0.006 0.032 0.125 0.63

All Small Systems 0.002 0.006 0.031 0.122 0.63

Sample of Large Systems (serving 10,001 - 100,000 people)

Ground Water 0.002 0.004 0.005 0.01 0.01

Surface Water 0.002 0.0045 0.016 0.0523 0.0656

All Large Systems 0.002 0.0041 0.0152 0.0477 0.0656

Census of Very Large Systems (serving > 100,000 people)

Ground Water 0.002 0.00297 0.00522 0.01073 0.01343

Surface Water 0.002 0.004 0.015 0.043 0.094

All Very Large Systems 0.002 0.004 0.014 0.042 0.094

All Systems

All Water Systems 0.002 0.004 0.016 0.063 0.63

Page 2 of 2
EPA-OGWDW

Appendix C. Summary of Samples (Relative to the HRL)

Occurrence Data from the UCMR 2

Table C11a. NMEA – UCMR 2 Screening Survey Data – Summary of Samples

Source Water Type Total Number 

of Samples

Samples with 

Detections: 

Number

Samples with 

Detections: 

Percent

Samples with 

Detections > 1⁄2 

HRL (10.5 

μg/L): Number

Samples with 

Detections > 1⁄2 

HRL (10.5 

μg/L): Percent

Samples with 

Detections > 

HRL (21 μg/L): 

Number

Samples with 

Detections > 

HRL (21 μg/L): 

Percent

Sample of Small Systems (serving ≤ 10,000 people)

Ground Water 1,237 0 0.00% 0 0.00% 0 0.00%

Surface Water 1,996 3 0.15% 3 0.15% 3 0.15%

All Small Systems 3,233 3 0.09% 3 0.09% 3 0.09%

Sample of Large Systems (serving 10,001 - 100,000 people)

Ground Water 1,932 0 0.00% 0 0.00% 0 0.00%

Surface Water 2,091 0 0.00% 0 0.00% 0 0.00%

All Large Systems 4,023 0 0.00% 0 0.00% 0 0.00%

Census of Very Large Systems (serving > 100,000 people)

Ground Water 2,966 0 0.00% 0 0.00% 0 0.00%

Surface Water 7,879 0 0.00% 0 0.00% 0 0.00%

All Very Large Systems 10,845 0 0.00% 0 0.00% 0 0.00%

All Systems

All Water Systems 18,101 3 0.02% 3 0.02% 3 0.02%

ND = No detection

Page 1 of 2
EPA-OGWDW

Appendix C. Summary of Samples (Relative to the HRL)

Occurrence Data from the UCMR 2

Table C11b. NMEA – UCMR 2 Screening Survey Data – Summary of Detected Concentrations

Source Water Type

Concentration 

Value of 

Detections (μg/L): 

Minimum

Concentration 

Value of 

Detections (μg/L): 

Median

Concentration 

Value of 

Detections (μg/L): 

90th Percentile

Concentration 

Value of 

Detections (μg/L): 

99th Percentile

Concentration 

Value of 

Detections (μg/L): 

Maximum

Sample of Small Systems (serving ≤ 10,000 people)

Ground Water ND ND ND ND ND

Surface Water 0.0036 0.0045 0.0048 0.0049 0.0049

All Small Systems 0.0036 0.0045 0.0048 0.0049 0.0049

Sample of Large Systems (serving 10,001 - 100,000 people)

Ground Water ND ND ND ND ND

Surface Water ND ND ND ND ND

All Large Systems ND ND ND ND ND

Census of Very Large Systems (serving > 100,000 people)

Ground Water ND ND ND ND ND

Surface Water ND ND ND ND ND

All Very Large Systems ND ND ND ND ND

All Systems

All Water Systems 0.0036 0.0045 0.0048 0.0049 0.0049

ND = No detection

Page 2 of 2
EPA-OGWDW

Appendix C. Summary of Samples (Relative to the HRL)

Occurrence Data from the UCMR 2

Table C12a. NPYR – UCMR 2 Screening Survey Data – Summary of Samples

Source Water Type Total Number 

of Samples

Samples with 

Detections: 

Number

Samples with 

Detections: 

Percent

Samples with 

Detections > 1⁄2 

HRL (10.5 

μg/L): Number

Samples with 

Detections > 1⁄2 

HRL (10.5 

μg/L): Percent

Samples with 

Detections > 

HRL (21 μg/L): 

Number

Samples with 

Detections > 

HRL (21 μg/L): 

Percent

Sample of Small Systems (serving ≤ 10,000 people)

Ground Water 1,237 0 0.00% 0 0.00% 0 0.00%

Surface Water 1,996 11 0.55% 11 0.55% 11 0.55%

All Small Systems 3,233 11 0.34% 11 0.34% 11 0.34%

Sample of Large Systems (serving 10,001 - 100,000 people)

Ground Water 1,932 0 0.00% 0 0.00% 0 0.00%

Surface Water 2,091 7 0.33% 7 0.33% 7 0.33%

All Large Systems 4,023 7 0.17% 7 0.17% 7 0.17%

Census of Very Large Systems (serving > 100,000 people)

Ground Water 2,966 1 0.03% 1 0.03% 1 0.03%

Surface Water 7,879 22 0.28% 22 0.28% 22 0.28%

All Very Large Systems 10,845 23 0.21% 23 0.21% 23 0.21%

All Systems

All Water Systems 18,101 41 0.23% 41 0.23% 41 0.23%

ND = No detection

Page 1 of 2
EPA-OGWDW

Appendix C. Summary of Samples (Relative to the HRL)

Occurrence Data from the UCMR 2

Table C12b. NPYR – UCMR 2 Screening Survey Data – Summary of Detected Concentrations

Source Water Type

Concentration 

Value of 

Detections (μg/L): 

Minimum

Concentration 

Value of 

Detections (μg/L): 

Median

Concentration 

Value of 

Detections (μg/L): 

90th Percentile

Concentration 

Value of 

Detections (μg/L): 

99th Percentile

Concentration 

Value of 

Detections (μg/L): 

Maximum

Sample of Small Systems (serving ≤ 10,000 people)

Ground Water ND ND ND ND ND

Surface Water 0.00207 0.00284 0.005 0.00599 0.0061

All Small Systems 0.00207 0.00284 0.005 0.00599 0.0061

Sample of Large Systems (serving 10,001 - 100,000 people)

Ground Water ND ND ND ND ND

Surface Water 0.0022 0.0054 0.0078 0.0095 0.0097

All Large Systems 0.0022 0.0054 0.0078 0.0095 0.0097

Census of Very Large Systems (serving > 100,000 people)

Ground Water 0.0036 0.0036 0.0036 0.0036 0.0036

Surface Water 0.0021 0.0047 0.0137 0.0224 0.0238

All Very Large Systems 0.0021 0.0045 0.0130 0.0223 0.0238

All Systems

All Water Systems 0.00207 0.0039 0.0076 0.02116 0.0238

ND = No detection

Page 2 of 2