867
3,301 - 10,000
                                                                             99
                                                                             49
                                                                            148
10,001 - 50,000
                                                                             10
                                                                             10
                                                                             20
50,001 - 100,000
                                                                              1
                                                                              1
                                                                              2
100,001 - 1M
                                                                              0
                                                                              1
                                                                              1
> 1M
                                                                              0
                                                                              0
                                                                              0
TOTAL
                                                                         16,832
                                                                            757
                                                                         17,589
Sources: SDWIS/Fed third quarter 2016 "frozen" dataset that contains information reported through June 30, 2016. Includes all active NTNCWSs. See Section <IP_ADDRESS> for detail on system classification (system type, source water type, and population served using SDWIS). Additional information can be found in "NTNCWS Inventory Characteristics_Final Rule.xlsx," available in the docket at EPA-HQ-OW-2017-0300 at www.regulations.gov.
Notes:
A: Includes 15 NTNCWSs serving 3,300 or fewer people for which no primary source type was reported to SDWIS/Fed. These systems were assigned to the source water type of ground water or surface water based on the ratio of systems with known ground water to surface water source type for each size category. The majority of small NTNCWSs are ground water systems and based on these ratios, all 15 systems were assigned to the source type of ground water.
Discussion of Data Limitations and Uncertainty
As described in Section <IP_ADDRESS>.1, EPA periodically performs program reviews to verify inventory information in SDWIS/Fed. From 2006 to 2016, EPA identified only 82 individual discrepancies (<1 percent), although some discrepancies in the reviews conducted prior to August 2007 could be unrelated to the population, source type, or system type, such as contact information or address, based on a detailed review of 2,180 systems, indicating a high level of completeness and accuracy.
There is uncertainty in the approach used to assign source water type to PWSs where no primary source type was reported to SDWIS/Fed. EPA assumed that the systems with an unknown source would have the same proportion of ground water to surface water source types as the overall population of PWSs. This could result in an under or overestimate of costs in those instances where the cost model inputs vary by source type, e.g., number of entry points per system; however, EPA expects the impact to be low because systems with no source type in SDWIS/Fed represent a small proportion of systems subject to the rule (30 (0.06 percent) of the total 50,067 CWSs and 15 (0.09 percent) of the total 17,589 NTNCWSs or 0.07 percent of all systems subject to the rule) and all serve fewer than 10,000 people.
Population and Households Served
An accurate characterization of the populations served by water systems is necessary when assessing the potential benefits of the final regulation. Population served is also used to estimate volume of water treated and associated CCT costs.
SDWIS/Fed tracks "retail" population served, meaning that it counts only the population that purchase water directly from the water system and does not include the population of a water system that purchase water from another system. Consecutive water systems are recorded in SDWIS/Fed as a separate system with a unique PWSID number.
Exhibit 4-5 and Exhibit 4-6 show the total population served and average population served per system by size category for both CWSs and NTNCWSs, respectively. Each exhibit is organized by source water type (surface water or ground water) and is based on SDWIS/Fed third quarter 2016 "frozen" dataset that contains information reported by Primacy Agencies through June 30, 2016.
Because systems often pass their costs onto customers in the form of rate increases, the LCRR cost analysis also includes analyses to assess the impact of the requirements on a household level. The number of households served by CWSs expected to be subject to the final LCRR requirements is estimated by dividing the population for each system size category by the average number of people per household. For CWSs, EPA assumed an average of 2.59 persons per household based on 2010 United States Census data (United States Census Bureau, 2010). This information is also included in Exhibit 4-5 by system size and source type. NTNCWSs do not serve households and thus, this information is not included in Exhibit 4-6.
As shown in Exhibit 4-5, although CWSs serving 3,300 or fewer account more than 80 percent of all CWSs, they serve fewer than 8 percent of the population and households that receive their water from a CWS. On the other hand, although CWSs serving more than 50,000 people account for only 2 percent of all CWSs, they serve more than half (59 percent) of the population and households that receive their water from a CWS.
Exhibit 4-5: Population and Number of Households Served by CWSs
                        System Size
(Population Served)
                                 Ground Water
                                 Surface Water
                                    TOTAL*
               (includes 30 CWSs with unspecified primary source)

                               Population Served
                         Average Population Per System
                          Number of Households Served
                               Population Served
                         Average Population Per System
                          Number of Households Served
                               Population Served
                         Average Population Per System
                          Number of Households Served

                                       A
                                       B
                                  C = A/2.59
                                       D
                                       E
                                   F=D/2.59
                                     G=A+D
                                       H
                                   I=G/2.59
<=100
                                                                        672,437
                                                                             61
                                                                        259,628
                                                                         50,352
                                                                             52
                                                                         19,441
                                                                        723,487
                                                                             60
                                                                        279,339
101 - 500
                                                                      3,292,950
                                                                            249
                                                                      1,271,409
                                                                        589,004
                                                                            285
                                                                        227,415
                                                                      3,884,780
                                                                            254
                                                                      1,499,915
501 - 1,000
                                                                      3,127,989
                                                                            736
                                                                      1,207,718
                                                                        860,236
                                                                            751
                                                                        332,137
                                                                      3,989,089
                                                                            739
                                                                      1,540,189
1,001 - 3,300
                                                                     10,297,561
                                                                          1,860
                                                                      3,975,892
                                                                      5,013,869
                                                                          2,007
                                                                      1,935,857
                                                                     15,312,930
                                                                          1,906
                                                                      5,912,328
3,301 - 10,000
                                                                     15,692,304
                                                                          5,665
                                                                      6,058,805
                                                                     13,371,843
                                                                          6,070
                                                                      5,162,874
                                                                     29,070,747
                                                                          5,844
                                                                     11,224,227
10,001 - 50,000
                                                                     27,286,028
                                                                         20,593
                                                                     10,535,146
                                                                     45,584,177
                                                                         22,724
                                                                     17,600,068
                                                                     72,870,205
                                                                         21,876
                                                                     28,135,214
50,001 - 100,000
                                                                     10,347,353
                                                                         66,757
                                                                      3,995,117
                                                                     27,786,667
                                                                         70,346
                                                                     10,728,443
                                                                     38,134,020
                                                                         69,335
                                                                     14,723,560
100,001 - 1M
                                                                     13,159,351
                                                                        199,384
                                                                      5,080,831
                                                                     85,367,218
                                                                        250,344
                                                                     32,960,316
                                                                     98,526,569
                                                                        242,080
                                                                     38,041,146
> 1M
                                                                      3,400,000
                                                                      1,700,000
                                                                      1,312,741
                                                                     38,643,440
                                                                      2,033,865
                                                                     14,920,247
                                                                     42,043,440
                                                                      2,002,069
                                                                     16,232,988
TOTAL
                                                                     87,275,973
                                                                          2,273
                                                                     33,697,287
                                                                    218,366,806
                                                                         18,755
                                                                     84,311,508
                                                                    304,555,267
                                                                          6,083
                                                                    117,588,906
Sources: A, B, D, and E: SDWIS/Fed third quarter 2016 "frozen" dataset that contains information reported through June 30, 2016. See file "CWS Inventory Characteristics_Final Rule.xlsx," available in the docket at EPA-HQ-OW-2017-0300 at www.regulations.gov.
Notes:
B, E, and H: Derived by dividing the population served by the number of systems presented in Exhibit 4-3.
C, F, and I: The average of 2.59 persons per household is from 2010 Census data (Table AVG1. Average Number of People per Household, by Race and Hispanic Origin/1, Marital Status, Age, and Education of Householder: 2010).
G-I: CWSs with unreported primary source were not summarized individually, however they were included in the "TOTAL" columns. Thus, the "TOTAL" column reflects an additional 30 CWSs with unreported primary source type.

As previously discussed, NTNCWSs serving 3,300 or fewer account for more than 99 percent of all NTNCWSs. As shown in Exhibit 4-6, these systems serve approximately 75 percent of the population that receives their water from a NTNCWS. Those serving 3,301 to 50,000 people and more than 50,000 people serve approximately 20 percent and 5 percent of the population that receives water from a NTNCWS, respectively.
Exhibit 4-6: Population Served by NTNCWSs
                        System Size
(Population Served)
                                 Ground Water
                                 Surface Water
                                     TOTAL

                               Population Served
                         Average Population Per System
                               Population Served
                         Average Population Per System
                               Population Served
                         Average Population Per System

                                       A
                                       B
                                       D
                                       E
                                       F
                                       G
<=100
                                                                        457,766
                                                                             56
                                                                         12,897
                                                                             51
                                                                        471,225
                                                                             56
101 - 500
                                                                      1,565,659
                                                                            250
                                                                         66,071
                                                                            253
                                                                      1,632,090
                                                                            251
501 - 1,000
                                                                      1,096,208
                                                                            719
                                                                         61,883
                                                                            755
                                                                      1,158,991
                                                                            721
1,001 - 3,300
                                                                      1,283,281
                                                                          1,680
                                                                        194,520
                                                                          1,907
                                                                      1,479,801
                                                                          1,707
3,301 - 10,000
                                                                        527,174
                                                                          5,325
                                                                        284,306
                                                                          5,802
                                                                        811,480
                                                                          5,483
10,001 - 50,000
                                                                        206,735
                                                                         20,674
                                                                        236,482
                                                                         23,648
                                                                        443,217
                                                                         22,161
50,001 - 100,000
                                                                         50,807
                                                                         50,807
                                                                         71,963
                                                                         71,963
                                                                        122,770
                                                                         61,385
100,001 - 1M
                                                                              0
                                                                              0
                                                                        203,375
                                                                        203,375
                                                                        203,375
                                                                        203,375
> 1M
                                                                              0
                                                                              0
                                                                              0
                                                                              0
                                                                              0
                                                                              0
TOTAL
                                                                      5,187,630
                                                                            308
                                                                      1,131,497
                                                                          1,495
                                                                      6,322,949
                                                                            359
Sources: SDWIS/Fed third quarter 2016 "frozen" dataset that contains information reported through June 30, 2016. See file "NTNCWS Inventory Characteristics_Final Rule.xlsx," available in the docket at EPA-HQ-OW-2017-0300 at www.regulations.gov.
Notes:
B, E, and G: Derived by dividing the population served by the number of systems presented in Exhibit 4-4.
F and G: NTNCWSs with unreported primary source were not summarized individually, however they were included in the "TOTAL" columns. Thus, the "TOTAL" column reflects an additional 15 systems with unspecified primary source.
Discussion of Data Limitations and Uncertainty
As described in Section <IP_ADDRESS>.1 , EPA periodically performs Program Reviews to verify key parameters in SDWIS/Fed including, but not limited to, population served, system type, and source type (USEPA, 2007). From 2006 to 2016, EPA identified only 82 individual inventory discrepancies (<1 percent) based on a detailed review of 2,180 systems, although some discrepancies could be unrelated to the population, source type, or system type, such as contact information or address. The results of the Program Review indicate a high level of completeness and accuracy in the -SDWIS/Fed population data (USEPA, 2007).
As noted previously, EPA consistently classifies systems in SDWIS/Fed according to the retail population served by the system and does not include the population served by wholesale customers. Wholesale customers that purchase water from another system and meet the PWS definition have their own unique PWSID, retail population, and associated regulatory requirements under the SDWA. As described in Chapter 5, Section 5.3.3, EPA uses retail population to estimate design and average daily flow parameters, which are then used to estimate CCT costs associated with the rule. Use of retail population may overestimate costs by assuming that each PWSID will have an individual treatment plant instead of the more common scenario of the seller having one large plant and selling treated water to its wholesale customers.
Corrosion Control Treatment (CCT) Status
Under both the previous rule and the LCRR, systems with CCT in place have different requirements than those without this treatment. This section includes EPA's derivation of the number of CWSs and NTNCWSs with CCT. As noted in the introduction to Section 4.3, EPA used system-specific CCT information for systems serving greater than one million people where available.
To estimate the percent of CWSs and NTNCWSs with CCT, EPA used one approach for systems serving 50,000 or fewer people and a different approach for those systems serving more than 50,000 people. Both approaches rely on information reported to SDWIS/Fed but use different data fields and assumptions. Systems serving 50,000 or fewer are required under the previous rule to install CCT if they have a lead and/or copper ALE. As a first step, EPA identified CWSs and NTNCWSs for which the Primacy Agency reported a treatment objective of "C" to identify those with CCT. As noted in Section <IP_ADDRESS>, treatment code data in SDWIS/Fed is not part of the program review; thus, there is more uncertainty associated with these data as compared to SDWIS/Fed population and violation data. Therefore, to supplement the treatment code analysis, EPA reviewed milestone and violation data to identify additional CWSs that were required to install CCT as follows:
 The Primacy Agency reported a "DONE" or "DEEM" milestone with a reason code of "WQP." This indicates systems for which the Primacy Agency has set OWQPs, and thus would have CCT.
 The system was in violation for failure to install CCT (i.e., was assigned violation code 58) and subsequently addressed this violation. Systems with an addressed code 58 violation were identified by the enforcement code of "SOX" or "EOX" that denotes compliance achieved.
 The system has an OWQP (59) violation code. As noted above, OWQPs are set for systems with CCT.
 The system purchased water from another system that EPA has identified as having CCT.
CWSs and NTNCWSs serving more than 50,000 people were required under the previous rule to install CCT unless they: 1) had completed treatment steps that are equivalent to those described in the 1991 LCR prior to December 7, 1992 (i.e., meet the criteria of 40 CFR 141.81(b)(2)) or 2) could demonstrate they have very low levels of lead and copper in the distribution system (i.e., qualify as a "b3" systems)  Therefore, EPA classified all systems as having CCT except those identified as a b3 system. EPA used the following criteria to identify b3 systems:
 Had a reported "b3" milestone,
 Did not have CCT using the criteria described above for systems serving <= 50,000 people, and
 Did not have a lead or copper ALE from 1992 - 2015 and all reported lead 90[th] percentile levels are <= 5 ug/L or non-detect.
Only 11 CWSs were found to be b3 systems.
As shown in Exhibit 4-7, EPA estimated that overall, approximately 29 percent of all CWSs have CCT. The percentage of CWSs with CCT is higher in the larger size categories. Specifically, about 28 percent of CWSs serving 3,300 or fewer have CCT. Whereas, more than 55 percent of those serving 3,301 to 50,000 people and approximately 99 percent of those serving more than 50,000 people have CCT.
As shown in Exhibit 4-8, EPA estimated that overall, approximately 13 percent of all NTNCWSs have CCT. Approximately 13 percent of those serving 3,300 or fewer and 46 percent of those serving 3,301 to 50,000 people have CCT. No NTNCWS met the b3 criteria, thus EPA assumed all systems serving more than 50,000 people had CCT.
Exhibit 4-7: Number of CWSs with and without CCT
                        System Size
(Population Served)
                            Number of CWSs with CCT
                          Number of CWSs without CCT
                                     TOTAL

                                 Ground Water
                                 Surface Water
                                     Total
                                 Ground Water
                                 Surface Water
                                     Total

                                       A
                                       B
                                     C=A+B
                                       D
                                       E
                                     F=D+E
                                     G=C+F
<=100
                                                                            938
                                                                            435
                                                                          1,373
                                                                         10,142
                                                                            531
                                                                         10,673
                                                                         12,046
101 - 500
                                                                          1,954
                                                                            955
                                                                          2,909
                                                                         11,281
                                                                          1,117
                                                                         12,398
                                                                         15,307
501 - 1,000
                                                                          1,006
                                                                            591
                                                                          1,597
                                                                          3,244
                                                                            555
                                                                          3,799
                                                                          5,396
1,001 - 3,300
                                                                          1,597
                                                                          1,490
                                                                          3,087
                                                                          3,940
                                                                          1,008
                                                                          4,948
                                                                          8,035
3,301 - 10,000
                                                                            958
                                                                          1,537
                                                                          2,495
                                                                          1,813
                                                                            666
                                                                          2,479
                                                                          4,974
10,001 - 50,000
                                                                            577
                                                                          1,540
                                                                          2,117
                                                                            748
                                                                            466
                                                                          1,214
                                                                          3,331
50,001 - 100,000
                                                                            153
                                                                            389
                                                                            542
                                                                              2
                                                                              6
                                                                              8
                                                                            550
100,001 - 1M
                                                                             64
                                                                            340
                                                                            404
                                                                              2
                                                                              1
                                                                              3
                                                                            407
> 1 M
                                                                              2
                                                                             19
                                                                             21
                                                                              0
                                                                              0
                                                                              0
                                                                             21
TOTAL
                                                                          7,249
                                                                          7,296
                                                                         14,545
                                                                         31,172
                                                                          4,350
                                                                         35,522
                                                                         50,067
Source: SDWIS/Fed third quarter 2016 "frozen" dataset that contains information reported through June 30, 2016. See file, "CWS Inventory Characteristics_Final Rule.xlsx," available in the docket at EPA-HQ-OW-2017-0300 at www.regulations.gov.
Notes:
D & E: Includes 30 CWSs serving 10,000 or fewer people with no CCT for which no primary source type was reported to SDWIS/Fed. These systems were assigned to the source type of ground water or surface water based on the ratio of systems with known ground water to surface water source type for each size category. Based on this ratio, 27 systems were assigned to the source type of ground water and 3 to surface water. All CWSs identified as having CCT had a reported source type. Also see note in Exhibit 4-3 for an explanation of the difference in assignment of systems with unknown source status between the proposed and final LCRR.

Exhibit 4-8: Number of NTNCWS with and without CCT
                        System Size
(Population Served)
                          Number of NTNCWSs with CCT
                         Number of NTNCWSs without CCT
                                     TOTAL

                                 Ground Water
                                 Surface Water
                                     Total
                                 Ground Water
                                 Surface Water
                                     Total

                                       A
                                       B
                                     C=A+B
                                       D
                                       E
                                     F=D+E
                                     G=C+F
<=100
                                                                            693
                                                                            112
                                                                            805
                                                                          7,485
                                                                            139
                                                                          7,624
                                                                          8,429
101 - 500
                                                                            819
                                                                            109
                                                                            928
                                                                          5,434
                                                                            152
                                                                          5,586
                                                                          6,514
501 - 1,000
                                                                            267
                                                                             51
                                                                            318
                                                                          1,259
                                                                             31
                                                                          1,290
                                                                          1,608
1,001 - 3,300
                                                                            159
                                                                             71
                                                                            230
                                                                            606
                                                                             31
                                                                            637
                                                                            867
3,301 - 10,000
                                                                             25
                                                                             40
                                                                             65
                                                                             74
                                                                              9
                                                                             83
                                                                            148
10,001 - 50,000
                                                                              4
                                                                              9
                                                                             13
                                                                              6
                                                                              1
                                                                              7
                                                                             20
50,001 - 100,000
                                                                              1
                                                                              1
                                                                              2
                                                                              0
                                                                              0
                                                                              0
                                                                              2
100,001 - 1M
                                                                              0
                                                                              1
                                                                              1
                                                                              0
                                                                              0
                                                                              0
                                                                              1
> 1 M
                                                                              0
                                                                              0
                                                                              0
                                                                              0
                                                                              0
                                                                              0
                                                                              0
TOTAL
                                                                          1,968
                                                                            394
                                                                          2,362
                                                                         14,864
                                                                            363
                                                                         15,227
                                                                         17,589
Source: SDWIS/Fed third quarter 2016 "frozen" dataset that contains information reported through June 30, 2016. See file, "NTNCWS Inventory Characteristics_Final Rule.xlsx," available in the docket at EPA-HQ-OW-2017-0300 at www.regulations.gov.
Notes:
D: Includes 15 NTNCWSs serving 3,300 or fewer people with no CCT for which no primary source type was reported to SDWIS/Fed. These systems were assigned to the source type of ground water or surface water based on the ratio of systems with known ground water to surface water source type for each size category. The majority of small NTNCWSs are ground water systems and based on these ratios, all 15 systems were assigned to the source type of ground water. All NTNCWSs identified as having CCT had a reported source type.

Discussion of Data Limitations and Uncertainty
There is uncertainty in the estimated percent of CWSs and NTNCWSs with CCT. For systems serving more than 50,000 people, the assumptions are based on the previous rule requirements that all systems must install CCT unless they had installed it previously (i.e., as required in the 1991 rule) or have very low lead and copper levels, which signifies that they have naturally non-corrosive water (i.e., they are b3 systems). Therefore, the uncertainty in these estimates is not expected to have a significant impact on benefits and costs of the final LCRR. For systems serving 50,000 or fewer people, EPA recognizes greater uncertainty in using treatment objective code data from SDWIS/Fed to identify systems with CCT. Thus, EPA supplemented these data with milestone and violation information to identify those systems that would have been required to install CCT under the previous LCR. The remaining uncertainty in the percent of systems with CCT may result in an under or overestimate of costs and benefits of the final LCRR.
LSL Inventory and Duration of Mandatory Replacement
The number of LSLs in the United States is a key input to calculating costs and benefits of the final LCRR. When present, LSLs provide the largest physical source of lead in a water system (Sandvig et al., 2008). Systems with LSLs have unique requirements and different burden and costs compared to non-LSL systems under the previous rule and final LCRR. Removing LSLs can have public health benefits, especially when sensitive subpopulations are present.
Service lines are defined as the physical pipe that connects the water main, which is typically under a street, to a building (e.g., home or small office). LSLs are often 1-inch in diameter and almost all have a 2-inch diameter or smaller (LSLR Collaborative, 2018). The use of LSLs was federally prohibited under the SDWA in 1986, but many states and localities had introduced their own bans much earlier.
LSLs can be configured in many ways. The following definitions are used for the purposes of benefit and cost analyses in this document:
 Full LSL: The service line is lead from the water main to the home or building.
 System or Utility-owned LSL: The portion of the LSL owned by the water utility, which is usually from the water main to the property line, curb stop, or water meter if it is in the yard. The customer's portion may or may not be made of lead.
 Customer-owned LSL: The portion of the LSL from the property line (or curb stop or water meter) to the home or building. The utility's portion may or may not be made of lead.
 Gooseneck, pigtail, or connector: A short section of piping, typically not exceeding two feet, which can be bent and used for connections between rigid service piping. For the purposes of the rule, lead goosenecks, pigtails and connectors are not considered to be part of the LSL.
Sections <IP_ADDRESS> and <IP_ADDRESS> provide the following baseline characterization of LSLs for CWSs and NTNCWSs, respectively:
 Systems with LSLs, specifically the percent and number of systems with LSLs for each of the nine system size categories used in the EA.
 Number of LSLs for each of the nine system size categories, including:
 The total number of LSLs nationally,
 The average number of LSLs per system for systems with LSLs, and
 The average percent of service connections that are lead for systems with LSLs.
EPA provides the above information for two scenarios, low and high. Note that for the purposes of the baseline LSL inventory, EPA does not distinguish between the different LSL configurations. Systems are categorized as having LSLs if they have any locations with full, system (or utility)-side, or customer-side LSLs. Similarly, the estimated number of LSLs per system includes all types of LSLs (full, water system owned, customer owned). The cost and benefit analyses in this EA explain the assumptions related to the type of LSLs in water systems and discusses how these assumptions affect national costs and benefits estimates. Note that the LSL inventory presented in Sections <IP_ADDRESS> and <IP_ADDRESS> may underestimate the number of service lines requiring replacement because the final LCRR requires systems to replace galvanized service lines if they are or ever were previously downstream of an LSL.
Section <IP_ADDRESS> provides EPA's review of the duration of mandatory LSLR under the previous rule for CWSs and NTNCWSs.
LSL Inventory for CWSs
In previous economic analyses for lead and copper regulations, EPA used results from the 1998 LIS conducted by AWWA to develop the LSL inventory for CWSs (USEPA, 1991). Recently, a new estimate of LSLs was presented in Cornwell et al. (2016) based on AWWA surveys conducted in 2011 and 2013. EPA used both sources, combined with the SDWIS/Fed third quarter 2016 "frozen" dataset, to inform the LSL inventory estimates. This section describes the derivation of two key parameters related to the LSL inventory: 1) the percent of systems with LSLs, and 2) the percent of lead service connections within LSL systems.
EPA recognizes that the characterization of the national LSL inventory is uncertain and has a significant impact on estimated costs and benefits of the final LCRR. In order to capture the uncertainty associated with the national LSL inventory, EPA used the 1991 RIA (USEPA, 1991) to generate a "high" estimate (Section <IP_ADDRESS>.1), and Cornwell et al. (2016) to generate a "low" estimate (Section <IP_ADDRESS>.2) of the two LSL inventory parameters. As noted in the introduction to Section 4.3, EPA used system-specific LSL inventory data for systems serving greater than one million people where available.
Section <IP_ADDRESS>.3 provides a discussion of the data limitations and uncertainties.
LSL Inventory for CWSs based on 1988 AWWA LIS (1991 RIA, Adjusted)  -  HIGH ESTIMATE
EPA developed the high estimate of LSLs in CWSs using the results of the 1988 AWWA LIS, as presented in the 1991 RIA. See Section 4.2.4 for information on the survey method, response, and representativeness. As a starting point, Exhibit 4-9 shows the number and percent of systems with LSLs, and the number of LSLs per system and total LSLs as presented in the 1991 RIA for the LCR for 12 system size categories. Note that the number of systems in this analysis reflects 1986 SDWIS data and was adjusted to remove mobile home parks.
Exhibit 4-9: LSL Estimates from the 1991 RIA
                        System Size (Population Served)
                               Number of Systems
                          Number of Systems with LSLs
                         Percent of Systems with LSLs
                       Average Number of LSLs per System
                             Total Number of LSLs

                                       A
                                       B
                                    C = B/A
                                       D
                                    E = B*D
25-100
                                                                         18,753
                                                                          2,731
                                                                          14.6%
                                                                             26
                                                                        71,006
101-500
                                                                         18,016
                                                                          3,654
                                                                          20.3%
                                                                             89
                                                                       325,206
501-1000
                                                                          6,777
                                                                          2,624
                                                                          38.7%
                                                                            237
                                                                       621,888
1001-3300
                                                                          7,690
                                                                          2,984
                                                                          38.8%
                                                                            257
                                                                       766,888
3301-10K
                                                                          4,169
                                                                          1,751
                                                                          42.0%
                                                                            613
                                                                     1,073,363
10K - 25K
                                                                          1,737
                                                                            764
                                                                          44.0%
                                                                          1,099
                                                                       839,636
25K - 50K
                                                                            785
                                                                            346
                                                                          44.1%
                                                                          2,824
                                                                       977,104
50K - 75K
                                                                            300
                                                                            132
                                                                          44.0%
                                                                          3,028
                                                                       399,696
75K - 100K
                                                                            154
                                                                             68
                                                                          44.2%
                                                                          3,254
                                                                       221,272
100K - 500K
                                                                            255
                                                                            159
                                                                          62.4%
                                                                         12,433
                                                                     1,976,847
500K  -  1M
                                                                             50
                                                                             31
                                                                          62.0%
                                                                         25,869
                                                                       801,939
1M+
                                                                             17
                                                                             11
                                                                          64.7%
                                                                        200,000
                                                                     2,200,000
TOTAL
                                                                         58,703
                                                                         15,255
                                                                          26.0%

                                                                    10,274,845
Source: USEPA, 1991.
Notes:
A: Total non-purchased and purchased water CWSs except mobile home parks as presented in Column 1, Exhibit 4-6 of the 1991 RIA (USEPA, 1991).
B: Based on EPA analysis of 1988 AWWA LIS data, as presented in Column 2, Exhibit 4-6 of the 1991 RIA (USEPA, 1991).
D: Based on EPA analysis of 1988 AWWA LIS data, as presented in Column 4, Exhibit 4-6 of the 1991 RIA (USEPA, 1991).
Because the survey was done approximately 30 years ago, but after the use of LSLs was federally prohibited under the SDWA in 1986,the total number of LSLs and average number of LSLs per system were adjusted to account for LSLR since 1988. For the purposes of this analysis, EPA evaluated the potential impact of two types of LSLR: mandatory replacement under the previous LCR, and voluntary utility replacement programs, as described below.
 Mandatory Replacement under the Previous LCR: A system that exceeded the lead AL after installing CCT, would have begun LSLR at a rate of 7 percent of the number of LSLs at the time the replacement program begins, per year. The Primacy Agency could have required systems that did not install the required treatment to initiate LSLR and/or to replace LSLs at a faster replacement rate. Systems could have stopped LSLR after two six-month tap sampling periods at or below the lead AL (40 CFR 141.84(f)), but they would have recommenced replacement if they had a subsequent lead ALE. Systems could also "test out" an LSL if samples collected from the LSL did not exceed 15 ug/L; they could then consider the LSL replaced for purposes of meeting the 7 percent mandatory annual replacement rate. EPA reviewed SDWIS/Fed data to determine how many systems had an LSLR "milestone," indicating that a system must commence LSLR, from 1988 to 2016. EPA identified a total of 85 CWSs  that had this milestone over the 29-year period. Because this is a very small fraction of the total CWSs with LSLs, EPA considered it negligible for this analysis and did not adjust the number of LSLs to account for mandatory replacement.
 Utility Replacement Programs: As reported in the 1991 RIA (p. 4-28), the AWWA LIS found that approximately 1 percent of all LSLs were replaced each year as part of ongoing utility replacement programs. The RIA did not indicate if these replacements were water system-owned, customer-owned, or full replacements of the entire line. A survey conducted by Black & Veatch in 2004 provides insights into the proportion of each replacement type (Black & Veatch, 2004). Based on survey results from 41 systems that were undertaking LSLR independently of LCR requirements, approximately 72 percent were conducting partial LSLR and 28 percent were undertaking full LSLR. For more information on the survey, see AWWA (2005). Based on this information, EPA assumed that utilities replaced an average of approximately 1 percent of their LSLs each year, and that 28 percent of those are full LSLRs, so approximately 0.28 percent (1 percent x 28 percent) of LSLs are fully replaced each year.
EPA started with the total numbers of LSLs from the 1991 RIA as shown in Exhibit 4-9 and reduced them by 0.28 percent per year from 1988 through 2024 or 36 years, which is equivalent to a 10.080 percent total reduction (1 percent*28 percent*36). EPA is assuming that 10.08 percent of LSLs have been replaced since 1991. An accurate count of the number of systems that fully removed all LSLs is unavailable, so EPA made a conservative assumption leaving the percent of systems with LSLs unchanged from the 1991 RIA, presented in Exhibit 4-9 above.
In order to reflect system consolidation that has occurred since 1988, EPA made a second adjustment to the number of LSLs accounting for movement in LSLs from smaller to larger CWS size categories. EPA assumed that the number of LSLs that moved to higher categories as a result of system consolidation was proportionate to the number of systems that were lost from the system size category of 100 or fewer between 1991 and 2016. These LSLs were re-assigned equally to the largest four system size categories.
Exhibit 4-10 shows the percent and number of systems with LSLs based on the 1991 RIA using the results of the 1988 AWWA LIS survey but using 2016 SDWIS/Fed data, adjusted to account for infrastructure replacement and system consolidation. The total projected number of CWSs is estimated at approximately 14,000, and the total number of LSLs is projected to be approximately 9.3 million using this methodology. The corresponding SafeWater LCR model data variable used to estimate costs in Chapter 5 is provided in red italics.
In general, inputs into the SafeWater LCR model are assigned a data variable name. Where appropriate, EPA has included data variable names in the drinking water system baseline tables in this and subsequent sections, and identified them using red italic font.

Exhibit 4-10: LSL Inventory Based on 1988 AWWA LIS (1991 RIA, Adjusted)
                        System Size (Population Served)
             System Information based on SDWIS/Fed frozen database
                               Systems with LSLs
                           Number of LSLs (Adjusted)

                             Inventory of Systems
                         Total Number of Service Lines
                     Average Number of Connections/ System
                         Percent of systems with LSLs
                          Number of Systems with LSLs
                Number of LSLs from 1991 RIA (represents 1988)
                         Percent Replaced through 2024
                       Projected Number of LSLs in 2024
      LSLs Adjusted by Size Category to Account for System Consolidation
            Average Number of LSLs per System for Systems with LSLs
          Percent of Service Connections in LSL Systems that are LSLs

                                   perc_lsl

                                       A
                                       B
                                    C= B/A
                                       D
                                    E = A*D
                                       F
                                       G
                                  H = F*(1-G)
                                       I
                                   J = I / E
                                   K = J / C
<=100
                                                                         12,046
                                                                        324,257
                                                                             27
                                                                          14.6%
                                                                          1,754
                                                                         71,006
                                                                         10.08%
                                                                         63,849
                                                                         41,013
                                                                             23
                                                                         86.85%
101-500
                                                                         15,307
                                                                      1,616,382
                                                                            106
                                                                          20.3%
                                                                          3,105
                                                                        325,206
                                                                         10.08%
                                                                        292,425
                                                                        292,425
                                                                             94
                                                                         89.20%
501-1,000
                                                                          5,396
                                                                      1,626,622
                                                                            301
                                                                          38.7%
                                                                          2,089
                                                                        621,888
                                                                         10.08%
                                                                        559,202
                                                                        559,202
                                                                            268
                                                                         88.79%
1,001-3,300
                                                                          8,035
                                                                      6,041,868
                                                                            752
                                                                          38.8%
                                                                          3,118
                                                                        766,888
                                                                         10.08%
                                                                        689,586
                                                                        689,586
                                                                            221
                                                                         29.41%
3,301-10,000
                                                                          4,974
                                                                     10,941,012
                                                                          2,200
                                                                          42.0%
                                                                          2,089
                                                                      1,073,363
                                                                         10.08%
                                                                        965,168
                                                                        965,168
                                                                            462
                                                                         21.00%
10,001-50,000
                                                                          3,331
                                                                     26,156,505
                                                                          7,852
                                                                          44.0%
                                                                          1,466
                                                                      1,816,740
                                                                         10.08%
                                                                      1,633,613
                                                                      1,639,321
                                                                          1,118
                                                                         14.24%
50,001-100,000
                                                                            550
                                                                     12,744,116
                                                                         23,171
                                                                          44.1%
                                                                            242
                                                                        620,968
                                                                         10.08%
                                                                        558,374
                                                                        564,083
                                                                          2,328
                                                                         10.05%
100,001-1M
                                                                            407
                                                                     32,161,495
                                                                         79,021
                                                                          62.3%
                                                                            254
                                                                      2,778,786
                                                                         10.08%
                                                                      2,498,684
                                                                      2,504,393
                                                                          9,878
                                                                         12.50%
> 1M
                                                                             21
                                                                     12,681,341
                                                                        603,873
                                                                          64.7%
                                                                             14
                                                                      2,200,000
                                                                         10.08%
                                                                      1,978,240
                                                                      1,983,949
                                                                        146,005
                                                                         24.18%
TOTAL
                                                                         50,067
                                                                    104,293,598

                                                                         14,131
                                                                     10,274,845

                                                                      9,239,141
                                                                      9,239,141

Source: See "Derivation of LSL Number_CWS_Final Rule.xlsx" for detailed calculations, available in the docket at EPA-HQ-OW-2017-0300 at www.regulations.gov
Notes:
A: See Exhibit 4-3.
B: SDWIS/Fed third quarter 2016 "frozen" dataset, reported number of service connection for each system, summed by size category and divided by the total number of systems in the size category from column A. EPA adjusted SDWIS service connection data in two ways: 1) EPA changed the population served to a minimum number of 25 people, and 2) EPA identified systems where the population per connection ratio was less than 1 or greater than 5. In these cases, EPA changed the number of connections so that the population per connection was the same as the average population per connection value for the size category. See the file "Derivation of LSL Number_CWS_Final Rule.xlsx," worksheet "Systems" for detailed calculations.
D. Percent of Systems with LSLs from the 1991 RIA Exhibit 4-6, Column 2 divided by Column 1 and adjusted to the 9 standard size categories for the LCRR.
F. Number of LSLs for each size strata from the 1991 RIA, Column 2 multiplied by Column 4 and adjusted to the 9 standard size categories for the LCRR.
G: Assumes replacement rate of 1 percent per year, 28 percent of those are full replacements, for 36 years (1988 - 2024 when the LSL replacement requirement of the LCRR is anticipated to begin). This equals 1 percent x 28 percent x 36 years = 10.08 percent. Note that EPA updated this value from the proposed LCRR EA. The proposal version used 2023, or 35 years assuming rule promulgation in 2019. EPA updated to 2024 or 36 years to reflect a 2020 promulgation.
I: Adjustments to reflect system consolidation. EPA assumed that the number of LSLs that moved to higher categories as a result of consolidation was proportionate to the number of systems that were lost from the <= 100 system size category between 1991 and 2016. These LSLs were re-assigned equally to the largest four system size categories for systems serving above 10,000 people.
EPA's final step in developing this LSL inventory based on the 1991 RIA was to allocate the total number of systems with LSLs from Exhibit 4-10, Column E to the "with CCT" and "without CCT" categories. EPA made the following assumptions to estimate the percent of systems with LSLs according to CCT status for each of the nine system size categories as follows (assuming system with LSLs are more likely than non-LSL systems to have installed CCT):
 If more systems have CCT than LSLs, 100 percent of the LSL systems were assigned to the "with CCT" category, and zero systems were assigned to the "without CCT" category.
 If fewer systems have CCT than have LSLs, 100 percent of the "with CCT" systems were assumed to have LSLs, and the remaining LSL system were assigned to the "without CCT" category.
The resulting numbers and percent of systems with LSLs for the "with CCT" and "without CCT" categories are shown in Exhibit 4-11, columns E and G, respectively. The corresponding SafeWater LCR model data variable used to estimate costs in Chapter 5 is provided in red italics.

Exhibit 4-11: Estimated Systems with LSLs by CCT Status (1991 RIA: Adjusted)
                      Number of CWSs with and without CCT
Number and Percent with LSLs for CWSs with and without CCT based on Adjusted 1991 RIA Data
                        System Size (Population Served)
                            Total Systems with CCT
                           Total Systems without CCT
             Total Number of Systems with LSLs (based on 1991 RIA)
                                   with CCT
                                  without CCT

                               Number with LSLs
                               Percent with LSLs
                               Number with LSLs
                               Percent with LSLs

                                     p_lsl

                                     p_lsl

                                       A
                                       B
                                       C
                                       D
                                     E=D/A
                                       F
                                     G=F/B
<=100
                                                                          1,373
                                                                         10,673
                                                                          1,754
                                                                          1,373
                                                                           100%
                                                                            381
                                                                           3.6%
101-500
                                                                          2,909
                                                                         12,398
                                                                          3,105
                                                                          2,909
                                                                           100%
                                                                            196
                                                                           1.6%
501-1,000
                                                                          1,597
                                                                          3,799
                                                                          2,089
                                                                          1,597
                                                                           100%
                                                                            492
                                                                          13.0%
1,001-3,300
                                                                          3,087
                                                                          4,948
                                                                          3,118
                                                                          3,087
                                                                           100%
                                                                             31
                                                                           0.6%
3,301-10,000
                                                                          2,495
                                                                          2,479
                                                                          2,089
                                                                          2,089
                                                                            84%
                                                                              0
                                                                           0.0%
10,001-50,000
                                                                          2,117
                                                                          1,214
                                                                          1,466
                                                                          1,466
                                                                            69%
                                                                              0
                                                                           0.0%
50,001-100,000
                                                                            542
                                                                              8
                                                                            242
                                                                            242
                                                                            45%
                                                                              0
                                                                           0.0%
100,001-1M
                                                                            404
                                                                              3
                                                                            254
                                                                            254
                                                                            63%
                                                                              0
                                                                           0.0%
> 1M
                                                                             21
                                                                              0
                                                                             14
                                                                             14
                                                                            65%
                                                                              0
                                                                           0.0%
TOTAL
                                                                         14,545
                                                                         35,522
                                                                         14,131
                                                                         13,031
                                                                            90%
                                                                          1,100
                                                                           3.1%
Source: See "Derivation of LSL Number_CWS_Final Rule.xlsx" for detailed calculations, available in the docket at EPA-HQ-OW-2017-0300 at www.regulations.gov
Notes:
A, B: Exhibit 4-3.
C: Exhibit 4-10, Column E.
D, F: EPA assumed systems with LSLs are more likely to have CCT than systems without LSLs. Therefore, to create percent of systems with LSLs according to CCT status, EPA used the following approach for each of the nine system size categories:
  1. If more systems have LSLs than have CCT (i.e., C > A), assume 100 percent of systems with CCT are LSL systems and assign the remaining LSL systems to the "without CCT" category.
  2. If fewer systems have LSLs than have CCT (i.e., C < A), assign all of the LSL systems to the "with CCT" category and zero to the "without CCT" category.

LSL Inventory based on 2011 and 2013 AWWA Surveys (Cornwell et al., 2016)  -  LOW ESTIMATE
The AWWA journal article, "National Survey of Lead Service Line Occurrence" (Cornwell et al., 2016) provides a characterization of LSLs based on combined results of surveys conducted in 2011 and 2013 for 978 CWSs. Of these CWSs, 251 reported that they had LSLs, 578 reported that they did not have LSLs, and 149 had incomplete responses or reported that they were "not sure" if they had LSLs. For the 251 CWSs that reported that they had LSLs, 179 provided an estimate of the number of LSLs in their system. See Section 4.2.5 for more information on these surveys including data cleaning and representativeness.
The authors observed differences in the distribution of LSLs based on system size. Therefore, they grouped the data by the following three population size categories:
 Systems serving < 10,000 people.
 Systems serving 10,000 to 50,000 people.
 Systems serving > 50,000 people.
Cornwell et al. (2016) also evaluated the survey results for geographic differences. They initially grouped results by state, but this approach resulted in many bins having no survey responses. Thus, the authors sorted the data into 5 regional groups (representing one or more of EPA regions) each with 3 population categories, totaling 15 groups for analysis.
Cornwell et al. (2016) calculated the average percent of systems with LSLs and the average number of LSLs per population for the 15 size/regional groups as shown in Exhibit 4-12. The authors combined these results with 2015 SDWIS data to produce an estimate of the total number of LSLs in the United States, 6.1 million.
Exhibit 4-12: Percent of water systems with lead service lines and number of LSLs per 1,000 persons for systems with LSLs from Cornwell et al. (2016)
                        System Size (population served)
                                  EPA Region
                         Percent of systems with LSLs
        Average number of LSLs/1,000 people for those systems with LSLs

                                       A
                                       B
< 10,000
1 & 2
                                                                            26%
                                                                            4.3

3 & 4
                                                                            14%
                                                                           29.4

5 & 7
                                                                            36%
                                                                          102.5

6
                                                                            16%
                                                                           43.5

8, 9, & 10
                                                                            15%
                                                                           97.3
10,000 - 50,000
1 & 2
                                                                            57%
                                                                          138.9

3 & 4
                                                                            39%
                                                                           50.7

5 & 7
                                                                            56%
                                                                          103.6

6
                                                                            33%
                                                                          124.8

8, 9, & 10
                                                                             2%
                                                                            7.4
> 50,000
1 & 2
                                                                            89%
                                                                            6.9

3 & 4
                                                                            40%
                                                                           26.2

5 & 7
                                                                            87%
                                                                             86

6
                                                                            33%
                                                                            3.6

8, 9, & 10
                                                                            33%
                                                                            9.1
      Sources:
      A: "Best Estimate" from Cornwell et al. (2016). Table 1, 5th column.
      B: Cornwell et al. (2016). Table 3, 5th column.
Note that the percent of systems with LSLs shown in Exhibit 4-12 are the "best estimates" from the article, meaning that they only reflect "yes" and "no" responses. Cornwell et al. (2016) further utilized survey responses where systems reported "not sure" to the question of whether they had LSLs to provide a possible minimum and maximum. To calculate a possible minimum value, the authors assumed "not sure" was "no." To calculate a possible maximum value, they assumed that "not sure" was "yes." The final potential range of LSLs in the United States reported by Cornwell et al. using this method was 5.5 million to 7.1 million.
EPA used the same LSL occurrence factors (the "Best Estimate" values) from Cornwell et al. (2016) to estimate the baseline LSL inventory; however, EPA combined Cornwell's findings with 2016 instead of 2015 SDWIS/Fed inventory data for consistency with other cost and benefit analyses in this EA. Also, for systems serving greater than 1 million, EPA used available data to characterize LSLs for individual systems where possible.
Exhibit 4-13 shows the baseline inventory based on Cornwell et al. (2016) for the nine size categories used in this EA. The total projected number of CWSs in Column C is estimated at approximately 11,000 systems, which is lower than the approximately 14,000 CWSs based on the Adjusted 1991 RIA. The total number of LSLs using Cornwell et al. (2016) is projected to be approximately 6.3 million, which is also lower than the estimate based on the 1991 RIA of 9.3 million. The corresponding SafeWater LCR model data variable used to estimate costs in Chapter 5 is provided in red italics.

Exhibit 4-13: LSL Inventory Based on 2011 and 2013 AWWA Surveys (Cornwell et al. 2016)
                        System Size (Population Served)
                               Systems with LSLs
                      Number of LSLs in Systems with LSLs

                            Total Number of Systems
                         Percent of Systems with LSLs
                       Total Number of Systems with LSLs
                             Total Number of LSLs
              Average Number of LSLs/System for Systems with LSLs
                 Average Number of Service Connections per CWS
          Percent of Service Connections in LSL Systems that are LSLs

                                   perc_lsl

                                       A
                                       B
                                    C = A*B
                                       D
                                    E = D/C
                                       F
                                    G = E/F
<=100
                                                                         12,046
                                                                          20.2%
                                                                         2,430
                                                                          9,457
                                                                           3.9
                                                                             27
                                                                          14.5%
101-500
                                                                         15,307
                                                                          20.8%
                                                                         3,182
                                                                         55,740
                                                                          17.5
                                                                            106
                                                                          16.6%
501-1,000
                                                                          5,396
                                                                          22.1%
                                                                         1,193
                                                                         63,611
                                                                          53.3
                                                                            301
                                                                          17.7%
1,001-3,300
                                                                          8,035
                                                                          21.5%
                                                                         1,729
                                                                        222,650
                                                                         128.8
                                                                            752
                                                                          17.1%
3,301-10,000
                                                                          4,974
                                                                          20.9%
                                                                         1,041
                                                                        401,740
                                                                         386.1
                                                                          2,200
                                                                          17.6%
10,001-50,000
                                                                          3,331
                                                                          38.0%
                                                                         1,267
                                                                      2,695,576
                                                                       2,128.0
                                                                          7,852
                                                                          27.1%
50,001-100,000
                                                                            550
                                                                          52.1%
                                                                           287
                                                                        727,541
                                                                       2,538.5
                                                                         23,171
                                                                          11.0%
100,001-1M
                                                                            407
                                                                          48.7%
                                                                           198
                                                                      1,444,272
                                                                       7,291.0
                                                                         79,021
                                                                           9.2%
> 1M
                                                                             21
                                                                          55.6%
                                                                            12
                                                                        666,376
                                                                      57,052.7
                                                                        603,873
                                                                           9.4%
TOTAL
                                                                         50,067
                                                                          22.6%
                                                                        11,338
                                                                      6,286,963

Source: See "Derivation of LSL Number_CWS_Final Rule.xlsx," available in the docket at EPA-HQ-OW-2017-0300 at www.regulations.gov.
Notes:
A: SDWIS/Fed third quarter 2016 "frozen" dataset that contains information reported through June 30, 2016. See Exhibit 4-3.
B & D: Cornwell et al. (2016), combined data for all geographic regions. For systems serving > 1M, EPA used system-level data for LSL estimates when available. A summary of this information ("VLS system-provided data tables for appendix.xlsx") is available in the docket at EPA-HQ-OW-2017-0300 at www.regulations.gov.
F: SDWIS/Fed third quarter 2016 "frozen" dataset, reported number of service connection for each system, summed by size category and divided by the total number of systems in the size category from column A. EPA adjusted SDWIS service connection data in two ways: 1) EPA changed the population served to a minimum number of 25 people, and 2) EPA identified systems where the population per connection ratio was less than 1 or greater than 5. In these cases, EPA changed the number of connections so that the population per connection was the same as the average population per connection value for the size category.
Consistent with the adjustments done for the Adjusted 1991 RIA estimate, EPA's final step in developing the LSL inventory estimate using Cornwell et al. (2016) was to allocate the total number of systems with LSLs from Exhibit 4-13, Column C to the "with CCT" and "without CCT" categories. As noted earlier in this chapter, CCT was required by the previous rule for systems serving more than 50,000 people (with a few exceptions) and for some systems serving 50,000 or fewer people that continued to exceed the lead and/or copper AL. See Exhibit 4-7 for the estimates of the number and percent of systems with CCT based on SDWIS/Fed data. EPA assumed that many of the smaller systems that installed CCT in response to the previous rule were LSL systems because LSLs represent a large source of lead in the distribution system and have been found to cause elevated lead at customer's taps (Sandvig et al., 2008). Thus, EPA estimated the percent of systems with LSLs according to CCT status for each of the nine system size categories using the following approach:
 If more systems have CCT than LSLs, 100 percent of the LSL systems were assigned to the "with CCT" category, and zero LSL systems were assigned to the "without CCT" category.
 If fewer systems have CCT than have LSLs, 100 percent of the "with CCT" systems were assumed to have LSLs, and the remaining LSL system were assigned to the "without CCT" category.
The resulting numbers and percent of systems with LSLs for the "with CCT" and "without CCT" categories are shown in Exhibit 4-14, column E and G, respectively. The corresponding SafeWater LCR model data variable used to estimate costs in Chapter 5 is provided in red italics.

Exhibit 4-14: Estimated Systems with LSLs by CCT Status (Cornwell et al. 2016)
                      Number of CWSs with and without CCT
          Number and Percent with LSLs for CWSs with and without CCT
                         based on Cornwell et al. 2016
                        System Size (Population Served)
                                   with CCT
                                  without CCT
       Total Number of Systems with LSLs (based on Cornwell et al. 2016)
                                   with CCT
                                  without CCT

                               Number with LSLs
                               Percent with LSLs
                               Number with LSLs
                               Percent with LSLs

                                     p_lsl

                                     p_lsl

                                       A
                                       B
                                       C
                                       D
                                     E=D/A
                                       F
                                     G=F/B
<=100
                                                                          1,373
                                                                         10,673
                                                                          2,430
                                                                          1,373
                                                                           100%
                                                                          1,057
                                                                           9.9%
101-500
                                                                          2,909
                                                                         12,398
                                                                          3,182
                                                                          2,909
                                                                           100%
                                                                            273
                                                                           2.2%
501-1,000
                                                                          1,597
                                                                          3,799
                                                                          1,193
                                                                          1,193
                                                                            75%
                                                                              0
                                                                           0.0%
1,001-3,300
                                                                          3,087
                                                                          4,948
                                                                          1,729
                                                                          1,729
                                                                            56%
                                                                              0
                                                                           0.0%
3,301-10,000
                                                                          2,495
                                                                          2,479
                                                                          1,041
                                                                          1,041
                                                                            42%
                                                                              0
                                                                           0.0%
10,001-50,000
                                                                          2,117
                                                                          1,214
                                                                          1,267
                                                                          1,267
                                                                            60%
                                                                              0
                                                                           0.0%
50,001-100,000
                                                                            542
                                                                              8
                                                                            287
                                                                            287
                                                                            53%
                                                                              0
                                                                           0.0%
100,001-1M
                                                                            404
                                                                              3
                                                                            198
                                                                            198
                                                                            49%
                                                                              0
                                                                           0.0%
> 1M
                                                                             21
                                                                              0
                                                                             12
                                                                             12
                                                                            57%
                                                                              0
                                                                           0.0%
TOTAL
                                                                         14,545
                                                                         35,522
                                                                         11,338
                                                                         10,008

                                                                          1,330

  Notes:
  A & B: Exhibit 4-7.
  C: Exhibit 4-13, Column C.
  D & F: EPA assumed that systems with LSLs are more likely to have CCT than systems without LSLs. Therefore, to create percent of systems with LSLs according to CCT status, EPA used the following approach for each of the nine system size categories:
   1. If more systems have LSLs than have CCT (i.e., C > A), assume 100 percent of systems with CCT are LSL systems and assign the remaining LSL systems to the non-CCT category.
   2. If fewer systems have LSLs than have CCT (i.e., C < A), assign all of the LSL systems to the "with CCT" category and zero to the "without CCT" category.

Discussion of Data Limitations and Uncertainty
The estimated number of LSLs nationally is based on surveys of water systems extrapolated nationally. EPA presents two possible data sources for estimating the percent of systems with LSLs, and the percent of lead connections in LSL systems: the 1988 LIS as presented in the 1991 LCR RIA (USEPA, 1991), and the 2011 and 2013 AWWA surveys of LSL occurrence as presented in Cornwell et al. (2016). Both sources and associated surveys are described in Sections 4.2.4 and 4.2.5 above for the 1991 LCR RIA and Cornwell et al. (2016), respectively. The 1988 and 2011/2013 surveys did not attempt to gather data by systematically sampling systems from a robust sample framework that would allow for detailed estimates of LSLs based on an understanding of associated system characteristics. Both surveys had low response rates resulting in low numbers of responses compared to the universe of systems. Neither survey conducted non-response follow-up efforts to attempt to characterize the degree and direction of bias these low response rates might produce in the survey results. Due to the quality of the survey data, uncertainty around the estimates of the number of systems with LSLs and the number of lead connections in those systems is high. Also, there is additional uncertainty in the adjustments made to the 1988 LIS results to account for infrastructure replacements and system consolidation. EPA does not account for LSLR conducted as a result of systems exceeding the AL and being required to replace lines. EPA also makes no adjustments for LSLR occurring as part of voluntary programs. Both of these omissions would overestimate the number of LSLs requiring replacement.
EPA recognizes that uncertainty in the characterization of the national LSL inventory has a significant impact on estimated costs and benefits of the final LCRR. In order to reflect the uncertainty associated with this variable in estimated costs and benefits, EPA used the Cornwell et al. (2016) estimate as the low cost model input, and the adjusted 1991 RIA as the high cost model input for the percent of systems with LSLs and the percent of service connections that are lead within systems that are known to have LSLs. Also as previously discussed, the estimated LSL inventory may underestimate the number of LSLs requiring replacement because it may not adequately reflect the number of galvanized service lines if they are or were previously downstream of an LSL.
LSL Inventory for NTNCWSs
Information comparable to the CWS surveys described in Section <IP_ADDRESS> has not been collected on the occurrence of LSLs in NTNCWSs. In the 1991 RIA for the original LCR (USEPA, 1991), EPA assumed NTNCWSs did not have LSLs because they lack extensive distribution systems. However, there is now evidence that some NTNCWSs may have LSLs. For example, milestone information reported to SDWIS/Fed, as of June 30, 2016, indicates that 30 NTNCWSs were required to initiate LSLR.
This section outlines EPA's approach for estimating the number of NTNCWSs with LSLs (Section <IP_ADDRESS>.1) and number of LSLs (Section <IP_ADDRESS>.2). A discussion of data limitations and uncertainties is provided in Section <IP_ADDRESS>.3.
Number of NTNCWSs with LSLs
In 2017, EPA disseminated a questionnaire to nine states regarding the burden and cost associated with the National Drinking Water Advisory Council's (NDWAC's) recommendation to require all systems to develop a comprehensive LSL inventory and to expand the definition of an LSL to include lead connectors even if the service line is not made of lead. The questionnaire included questions on the estimated number or percentage of NTNCWSs with one or more LSLs and the total number of LSLs in NTNCWSs. States were selected for geographical diversity, known occurrence of LSLs in CWSs, and active LSLR projects. EPA received responses from seven states. Four states did not provide any estimate. The remaining three states provided estimates ranging from 0 to 5 percent. Exhibit 4-15 below provides a summary of the seven states' responses.
Exhibit 4-15: Summary of State Responses Regarding the Percentage of NTNCWSs with LSLs
                                   Response
                      Number of States with this Response
Unknown/Information not readily available
                                                                              3
Unknown but expected to be very low
                                                                              1
Unknown but expected to be 0
                                                                              1
Estimated to be 0  -  5 percent
                                                                              1
Estimated to be <5 percent (gross estimate)
                                                                              1
Estimated to be >=5 percent
                                                                              0
Total
                                                                              7
      Source: A copy of the questionnaire and each state's response is available in the docket at EPA-HQ-OW-2017-0300 at www.regulations.gov.
Due to the uncertainty of the responses and the respondents being in states with known LSLs in CWSs, EPA used the midpoint of the range reported by states to estimate the number of NTNCWSs that had LSLs. Specifically, EPA assumed 2.5 percent (corresponds to SafeWater LCR model data variable, p_lsl) or 440 NTNCWSs have LSLs. EPA further assumed that systems without CCT are less likely to have LSLs because they would have installed CCT if they had sustained lead ALEs. Thus, EPA assumed all 440 NTNCWSs with LSLs are those with CCT. Exhibit 4-16 indicates the estimated number and percent of NTNCWSs with LSLs for systems with and without CCT.
Exhibit 4-16: Estimated Number and Percentage of NTNCWSs with LSLs by CCT Status
                                  System Size

                        Number of NTNCWSs
by CCT Status
                   Estimated Number with LSLs
by CCT Status
                 Estimated Percentage with LSLs by CCT Status

                                   With CCT
                                    No CCT
                                     Total
                                   With CCT
                                    No CCT
                                   With CCT
                                    No CCT

                                       A
                                       B
                                    C = A+B
                                  D = C*0.025
                                     E = 0
                                     F=D/A
                                    G = 0%

                                     p_lsl

<=100
                                                                            805
                                                                          7,624
                                                                          8,429
                                                                            211
                                                                              0
                                                                            26%
                                                                             0%
101 - 500
                                                                            928
                                                                          5,586
                                                                          6,514
                                                                            163
                                                                              0
                                                                            18%
                                                                             0%
501 - 1,000
                                                                            318
                                                                          1,290
                                                                          1,608
                                                                             40
                                                                              0
                                                                            13%
                                                                             0%
1,001 - 3,300
                                                                            230
                                                                            637
                                                                            867
                                                                             22
                                                                              0
                                                                             9%
                                                                             0%
3,301 - 10,000
                                                                             65
                                                                             83
                                                                            148
                                                                              4
                                                                              0
                                                                             6%
                                                                             0%
10,001 - 50,000
                                                                             13
                                                                              7
                                                                             20
                                                                              1
                                                                              0
                                                                             4%
                                                                             0%
50,001 - 100,000
                                                                              2
                                                                              0
                                                                              2
                                                                           0.05
                                                                              0
                                                                             3%
                                                                             0%
100,001 - 1M
                                                                              1
                                                                              0
                                                                              1
                                                                           0.03
                                                                              0
                                                                             3%
                                                                             0%
> 1M
                                                                              0
                                                                              0
                                                                              0
                                                                            N/A
                                                                            N/A
                                                                            N/A
                                                                            N/A
Total
                                                                          2,362
                                                                         15,227
                                                                         17,589
                                                                            440
                                                                              0
                                                                            19%
                                                                             0%
           Notes:
           A, B: Exhibit 4-8.
           D, E: Estimate of 2.5 percent based on information from three states regarding the percentage of NTNCWSs in their state with any LSLs (see Exhibit 4-15). As a simplifying assumption, EPA assumed that all 2.5 percent of NTNCWSs with LSLs are those with existing CCT.

Number of LSLs in NTNCWSs
Two states provided an estimate of the number of LSLs in NTNCWSs in response to the August 2017 questionnaire. One estimated the number to be between 0 and 5. The second estimated between 0 and 50 LSLs and noted that the majority of their NTNCWSs (67 percent) have 5 or fewer connections. Due to the uncertainty of the responses and representativeness of the data, EPA did not use the responses to the state questionnaire to develop the national number of LSLs in NTNCWSs. Instead, EPA used the following approach.
 Determined the median number of service connections from SDWIS/Fed for each of the NTNCWS size categories serving 1 million or fewer people.
 For systems with LSLs:
 Assume 100 percent of service connections are lead when the median number of service connections is 10 or fewer.
 Assume NTNCWSs with more than 10 service connections have experienced expansion over time resulting in service lines of different materials. For these systems EPA developed a range, with a minimum of 50 percent and a maximum of 100 percent of service lines assumed to be lead.
Exhibit 4-17 provides the estimated total number of LSLs for each system size category. The corresponding SafeWater LCR model data variable used to estimate costs in Chapter 5 is provided in red italics. Note that the minimum is the same as the maximum except for the three size categories that serve populations of 10,001  -  1 million where the median number of service connections is above 10. As previously stated, EPA assumes that LSLs in NTNCWSs are limited to the subset of NTNCWSs with CCT.
Exhibit 4-17: Number of LSLs in NTNCWSs with CCT by Size Category
                             System Size Category
                  Number of Systems with LSLs (assumes 2.5%)
                     Median Number of Service Connections
            Estimated Percent of Service Connections that Are LSLs
               Total Estimated Number of LSLs per Size Category

                                   perc_lsl

                                    Minimum
                                    Maximum
                                    Minimum
                                    Maximum

                                       A
                                       B
                                       C
                                       D
                                    E=A*B*C
                                    F=A*B*D
<=100
                                                                            211
                                                                              1
                                                                           100%
                                                                           100%
                                                                            211
                                                                            211
101 - 500
                                                                            163
                                                                              1
                                                                           100%
                                                                           100%
                                                                            163
                                                                            163
501 - 1,000
                                                                             40
                                                                              1
                                                                           100%
                                                                           100%
                                                                             40
                                                                             40
1,001 - 3,300
                                                                             22
                                                                              2
                                                                           100%
                                                                           100%
                                                                             44
                                                                             44
3,301 - 10,000
                                                                              4
                                                                              6
                                                                           100%
                                                                           100%
                                                                             24
                                                                             24
10,001 - 50,000
                                                                              1
                                                                             29
                                                                            50%
                                                                           100%
                                                                             15
                                                                             29
50,001 - 100,000
                                                                           0.05
                                                                            112
                                                                            50%
                                                                           100%
                                                                              3
                                                                              6
100,001 - 1M
                                                                           0.03
                                                                          1,109
                                                                            50%
                                                                           100%
                                                                             17
                                                                             33
>1M

Total
                                                                            440

                                                                            516
                                                                            550
Notes:
General: Only systems with CCT are assumed to have LSLs. No NTNCWSs serve more than 1 million people.
A: Exhibit 4-16, Column D. As shown in Exhibit 4-16 very few NTNCWSs serve 50,001 to 1 million people. Thus, multiplying 2.5 percent by the number of systems in the 50,001  -  100,000 and 100,001  -  1 M size categories results in a fraction of systems with LSLs.
C, D: For systems with LSLs, EPA assumed 100 percent of service connections are lead when the median number of service connections was <= 10. For NTNCWSs with > 10 service connections, EPA assumed that service connections have been laid over a period of time and may be composed of different materials. Thus, for these systems, EPA assumed a minimum of 50 percent and maximum of 100 percent of service lines are lead.
Discussion of Data Limitations and Uncertainty
There is a high degree of uncertainty in using the 2.5 midpoint of the range as the estimated percentage of NTNCWSs with LSLs based on survey results from three states. This uncertainty could result in an under- or overestimate of national costs and benefits of the LCRR. EPA conservatively assumed that all service lines would be lead in those NTNCWSs with LSLs serving 10,000 or fewer based on the reported median number of service connections in SDWIS/Fed for each size category. This may result in an overestimate of costs and benefits based on the accuracy of the service connection information. However, the impact of these uncertainties is expected to be small due to the small estimated number of NTNCWSs with LSLs.