to reduce disinfectant demand
                                          and control of disinfection
                                          treatment processes to reduce
                                          disinfectant levels
------------------------------------------------------------------------

    (b) TTHM and HAA5. (1) Subpart L--RAA compliance. (i) Compliance
dates. Subpart H systems serving 10,000 or more persons must comply
with this paragraph (b)(1) beginning January 1, 2002. Subpart H systems
serving fewer than 10,000 persons and systems using only ground water
not under the direct influence of surface water must comply with this
paragraph (b)(1) beginning January 1, 2004. All systems must comply
with these MCLs until the date specified for subpart V compliance in
Sec.  141.620(c).

------------------------------------------------------------------------
                   Disinfection byproduct                     MCL (mg/L)
------------------------------------------------------------------------
Total trihalomethanes (TTHM)...............................        0.080
Haloacetic acids (five) (HAA5).............................        0.060
------------------------------------------------------------------------

    (ii) The Administrator, pursuant to section 1412 of the Act, hereby
identifies the following as the best technology, treatment techniques,
or other means available for achieving compliance with the maximum
contaminant levels for TTHM and HAA5 identified in this paragraph
(b)(1):

------------------------------------------------------------------------
          Disinfection byproduct              Best available technology
------------------------------------------------------------------------
Total trihalomethanes (TTHM) and            Enhanced coagulation or
 Haloacetic acids (five) (HAA5).             enhanced softening or
                                             GAC10, with chlorine as the
                                             primary and residual
                                             disinfectant
------------------------------------------------------------------------

    (2) Subpart V--LRAA compliance. (i) Compliance dates. The subpart V
MCLs for TTHM and HAA5 must be complied with as a locational running
annual average at each monitoring location beginning the date specified
for subpart V compliance in Sec.  141.620(c).

------------------------------------------------------------------------
                   Disinfection byproduct                     MCL (mg/L)
------------------------------------------------------------------------
Total trihalomethanes (TTHM)...............................        0.080
Haloacetic acids (five) (HAA5).............................        0.060
------------------------------------------------------------------------

    (ii) The Administrator, pursuant to section 1412 of the Act, hereby
identifies the following as the best technology, treatment techniques,
or other means available for achieving compliance with the maximum
contaminant levels for TTHM and HAA5 identified in this paragraph
(b)(2)

for all systems that disinfect their source water:

------------------------------------------------------------------------
         Disinfection byproduct             Best available technology
------------------------------------------------------------------------
Total trihalomethanes (TTHM) and         Enhanced coagulation or
 Haloacetic acids (five) (HAA5).          enhanced softening, plus
                                          GAC10; or nanofiltration with
                                          a molecular weight cutoff
                                          < =1000 Daltons; or GAC20
------------------------------------------------------------------------

    (iii) The Administrator, pursuant to section 1412 of the Act,
hereby identifies the following as the best technology, treatment
techniques, or other means available for achieving compliance with the
maximum contaminant levels for TTHM and HAA5 identified in this
paragraph (b)(2) for consecutive systems and applies only to the
disinfected water that consecutive systems buy or otherwise receive:

------------------------------------------------------------------------
         Disinfection byproduct             Best available technology
------------------------------------------------------------------------
Total trihalomethanes (TTHM) and         Systems serving >=10,000:
 Haloacetic acids (five) (HAA5).          Improved distribution system
                                          and storage tank management to
                                          reduce residence time, plus
                                          the use of chloramines for
                                          disinfectant residual
                                          maintenance
                                         Systems serving < 10,000:
                                          Improved distribution system
                                          and storage tank management to
                                          reduce residence time
------------------------------------------------------------------------

0
11. Section 141.131 is amended as follows:
0
a. By revising paragraph (a),
0
b. By revising paragraphs (b)(1) and (b)(2),
0
c. By revising the table in paragraph (c)(1),
0
d. By revising paragraphs (d)(2), (d)(3), (d)(4)(i), and (d)(4)(ii),
0
e. By adding paragraph (d)(6).

Sec.  141.131  Analytical requirements.

    (a) General. (1) Systems must use only the analytical methods
specified in this section, or their equivalent as approved by EPA, to
demonstrate compliance with the requirements of this subpart and with
the requirements of subparts U and V of this part. These methods are
effective for compliance monitoring February 16, 1999, unless a
different effective date is specified in this section or by the State.
    (2) The following documents are incorporated by reference. The
Director of the Federal Register approves this incorporation by
reference in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies
may be inspected at EPA's Drinking Water Docket, 1301 Constitution
Avenue, NW., EPA West, Room B102, Washington, DC 20460, or at the
National Archives and Records Administration (NARA). For information on
the availability of this material at NARA, call<PHONE_NUMBER>, or go to:
http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html.
 EPA Method 552.1 is in Methods for the

Determination of Organic Compounds in Drinking Water-Supplement II,
USEPA, August 1992, EPA/600/R-92/129 (available through National
Information Technical Service (NTIS), PB92-207703). EPA Methods 502.2,
524.2, 551.1, and 552.2 are in Methods for the Determination of Organic
Compounds in Drinking Water-Supplement III, USEPA, August 1995, EPA/
600/R-95/131 (available through NTIS, PB95-261616). EPA Method 300.0 is
in Methods for the Determination of Inorganic Substances in
Environmental Samples, USEPA, August 1993, EPA/600/R-93/100 (available
through NTIS, PB94-121811). EPA Methods 300.1 and 321.8 are in Methods
for the Determination of Organic and Inorganic Compounds in Drinking
Water, Volume 1, USEPA, August 2000, EPA 815-R-00-014 (available
through NTIS, PB2000-106981). EPA Method 317.0, Revision 2.0,
``Determination of Inorganic Oxyhalide Disinfection By-Products in
Drinking Water Using Ion Chromatography with the Addition of a
Postcolumn Reagent for Trace Bromate Analysis,'' USEPA, July 2001, EPA
815-B-01-001, EPA Method 326.0, Revision 1.0, ``Determination of
Inorganic Oxyhalide Disinfection By-Products in Drinking Water Using
Ion Chromatography Incorporating the Addition of a Suppressor Acidified
Postcolumn Reagent for Trace Bromate Analysis,'' USEPA, June 2002, EPA
815-R-03-007, EPA Method 327.0, Revision 1.1, ``Determination of
Chlorine Dioxide and Chlorite Ion in Drinking Water Using Lissamine
Green B and Horseradish Peroxidase with Detection by Visible
Spectrophotometry,'' USEPA, May 2005, EPA 815-R-05-008 and EPA Method
552.3, Revision 1.0, ``Determination of Haloacetic Acids and Dalapon in
Drinking Water by Liquid-liquid Microextraction, Derivatization, and
Gas Chromatography with Electron Capture Detection,'' USEPA, July 2003,
EPA-815-B-03-002 can be accessed and downloaded directly on-line at
http://www.epa.gov/safewater/methods/sourcalt.html. EPA Method 415.3,

Revision 1.1, ``Determination of Total Organic Carbon and Specific UV
Absorbance at 254 nm in Source Water and Drinking Water,'' USEPA,
February 2005, EPA/600/R-05/055 can be accessed and downloaded directly
on-line at http://www.epa.gov/nerlcwww/ordmeth.htm. Standard Methods 4500-Cl

D, 4500-Cl E, 4500-Cl F, 4500-Cl G, 4500-Cl H, 4500-Cl I, 4500-
ClO2 D, 4500-ClO2 E, 6251 B, and 5910 B shall be
followed in accordance with Standard Methods for the Examination of
Water and Wastewater, 19th or 20th Editions, American Public Health
Association, 1995 and 1998, respectively. The cited methods published
in either edition may be used. Standard Methods 5310 B, 5310 C, and
5310 D shall be followed in accordance with the Supplement to the 19th
Edition of Standard Methods for the Examination of Water and
Wastewater, or the Standard Methods for the Examination of Water and
Wastewater, 20th Edition, American Public Health Association, 1996 and
1998, respectively. The cited methods published in either edition may
be used. Copies may be obtained from the American Public Health
Association, 1015 Fifteenth Street, NW., Washington, DC 20005. Standard
Methods 4500-Cl D-00, 4500-Cl E-00, 4500-Cl F-00, 4500-Cl G-00, 4500-Cl
H-00, 4500-Cl I-00, 4500-ClO2 E-00, 6251 B-94, 5310 B-00,
5310 C-00, 5310 D-00 and 5910 B-00 are available at http://www.standardmethods.org
 or at EPA's Water Docket. The year in which

each method was approved by the Standard Methods Committee is
designated by the last two digits in the method number. The methods
listed are the only Online versions that are IBR-approved. ASTM Methods
D 1253-86 and D 1253-86 (Reapproved 1996) shall be followed in
accordance with the Annual Book of ASTM Standards, Volume 11.01,
American Society for Testing and Materials International, 1996 or any
ASTM edition containing the IBR-approved version of the method may be
used. ASTM Method D1253-03 shall be followed in accordance with the
Annual Book of ASTM Standards, Volume 11.01, American Society for
Testing and Materials International, 2004 or any ASTM edition
containing the IBR-approved version of the method may be used. ASTM
Method D 6581-00 shall be followed in accordance with the Annual Book
of ASTM Standards, Volume 11.01, American Society for Testing and
Materials International, 2001 or any ASTM edition containing the IBR-
approved version of the method may be used; copies may be obtained from
the American Society for Testing and

Materials International, 100 Barr Harbor Drive, West Conshohocken, PA
19428-2959.
    (b) Disinfection byproducts. (1) Systems must measure disinfection
byproducts by the methods (as modified by the footnotes) listed in the
following table:

                        Approved Methods for Disinfection Byproduct Compliance Monitoring
----------------------------------------------------------------------------------------------------------------
                                                     Standard method
Contaminant and methodology \1\      EPA method            \2\           SM online \9\        ASTM method \3\
----------------------------------------------------------------------------------------------------------------
TTHM
    P&T/GC/ElCD & PID..........  502.2 \4\........  .................  .................  ......................
    P&T/GC/MS..................  524.2............  .................  .................  ......................
    LLE/GC/ECD.................  551.1............  .................  .................  ......................
HAA5
    LLE (diazomethane)/GC/ECD..  .................  6251 B \5\.......  6251 B-94........  ......................
    SPE (acidic methanol)/GC/    552.1 \5\........  .................  .................  ......................
     ECD.
    LLE (acidic methanol)/GC/    552.2, 552.3.....  .................  .................  ......................
     ECD.
Bromate
    Ion chromatography.........  300.1............  .................  .................  D 6581-00
    Ion chromatography & post    317.0 Rev 2.0      .................  .................  ......................
     column reaction.             \6\, 326.0 \6\.
    IC/ICP-MS..................  321.86 7.........  .................  .................  ......................
Chlorite
    Amperometric titration.....  .................  4500-ClO2 E \8\..  4500-ClO2 E-00     ......................
                                                                        \8\.
    Spectrophotometry..........  327.0 Rev 1.1 \8\  .................  .................  ......................
    Ion chromatography.........  300.0, 300.1,      .................  .................  D 6581-00
                                  317.0 Rev 2.0,
                                  326.0.
----------------------------------------------------------------------------------------------------------------
\1\ P&T = purge and trap; GC = gas chromatography; ElCD = electrolytic conductivity detector; PID =
  photoionization detector; MS = mass spectrometer; LLE = liquid/liquid extraction; ECD = electron capture
  detector; SPE = solid phase extraction; IC = ion chromatography; ICP-MS = inductively coupled plasma/mass
  spectrometer.
\2\ 19th and 20th editions of Standard Methods for the Examination of Water and Wastewater, 1995 and 1998,
  respectively, American Public Health Association; either of these editions may be used.
\3\ Annual Book of ASTM Standards, 2001 or any year containing the cited version of the method, Vol 11.01.
\4\ If TTHMs are the only analytes being measured in the sample, then a PID is not required.
\5\ The samples must be extracted within 14 days of sample collection.
\6\ Ion chromatography & post column reaction or IC/ICP-MS must be used for monitoring of bromate for purposes
  of demonstrating eligibility of reduced monitoring, as prescribed in Sec.   141.132(b)(3)(ii).
\7\ Samples must be preserved at the time of sampling with 50 mg ethylenediamine (EDA)/L of sample and must be
  analyzed within 28 days.
\8\ Amperometric titration or spectrophotometry may be used for routine daily monitoring of chlorite at the
  entrance to the distribution system, as prescribed in Sec.   141.132(b)(2)(i)(A). Ion chromatography must be
  used for routine monthly monitoring of chlorite and additional monitoring of chlorite in the distribution
  system, as prescribed in Sec.   141.132(b)(2)(i)(B) and (b)(2)(ii).
\9\ The Standard Methods Online version that is approved is indicated by the last two digits in the method
  number which is the year of approval by the Standard Method Committee. Standard Methods Online are available
  at http://www.standardmethods.org.

    (2) Analyses under this section for disinfection byproducts must be
conducted by laboratories that have received certification by EPA or
the State, except as specified under paragraph (b)(3) of this section.
To receive certification to conduct analyses for the DBP contaminants
in Sec. Sec.  141.64, 141.135, and subparts U and V of this part, the
laboratory must:
    (i) Analyze Performance Evaluation (PE) samples that are acceptable
to EPA or the State at least once during each consecutive 12 month
period by each method for which the laboratory desires certification.
    (ii) Until March 31, 2007, in these analyses of PE samples, the
laboratory must achieve quantitative results within the acceptance
limit on a minimum of 80% of the analytes included in each PE sample.
The acceptance limit is defined as the 95% confidence interval
calculated around the mean of the PE study between a maximum and
minimum acceptance limit of +/-50% and +/-15% of the study mean.
    (iii) Beginning April 1, 2007, the laboratory must achieve
quantitative results on the PE sample analyses that are within the
following acceptance limits:

------------------------------------------------------------------------
                                      Acceptance
                                        limits
                DBP                   (percent of         Comments
                                      true value)
------------------------------------------------------------------------
TTHM
    Chloroform....................  20  Laboratory must meet
                                                     all 4 individual
                                                     THM acceptance
                                                     limits in order to
                                                     successfully pass a
                                                     PE sample for TTHM
    Bromodichloromethane..........  20  ....................
    Dibromochloromethane..........  20  ....................
    Bromoform.....................  20  ....................
HAA5
    Monochloroacetic Acid.........  40  Laboratory must meet
                                                     the acceptance
                                                     limits for 4 out of
                                                     5 of the HAA5
                                                     compounds in order
                                                     to successfully
                                                     pass a PE sample
                                                     for HAA5
    Dichloroacetic Acid...........  40  ....................
    Trichloroacetic Acid..........  40  ....................
    Monobromoacetic Acid..........  40  ....................
    Dibromoacetic Acid............  40  ....................
Chlorite..........................  30  ....................

Bromate...........................  30  ....................
------------------------------------------------------------------------

    (iv) Beginning April 1, 2007, report quantitative data for
concentrations at least as low as the ones listed in the following
table for all DBP samples analyzed for compliance with Sec. Sec.
141.64, 141.135, and subparts U and V of this part:

------------------------------------------------------------------------
                                       Minimum
                                      reporting
                DBP                   level (mg/         Comments
                                        L) \1\
------------------------------------------------------------------------
TTHM \2\
    Chloroform.....................       0.0010
    Bromodichloromethane...........       0.0010
    Dibromochloromethane...........       0.0010
    Bromoform......................       0.0010
HAA5 \2\
    Monochloroacetic Acid..........       0.0020
    Dichloroacetic Acid............       0.0010
    Trichloroacetic Acid...........       0.0010
    Monobromoacetic Acid...........       0.0010
    Dibromoacetic Acid.............       0.0010
Chlorite...........................        0.020  Applicable to
                                                   monitoring as
                                                   prescribed in Sec.
                                                   141.132(b)(2)(1)(B)
                                                   and (b)(2)(ii).
Bromate............................    0.0050 or  Laboratories that use
                                          0.0010   EPA Methods 317.0
                                                   Revision 2.0, 326.0
                                                   or 321.8 must meet a
                                                   0.0010 mg/L MRL for
                                                   bromate.
------------------------------------------------------------------------
\1\ The calibration curve must encompass the regulatory minimum
  reporting level (MRL) concentration. Data may be reported for
  concentrations lower than the regulatory MRL as long as the precision
  and accuracy criteria are met by analyzing an MRL check standard at
  the lowest reporting limit chosen by the laboratory. The laboratory
  must verify the accuracy of the calibration curve at the MRL
  concentration by analyzing an MRL check standard with a concentration
  less than or equal to 110% of the MRL with each batch of samples. The
  measured concentration for the MRL check standard must be < plus-
  minus>50% of the expected value, if any field sample in the batch has
  a concentration less than 5 times the regulatory MRL. Method
  requirements to analyze higher concentration check standards and meet
  tighter acceptance criteria for them must be met in addition to the
  MRL check standard requirement.
\2\ When adding the individual trihalomethane or haloacetic acid
  concentrations to calculate the TTHM or HAA5 concentrations,
  respectively, a zero is used for any analytical result that is less
  than the MRL concentration for that DBP, unless otherwise specified by
  the State.

* * * * *
    (c) * * *
    (1) * * *

------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Residual measured 1
           Methodology              SM (19th or 20th       SM  Online 2           ASTM  method           EPA  method     -----------------------------------------------------------------------
                                          ed)                                                                                Free  Cl2       Combined  Cl2      Total  Cl2           ClO2
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Amperometric Titration..........  4500-C D             4500-C D-00          D 1253-86 (96), 03       ...................  X                 X                 X                 ................
Low Level Amperometric Titration  4500-C E             4500-C E-00          .......................  ...................  ................  ................  X
DPD Ferrous Titrimetric.........  4500-C F             4500-C F-00          .......................  ...................  X                 X                 X                 ................
DPD Colorimetric................  4500-C G             4500-C G-00          .......................  ...................  X                 X                 X                 ................
Syringaldazine (FACTS)..........  4500-C H             4500-C H-00          .......................  ...................  X                 ................  ................  ................
Iodometric Electrode............  4500-C I             4500-C I-00          .......................  ...................  ................  ................  X                 ................
DPD.............................  4500-C O2 D          ...................  .......................  ...................  ................  ................  ................  X
Amperometric Method II..........  4500-C O2 E          4500-C O2 E-00       .......................  ...................  ................  ................  ................  X
Lissamine Green                   ...................  ...................  .......................  327.0 Rev 1.1        ................  ................  ................  X
 Spectrophotometric.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
1 X indicates method is approved for measuring specified disinfectant residual. Free chlorine or total chlorine may be measured for demonstrating compliance with the chlorine MRDL and combined
  chlorine, or total chlorine may be measured for demonstrating compliance with the chloramine MRDL.
2 The Standard Methods Online version that is approved is indicated by the last two digits in the method number which is the year of approval by the Standard Method Committee. Standard Methods
  Online are available at http://www.standardmethods.org.

* * * * *
    (d) * * *
    (2) Bromide. EPA Methods 300.0, 300.1, 317.0 Revision 2.0, 326.0,
or ASTM D 6581-00.
    (3) Total Organic Carbon (TOC). Standard Method 5310 B or 5310 B-00
(High-Temperature Combustion

Method) or Standard Method 5310 C or 5310 C-00 (Persulfate-Ultraviolet
or Heated-Persulfate Oxidation Method) or Standard Method 5310 D or
5310 D-00 (Wet-Oxidation Method) or EPA Method 415.3 Revision 1.1.
Inorganic carbon must be removed from the samples prior to analysis.
TOC samples may not be filtered prior to analysis. TOC samples must be
acidified at the time of sample collection to achieve pH less than or
equal to 2 with minimal addition of the acid specified in the method or
by the instrument manufacturer. Acidified TOC samples must be analyzed
within 28 days.
    (4) * * *
    (i) Dissolved Organic Carbon (DOC). Standard Method 5310 B or 5310
B-00 (High-Temperature Combustion Method) or Standard Method 5310 C or
5310 C-00 (Persulfate-Ultraviolet or Heated-Persulfate Oxidation
Method) or Standard Method 5310 D or 5310 D-00 (Wet-Oxidation Method)
or EPA Method 415.3 Revision 1.1. DOC samples must be filtered through
the 0.45 [mu]m pore-diameter filter as soon as practical after
sampling, not to exceed 48 hours. After filtration, DOC samples must be
acidified to achieve pH less than or equal to 2 with minimal addition
of the acid specified in the method or by the instrument manufacturer.
Acidified DOC samples must be analyzed within 28 days of sample
collection. Inorganic carbon must be removed from the samples prior to
analysis. Water passed through the filter prior to filtration of the
sample must serve as the filtered blank. This filtered blank must be
analyzed using procedures identical to those used for analysis of the
samples and must meet the following criteria: DOC <  0.5 mg/L.
    (ii) Ultraviolet Absorption at 254 nm (UV254). Standard
Method 5910 B or 5910 B-00 (Ultraviolet Absorption Method) or EPA
Method 415.3 Revision 1.1. UV absorption must be measured at 253.7 nm
(may be rounded off to 254 nm). Prior to analysis, UV254
samples must be filtered through a 0.45 [mu]m pore-diameter filter. The
pH of UV254 samples may not be adjusted. Samples must be
analyzed as soon as practical after sampling, not to exceed 48 hours.
* * * * *
    (6) Magnesium. All methods allowed in Sec.  141.23(k)(1) for
measuring magnesium.

0
12. Section 141.132 is amended by:
0
a. Redesignating paragraphs (b)(1)(iii) through (b)(1)(v) as paragraphs
(b)(1)(iv) through (b)(1)(vi);
0
b. Adding a new paragraph (b)(1)(iii);
0
c. Revising newly redesignated paragraph (b)(1)(iv); and
0
d. Revising paragraph (b)(3)(ii).
    The addition and revisions read as follows:

Sec.  141.132  Monitoring requirements.

* * * * *
    (b) * * *
    (1) * * *
    (iii) Monitoring requirements for source water TOC. In order to
qualify for reduced monitoring for TTHM and HAA5 under paragraph
(b)(1)(ii) of this section, subpart H systems not monitoring under the
provisions of paragraph (d) of this section must take monthly TOC
samples every 30 days at a location prior to any treatment, beginning
April 1, 2008 or earlier, if specified by the State. In addition to
meeting other criteria for reduced monitoring in paragraph (b)(1)(ii)
of this section, the source water TOC running annual average must be
< =4.0 mg/L (based on the most recent four quarters of monitoring) on a
continuing basis at each treatment plant to reduce or remain on reduced
monitoring for TTHM and HAA5. Once qualified for reduced monitoring for
TTHM and HAA5 under paragraph (b)(1)(ii) of this section, a system may
reduce source water TOC monitoring to quarterly TOC samples taken every
90 days at a location prior to any treatment.
    (iv) Systems on a reduced monitoring schedule may remain on that
reduced schedule as long as the average of all samples taken in the
year (for systems which must monitor quarterly) or the result of the
sample (for systems which must monitor no more frequently than
annually) is no more than 0.060 mg/L and 0.045 mg/L for TTHMs and HAA5,
respectively. Systems that do not meet these levels must resume
monitoring at the frequency identified in paragraph (b)(1)(i) of this
section (minimum monitoring frequency column) in the quarter
immediately following the monitoring period in which the system exceeds
0.060 mg/L or 0.045 mg/L for TTHMs and HAA5, respectively. For systems
using only ground water not under the direct influence of surface water
and serving fewer than 10,000 persons, if either the TTHM annual
average is >0.080 mg/L or the HAA5 annual average is >0.060 mg/L, the
system must go to the increased monitoring identified in paragraph
(b)(1)(i) of this section (sample location column) in the quarter
immediately following the monitoring period in which the system exceeds
0.080 mg/L or 0.060 mg/L for TTHMs or HAA5 respectively.
* * * * *
    (3) ***
    (i) ***
    (ii) Reduced monitoring.
    (A) Until March 31, 2009, systems required to analyze for bromate
may reduce monitoring from monthly to quarterly, if the system's
average source water bromide concentration is less than 0.05 mg/L based
on representative monthly bromide measurements for one year. The system
may remain on reduced bromate monitoring until the running annual
average source water bromide concentration, computed quarterly, is
equal to or greater than 0.05 mg/L based on representative monthly
measurements. If the running annual average source water bromide
concentration is >=0.05 mg/L, the system must resume routine monitoring
required by paragraph (b)(3)(i) of this section in the following month.
    (B) Beginning April 1, 2009, systems may no longer use the
provisions of paragraph (b)(3)(ii)(A) of this section to qualify for
reduced monitoring. A system required to analyze for bromate may reduce
monitoring from monthly to quarterly, if the system's running annual
average bromate concentration is < =0.0025 mg/L based on monthly bromate
measurements under paragraph (b)(3)(i) of this section for the most
recent four quarters, with samples analyzed using Method 317.0 Revision
2.0, 326.0 or 321.8. If a system has qualified for reduced bromate
monitoring under paragraph (b)(3)(ii)(A) of this section, that system
may remain on reduced monitoring as long as the running annual average
of quarterly bromate samples < =0.0025 mg/L based on samples analyzed
using Method 317.0 Revision 2.0, 326.0, or 321.8. If the running annual
average bromate concentration is >0.0025 mg/L, the system must resume
routine monitoring required by paragraph (b)(3)(i) of this section.
* * * * *

Sec.  141.133  [Amended]

0
13. Section 141.133 is amended in the last sentence of paragraph (d) by
revising the reference ``Sec.  141.32'' to read ``subpart Q of this
part''.

0
14. Section 141.135 is amended by revising paragraph (a)(3)(ii) to read
as follows:

Sec.  141.135  Treatment technique for control of disinfection
byproduct (DBP) precursors.

    (a) * * *
    (3) * * *
    (ii) Softening that results in removing at least 10 mg/L of
magnesium hardness (as CaCO3), measured monthly according to
Sec.  141.131(d)(6) and calculated quarterly as a running annual
average.
* * * * *

0
15. Section 141.151 is amended by revising paragraph (d) to read as
follows:

Sec.  141.151  Purpose and applicability of this subpart.

* * * * *
    (d) For the purpose of this subpart, detected means: at or above
the levels prescribed by Sec.  141.23(a)(4) for inorganic contaminants,
at or above the levels prescribed by Sec.  141.24(f)(7) for the
contaminants listed in Sec.  141.61(a), at or above the levels
prescribed by Sec.  141.24(h)(18) for the contaminants listed in Sec.
141.61(c), at or above the levels prescribed by Sec.  141.131(b)(2)(iv)
for the contaminants or contaminant groups listed in Sec.  141.64, and
at or above the levels prescribed by Sec.  141.25(c) for radioactive
contaminants.
* * * * *

0
16. Section 141.153 is amended by revising paragraphs (d)(4)(iv)(B) and
(d)(4)(iv)(C) to read as follows:

Sec.  141.153  Content of the reports.

* * * * *
    (d) * * *
    (4) * * *
    (iv) * * *
    (B) When compliance with the MCL is determined by calculating a
running annual average of all samples taken at a monitoring location:
the highest average of any of the monitoring locations and the range of
all monitoring locations expressed in the same units as the MCL. For
the MCLs for TTHM and HAA5 in Sec.  141.64(b)(2), systems must include
the highest locational running annual average for TTHM and HAA5 and the
range of individual sample results for all monitoring locations
expressed in the same units as the MCL. If more than one location
exceeds the TTHM or HAA5 MCL, the system must include the locational
running annual averages for all locations that exceed the MCL.
    (C) When compliance with the MCL is determined on a system-wide
basis by calculating a running annual average of all samples at all
monitoring locations: the average and range of detection expressed in
the same units as the MCL. The system is required to include individual
sample results for the IDSE conducted under subpart U of this part when
determining the range of TTHM and HAA5 results to be reported in the
annual consumer confidence report for the calendar year that the IDSE
samples were taken.
* * * * *

Appendix A to Subpart Q [Amended]

0
17. In Subpart Q, Appendix A is amended as follows:
0
a. In entry I.B.2. in the fifth column, remove the endnote citation
``9'' and add in its place ``11'';
0
b. In entry I.B.11. in the fourth column, remove the endnote citation
``10'' and add in its place ``12'';
0
c. In entry I.B.12. in the fourth column, remove the endnote citation
``10'' and add in its place ``12'';
0
d. In entry I.G. in the first column, remove the endnote citation
``11'' and add in its place ``13'';
0
e. In entry I.G.1. in the third column, remove the endnote citation
``12'' and add in its place ``14'' and remove the citation in the third
column ``141.12, 141.64(a)'' and in its place add ``141.64(b)''
(keeping the endnote citation to endnote 14) and in the fifth column
remove the citation ``141.30'' and add in numerical order the citations
``141.600-141.605, 141.620-141.629'';
0
f. In entry I.G.2. revise the entry ``141.64(a)'' to read ``141.64(b)''
and in the fifth column add in numerical order the citations ``141.600-
141.605, 141.620-141.629''.
0
g. In entry I.G.7. in the fourth column, remove the endnote citation
``13'' and add in its place ``15'';
0
h. In entry I.G.8. in the second column, remove the endnote citation
``14'' and add in its place ``16'';
0
i. In entry II. in the first column, remove the endnote citation ``15''
and add in its place ``17'';
0
j. In entry III.A. in the third column, remove the endnote citation
``16'' and add in its place ``18'';
0
k. In entry III.B in the third column, remove the endnote citation
``17'' and add in its place ``19'';
0
l. In entry IV.E. in the first column, remove the endnote citation
``18'' and add in its place 20''; and
0
m. In entry III.F in the second column, remove the endnote citation
``19'' and add in its place ``21''.
0
18. In Subpart Q, Appendix A, remove endnote 14 and add in its place,
to read as follows: ``14.Sec. Sec.  141.64(b)(1) 141.132(a)-(b) apply
until Sec. Sec.  141.620-141.630 take effect under the schedule in
Sec.  141.620(c).

0
19-20. In Subpart Q, Appendix B is amended as follows:
0
a. In entry G.77. in the third column, remove the endnote citation
``16'' and add in its place ``17'';
0
b. In entry H. (the title) in the first column, remove the endnote
citation ``17'' and add in its place ``18'';
0
c. In entry H.80. in the third column, remove the endnote citations
``17, 18'' and add in its place ``19, 20'' and remove the number
``0.10/'';
0
d. In entry H.81. in the third column, remove the endnote citation
``20'' and add in its place ``21''; and
0
e. In entry H.84. in the second column, remove the endnote citation
``21'' and add in its place ``22'' and in the third column remove the
endnote citation ``22'' and add in its place ``23''.
0
f. Revise endnotes 18 and 19.
    The revisions read as follows:

Appendix B to Subpart Q

* * * * *
0
18. Surface water systems and ground water systems under the direct
influence of surface water are regulated under subpart H of 40 CFR 141.
Subpart H community and non-transient non-community systems serving
>=10,000 must comply with subpart L DBP MCLs and disinfectant maximum
residual disinfectant levels (MRDLs) beginning January 1, 2002. All
other community and non-transient non-community systems must comply
with subpart L DBP MCLs and disinfectant MRDLs beginning January 1,
2004. Subpart H transient non-community systems serving >=10,000 that
use chlorine dioxide as a disinfectant or oxidant must comply with the
chlorine dioxide MRDL beginning January 1, 2002. All other transient
non-community systems that use chlorine dioxide as a disinfectant or
oxidant must comply with the chlorine dioxide MRDL beginning January 1,
2004.
0
19. Community and non-transient non-community systems must comply with
subpart V TTHM and HAA5 MCLs of 0.080 mg/L and 0.060 mg/L, respectively
(with compliance calculated as a locational running annual average) on
the schedule in Sec.  141.620.
* * * * *

0
21. Part 141 is amended by adding new subpart U to read as follows:

Subpart U--Initial Distribution System Evaluations

141.600 General requirements.
141.601 Standard monitoring.
141.602 System specific studies.
141.603 40/30 certification.
141.604 Very small system waivers.
141.605 Subpart V compliance monitoring location recommendations.

Subpart U--Initial Distribution System Evaluations

Sec.  141.600  General requirements.

    (a) The requirements of subpart U of this part constitute national
primary drinking water regulations. The regulations in this subpart
establish monitoring and other requirements for identifying subpart V
compliance monitoring locations for determining compliance with maximum
contaminant levels for total

trihalomethanes (TTHM) and haloacetic acids (five)(HAA5). You must use
an Initial Distribution System Evaluation (IDSE) to determine locations
with representative high TTHM and HAA5 concentrations throughout your
distribution system. IDSEs are used in conjunction with, but separate
from, subpart L compliance monitoring, to identify and select subpart V
compliance monitoring locations.
    (b) Applicability. You are subject to these requirements if your
system is a community water system that uses a primary or residual
disinfectant other than ultraviolet light or delivers water that has
been treated with a primary or residual disinfectant other than
ultraviolet light; or if your system is a nontransient noncommunity
water system that serves at least 10,000 people and uses a primary or
residual disinfectant other than ultraviolet light or delivers water
that has been treated with a primary or residual disinfectant other
than ultraviolet light.
    (c) Schedule. (1) You must comply with the requirements of this
subpart on the schedule in the table in this paragraph (c)(1).

----------------------------------------------------------------------------------------------------------------
                                        You must submit your
                                      standard monitoring plan
                                      or system specific study   You must complete your
                                          plan \1\ or 40/30      standard monitoring or    You must submit your
    If you serve this population      certification \2\ to the   system specific study      IDSE report to the
                                      State by or receive very             by                  State by \3\
                                      small system waiver from
                                                State
----------------------------------------------------------------------------------------------------------------
Systems that are not part of a combined distribution system and systems that serve the largest population in the
                                          combined distribution system
----------------------------------------------------------------------------------------------------------------
(i) >=100,000.......................  October 1, 2006.........  September 30, 2008.....  January 1, 2009.
(ii) 50,000-99,999..................  April 1, 2007...........  March 31, 2009.........  July 1, 2009.
(iii) 10,000-49,999.................  October 1, 2007.........  September 30, 2009.....  January 1, 2010.
(iv) < 10,000 (CWS Only).............  April 1, 2008...........  March 31, 2010.........  July 1, 2010.
-------------------------------------
                          Other systems that are part of a combined distribution system
----------------------------------------------------------------------------------------------------------------
(v) Wholesale system or consecutive   --at the same time as     --at the same time as    --at the same time as
 system.                               the system with the       the system with the      the system with the
                                       earliest compliance       earliest compliance      earliest compliance
                                       date in the combined      date in the combined     date in the combined
                                       distribution system.      distribution system.     distribution system.
----------------------------------------------------------------------------------------------------------------
\1\ If, within 12 months after the date identified in this column, the State does not approve your plan or
  notify you that it has not yet completed its review, you may consider the plan that you submitted as approved.
  You must implement that plan and you must complete standard monitoring or a system specific study no later
  than the date identified in the third column.
\2\ You must submit your 40/30 certification under Sec.   141.603 by the date indicated.
\3\ If, within three months after the date identified in this column (nine months after the date identified in
  this column if you must comply on the schedule in paragraph (c)(1)(iii) of this section), the State does not
  approve your IDSE report or notify you that it has not yet completed its review, you may consider the report
  that you submitted as approved and you must implement the recommended subpart V monitoring as required.

    (2) For the purpose of the schedule in paragraph (c)(1) of this
section, the State may determine that the combined distribution system
does not include certain consecutive systems based on factors such as
receiving water from a wholesale system only on an emergency basis or
receiving only a small percentage and small volume of water from a
wholesale system. The State may also determine that the combined
distribution system does not include certain wholesale systems based on
factors such as delivering water to a consecutive system only on an
emergency basis or delivering only a small percentage and small volume
of water to a consecutive system.
    (d) You must conduct standard monitoring that meets the
requirements in Sec.  141.601, or a system specific study that meets
the requirements in Sec.  141.602, or certify to the State that you
meet 40/30 certification criteria under Sec.  141.603, or qualify for a
very small system waiver under Sec.  141.604.
    (1) You must have taken the full complement of routine TTHM and
HAA5 compliance samples required of a system with your population and
source water under subpart L of this part (or you must have taken the
full complement of reduced TTHM and HAA5 compliance samples required of
a system with your population and source water under subpart L if you
meet reduced monitoring criteria under subpart L of this part) during
the period specified in Sec.  141.603(a) to meet the 40/30
certification criteria in Sec.  141.603. You must have taken TTHM and
HAA5 samples under Sec. Sec.  141.131 and 141.132 to be eligible for
the very small system waiver in Sec.  141.604.
    (2) If you have not taken the required samples, you must conduct
standard monitoring that meets the requirements in Sec.  141.601, or a
system specific study that meets the requirements in Sec.  141.602.
    (e) You must use only the analytical methods specified in Sec.
141.131, or otherwise approved by EPA for monitoring under this
subpart, to demonstrate compliance with the requirements of this
subpart.
    (f) IDSE results will not be used for the purpose of determining
compliance with MCLs in Sec.  141.64.

Sec.  141.601  Standard monitoring.

    (a) Standard monitoring plan. Your standard monitoring plan must
comply with paragraphs (a)(1) through (a)(4) of this section. You must
prepare and submit your standard monitoring plan to the State according
to the schedule in Sec.  141.600(c).
    (1) Your standard monitoring plan must include a schematic of your
distribution system (including distribution system entry points and
their sources, and storage facilities), with notes indicating locations
and dates of all projected standard monitoring, and all projected
subpart L compliance monitoring.
    (2) Your standard monitoring plan must include justification of
standard monitoring location selection and a summary of data you relied
on to justify standard monitoring location selection.
    (3) Your standard monitoring plan must specify the population
served and system type (subpart H or ground water).
    (4) You must retain a complete copy of your standard monitoring
plan submitted under this paragraph (a), including any State
modification of your standard monitoring plan, for as long as

you are required to retain your IDSE report under paragraph (c)(4) of
this section.
    (b) Standard monitoring. (1) You must monitor as indicated in the
table in this paragraph (b)(1). You must collect dual sample sets at
each monitoring location. One sample in the dual sample set must be
analyzed for TTHM. The other sample in the dual sample set must be
analyzed for HAA5. You must conduct one monitoring period during the
peak historical month for TTHM levels or HAA5 levels or the month of
warmest water temperature. You must review available compliance, study,
or operational data to determine the peak historical month for TTHM or
HAA5 levels or warmest water temperature.

--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Distribution system monitoring locations \1\
                                                                                -------------------------------------------------------
            Source water type              Population size category     Monitoring periods and     Total per     Near     Average
                                                                         frequency of sampling    monitoring    entry    residence  High TTHM  High HAA5
                                                                                period      points      time    locations  locations
--------------------------------------------------------------------------------------------------------------------------------------------------------
Subpart H
                                          < 500 consecutive systems..  one (during peak                     2          1  .........          1
                                                                       historical month) \2\.
                                          < 500 non-consecutive        ..........................           2  .........  .........          1          1
                                           systems.
                                          500-3,300 consecutive       four (every 90 days)......           2          1  .........          1
                                           systems.
                                          500-3,300 non-consecutive   ..........................           2  .........  .........          1          1
                                           systems.
                                          3,301-9,999...............  ..........................           4  .........          1          2          1
                                          10,000-49,999.............  six (every 60 days).......           8          1          2          3          2
                                          50,000-249,999............  ..........................          16          3          4          5          4
                                          250,000-999,999...........  ..........................          24          4          6          8          6
                                          1,000,000-4,999,999.......  ..........................          32          6          8         10          8
                                          >=5,000,000...............  ..........................          40          8         10         12         10
Ground Water
                                          < 500 consecutive systems..  one (during peak                     2          1  .........          1
                                                                       historical month) \2\.
                                          < 500 non-consecutive        ..........................           2  .........  .........          1          1
                                           systems.
                                          500-9,999.................  four (every 90 days)......           2  .........  .........          1          1
                                          10,000-99,999.............  ..........................           6          1          1          2          2
                                          100,000-499,999...........  ..........................           8          1          1          3          3
                                          >=500,000.................  ..........................          12          2          2          4          4
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ A dual sample set (i.e., a TTHM and an HAA5 sample) must be taken at each monitoring location during each monitoring period.
\2\ The peak historical month is the month with the highest TTHM or HAA5 levels or the warmest water temperature.

    (2) You must take samples at locations other than the existing
subpart L monitoring locations. Monitoring locations must be
distributed throughout the distribution system.
    (3) If the number of entry points to the distribution system is
fewer than the specified number of entry point monitoring locations,
excess entry point samples must be replaced equally at high TTHM and
HAA5 locations. If there is an odd extra location number, you must take
a sample at a high TTHM location. If the number of entry points to the
distribution system is more than the specified number of entry point
monitoring locations, you must take samples at entry points to the
distribution system having the highest annual water flows.
    (4) Your monitoring under this paragraph (b) may not be reduced
under the provisions of Sec.  141.29 and the State may not reduce your
monitoring using the provisions of Sec.  142.16(m).
    (c) IDSE report. Your IDSE report must include the elements
required in paragraphs (c)(1) through (c)(4) of this section. You must
submit your IDSE report to the State according to the schedule in Sec.
141.600(c).
    (1) Your IDSE report must include all TTHM and HAA5 analytical
results from subpart L compliance monitoring and all standard
monitoring conducted during the period of the IDSE as individual
analytical results and LRAAs presented in a tabular or spreadsheet
format acceptable to the State. If changed from your standard
monitoring plan submitted under paragraph (a) of this section, your
report must also include a schematic of your distribution system, the
population served, and system type (subpart H or ground water).
    (2) Your IDSE report must include an explanation of any deviations
from your approved standard monitoring plan.
    (3) You must recommend and justify subpart V compliance monitoring
locations and timing based on the protocol in Sec.  141.605.
    (4) You must retain a complete copy of your IDSE report submitted
under this section for 10 years after the date that you submitted your
report. If the State modifies the subpart V monitoring requirements
that you recommended in your IDSE report or if the State approves
alternative monitoring locations, you must keep a copy of the State's
notification on file for 10 years after the date of the State's
notification. You must make the IDSE report and any State notification
available for review by the State or the public.

Sec.  141.602  System specific studies.

    (a) System specific study plan. Your system specific study plan
must be based on either existing monitoring results as required under
paragraph (a)(1) of this section or modeling as required under
paragraph (a)(2) of this section. You must prepare and submit your
system specific study plan to the State according to the schedule in
Sec.  141.600(c).
    (1) Existing monitoring results. You may comply by submitting
monitoring results collected before you are required to begin
monitoring under Sec.  141.600(c). The monitoring results and analysis
must meet the criteria in paragraphs (a)(1)(i) and (a)(1)(ii) of this
section.
    (i) Minimum requirements. (A) TTHM and HAA5 results must be based
on samples collected and analyzed in accordance with Sec.  141.131.
Samples must be collected no earlier than five years prior to the study
plan submission date.

    (B) The monitoring locations and frequency must meet the conditions
identified in this paragraph (a)(1)(i)(B). Each location must be
sampled once during the peak historical month for TTHM levels or HAA5
levels or the month of warmest water temperature for every 12 months of
data submitted for that location. Monitoring results must include all
subpart L compliance monitoring results plus additional monitoring
results as necessary to meet minimum sample requirements.

----------------------------------------------------------------------------------------------------------------
                                                                               Number of      Number of samples
                        System Type                           Population      monitoring   ---------------------
                                                             size category     locations       TTHM       HAA5
----------------------------------------------------------------------------------------------------------------
Subpart H:
                                                                      < 500               3          3          3
                                                                 500-3,300               3          9          9
                                                               3,301-9,999               6         36         36
                                                             10,000-49,999              12         72         72
                                                            50,000-249,999              24        144        144
                                                            250,000-999,99              36        216        216
                                                                         9
                                                            1,000,000-4,99              48        288        288
                                                                     9,999
                                                              >= 5,000,000              60        360        360
Ground Water:
                                                                      < 500               3          3          3
                                                                 500-9,999               3          9          9
                                                             10,000-99,999              12         48         48
                                                            100,000-499,99              18         72         72
                                                                         9
                                                                >= 500,000              24         96         96
----------------------------------------------------------------------------------------------------------------

    (ii) Reporting monitoring results. You must report the information
in this paragraph (a)(1)(ii).
    (A) You must report previously collected monitoring results and
certify that the reported monitoring results include all compliance and
non-compliance results generated during the time period beginning with
the first reported result and ending with the most recent subpart L
results.
    (B) You must certify that the samples were representative of the
entire distribution system and that treatment, and distribution system
have not changed significantly since the samples were collected.
    (C) Your study monitoring plan must include a schematic of your
distribution system (including distribution system entry points and
their sources, and storage facilities), with notes indicating the
locations and dates of all completed or planned system specific study
monitoring.
    (D) Your system specific study plan must specify the population
served and system type (subpart H or ground water).
    (E) You must retain a complete copy of your system specific study
plan submitted under this paragraph (a)(1), including any State
modification of your system specific study plan, for as long as you are
required to retain your IDSE report under paragraph (b)(5) of this
section.
    (F) If you submit previously collected data that fully meet the
number of samples required under paragraph (a)(1)(i)(B) of this section
and the State rejects some of the data, you must either conduct
additional monitoring to replace rejected data on a schedule the State
approves or conduct standard monitoring under Sec.  141.601.
    (2) Modeling. You may comply through analysis of an extended period
simulation hydraulic model. The extended period simulation hydraulic
model and analysis must meet the criteria in this paragraph (a)(2).
    (i) Minimum requirements. (A) The model must simulate 24 hour
variation in demand and show a consistently repeating 24 hour pattern
of residence time.
    (B) The model must represent the criteria listed in paragraphs
(a)(2)(i)(B)(1) through (9) of this section.
    (1) 75% of pipe volume;
    (2) 50% of pipe length;
    (3) All pressure zones;
    (4) All 12-inch diameter and larger pipes;
    (5) All 8-inch and larger pipes that connect pressure zones,
influence zones from different sources, storage facilities, major
demand areas, pumps, and control valves, or are known or expected to be
significant conveyors of water;
    (6) All 6-inch and larger pipes that connect remote areas of a
distribution system to the main portion of the system;
    (7) All storage facilities with standard operations represented in
the model; and
    (8) All active pump stations with controls represented in the
model; and
    (9) All active control valves.
    (C) The model must be calibrated, or have calibration plans, for
the current configuration of the distribution system during the period
of high TTHM formation potential. All storage facilities must be
evaluated as part of the calibration process. All required calibration
must be completed no later than 12 months after plan submission.
    (ii) Reporting modeling. Your system specific study plan must
include the information in this paragraph (a)(2)(ii).
    (A) Tabular or spreadsheet data demonstrating that the model meets
requirements in paragraph (a)(2)(i)(B) of this section.
    (B) A description of all calibration activities undertaken, and if
calibration is complete, a graph of predicted tank levels versus
measured tank levels for the storage facility with the highest
residence time in each pressure zone, and a time series graph of the
residence time at the longest residence time storage facility in the
distribution system showing the predictions for the entire simulation
period (i.e., from time zero until the time it takes to for the model
to reach a consistently repeating pattern of residence time).
    (C) Model output showing preliminary 24 hour average residence time
predictions throughout the distribution system.
    (D) Timing and number of samples representative of the distribution
system planned for at least one monitoring period of TTHM and HAA5 dual
sample monitoring at a number of locations no

[[Continued on page 487]]

]

[[pp. 487-493]] National Primary Drinking Water Regulations: Stage 2
Disinfectants and Disinfection Byproducts Rule

[[Continued from page 486]]

less than would be required for the system under standard monitoring in
Sec.  141.601 during the historical month of high TTHM. These samples
must be taken at locations other than existing subpart L compliance
monitoring locations.
    (E) Description of how all requirements will be completed no later
than 12 months after you submit your system specific study plan.
    (F) Schematic of your distribution system (including distribution
system entry points and their sources, and storage facilities), with
notes indicating the locations and dates of all completed system
specific study monitoring (if calibration is complete) and all subpart
L compliance monitoring.
    (G) Population served and system type (subpart H or ground water).
    (H) You must retain a complete copy of your system specific study
plan submitted under this paragraph (a)(2), including any State
modification of your system specific study plan, for as long as you are
required to retain your IDSE report under paragraph (b)(7) of this
section.
    (iii) If you submit a model that does not fully meet the
requirements under paragraph (a)(2) of this section, you must correct
the deficiencies and respond to State inquiries concerning the model.
If you fail to correct deficiencies or respond to inquiries to the
State's satisfaction, you must conduct standard monitoring under Sec.
141.601.
    (b) IDSE report. Your IDSE report must include the elements
required in paragraphs (b)(1) through (b)(6) of this section. You must
submit your IDSE report according to the schedule in Sec.  141.600(c).
    (1) Your IDSE report must include all TTHM and HAA5 analytical
results from subpart L compliance monitoring and all system specific
study monitoring conducted during the period of the system specific
study presented in a tabular or spreadsheet format acceptable to the
State. If changed from your system specific study plan submitted under
paragraph (a) of this section, your IDSE report must also include a
schematic of your distribution system, the population served, and
system type (subpart H or ground water).
    (2) If you used the modeling provision under paragraph (a)(2) of
this section, you must include final information for the elements
described in paragraph (a)(2)(ii) of this section, and a 24-hour time
series graph of residence time for each subpart V compliance monitoring
location selected.
    (3) You must recommend and justify subpart V compliance monitoring
locations and timing based on the protocol in Sec.  141.605.
    (4) Your IDSE report must include an explanation of any deviations
from your approved system specific study plan.
    (5) Your IDSE report must include the basis (analytical and
modeling results) and justification you used to select the recommended
subpart V monitoring locations.
    (6) You may submit your IDSE report in lieu of your system specific
study plan on the schedule identified in Sec.  141.600(c) for
submission of the system specific study plan if you believe that you
have the necessary information by the time that the system specific
study plan is due. If you elect this approach, your IDSE report must
also include all information required under paragraph (a) of this
section.
    (7) You must retain a complete copy of your IDSE report submitted
under this section for 10 years after the date that you submitted your
IDSE report. If the State modifies the subpart V monitoring
requirements that you recommended in your IDSE report or if the State
approves alternative monitoring locations, you must keep a copy of the
State's notification on file for 10 years after the date of the State's
notification. You must make the IDSE report and any State notification
available for review by the State or the public.

Sec.  141.603  40/30 certification.

    (a) Eligibility. You are eligible for 40/30 certification if you
had no TTHM or HAA5 monitoring violations under subpart L of this part
and no individual sample exceeded 0.040 mg/L for TTHM or 0.030 mg/L for
HAA5 during an eight consecutive calendar quarter period beginning no
earlier than the date specified in this paragraph (a).

------------------------------------------------------------------------
                                         Then your eligibility for 40/30
                                         certification is based on eight
                                          consecutive calendar quarters
   If your 40/30 certification is due        of subpart L compliance
                                         monitoring results beginning no
                                                 earlier than \1\
------------------------------------------------------------------------
(1) October 1, 2006....................  January 2004.
(2) April 1, 2007......................  January 2004.
(3) October 1, 2007....................  January 2005.
(4) April 1, 2008......................  January 2005.
------------------------------------------------------------------------
\1\ Unless you are on reduced monitoring under subpart L of this part
  and were not required to monitor during the specified period. If you
  did not monitor during the specified period, you must base your
  eligibility on compliance samples taken during the 12 months preceding
  the specified period.

    (b) 40/30 certification. (1) You must certify to your State that
every individual compliance sample taken under subpart L of this part
during the periods specified in paragraph (a) of this section were
< =0.040 mg/L for TTHM and < =0.030 mg/L for HAA5, and that you have not
had any TTHM or HAA5 monitoring violations during the period specified
in paragraph (a) of this section.
    (2) The State may require you to submit compliance monitoring
results, distribution system schematics, and/or recommended subpart V
compliance monitoring locations in addition to your certification. If
you fail to submit the requested information, the State may require
standard monitoring under Sec.  141.601 or a system specific study
under Sec.  141.602.
    (3) The State may still require standard monitoring under Sec.
141.601 or a system specific study under Sec.  141.602 even if you meet
the criteria in paragraph (a) of this section.
    (4) You must retain a complete copy of your certification submitted
under this section for 10 years after the date that you submitted your
certification. You must make the certification, all data upon which the
certification is based, and any State notification available for review
by the State or the public.

Sec.  141.604  Very small system waivers.

    (a) If you serve fewer than 500 people and you have taken TTHM and
HAA5 samples under subpart L of this part, you are not required to
comply with this subpart unless the State notifies you that you must
conduct standard monitoring under Sec.  141.601 or a system specific
study under Sec.  141.602.
    (b) If you have not taken TTHM and HAA5 samples under subpart L of
this part or if the State notifies you that you must comply with this
subpart, you must conduct standard monitoring under Sec.  141.601 or a
system specific study under Sec.  141.602.

Sec.  141.605  Subpart V compliance monitoring location
recommendations.

    (a) Your IDSE report must include your recommendations and
justification for where and during what month(s) TTHM and HAA5
monitoring for subpart V of this part should be conducted. You must
base your recommendations on the criteria in paragraphs (b) through (e)
of this section.
    (b) You must select the number of monitoring locations specified in
the table in this paragraph (b). You will use these recommended
locations as subpart V routine compliance monitoring locations, unless
State requires different

or additional locations. You should distribute locations throughout the
distribution system to the extent possible.

--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Distribution system monitoring location
                                                                                ---------------------------------------------------
                                                                                Existing
            Source water type               Population size category      Monitoring frequency \1\     Total per     Highest      Highest     subpart L
                                                                                monitoring      TTHM         HAA5      compliance
                                                                                period \2\   locations    locations    locations
--------------------------------------------------------------------------------------------------------------------------------------------------------
Subpart H:
                                          < 500                          per year                                2            1            1  ...........
                                          500-3,300                     per quarter                             2            1            1
                                          3,301-9,999                   per quarter                             2            1            1  ...........
                                          10,000-49,999                 per quarter                             4            2            1            1
                                          50,000-249,999                per quarter                             8            3            3            2
                                          250,000-999,999               per quarter                            12            5            4            3
                                          1,000,000-4,999,999           per quarter                            16            6            6            4
                                          >=5,000,000                   per quarter                            20            8            7            5
Ground water:
                                          < 500                          per year                                2            1            1
                                          500-9,999                     per year                                2            1            1
                                          10,000-99,999                 per quarter                             4            2            1            1
                                          100,000-499,999               per quarter                             6            3            2            1
                                          >=500,000                     per quarter                             8            3            3           2
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ All systems must monitor during month of highest DBP concentrations.
\2\ Systems on quarterly monitoring must take dual sample sets every 90 days at each monitoring location, except for subpart H systems serving 500-
  3,300. Systems on annual monitoring and subpart H systems serving 500-3,300 are required to take individual TTHM and HAA5 samples (instead of a dual
  sample set) at the locations with the highest TTHM and HAA5 concentrations, respectively. Only one location with a dual sample set per monitoring
  period is needed if highest TTHM and HAA5 concentrations occur at the same location, and month, if monitored annually).

    (c) You must recommend subpart V compliance monitoring locations
based on standard monitoring results, system specific study results,
and subpart L compliance monitoring results. You must follow the
protocol in paragraphs (c)(1) through (c)(8) of this section. If
required to monitor at more than eight locations, you must repeat the
protocol as necessary. If you do not have existing subpart L compliance
monitoring results or if you do not have enough existing subpart L
compliance monitoring results, you must repeat the protocol, skipping
the provisions of paragraphs (c)(3) and (c)(7) of this section as
necessary, until you have identified the required total number of
monitoring locations.
    (1) Location with the highest TTHM LRAA not previously selected as
a subpart V monitoring location.
    (2) Location with the highest HAA5 LRAA not previously selected as
a subpart V monitoring location.
    (3) Existing subpart L average residence time compliance monitoring
location (maximum residence time compliance monitoring location for
ground water systems) with the highest HAA5 LRAA not previously
selected as a subpart V monitoring location.
    (4) Location with the highest TTHM LRAA not previously selected as
a subpart V monitoring location.
    (5) Location with the highest TTHM LRAA not previously selected as
a subpart V monitoring location.
    (6) Location with the highest HAA5 LRAA not previously selected as
a subpart V monitoring location.
    (7) Existing subpart L average residence time compliance monitoring
location (maximum residence time compliance monitoring location for
ground water systems) with the highest TTHM LRAA not previously
selected as a subpart V monitoring location.
    (8) Location with the highest HAA5 LRAA not previously selected as
a subpart V monitoring location.
    (d) You may recommend locations other than those specified in
paragraph (c) of this section if you include a rationale for selecting
other locations. If the State approves the alternate locations, you
must monitor at these locations to determine compliance under subpart V
of this part.
    (e) Your recommended schedule must include subpart V monitoring
during the peak historical month for TTHM and HAA5 concentration,
unless the State approves another month. Once you have identified the
peak historical month, and if you are required to conduct routine
monitoring at least quarterly, you must schedule subpart V compliance
monitoring at a regular frequency of every 90 days or fewer.

0
20. Part 141 is amended by adding new subpart V to read as follows:

Subpart V--Stage 2 Disinfection Byproducts Requirements

141.620 General requirements.
141.621 Routine monitoring.
141.622 Subpart V monitoring plan.
141.623 Reduced monitoring.
141.624 Additional requirements for consecutive systems.
141.625 Conditions requiring increased monitoring.
141.626 Operational evaluation levels.
141.627 Requirements for remaining on reduced TTHM and HAA5
monitoring based on subpart L results.
141.628 Requirements for remaining on increased TTHM and HAA5
monitoring based on subpart L results.
141.629 Reporting and recordkeeping requirements.

Subpart V--Stage 2 Disinfection Byproducts Requirements

Sec.  141.620  General requirements.

    (a) General. The requirements of subpart V of this part constitute
national primary drinking water regulations. The regulations in this
subpart establish monitoring and other requirements for

achieving compliance with maximum contaminant levels based on
locational running annual averages (LRAA) for total trihalomethanes
(TTHM) and haloacetic acids (five)(HAA5), and for achieving compliance
with maximum residual disinfectant residuals for chlorine and
chloramine for certain consecutive systems.
    (b) Applicability. You are subject to these requirements if your
system is a community water system or a nontransient noncommunity water
system that uses a primary or residual disinfectant other than
ultraviolet light or delivers water that has been treated with a
primary or residual disinfectant other than ultraviolet light.
    (c) Schedule. You must comply with the requirements in this subpart
on the schedule in the following table based on your system type.

------------------------------------------------------------------------
                                       You must comply with subpart V
  If you are this type of system             monitoring by: \1\
------------------------------------------------------------------------
 Systems that are not part of a combined distribution system and systems
  that serve the largest population in the combined distribution system
------------------------------------------------------------------------
(1) System serving >= 100,000.....  April 1, 2012.
(2) System serving 50,000-99,999..  October 1, 2012.
(3) System serving 10,000-49,999..  October 1, 2013.
(4) System serving > 10,000.......  October 1, 2013 if no
                                     Cryptosporidium monitoring is
                                     required under Sec.   141.701(a)(4)
                                     or
                                    October 1, 2014 if Cryptosporidium
                                     monitoring is required under Sec.
                                     141.701(a)(4) or (a)(6)
-----------------------------------
      Other systems that are part of a combined distribution system
------------------------------------------------------------------------
(5) Consecutive system or           --at the same time as the system
 wholesale system.                   with the earliest compliance date
                                     in the combined distribution
                                     system.
------------------------------------------------------------------------
\1\ The State may grant up to an additional 24 months for compliance
  with MCLs and operational evaluaton levels if you require capital
  improvements to comply with an MCL.

    (6) Your monitoring frequency is specified in Sec.  141.621(a)(2).
    (i) If you are required to conduct quarterly monitoring, you must
begin monitoring in the first full calendar quarter that includes the
compliance date in the table in this paragraph (c).
    (ii) If you are required to conduct monitoring at a frequency that
is less than quarterly, you must begin monitoring in the calendar month
recommended in the IDSE report prepared under Sec.  141.601 or Sec.
141.602 or the calendar month identified in the subpart V monitoring
plan developed under Sec.  141.622 no later than 12 months after the
compliance date in this table.
    (7) If you are required to conduct quarterly monitoring, you must
make compliance calculations at the end of the fourth calendar quarter
that follows the compliance date and at the end of each subsequent
quarter (or earlier if the LRAA calculated based on fewer than four
quarters of data would cause the MCL to be exceeded regardless of the
monitoring results of subsequent quarters). If you are required to
conduct monitoring at a frequency that is less than quarterly, you must
make compliance calculations beginning with the first compliance sample
taken after the compliance date.
    (8) For the purpose of the schedule in this paragraph (c), the
State may determine that the combined distribution system does not
include certain consecutive systems based on factors such as receiving
water from a wholesale system only on an emergency basis or receiving
only a small percentage and small volume of water from a wholesale
system. The State may also determine that the combined distribution
system does not include certain wholesale systems based on factors such
as delivering water to a consecutive system only on an emergency basis
or delivering only a small percentage and small volume of water to a
consecutive system.
    (d) Monitoring and compliance. (1) Systems required to monitor
quarterly. To comply with subpart V MCLs in Sec.  141.64(b)(2), you
must calculate LRAAs for TTHM and HAA5 using monitoring results
collected under this subpart and determine that each LRAA does not
exceed the MCL. If you fail to complete four consecutive quarters of
monitoring, you must calculate compliance with the MCL based on the
average of the available data from the most recent four quarters. If
you take more than one sample per quarter at a monitoring location, you
must average all samples taken in the quarter at that location to
determine a quarterly average to be used in the LRAA calculation.
    (2) Systems required to monitor yearly or less frequently. To
determine compliance with subpart V MCLs in Sec.  141.64(b)(2), you
must determine that each sample taken is less than the MCL. If any
sample exceeds the MCL, you must comply with the requirements of Sec.
141.625. If no sample exceeds the MCL, the sample result for each
monitoring location is considered the LRAA for that monitoring
location.
    (e) Violation. You are in violation of the monitoring requirements
for each quarter that a monitoring result would be used in calculating
an LRAA if you fail to monitor.

Sec.  141.621  Routine monitoring.

    (a) Monitoring. (1) If you submitted an IDSE report, you must begin
monitoring at the locations and months you have recommended in your
IDSE report submitted under Sec.  141.605 following the schedule in
Sec.  141.620(c), unless the State requires other locations or
additional locations after its review. If you submitted a 40/30
certification under Sec.  141.603 or you qualified for a very small
system waiver under Sec.  141.604 or you are a nontransient
noncommunity water system serving < 10,000, you must monitor at the
location(s) and dates identified in your monitoring plan in Sec.
141.132(f), updated as required by Sec.  141.622.
    (2) You must monitor at no fewer than the number of locations
identified in this paragraph (a)(2).

----------------------------------------------------------------------------------------------------------------
                                                                                Distribution
                                                                                system
                                                                                monitoring
            Source water type              Population size category    Monitoring Frequency \1\   location total
                                                                                per monitoring
                                                                                period \2\
----------------------------------------------------------------------------------------------------------------
Subpart H:
                                          < 500......................  per year..................               2
                                          500-3,300.................  per quarter...............               2
                                          3,301-9,999...............  per quarter...............               2
                                          10,000-49,999.............  per quarter...............               4
                                          50,000-249,999............  per quarter...............               8
                                          250,000-999,999...........  per quarter...............              12
                                          1,000,000-4,999,999.......  per quarter...............              16
                                          >= 5,000,000..............  per quarter...............              20
Ground Water:
                                          < 500......................  per year..................               2
                                          500-9,999.................  per year..................               2
                                          10,000-99,999.............  per quarter...............               4
                                          100,000-499,999...........  per quarter...............               6
                                          >= 500,000................  per quarter...............               8
----------------------------------------------------------------------------------------------------------------
\1\ All systems must monitor during month of highest DBP concentrations.
\2\ Systems on quarterly monitoring must take dual sample sets every 90 days at each monitoring location, except
  for subpart H systems serving 500-3,300. Systems on annual monitoring and subpart H systems serving 500-3,300
  are required to take individual TTHM and HAA5 samples (instead of a dual sample set) at the locations with the
  highest TTHM and HAA5 concentrations, respectively. Only one location with a dual sample set per monitoring
  period is needed if highest TTHM and HAA5 concentrations occur at the same location (and month, if monitored
  annually).

    (3) If you are an undisinfected system that begins using a
disinfectant other than UV light after the dates in subpart U of this
part for complying with the Initial Distribution System Evaluation
requirements, you must consult with the State to identify compliance
monitoring locations for this subpart. You must then develop a
monitoring plan under Sec.  141.622 that includes those monitoring
locations.
    (b) Analytical methods. You must use an approved method listed in
Sec.  141.131 for TTHM and HAA5 analyses in this subpart. Analyses must
be conducted by laboratories that have received certification by EPA or
the State as specified in Sec.  141.131.

Sec.  141.622  Subpart V monitoring plan.

    (a)(1) You must develop and implement a monitoring plan to be kept
on file for State and public review. The monitoring plan must contain
the elements in paragraphs (a)(1)(i) through (a)(1)(iv) of this section
and be complete no later than the date you conduct your initial
monitoring under this subpart.
    (i) Monitoring locations;
    (ii) Monitoring dates;
    (iii) Compliance calculation procedures; and
    (iv) Monitoring plans for any other systems in the combined
distribution system if the State has reduced monitoring requirements
under the State authority in Sec.  142.16(m).
    (2) If you were not required to submit an IDSE report under either
Sec.  141.601 or Sec.  141.602, and you do not have sufficient subpart
L monitoring locations to identify the required number of subpart V
compliance monitoring locations indicated in Sec.  141.605(b), you must
identify additional locations by alternating selection of locations
representing high TTHM levels and high HAA5 levels until the required
number of compliance monitoring locations have been identified. You
must also provide the rationale for identifying the locations as having
high levels of TTHM or HAA5. If you have more subpart L monitoring
locations than required for subpart V compliance monitoring in Sec.
141.605(b), you must identify which locations you will use for subpart
V compliance monitoring by alternating selection of locations
representing high TTHM levels and high HAA5 levels until the required
number of subpart V compliance monitoring locations have been
identified.
    (b) If you are a subpart H system serving > 3,300 people, you must
submit a copy of your monitoring plan to the State prior to the date
you conduct your initial monitoring under this subpart, unless your
IDSE report submitted under subpart U of this part contains all the
information required by this section.
    (c) You may revise your monitoring plan to reflect changes in
treatment, distribution system operations and layout (including new
service areas), or other factors that may affect TTHM or HAA5
formation, or for State-approved reasons, after consultation with the
State regarding the need for changes and the appropriateness of
changes. If you change monitoring locations, you must replace existing
compliance monitoring locations with the lowest LRAA with new locations
that reflect the current distribution system locations with expected
high TTHM or HAA5 levels. The State may also require modifications in
your monitoring plan. If you are a subpart H system serving > 3,300
people, you must submit a copy of your modified monitoring plan to the
State prior to the date you are required to comply with the revised
monitoring plan.

Sec.  141.623  Reduced monitoring.

    (a) You may reduce monitoring to the level specified in the table
in this paragraph (a) any time the LRAA is < =0.040 mg/L for TTHM and
< =0.030 mg/L for HAA5 at all monitoring locations. You may only use
data collected under the provisions of this subpart or subpart L of
this part to qualify for reduced monitoring. In addition, the source
water annual average TOC level, before any treatment, must be < =4.0 mg/
L at each treatment plant treating surface water or ground water under
the direct influence of surface water, based on monitoring conducted
under either Sec.  141.132(b)(1)(iii) or Sec.  141.132(d).

----------------------------------------------------------------------------------------------------------------
                                                                                Distribution system
            Source water type               Population     Monitoring frequency \1\     monitoring location per
                                           size category                                   monitoring period
----------------------------------------------------------------------------------------------------------------
Subpart H:
                                                    < 500  ..........................  monitoring may not be
                                                                                reduced.
                                               500-3,300  per year..................  1 TTHM and 1 HAA5 sample:
                                                                                one at the location and
                                                                                during the quarter with
                                                                                the highest TTHM single
                                                                                measurement, one at the
                                                                                location and during the
                                                                                quarter with the highest
                                                                                HAA5 single measurement;
                                                                                1 dual sample set per
                                                                                year if the highest TTHM
                                                                                and HAA5 measurements
                                                                                occurred at the same
                                                                                location and quarter.
                                             3,301-9,999  per year..................  2 dual sample sets: one at
                                                                                the location and during
                                                                                the quarter with the
                                                                                highest TTHM single
                                                                                measurement, one at the
                                                                                location and during the
                                                                                quarter with the highest
                                                                                HAA5 single measurement.
                                           10,000-49,999  per quarter...............  2 dual sample sets at the
                                                                                locations with the
                                                                                highest TTHM and highest
                                                                                HAA5 LRAAs.
                                          50,000-249,999  per quarter...............  4 dual sample sets--at the
                                                                                locations with the two
                                                                                highest TTHM and two
                                                                                highest HAA5 LRAAs.
                                          250,000-999,99  per quarter...............  6 dual sample sets--at the
                                                       9                               locations with the three
                                                                                highest TTHM and three
                                                                                highest HAA5 LRAAs.
                                          1,000,000-4,99  per quarter...............  8 dual sample sets--at the
                                                   9,999                               locations with the four
                                                                                highest TTHM and four
                                                                                highest HAA5 LRAAs.
                                            >= 5,000,000  per quarter...............  10 dual sample sets--at
                                                                                the locations with the
                                                                                five highest TTHM and
                                                                                five highest HAA5 LRAAs.
Ground Water:
                                                    < 500  every third year..........  1 TTHM and 1 HAA5 sample:
                                                                                one at the location and
                                                                                during the quarter with
                                                                                the highest TTHM single
                                                                                measurement, one at the
                                                                                location and during the
                                                                                quarter with the highest
                                                                                HAA5 single measurement;
                                                                                1 dual sample set per
                                                                                year if the highest TTHM
                                                                                and HAA5 measurements
                                                                                occurred at the same
                                                                                location and quarter.
                                               500-9,999  per year..................  1 TTHM and 1 HAA5 sample:
                                                                                one at the location and
                                                                                during the quarter with
                                                                                the highest TTHM single
                                                                                measurement, one at the
                                                                                location and during the
                                                                                quarter with the highest
                                                                                HAA5 single measurement;
                                                                                1 dual sample set per
                                                                                year if the highest TTHM
                                                                                and HAA5 measurements
                                                                                occurred at the same
                                                                                location and quarter.
                                           10,000-99,999  per year..................  2 dual sample sets: one at
                                                                                the location and during
                                                                                the quarter with the
                                                                                highest TTHM single
                                                                                measurement, one at the
                                                                                location and during the
                                                                                quarter with the highest
                                                                                HAA5 single measurement.
                                          100,000-499,99  per quarter...............  2 dual sample sets; at the
                                                       9                               locations with the
                                                                                highest TTHM and highest
                                                                                HAA5 LRAAs.
                                              >= 500,000  per quarter...............  4 dual sample sets at the
                                                                                locations with the two
                                                                                highest TTHM and two
                                                                                highest HAA5 LRAAs.
----------------------------------------------------------------------------------------------------------------
\1\ Systems on quarterly monitoring must take dual sample sets every 90 days.

    (b) You may remain on reduced monitoring as long as the TTHM LRAA
< =0.040 mg/L and the HAA5 LRAA < =0.030 mg/L at each monitoring location
(for systems with quarterly reduced monitoring) or each TTHM sample
< =0.060 mg/L and each HAA5 sample < =0.045 mg/L (for systems with annual
or less frequent monitoring). In addition, the source water annual
average TOC level, before any treatment, must be < =4.0 mg/L at each
treatment plant treating surface water or ground water under the direct
influence of surface water, based on monitoring conducted under either
Sec.  141.132(b)(1)(iii) or Sec.  141.132(d).
    (c) If the LRAA based on quarterly monitoring at any monitoring
location exceeds either 0.040 mg/L for TTHM or 0.030 mg/L for HAA5 or
if the annual (or less frequent) sample at any location exceeds either
0.060 mg/L for TTHM or 0.045 mg/L for HAA5, or if the source water
annual average TOC level, before any treatment, >4.0 mg/L at any
treatment plant treating surface water or ground water under the direct
influence of surface water, you must resume routine monitoring under
Sec.  141.621 or begin increased monitoring if Sec.  141.625 applies.
    (d) The State may return your system to routine monitoring at the
State's discretion.

Sec.  141.624  Additional requirements for consecutive systems.

    If you are a consecutive system that does not add a disinfectant
but delivers water that has been treated with a primary or residual
disinfectant other than ultraviolet light, you must comply with
analytical and monitoring requirements for chlorine and chloramines in
Sec.  141.131 (c) and Sec.  141.132(c)(1) and the compliance
requirements in Sec.  141.133(c)(1) beginning April 1, 2009, unless
required earlier by the State, and report monitoring results under
Sec.  141.134(c).

Sec.  141.625  Conditions requiring increased monitoring.

    (a) If you are required to monitor at a particular location
annually or less frequently than annually under Sec.  141.621 or Sec.
141.623, you must increase monitoring to dual sample sets once per
quarter (taken every 90 days) at all locations if a TTHM sample is
>0.080 mg/L or a HAA5 sample is >0.060 mg/L at any location.

    (b) You are in violation of the MCL when the LRAA exceeds the
subpart V MCLs in Sec.  141.64(b)(2), calculated based on four
consecutive quarters of monitoring (or the LRAA calculated based on
fewer than four quarters of data if the MCL would be exceeded
regardless of the monitoring results of subsequent quarters). You are
in violation of the monitoring requirements for each quarter that a
monitoring result would be used in calculating an LRAA if you fail to
monitor.
    (c) You may return to routine monitoring once you have conducted
increased monitoring for at least four consecutive quarters and the
LRAA for every monitoring location is < =0.060 mg/L for TTHM and < =0.045
mg/L for HAA5.

Sec.  141.626  Operational evaluation levels.

    (a) You have exceeded the operational evaluation level at any
monitoring location where the sum of the two previous quarters' TTHM
results plus twice the current quarter's TTHM result, divided by 4 to
determine an average, exceeds 0.080 mg/L, or where the sum of the two
previous quarters' HAA5 results plus twice the current quarter's HAA5
result, divided by 4 to determine an average, exceeds 0.060 mg/L.
    (b)(1) If you exceed the operational evaluation level, you must
conduct an operational evaluation and submit a written report of the
evaluation to the State no later than 90 days after being notified of
the analytical result that causes you to exceed the operational
evaluation level. The written report must be made available to the
public upon request.
    (2) Your operational evaluation must include an examination of
system treatment and distribution operational practices, including
storage tank operations, excess storage capacity, distribution system
flushing, changes in sources or source water quality, and treatment
changes or problems that may contribute to TTHM and HAA5 formation and
what steps could be considered to minimize future exceedences.
    (i) You may request and the State may allow you to limit the scope
of your evaluation if you are able to identify the cause of the
operational evaluation level exceedance.
    (ii) Your request to limit the scope of the evaluation does not
extend the schedule in paragraph (b)(1) of this section for submitting
the written report. The State must approve this limited scope of
evaluation in writing and you must keep that approval with the
completed report.

Sec.  141.627  Requirements for remaining on reduced TTHM and HAA5
monitoring based on subpart L results.

    You may remain on reduced monitoring after the dates identified in
Sec.  141.620(c) for compliance with this subpart only if you qualify
for a 40/30 certification under Sec.  141.603 or have received a very
small system waiver under Sec.  141.604, plus you meet the reduced
monitoring criteria in Sec.  141.623(a), and you do not change or add
monitoring locations from those used for compliance monitoring under
subpart L of this part. If your monitoring locations under this subpart
differ from your monitoring locations under subpart L of this part, you
may not remain on reduced monitoring after the dates identified in
Sec.  141.620(c) for compliance with this subpart.

Sec.  141.628  Requirements for remaining on increased TTHM and HAA5
monitoring based on subpart L results.

    If you were on increased monitoring under Sec.  141.132(b)(1), you
must remain on increased monitoring until you qualify for a return to
routine monitoring under Sec.  141.625(c). You must conduct increased
monitoring under Sec.  141.625 at the monitoring locations in the
monitoring plan developed under Sec.  141.622 beginning at the date
identified in Sec.  141.620(c) for compliance with this subpart and
remain on increased monitoring until you qualify for a return to
routine monitoring under Sec.  141.625(c).

Sec.  141.629  Reporting and recordkeeping requirements.

    (a) Reporting. (1) You must report the following information for
each monitoring location to the State within 10 days of the end of any
quarter in which monitoring is required:
    (i) Number of samples taken during the last quarter.
    (ii) Date and results of each sample taken during the last quarter.
    (iii) Arithmetic average of quarterly results for the last four
quarters for each monitoring location (LRAA), beginning at the end of
the fourth calendar quarter that follows the compliance date and at the
end of each subsequent quarter. If the LRAA calculated based on fewer
than four quarters of data would cause the MCL to be exceeded
regardless of the monitoring results of subsequent quarters, you must
report this information to the State as part of the first report due
following the compliance date or anytime thereafter that this
determination is made. If you are required to conduct monitoring at a
frequency that is less than quarterly, you must make compliance
calculations beginning with the first compliance sample taken after the
compliance date, unless you are required to conduct increased
monitoring under Sec.  141.625.
    (iv) Whether, based on Sec.  141.64(b)(2) and this subpart, the MCL
was violated at any monitoring location.
    (v) Any operational evaluation levels that were exceeded during the
quarter and, if so, the location and date, and the calculated TTHM and
HAA5 levels.
    (2) If you are a subpart H system seeking to qualify for or remain
on reduced TTHM/HAA5 monitoring, you must report the following source
water TOC information for each treatment plant that treats surface
water or ground water under the direct influence of surface water to
the State within 10 days of the end of any quarter in which monitoring
is required:
    (i) The number of source water TOC samples taken each month during
last quarter.
    (ii) The date and result of each sample taken during last quarter.
    (iii) The quarterly average of monthly samples taken during last
quarter or the result of the quarterly sample.
    (iv) The running annual average (RAA) of quarterly averages from
the past four quarters.
    (v) Whether the RAA exceeded 4.0 mg/L.
    (3) The State may choose to perform calculations and determine
whether the MCL was exceeded or the system is eligible for reduced
monitoring in lieu of having the system report that information
    (b) Recordkeeping. You must retain any subpart V monitoring plans
and your subpart V monitoring results as required by Sec.  141.33.

PART 142--NATIONAL PRIMARY DRINKING WATER REGULATIONS
IMPLEMENTATION

0
21. The authority citation for part 142 continues to read as follows:

    Authority: 42 U.S.C. 300f, 300g-1, 300g-2, 300g-3, 300g-4, 300g-
5, 300g-6, 300j-4, 300j-9, and 300j-11.

0
22. Section 142.14 is amended by adding paragraph (a)(8) to read as
follows:

Sec.  142.14  Records kept by States.

    (a) * * *
    (8) Any decisions made pursuant to the provisions of 40 CFR part
141, subparts U and V of this part.
    (i) IDSE monitoring plans, plus any modifications required by the
State, must be kept until replaced by approved IDSE reports.
    (ii) IDSE reports and 40/30 certifications, plus any modifications

required by the State, must be kept until replaced or revised in their
entirety.
    (iii) Operational evaluations submitted by a system must be kept
for 10 years following submission.
* * * * *

0
23. Section 142.16 is amended by adding paragraph (m) to read as
follows:

Sec.  142.16  Special primacy requirements.

* * * * *
    (m) Requirements for States to adopt 40 CFR part 141, subparts U
and V. In addition to the general primacy requirements elsewhere in
this part, including the requirements that State regulations be at
least as stringent as federal requirements, an application for approval
of a State program revision that adopts 40 CFR part 141, subparts U and
V, must contain a description of how the State will implement a
procedure for addressing modification of wholesale system and
consecutive system monitoring on a case-by-case basis for part 141
subpart V outside the provisions of Sec.  141.29 of this chapter, if
the State elects to use such an authority. The procedure must ensure
that all systems have at least one compliance monitoring location.
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[FR Doc. 06-3 Filed 1-3-06; 8:45 am]

BILLING CODE 6560-50-P