Wisconsin Administrative Code
Department of Natural Resources
NR 800 - Environmental Protection - Water Supply
Chapter NR 809 - Safe Drinking Water
Subchapter III - Maximum Contaminant Levels, Maximum Residual Disinfectant Levels, Monitoring, Analytical Requirements and Control of Disinfection Byproducts, Disinfection Residuals and Stage 1 and Stage 2 DBP
Section NR 809.60 - General requirements for Stage 2 DBP disinfection byproducts control

Universal Citation: WI Admin Code § NR 809.60

Current through August 26, 2024

(1) GENERAL. The following 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 levels for chlorine and chloramine for certain consecutive systems.

(2) APPLICABILITY. A public water system is subject to these requirements if the public water 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 or receives water that has been treated with a primary or residual disinfectant other than ultraviolet light.

(3) SCHEDULE. Public water systems shall comply with the requirements on the schedule in Table X based on public water system population:

Table X

Public Water System Population	Monitoring Compliance Dates:1
Public water systems that are not part of a combined distribution system and public water systems that serve the largest population in the combined distribution system
(1) PWS serving >= 100,000	April 1, 2012.
(2) PWS serving 50,000-99,999	October 1, 2012.
(3) PWS serving 10,000-49,999	October 1, 2013.
(4) PWS serving < 10,000	October 1, 2013 if no Cryptosporidium monitoring is required under s. NR 809.331(1) (d), or October 1, 2014 if Cryptosporidium monitoring is required under s. NR 809.331(1) (d) or (f)
Public water systems that are part of a combined distribution system
(5) Consecutive system or wholesale system	Water suppliers shall sample using the earliest compliance date of all the public water systems in the combined distribution system determined by the public water system with the largest population using the dates indicated in (1) to (4) of this table.

1 The department may grant up to an additional 24 months for compliance with MCLs and operational evaluation levels if the public water system requires capital improvements to comply with an MCL.

(4) MONITORING FREQUENCY. The frequency of monitoring is specified in s. NR 809.61(1) (c), Table Y.

(a) Water suppliers for public water systems required to be monitored quarterly shall begin monitoring in the first full calendar quarter that includes the compliance date in the table in sub. (3).

(b) Water suppliers for public water systems required to be monitored at a frequency less than quarterly shall begin monitoring in the calendar month recommended in the initial distribution system evaluation (IDSE) report they prepared for the EPA under Subpart U of 40 CFR part 141 or in the calendar month identified in the monitoring plan developed under s. NR 809.62 which shall be no later than 12 months after the compliance date in the table in par. (3).

(c) Water suppliers for public water systems required to be monitored quarterly, shall 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.

(d) If the public water system is required to be monitored at a frequency that is less than quarterly, the water supplier shall make compliance calculations beginning with the first compliance sample taken after the compliance date.

(5) CONSECUTIVE SYSTEMS. The department may determine that a public water system that receives some or all of its water supply from a wholesale system is not a consecutive system, based on any of the following factors:

(a) Receives water from a wholesale system only on an emergency basis.

(b) Receives only a small percentage and small volume of water from a wholesale system.

(6) WHOLESALE SYSTEMS. The department may determine that a public water system that provides some or all of the water supply for another public water system is not a wholesale system, based on any of the following factors:

(a) Delivers water to a consecutive system only on an emergency basis.

(b) Delivers only a small percentage and small volume of water to a consecutive system.

(7) MONITORING AND COMPLIANCE.

(a) Water suppliers for public water systems required to be monitored quarterly shall calculate LRAAs for TTHM and HAA5 to determine that each monitoring location LRAA does not exceed the MCL.

1. If four consecutive quarters of monitoring are not completed, compliance with the MCL shall be based on the average of the available data from the most recent four quarters.

2. If more than one sample per quarter is collected at a monitoring location, all samples taken in the quarter at that location shall be averaged to determine a quarterly average to be used in the LRAA calculation.

(b) Water suppliers for public water systems required to be monitored yearly or less frequently shall establish compliance for TTHM and HAA5 by using each sample collected to determine if it is less than the MCL.

1. If any sample exceeds the MCL, the public water system shall comply with the requirements of s. NR 809.63(2).

2. If no sample exceeds the MCL, the sample result for each monitoring location is considered the LRAA for that monitoring location.

(c) A public water system is in violation of the monitoring requirements for each quarter that a LRAA is calculated using a quarter in which the water supplier failed to monitor.

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