Michigan Administrative Code › Department - Environmental Quality › Drinking Water And Municipal Assistance Division › Supplying Water to the Public › Part 7 - SURVEILLANCE, INSPECTION, AND MONITORING › Section R. 325.10719j - Disinfection byproducts; reduced monitoring

Current through Vol. 24-12, July 15, 2024
Rule 719j.
(1) The
				  community or nontransient noncommunity water supply that is subject to
				  disinfection byproducts requirements of R 325.10610d may reduce monitoring any
				  time the LRAA is less than or equal to 0.040 mg/L for TTHM and less than or
				  equal to 0.030 mg/L for HAA5 at all monitoring locations. The supply may only
				  use data collected under R 325.10610b to R 325.10610d, R 325.10719e to R
				  325.10719f, and R 325.10719h to R 325.10719n to qualify for reduced monitoring.
				  In addition, the source water annual average TOC level, before treatment, shall
				  be less than or equal to 4.0 mg/L at each treatment plant treating surface
				  water or groundwater under the direct influence of surface water, based on
				  monitoring conducted under either R 325.10719e (2) (a) (3) or R 325.10719e (4).
				  Reduced monitoring shall be to the level specified in the following table:
Source Water Type
Populatio n size category
Monitorin g Frequency *
Distribution system monitoring location per
								monitoring period
Subpart H
less than 500
monitoring may not be reduced
Subpart H
500 to 3,300
per year
1 TTHM and 1 HAA5 sample: 1 at the location and
								during the quarter with the highest TTHM single measurement, 1 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.
Subpart H
3,301 to 9,999
per year
2 dual sample sets: 1 at the location and during the
								quarter with the highest TTHM single measurement, 1 at the location and during
								the quarter with the highest HAA5 single measurement.
Subpart H
10,000 to 49,999
per quarter
2 dual sample sets at the locations with the highest
								TTHM and highest HAA5 LRAAs.
Subpart H
50,000 to 249,999
per quarter
4 dual sample sets--at the locations with the 2
								highest TTHM and 2 highest HAA5 LRAAs.
Subpart H
250,000 to 999,999
per quarter
6 dual sample sets--at the locations with the 3
								highest TTHM and 3 highest HAA5 LRAAs.
Subpart H
1,000,000 to 4,999,999
per quarter
8 dual sample sets--at the locations with the 4
								highest TTHM and 4 highest HAA5 LRAAs.
Subpart H
greater than or equal to 5,000,000
per quarter
10 dual sample sets--at the locations with the 5
								highest TTHM and 5 highest HAA5 LRAAs.
Groundw ater
less than 500
every third year
1 TTHM and 1 HAA5 sample: 1 at the location and
								during the quarter with the highest TTHM single measurement, 1 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.
Groundw ater
500 to 9,999
per year
1 TTHM and 1 HAA5 sample: 1 at the location and
								during the quarter with the highest TTHM single measurement, 1 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.
Groundw ater
10,000 to 99,999
per year
2 dual sample sets: 1 at the location and during the
								quarter with the highest TTHM single measurement, 1 at the location and during
								the quarter with the highest HAA5 single measurement.
Groundw ater
100,000 to 499,999
per quarter
2 dual sample sets; at the locations with the
								highest TTHM and highest HAA5 LRAAs.
Groundw ater
greater than or equal to 500,000
per quarter
4 dual sample sets at the locations with the 2
								highest TTHM and 2 highest HAA5 LRAAs.
* Supplies on quarterly monitoring shall take dual sample
					 sets every 90 days.
(2) The
				  supply may remain on reduced monitoring as long as the TTHM LRAA less than or
				  equal to 0.040 mg/L and the HAA5 LRAA less than or equal to 0.030 mg/L at each
				  monitoring location (for supplies with quarterly reduced monitoring) or each
				  TTHM sample less than or equal to 0.060 mg/L and each HAA5 sample less than or
				  equal to 0.045 mg/L (for supplies with annual or less frequent monitoring). In
				  addition, the source water annual average TOC level, before treatment, shall be
				  less than or equal to 4.0 mg/L at each treatment plant treating surface water
				  or groundwater under the direct influence of surface water, based on monitoring
				  conducted under either R 325.10719e (2) (a) (iii) or R 325.10719e
				  (4).
(3) If the LRAA based on
				  quarterly monitoring at a 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 a
				  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 treatment, is greater than 4.0
				  mg/L at a treatment plant treating surface water or groundwater under the
				  direct influence of surface water, the supply shall resume routine monitoring
				  under R 325.10719h or begin increased monitoring if R 325.10719k
				  applies.
(4) The department may
				  return the supply to routine monitoring under R 325.10732.