Nebraska Administrative Code › Topic - HEALTH AND HUMAN SERVICES SYSTEM › Title 179 - PUBLIC WATER SYSTEMS › Chapter 24 - STAGE 2 DISINFECTANTS AND DISINFECTION BYPRODUCTS (DBPs) › Section 179-24-006 - REDUCED MONITORING

Current through June 17, 2024
006.01 A system may
				reduce monitoring to the level specified in the following table any time the
				LRAA is < 0.040 mg/L for TTHMs and < 0.030 mg/L for HAA5 at all
				monitoring locations. A system may only use data collected under the provisions
				of this chapter or 179 NAC 16 to qualify for reduced monitoring. In addition,
				the source water annual average total organic carbon (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 179 NAC 16-005.02 item 1.c. or 16-005.04.
Source water type
Population size category
Monitoring frequency1
Distribution system monitoring location per
						  monitoring period
Surface water or GWUDI:
<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, 000-999,999
per quarter
6 dual sample sets - at the locations with the three
						  highest TTHM and three highest HAA5 LRAAs.
1,000, 000-4,999,999
per quarter
8 dual sample sets - at the 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, 000-499,999
per quarter
2 dual sample sets: at the 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.
006.02 A system 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 179 NAC 16-005.02 item 1.c or 179 NAC 16-005.04.
006.03 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, is > 4.0 mg/L at any
				treatment plant treating surface water or ground water under the direct
				influence of surface water, the system must resume routine monitoring under 179
				NAC
				24-004 or begin increased monitoring
				if 179 NAC
				24-008 applies.
006.04 The Department may return a system to
				routine monitoring at the Department's discretion.