NR 809.548(3)(3) Monitoring after installation of corrosion control. The water supplier of any large system which installs optimal corrosion control treatment pursuant to s. NR 809.542 (4) (d) shall measure the water quality parameters at the following locations and frequencies during each 6-month monitoring period specified in s. NR 809.547 (4) (b) 1. The water supplier of any small or medium-size system which installs optimal corrosion control treatment shall conduct such monitoring during each 6-month monitoring period specified in s. NR 809.547 (4) (b) 2. in which the public water system exceeds the lead or copper action level.

NR 809.548(3)(c)(c) The water supplier for a groundwater system can limit entry point sampling described in par. (b) to those entry points that are representative of water quality and treatment conditions throughout the public water system. If water from untreated groundwater sources mixes with water from treated groundwater sources, the water supplier shall monitor for water quality parameters both at representative entry points receiving treatment and representative entry points receiving no treatment. Prior to the start of any monitoring under this subsection, the water supplier shall provide to the department written information identifying the selected entry points and documentation, including information on seasonal variability, sufficient to demonstrate that the sites are representative of water quality and treatment conditions throughout the public water system.

NR 809.548(4)(4) Monitoring after the department specifies water quality parameter values for optimal corrosion control. After the department specifies the values for applicable water quality control parameters reflecting optimal corrosion control treatment under s. NR 809.543 (6) and (7), water suppliers for all large systems shall measure the applicable water quality parameters in accordance with sub. (3) and determine compliance with the requirements of s. NR 809.543 (8) every six months with the first six-month period to begin on either January 1 or July 1, whichever comes first, after the department specifies the optimal values under s. NR 809.543 (6). Water suppliers for any small or medium-size systems shall conduct such monitoring during each six-month period specified in this paragraph in which the public water system exceeds the lead or copper action level. For any such small and medium-size system that is subject to a reduced monitoring frequency pursuant to s. NR 809.547 (4) (d) at the time of the action level exceedance, the start of the applicable six-month monitoring period under this paragraph shall coincide with the start of the applicable monitoring period under s. NR 809.547 (4) (d). Compliance with department designated optimal water quality parameter values shall be determined as specified under s. NR 809.543 (8).

NR 809.548(5)(5) Reduced monitoring.

NR 809.548(5)(a)(a) Water suppliers for any public water system that maintains the range of values for the water quality parameters reflecting optimal corrosion control treatment during each of 2 consecutive 6-month monitoring periods under sub. (4) shall continue monitoring at the entry points to the distribution system as specified in sub. (3) (b). Water suppliers for such public water systems may collect 2 tap samples for applicable water quality parameters from the following reduced number of sites during each 6-month monitoring period.

NR 809.548(5)(b)1.1. Water suppliers for any public water system that maintains the range of values for the water quality parameters reflecting optimal corrosion control treatment specified by the department under s. NR 809.543 (6) during 3 consecutive years of monitoring may reduce the frequency with which they collect the number of tap samples for applicable water quality parameters specified in par. (a) from every six months to annually. This sampling begins during the calendar year immediately following the end of the monitoring period in which the third consecutive year of six-month monitoring occurs. Water suppliers for any public water system that maintains the range of values for the water quality parameters reflecting optimal corrosion control treatment specified by the department under s. NR 809.543 (6) during 3 consecutive years of annual monitoring under this paragraph may reduce the frequency with which they collect the number of tap samples for applicable water quality parameters specified in par. (a) of this section from annually to every 3 years. This sampling begins no later than the third calendar year following the end of the monitoring period in which the third consecutive year of monitoring occurs.

NR 809.548(5)(b)2.2. A water supplier for a public water system may reduce the frequency with which they collect tap samples for applicable water quality parameters specified in par. (a) to every 3 years if the public water system demonstrates during 2 consecutive monitoring periods that the public water system’s tap water lead level at the 90th percentile is less than or equal to the practical quantitation limit for lead specified in s. NR 809.541 (4) (a), that its tap water copper level at the 90th percentile is less than or equal to 0.65 mg/L for copper in s. NR 809.54 (3) (b), and that it also has maintained the range of values for the water quality parameters reflecting optimal corrosion control treatment specified by the department under s. NR 809.543 (6). Monitoring conducted every three years shall be done no later than every third calendar year.

NR 809.548(5)(c)(c) Water suppliers for any public water system that maintains the range of values for the water quality parameters reflecting optimal corrosion control treatment specified by the department under s. NR 809.543 (6) during 3 consecutive years of annual monitoring may reduce the frequency with which they collect the number of tap samples for applicable water quality parameters specified in par. (a) from annually to every 3 years.