Section NR 809.331 - Surface water source monitoring(1) INITIAL ROUND OF SOURCE WATER MONITORING. Water suppliers shall have conducted the following monitoring according to the schedule in sub. (3) Table H, at treatment plants existing as of January 5, 2006 unless the public water system meets the monitoring exemption criteria in sub. (4). The initial source water monitoring requirements were conducted under 40 CFR part 141 National Primary Drinking Water Regulations Subpart W with EPA wholly responsible for implementation. For public water systems with treatment plants constructed after January 5, 2006 the department may require the following initial monitoring as part of the approval process under s. NR 811.21(1) (f). (a) Water suppliers for filtered public water systems serving at least 10,000 people shall sample their source water for Cryptosporidium, E. coli, and turbidity at least monthly for 24 months.(b) Water suppliers for unfiltered public water systems serving at least 10,000 people shall sample their source water for Cryptosporidium at least monthly for 24 months.(c) Water suppliers for filtered public water systems serving fewer than 10,000 people shall sample their source water for E. coli at least once every two weeks for 12 months. A filtered public water system serving fewer than 10,000 people may avoid E. coli monitoring if the water supplier notifies the department that Cryptosporidium will be monitored for as described in sub. (3). The water supplier shall notify the department no later than 3 months prior to the date the public water system is required to start E. coli monitoring under sub. (3).(d) Water suppliers for filtered public water systems serving fewer than 10,000 people shall sample their source water for Cryptosporidium at least twice per month for 12 months or at least monthly for 24 months if based on monitoring conducted under par. (c), and if they meet one of the following: 1. For public water systems using lake or reservoir sources, the annual mean E. coli concentration is greater than 10 E. coli /100 mL.2. For public water systems using flowing stream sources, the annual mean E. coli concentration is greater than 50 E. coli /100 mL.3. The public water system was not monitored for E. coli as described in par. (c).4. Public water systems using groundwater under the direct influence of surface water (GWUDI) shall comply with the requirements of this paragraph based on the E. coli level that applies to the nearest surface water body. If no surface water body is nearby, the public water system shall comply based on the requirements that apply to public water systems using lake or reservoir sources.(e) For filtered public water systems serving fewer than 10,000 people, the department may approve monitoring for an indicator other than E. coli under par. (c). The department also may approve an alternative to the E. coli concentration in par. (d) 1. to 3. to trigger Cryptosporidium monitoring. This approval by the department shall be provided to the public water system in writing and shall include the basis for the department's determination that the alternative indicator or trigger level will provide a more accurate identification of whether a public water system will exceed the Bin 1 Cryptosporidium level in s. NR 810.34.(f) Water suppliers for unfiltered public water systems serving fewer than 10,000 people shall sample their source water for Cryptosporidium at least twice per month for 12 months or at least monthly for 24 months.(g) Water suppliers may sample more frequently than required under this section if the sampling frequency is evenly spaced throughout the monitoring period.(2) SECOND ROUND OF SOURCE WATER MONITORING. Water supplier shall conduct a second round of source water monitoring that meets the requirements for monitoring parameters, frequency, and duration described in sub. (1), unless they meet the monitoring exemption criteria in sub. (4). Water suppliers shall conduct this monitoring on the schedule in sub. (3). (3) MONITORING SCHEDULE. According to EPA requirements, water supplier shall begin the monitoring required in subs. (1) and (2) no later than the month beginning with the date listed in Table H: TABLE H
Source Water Monitoring Starting Dates
| Public water systems that serve . . . | The initial round of source water monitoring shall begin no later than the month beginning: | The second round of source water monitoring shall begin no later than the month beginning: |
| (1) At least 100,000 people | October 1, 2006 | April 1, 2015 |
| (2) From 50,000 to 99,999 people | April 1, 2007 | October 1, 2015 |
| (3) From 10,000 to 49,999 people | April 1, 2008 | October 1, 2016 |
| (4) Fewer than 10,000 and monitor for E. coli1 | October 1, 2008 | October 1, 2017 |
| (5) Fewer than 10,000 and monitor for Cryptosporidium 2 | April 1, 2010 | April 1, 2019 |
1 Applies only to filtered public water systems.
2 Applies to filtered public water systems that meet the conditions of sub. (1) (e) and unfiltered public water systems.
(4) MONITORING AVOIDANCE. (a) Water suppliers for filtered public water systems are not required to conduct source water monitoring under this section if the public water system will provide a total of at least 5.5-log of treatment for Cryptosporidium, equivalent to meeting the treatment requirements of Bin 4 in s. NR 810.35.(b) Water supplier for unfiltered public water systems are not required to conduct source water monitoring under this section if the public water system will provide a total of at least 3-log Cryptosporidium inactivation, equivalent to meeting the treatment requirements for unfiltered public water systems with a mean Cryptosporidium concentration of greater than 0.01 oocysts/L in s. NR 810.36.(c) If a water supplier chooses to provide the level of treatment in par. (a) or (b), as applicable, rather than start source water monitoring, the water supplier shall notify the department in writing no later than the date the public water system is otherwise required to submit a sampling schedule for monitoring under s. NR 809.332. Alternatively, a water supplier may choose to stop sampling at any point after the public water system has initiated monitoring if the water supplier notifies the department in writing that the public water system will provide this level of treatment. Water supplier shall install and operate technologies to provide this level of treatment by the applicable treatment compliance date in s. NR 810.37. (5) PLANTS OPERATING ONLY PART OF THE YEAR. Water suppliers for public water systems with surface water treatment plants that operate for only part of the year shall conduct source water monitoring in accordance with this section, but with the following modifications: (a) Water supplier shall sample their source water only during the months that the plant operates unless the department specifies another monitoring period based on plant operating practices.(b) Water supplier for public water systems with plants that operate less than six months per year and that monitor for Cryptosporidium shall collect at least six Cryptosporidium samples per year during each of two years of monitoring. Samples shall be evenly spaced throughout the period the plant operates.(6) NEW SOURCES. (a) A water supplier for a public water system that begins using a new source of surface water or GWUDI after the public water system is required to begin monitoring under sub. (3) shall monitor the new source on a schedule the department approves. Source water monitoring shall meet the requirements of this section. The public water system shall also meet the bin classification and Cryptosporidium treatment requirements of ss. NR 810.34 and 810.35 or s. NR 810.36, as applicable, for the new source on a schedule the department approves.(b) The requirements of this section apply to public water systems with surface water treatment plants that begin operation after the monitoring start date applicable to the public water system's size under sub. (3).(c) The water supplier shall begin a second round of source water monitoring no later than 6 years following initial bin classification under s. NR 810.34 or determination of the mean Cryptosporidium level under s. NR 810.36, as applicable.(7) MONITORING VIOLATION. Failure to collect any source water sample required under this section in accordance with the sampling schedule, sampling location, analytical method, approved laboratory, and reporting requirements of s. NR 809. 332 to s. NR 809.336 is a monitoring violation.(8) GRANDFATHERING MONITORING DATA. The water supplier may use monitoring data collected prior to the applicable monitoring start date in sub. (3) to meet the initial source water monitoring requirements in sub. (1). This data, referred to as grandfathered data, may substitute for an equivalent number of months of data at the end of the monitoring period. All data submitted under this section shall meet the requirements in s. NR 809.334. Wis. Admin. Code Department of Natural Resources NR 809.331
CR 09-073: cr. Register November 2010 No. 659, eff. 12-1-10; correction in (8) made under s. 13.92(4) (b) 7, Stats., Register November 2010 No. 659.