Wisconsin Administrative Code › Department of Natural Resources › NR 800 - Environmental Protection - Water Supply › Chapter NR 809 - Safe Drinking Water › Subchapter I - Maximum Contaminant Levels, Monitoring and Analytical Requirements for Primary Drinking Water Contaminants › Section NR 809.331 - Surface water source monitoring

Current through June 24, 2024
(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.