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 809.117 - Compliance requirements for inorganic contaminants

Current through June 24, 2024
(1) COMPLIANCE
				  DETERMINATIONS. Compliance for inorganic contaminants shall be determined based
				  on all of the following:
(a) Compliance with
				  s.
				  NR
				  809.11 shall be determined based on the analytical
				  results obtained at each entry point. Any contaminant listed in s.
				  NR
				  809.11 which is detected shall be
				  quantified.
(b) For public water
				  systems which are monitored more frequently than annually, compliance with the
				  MCLs for antimony, arsenic, asbestos, barium, beryllium, cadmium, chromium,
				  cyanide, fluoride, mercury, nickel, selenium or thallium is determined by a
				  running annual average at each entry point. If the average at any sampling
				  point is greater than the MCL, then the public water system is out of
				  compliance. If any one or more samples would cause the annual average to exceed
				  an MCL, then the public water system is out of compliance immediately. Any
				  sample below the reported method detection limit shall be calculated at zero
				  for the purpose of determining the annual average. If a water supplier fails to
				  collect the required number of samples, compliance shall be based on the total
				  number of samples collected.
(c)
				  For public water systems which are monitored annually, or less frequently, the
				  public water system is out of compliance with the MCL for antimony, arsenic,
				  asbestos, barium, beryllium, cadmium, chromium, cyanide, fluoride, mercury,
				  nickel, selenium or thallium if the level of a contaminant at any entry point
				  is greater than the MCL. If a confirmation sample is required by the
				  department, compliance shall be based on the average of the 2 samples. If a
				  water supplier fails to collect the required number of samples, compliance
				  shall be based on the total number of samples collected.
(d) Compliance with the MCLs for nitrate,
				  nitrite or combined nitrate and nitrite is determined based on one sample if
				  the levels of these contaminants are below the MCLs. If the levels exceed a MCL
				  in the initial sample, a confirmation sample is required in accordance with s.
				  NR
				  809.115(6) (b). Compliance shall be
				  determined based on the average of the initial and confirmation
				  samples.
(e) Arsenic sampling
				  results shall be reported to the nearest 0.001 mg/L.
(f) Public water systems remain out of
				  compliance with the MCLs for nitrate, nitrite, or combined nitrate and nitrite
				  until the results of 4 consecutive quarterly samples do not exceed the MCL. The
				  department may specify alternate means for returning to compliance with the
				  MCLs for nitrate, nitrite, or combined nitrate and nitrite. Alternate
				  compliance agreements shall be in writing.