Wisconsin Administrative Code, Subchapter I, Section NR 809.115 - Monitoring requirements for inorganic contaminants | Wisconsin Administrative Code

(1) GENERAL. Water suppliers shall conduct monitoring for the contaminants listed in s. NR 809.11(2) for the purpose of determining compliance with the maximum contaminant levels shall be conducted as follows:

(a) Groundwater sources shall be sampled under normal operating conditions at every entry point to the distribution system which is representative of each well being used after treatment, beginning in the initial compliance period. Each sample shall be taken at the same location unless conditions make another location more representative of each source or treatment plant.

(b) Surface water sources or combined surface water and groundwater sources shall be sampled under normal operating conditions, at every entry point to the distribution system after any application of treatment or in the distribution system at a point which is representative of each source after treatment, beginning in the initial compliance period. Each sample shall be taken at the same location unless conditions make another location more representative of each source or treatment plant.

(c) If a public water system draws water from more than one source and the sources are combined before distribution, the public water system shall be sampled at an entry point to the distribution system during periods of normal operating conditions when water is representative of all sources being used.

(d) Water suppliers for all new public water systems or for public water systems that use a new source of water that begin operation after January 22, 2004 shall demonstrate compliance with the MCLs specified in s. NR 809.11(2) in accordance with the requirements in this section. The water supplier shall also comply with the initial and routine sampling frequencies specified by the department to ensure a water supplier can demonstrate that the public water supply is in compliance with the MCLs. Routine and increased monitoring frequencies shall be conducted in accordance with the requirements of this section.

(2) MONITORING FREQUENCY FOR ASBESTOS. Water suppliers shall monitor public water systems to determine compliance with the maximum contaminant level for asbestos specified in s. NR 809.11(2) at the following frequencies:

(a) Initial and routine monitoring. Each community and non-transient, non-community water system shall monitor for asbestos during the first 3-year compliance period of each 9-year compliance cycle beginning in the compliance period starting January 1, 1993, unless a waiver is granted under par. (d).

(b) Waiver request. If the water supplier believes the public water system it is not vulnerable to either asbestos contamination in its source water or due to corrosion of asbestos-cement pipe, or both, the water supplier may apply to the department for a waiver of the monitoring requirement in par. (a).

(c) Waiver evaluation. The department may grant a waiver based on a consideration of all the following factors:

1. Potential asbestos contamination of the water source.

2. The use of asbestos-cement pipe for finished water distribution.

3. The corrosive nature of the water.

(d) Waiver conditions. The department may grant a waiver if the conditions in par. (b) and (c) are satisfied. A waiver remains in effect until the completion of the 3-year compliance period. Water suppliers for public water systems that do not receive a waiver shall monitor in accordance with the provisions of par. (a).

(e) Monitoring frequency with waiver. If the department grants the waiver, the water supplier is not required to monitor under par. (a).

(f) Sample location for vulnerable public water systems.

1. A public water system vulnerable to asbestos contamination due solely to corrosion of asbestos-cement pipe shall be sampled once at a tap served by asbestos-cement pipe and under conditions where asbestos contamination is most likely to occur.

2. A public water system vulnerable to asbestos contamination due both to its source water supply and corrosion of asbestos-cement pipe shall be sampled once at a tap served by asbestos-cement pipe and under conditions where asbestos contamination is most likely to occur.

(g) Sample frequency for public water systems with vulnerable source water. A public water system vulnerable to asbestos contamination due solely to source water shall be monitored in accordance with the provisions in par. (a).

(h) Monitoring when an MCL is exceeded. A public water system which exceeds the MCL as determined in s. NR 809.117 shall be monitored quarterly beginning in the next quarter after the violation occurred. The department may decrease the quarterly monitoring requirement to one sample as specified in par. (a) if the department has determined that the public water system is reliably and consistently below the maximum contaminant level. In no case may the department make this determination unless a groundwater system takes a minimum of 2 quarterly samples and a surface water system or a combined surface water and groundwater system takes a minimum of 4 quarterly samples.

(i) Grandfathered data. If monitoring data collected after January 1, 1990 is generally consistent with the requirements of this subsection, then the department may allow water suppliers for public water systems to use that data to satisfy the monitoring requirement for the initial compliance period beginning January 1, 1993.

(3) MONITORING FREQUENCY FOR MCLS OTHER than ASBESTOS, NITRATE, AND NITRITE. The water supplier shall conduct monitoring for each community and non-transient, non-community water system to determine compliance with the MCLs specified in s. NR 809.11(2) for antimony, arsenic, barium, beryllium, cadmium, chromium, cyanide, mercury, nickel, selenium and thallium at the frequencies specified in this subsection. The water supplier shall conduct monitoring for each community water system to determine compliance with the MCL in s. NR 809.11(2) for fluoride at the frequencies specified in this subsection:

(a) Initial monitoring. New community public water systems or community public water systems with new sources shall demonstrate compliance with the MCLs listed under s. NR 809.11(2) for antimony, arsenic, barium, beryllium, cadmium, chromium, cyanide, fluoride, mercury, nickel, selenium and thallium prior to initiating water service. New non-transient non-community public water systems or non-transient non-community public water systems with new sources shall take one sample for each contaminant listed in s. NR 809.11(2) beginning with the year the public water system initiates service or the new water source is put into service. If a waiver from cyanide monitoring has been granted under par. (c) cyanide is not required to be sampled for in the initial monitoring.

(b) Routine monitoring. Groundwater sources shall be sampled at each sampling point during each compliance period as determined by the department. Water suppliers for public water systems having surface water sources or combined surface water and groundwater sources shall take one sample annually at each sampling point. If a waiver from cyanide monitoring has been granted under par. (c), cyanide is not required to be sampled for routine monitoring.

(c) Waiver request. The water supplier may apply to the department for a waiver from the monitoring frequencies specified in par. (b). Public water systems that use a new water source are not eligible for a waiver until monitoring from the new source has been conducted in at least three compliance periods except that the department may grant a waiver for monitoring of cyanide beginning with initial monitoring, provided the public water system is not vulnerable to contamination because there is no industrial source of cyanide present.

(d) Waiver evaluation. In determining the appropriate reduced monitoring frequency, the department shall consider all of the following:

1. Reported concentrations from all previous monitoring.

2. The degree of variation in reported concentrations.

3. Other factors which may affect contaminant concentrations such as changes in groundwater pumping rates, changes in the public water system's configuration, changes in the public water system's operating procedures, or changes in stream flows or characteristics.

(e) Waiver conditions. The department may grant a waiver if surface water systems have been monitored annually for at least 3 years and groundwater systems have been monitored in at least three compliance periods. At least one of the 3 samples shall have been taken since January 1, 1990. Water suppliers for both surface and groundwater systems shall demonstrate that all previous analytical results were less than the maximum contaminant level. Public water systems that use a new water source are not eligible for a waiver until monitoring from the new source has been conducted in at least three compliance periods. A condition of the waiver shall be the collection of a minimum of one sample while the waiver is effective. The term during which the waiver is effective may not exceed 9 years.

(f) Monitoring frequency when an MCL has been exceeded. Public water systems which exceed the MCLs in s. NR 809.11(2) shall be monitored quarterly beginning in the next quarter after the violation occurred. The department may decrease the quarterly monitoring requirement to the frequencies specified in pars. (a) and (b) if the department has determined that the public water system is reliably and consistently below the maximum contaminant level. In no case may the department make this determination unless a groundwater system takes a minimum of 2 quarterly samples and a surface water system takes a minimum of 4 quarterly samples.

(4) MONITORING FREQUENCY FOR NITRATE. The water supplier for public water systems shall conduct monitoring for the public water systems to determine compliance with the MCL for nitrate specified in s. NR 809.11(2) at the following frequencies:

(a) Initial monitoring. Water suppliers for new public water systems or public water systems with new sources shall demonstrate compliance with the MCLs listed under s. NR 809.11(2) for nitrate prior to initiating water service.

(b) Routine monitoring. Each community water system and non-community water system shall be monitored according to the following frequencies:

1. Community water systems and non-transient non-community water systems served by groundwater shall be monitored annually.

2. Community water systems and non-transient non-community water systems served by surface water shall be monitored quarterly.

3. Transient non-community water systems shall be monitored annually.

(c) Increased monitoring due to detection at one-half the MCL and greater. For community and non-transient non-community water systems, the repeat monitoring frequency for groundwater systems shall be quarterly for at least one year following any one sample in which the concentration is greater than or equal to 5 mg/L nitrate as nitrogen. The department may reduce a groundwater system's sampling frequency to annual after 4 consecutive quarterly samples are reliably and consistently less than the MCL.

(d) Timing of samples after increased monitoring is ended. After quarterly sampling is completed, any community or non-transient non- community water system which is allowed to resume routine monitoring, under par. (b), shall be monitored during the quarter which previously resulted in the highest analytical result.

(e) Reduction of quarterly monitoring for surface water systems. The department may reduce a surface water system's sampling frequency to annual if all analytical results from 4 consecutive quarters are less than 5 mg/L nitrate as nitrogen. A surface water system shall return to quarterly monitoring if any one sample is greater than or equal to 5 mg/L nitrate.

(f) Monitoring if an MCL is exceeded. Where nitrate sampling results indicate an exceedance of the MCL, the water supplier shall take a confirmation sample as required under sub. (6) (b)

(5) MONITORING FREQUENCY FOR NITRITE. The water supplier shall conduct monitoring for the public water system to determine compliance with the MCL for nitrite specified in s. NR 809.11(2) at the following frequencies:

(a) Initial monitoring. Water suppliers for new public water systems or public water systems with new sources shall demonstrate compliance with the MCLs listed under s. NR 809.11(2) for nitrite prior to initiating water service.

(b) Routine monitoring. After the initial sample, water suppliers for public water systems where an analytical result for nitrite is less than 0.5 mg/L nitrite as nitrogen shall monitor at the frequency specified by the department. Community and non-transient non-community water systems shall be sampled at the same frequency as the monitoring required under sub. (3).

(c) Increased monitoring due to detection at one-half the MCL and greater. The repeat monitoring frequency shall be quarterly for at least one year following any one sample in which the concentration of nitrite is greater than or equal to 0.5 mg/L nitrite as nitrogen. The department may reduce the sampling frequency to annual after determining the concentration is reliably and consistently less than the MCL. Each subsequent annual sample shall be taken during the quarter which previously resulted in the highest analytical result.

(d) Monitoring if an MCL is exceeded. If nitrite sampling results indicate an exceedance of the MCL, the water supplier shall take a confirmation sample as required under sub. (6) (b).

(6) CONFIRMATION SAMPLES. The collection of confirmation samples shall comply with the following requirements:

(a) Department required confirmation samples. The department may require the collection of a confirmation sample where sample results indicate an exceedance of the MCL for antimony, arsenic, asbestos, barium, beryllium, cadmium, chromium, cyanide, fluoride, mercury, nickel, selenium or thallium. The confirmation sample shall be collected as soon as possible after the initial sample results were received, but not exceeding 2 weeks, at the same entry point.

(b) Mandatory confirmation samples. If nitrate or nitrite sampling results indicate an exceedance of the MCL, the water supplier shall take a confirmation sample within 24 hours of the water supplier's receipt of notification of the analytical results of the first sample. Water suppliers unable to comply with the 24-hour sampling requirement shall immediately notify the consumers served by the public water system in accordance with subch. VII and meet other Tier 1 public notification requirements under subch. VII. Water suppliers exercising this option shall take and analyze a confirmation sample within 2 weeks of notification of the analytical results of the first sample.

(c) Averaging of confirmation samples. If a confirmation sample is required for any contaminant, the results of the original and the confirmation sample shall be averaged. The resultant average shall be used to determine the public water system's compliance in accordance with s. NR 809.117(1).

(7) SAMPLING FREQUENCY. The department may require more frequent monitoring than specified in subs. (2), (3), (4) and (5) and may require confirmation samples for positive and negative results at its discretion.

(8) INCREASED MONITORING. Water suppliers may apply to the department to conduct more frequent monitoring than the minimum monitoring frequencies specified in this section.

(9) DESIGNATED SAMPLING TIME. Each public water system shall be monitored during the month, quarter or year designated by the department during each compliance period for all monitoring required under subs. (2), (3), (4) and (5).

(10) SAMPLING ERRORS. The department may delete results of obvious sampling errors, or may require the collection of additional samples to determine whether the result is or is not in error.