Community water systems and non-transient, non-community water systems shall conduct monitoring to determine compliance with the maximum contaminant levels specified in §290.103 of this title (relating to Standards of Chemical Quality). Transient, non-community water systems shall conduct monitoring to determine compliance with the nitrate and nitrite maximum contaminant levels in §290.103 of this title (relating to Standards of Chemical Quality) (as appropriate) in accordance with this section.

1. (1) Monitoring locations for inorganic constituents other than asbestos shall be determined as follows.

   1. (A) Groundwater systems shall take a minimum of one sample at every entry point to the distribution system (hereafter called a sampling point).
   2. (B) Surface water systems and systems using a combination of groundwater and surface water sources shall take a minimum of one sample at every entry point to the distribution system (hereafter called a sampling point).
   3. (C) If a system draws water from more than one source and the sources are combined before distribution, the system must sample at an entry point to the distribution system during periods of normal operating conditions (i.e., when water is representative of all sources being used).
   4. (D) Systems shall take subsequent samples at the same sampling points unless conditions make another sampling point more representative of each source or treatment plant.

   5. (E) The commission may reduce the total number of samples which must be analyzed by allowing the use of compositing. Composite samples from a maximum of five sampling points are allowed. Compositing of samples must be done in the laboratory or in the field by commission staff.

      1. (i) If the concentration in the composite sample is greater than or equal to the proportional contribution of the MCL of any inorganic chemical, then a follow-up sample must be collected within 14 days from each sampling point included in the composite (i.e., 20% of MCL when five points are composited). These samples must be analyzed for the contaminant(s) which were excessive in the composite sample. Detection limits for each analytical method are as listed in 40 Code of Federal Regulations §141.23(a)(4)(i).
      2. (ii) Compositing may be permitted only at groundwater sampling points within a single system.
      3. (iii) If duplicates of the original sample taken from each sampling point used in the composite are available, the system may use these instead of resampling. The duplicates must be analyzed within 14 days of the composite.

2. (2) The frequency of monitoring to determine compliance with the MCL for asbestos specified in §290.103 of this title (relating to Standards of Chemical Quality) shall be as follows.

   1. (A) Each community and non-transient, non-community water system not receiving a waiver is required to monitor for asbestos during the first three-year compliance period of each nine-year compliance cycle beginning with the initial compliance period.

   2. (B) The commission may grant a waiver based on a consideration of the following factors:

      1. (i) potential for asbestos contamination of the water source; and
      2. (ii) the use of asbestos-cement pipe for finished water distribution and the corrosive nature of the water.
   3. (C) A waiver remains in effect until the completion of the three-year compliance period.
   4. (D) A system vulnerable to asbestos contamination due solely to corrosion of asbestos-cement pipe shall take one sample at a tap served by asbestos-cement pipe, under conditions where asbestos contamination is most likely to occur.
   5. (E) A system vulnerable to asbestos contamination due solely to source water shall monitor in accordance with the provisions of paragraph (1) of this section.
   6. (F) A system vulnerable to asbestos contamination due both to its source water supply and corrosion of asbestos-cement pipe shall take one sample at a tap served by asbestos-cement pipe, under conditions where asbestos contamination is most likely to occur.
   7. (G) A system which exceeds the MCL for asbestos as determined in paragraph (9) of this section shall monitor quarterly beginning in the next quarter after the violation occurs.
   8. (H) The commission may decrease the quarterly monitoring requirement to the frequency specified in paragraph (2)(A) of this section provided the commission has determined that the system is reliably and consistently below the maximum contaminant level. In no case can the commission make this determination unless a groundwater system takes a minimum of two quarterly samples and a surface (or combined surface/ground) water system takes a minimum of four quarterly samples.
   9. (I) If monitoring data collected after January 1, 1990, are generally consistent with the requirements of paragraph (2) of this section (relating to Standards of Chemical Quality), then the commission may allow systems to use that data to satisfy the monitoring requirement for the initial compliance period.

3. (3) Monitoring conducted to determine compliance with the maximum contaminant levels in §290.103 of this title (relating to Standards of Chemical Quality) for antimony, arsenic, barium, beryllium, cadmium, chromium, cyanide, fluoride, mercury, nickel, selenium, and thallium shall be as follows.

   1. (A) Beginning in the initial compliance period, groundwater systems shall take one sample at each sampling point once every three years. Beginning in the initial compliance period, surface water systems (or combined surface/ground) shall take one sample annually at each sampling point. Each of the sampling frequencies listed in this paragraph constitute one round of sampling for groundwater and surface water systems, respectively.
   2. (B) The commission may grant waivers from the monitoring frequencies specified in subparagraph (A) of this paragraph. The term during which the waiver is effective shall not exceed one compliance cycle (nine years).
   3. (C) A condition of the waiver shall be that a system must take a minimum of one sample while the waiver is effective.
   4. (D) The commission may grant a waiver provided surface water systems have monitored annually for at least three years and groundwater systems have conducted a minimum of three rounds of monitoring. (At least one sample shall have been taken since January 1, 1990.) Both surface and groundwater systems shall demonstrate that all previous analytical results were less than the MCL. Systems that use a new water source are not eligible for a waiver until three rounds of monitoring from the new source have been completed.

   5. (E) In determining the appropriate reduced monitoring frequency, the commission shall consider:

      1. (i) reported contaminant concentrations from all previous monitoring;
      2. (ii) the degree of variation in reported concentrations; and
      3. (iii) other factors which may affect contaminant concentrations such as changes in groundwater pumping rates, changes in the system's configuration, changes in the system's operating procedures, or changes in the flow or characteristics of a reservoir or stream used as the water source.
   6. (F) If a decision by the commission is made to grant a waiver it shall be made in writing and shall set forth the basis for the determination. The determination may be initiated by the commission. The commission shall review and, where appropriate, revise the waiver of monitoring frequency when other data relevant to the system become available.
   7. (G) Systems which exceed the IOC MCLs as calculated in paragraph (9) of this section shall monitor quarterly beginning in the next quarter after the violation occurs.
   8. (H) The commission may decrease the quarterly monitoring requirement to the frequencies specified in subparagraphs (A) and (B) of this paragraph provided it has determined that the system is reliably and consistently below the MCL. In no case can the commission make this determination unless a groundwater system takes a minimum of two quarterly samples and a surface water system takes a minimum of four quarterly samples.

4. (4) All public water systems (community; non-transient, non-community; and transient, non-community) shall monitor to determine compliance with the maximum contaminant level for nitrate as follows.

   1. (A) Community and non-transient, non-community water systems served by groundwater shall monitor annually beginning January 1, 1993; systems served by surface water shall monitor quarterly beginning January 1, 1993.
   2. (B) Each transient non-community water system shall monitor annually beginning January 1, 1993.
   3. (C) The repeat monitoring frequency for community and non-transient, non-community groundwater systems shall be quarterly for at least one year following any one sample in which the concentration is greater than or equal to 50% of the MCL. The commission may allow a groundwater system to reduce the sampling frequency to annually after four consecutive quarterly samples are reliably and consistently less than the MCL.
   4. (D) The commission may allow community and non-transient, non-community water systems to reduce the sampling frequency to annually if all analytical results from four consecutive quarters are less than 50% of the MCL. A surface water system shall return to quarterly monitoring if any one sample is greater than 50% of the MCL.
   5. (E) After the initial round of quarterly sampling for surface water systems is completed, any community or non-transient non-community system which is monitoring annually shall take subsequent samples during the quarter which previously resulted in the highest analytical result.

5. (5) All public water systems (community; non-transient, non-community; and transient, non-community systems) shall monitor to determine compliance with the maximum contaminant level for nitrite as follows.

   1. (A) All public water systems shall take one sample at each sampling point during the initial compliance period.
   2. (B) After the initial sample, systems where the analytical result for nitrite is less than 50% of the MCL shall monitor at the frequency specified by the commission.
   3. (C) The repeat monitoring frequency for nitrite for all public water systems shall be quarterly for at least one year following any one sample in which the concentration is greater than or equal to 50% of the MCL. The commission may allow a system to reduce the sampling frequency to annual after determining the system is reliably and consistently less than the MCL.
   4. (D) Systems which are monitoring annually shall take each subsequent sample during the quarter which previously resulted in the highest analytical result.

6. (6) Confirmation sampling.

   1. (A) Where the results of sampling for antimony, arsenic, asbestos, barium, beryllium, cadmium, chromium, cyanide, fluoride, mercury, nickel, selenium, or thallium indicate an exceedance of the MCL, one additional sample from the same sampling point shall be collected as soon as possible after the initial sample.
   2. (B) Where nitrate or nitrite sampling results indicate an exceedance of the maximum contaminant level, the system shall take a confirmation sample within 24 hours of the system's receipt of notification of the analytical results of the first sample. Systems unable to comply with the 24-hour sampling requirement must immediately notify the consumers served by the public water system in accordance with §290.103(8)(A)(iii) of this title (relating to Standards of Chemical Quality). Systems exercising this option must take and analyze a confirmation sample within two weeks of notification of the analytical results of the first sample.
   3. (C) If a commission-required confirmation sample is taken for any contaminant, then the results of the initial and confirmation sample shall be averaged. The resulting average shall be used to determine the system's compliance in accordance with paragraph (9) of this section. The commission has the discretion to delete results of obvious sampling errors.
7. (7) The commission may require more frequent monitoring than specified in paragraphs (2)-(5) of this section or may require confirmation samples for positive and negative results at its discretion.
8. (8) Systems may apply to the commission to conduct more frequent monitoring than the minimum monitoring frequencies specified in this section.

9. (9) Compliance with §290.103 of this title (relating to Standards of Chemical Quality) (as appropriate) shall be determined based on the analytical result(s) obtained at each sampling point.

   1. (A) For systems which are conducting monitoring at a frequency greater than annual, compliance with the MCLs for antimony, arsenic, asbestos, barium, beryllium, cadmium, chromium, cyanide, fluoride, mercury, nickel, selenium, and thallium is determined by a running annual average at each sampling point. If the average at any sampling point is greater than the MCL, then the system is out of compliance. If any one sample would cause the annual average to be exceeded, then the system is out of compliance immediately. Any sample below the method detection limit shall be calculated at zero for the purpose of determining the annual average.
   2. (B) For systems which are monitoring annually, or less frequently, the system is out of compliance for antimony, arsenic, asbestos, barium, beryllium, cadmium, chromium, cyanide, fluoride, mercury, nickel, selenium, and thallium if the level of a contaminant at any sampling point is greater than the MCL. If a confirmation sample is required by the commission, the determination of compliance will be based on the average of the two samples.
   3. (C) Compliance with the MCLs for nitrate and nitrite is based on one sample if the levels of these contaminants are below the MCLs. If the levels of nitrate or nitrite exceed the MCLs in any sample, a confirmation sample is required in accordance with paragraph (6)(B) of this section, and compliance shall be based on the average of the initial and confirmation samples.
   4. (D) If a public water system has a distribution system separable from other parts of the distribution system with no interconnections, the commission may allow the system to give public notice to only the area served by that portion of the system which is out of compliance.
10. (10) Each public water system shall monitor at the time designated by the commission during each compliance period.

Source Note:The provisions of this §290.108 adopted to be effective April 15, 1994, 19 TexReg 2282.