1. (1) Initial round of source water monitoring. Systems shall conduct the following monitoring, based on the monitoring schedule prescribed in paragraph (3) of this subdivision, unless they meet the monitoring exemption criteria in paragraph (4) of this subdivision:

   1. (i) Filtered systems serving at least 10,000 people shall sample their source water for Cryptosporidium, E. coli, and turbidity at least monthly for 24 months.
   2. (ii) Unfiltered systems serving at least 10,000 people shall sample their source water for Cryptosporidium at least monthly for 24 months.

   3. (iii) Filtered systems serving fewer than 10,000 people:

      1. (a) shall sample their source water for E. coli and use an approved method to enumerate the presence of E. coli at least once every two weeks for 12 months;
      2. (b) may avoid E. coli monitoring if the system notifies the State that it will monitor for Cryptosporidium as described in subparagraph (iv) of this paragraph. The system shall notify the State no later than three months prior to the date the system is otherwise required to start E. coli monitoring under paragraph (3) of this subdivision; and

      3. (c) 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 this subparagraph, they meet one of the following criteria:

         1. (1) the annual mean E. coli concentration is greater than 10 E. coli/ 100 mL; or
         2. (2) the system does not conduct E. coli monitoring at least once every two weeks for 12 months;
         3. (3) the State may approve an alternative to the E. coli concentration specified in subclause (1) of this clause to trigger Cryptosporidium monitoring. This approval by the State will be provided to the system in writing and will include the basis for the State’s determination that the alternative trigger concentration will provide a more accurate identification of whether a system will exceed the Bin 1 Cryptosporidium level specified in section 5-1.83(a)(2) of this Subpart.
   4. (iv) Unfiltered 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.
   5. (v) Systems may sample more frequently than required under this section if the sampling frequency is evenly spaced throughout the monitoring period.
2. (2) Second round of source water monitoring. Systems shall conduct a second round of source water monitoring that meets the requirements for monitoring parameters, frequency, and duration described in paragraph (1) of this subdivision, unless they meet the monitoring exemption criteria in paragraph (4) of this subdivision. Systems shall conduct this monitoring on the schedule in paragraph (3) of this subdivision.
3. (3) Monitoring schedule. Systems shall comply with the monitoring schedule prescribed in 40 CFR 141.701(c).

4. (4) Monitoring avoidance.

   1. (i) Filtered systems are not required to conduct source water monitoring under this section if the 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 section 5-1.83(b) of this Subpart.
   2. (ii) Unfiltered systems are not required to conduct source water monitoring under this section if the system will provide a total of at least 3-log Cryptosporidium inactivation, equivalent to meeting the treatment requirements for unfiltered systems with a mean Cryptosporidium concentration of greater than 0.01 oocysts/L in section 5-1.83(c) of this Subpart.
   3. (iii) If a system chooses to provide the level of treatment in subparagraph (i) or (ii) of this paragraph, as applicable, rather than start source water monitoring, the system shall notify the State in writing no later than the date the system is otherwise required to submit a sampling schedule for monitoring under subdivision (b) of this section. Alternatively, a system may choose to stop sampling at any point after it has initiated monitoring if it notifies the State in writing that it will provide this level of treatment. Systems shall install and operate technologies to provide this level of treatment by the applicable treatment compliance date in section 5-1.83(d) of this Subpart.

5. (5) Plants operating only part of the year. Systems with surface water sources or ground water sources directly influenced by surface water and with plants that operate for only part of the year shall conduct source water monitoring in accordance with this section and section 5-1.80 of this Subpart, but with the following modifications:

   1. (i) systems shall sample their source water only during the months that the plant operates unless the State specifies another monitoring period based on plant operating practices;
   2. (ii) 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. (6) New sources.

   1. (i) A system that begins using a new source of surface water or ground water directly influenced by surface water after the system is required to begin monitoring under paragraph (3) of this subdivision shall monitor the new source on a schedule approved by the State. Source water monitoring shall meet the requirements of this section. The system also shall meet the bin classification of section 5-1.83(a) of this Subpart and Cryptosporidium treatment requirements of section 5-1.83(b) or (c) of this Subpart, as applicable, for the new source on a schedule approved by the State.
   2. (ii) The requirements of this paragraph also apply to new systems that use surface water or ground water directly influenced by surface water, that begin operation after the monitoring start date applicable to the system’s size under paragraph (3) of this subdivision.

   3. (iii) The system shall begin a second round of source water monitoring no later than six years following initial bin classification or determination of the mean Cryptosporidium level, as applicable.

      (b) Sampling schedules.

7. (1) Systems required to conduct source water monitoring under this section shall submit a sampling schedule that specifies the calendar dates when the system will collect each required sample. Systems shall submit sampling schedules to the State no later than three months prior to any applicable date referenced in paragraph (a)(3) of this section. If the State does not respond to a system regarding its sampling schedule, the system shall sample at the reported schedule.

8. (2) Systems shall collect samples within two days before or two days after the dates indicated in their sampling schedule, unless one of the following conditions applies:

   1. (i) If an extreme condition or situation exists that may pose danger to the sample collector, or that cannot be avoided and causes the system to be unable to sample in the scheduled five-day period, the system shall sample as close to the scheduled date as is feasible, unless the State approves an alternate sampling date. The system shall submit an explanation for the delayed sampling date to the State concurrent with the shipment of the sample to the laboratory.
   2. (ii) If a system is unable to report a valid analytical result for a scheduled sampling date due to equipment failure, loss of or damage to the sample, failure to comply with the analytical method requirements, including the quality control requirements in subdivision (d) of this section, or the failure of an approved laboratory to analyze the sample, then the system shall collect a replacement sample. The replacement sample shall be collected no later than 21 days after receiving information that an analytical result cannot be reported for the scheduled date, unless the system demonstrates that collecting a replacement sample within this time frame is not feasible, or the State approves an alternative resampling date. The system shall submit an explanation for the delayed sampling date to the State concurrent with the shipment of the replacement sample to the laboratory.

9. (3) Systems that fail to meet the criteria of paragraph (2) of this subdivision for any source water sample required under subdivision (a) of this section shall revise their sampling schedules to add dates for collecting all missed samples. Systems shall submit the revised schedule to the State for approval prior to when the system begins collecting the missed samples.

   (c) Sampling locations.

10. (1) Systems required to conduct source water monitoring under subdivision (a) of this section shall collect samples for each plant that treats a surface water or GWUDI source. Where multiple plants draw water from the same influent, such as the same pipe or intake, the State may approve one set of monitoring results to be used to satisfy the requirements for all plants.
11. (2) Systems shall collect source water samples prior to chemical treatment, such as coagulants, oxidants, and disinfectants, unless the State determines that collecting a sample prior to chemical treatment is not feasible for the system and that the chemical treatment is unlikely to have a significant adverse effect on the analysis of the sample.
12. (3) Systems that recycle filter backwash water shall collect source water samples prior to the point of filter backwash water addition.

13. (4) Bank filtration.

    1. (i) Systems that receive Cryptosporidium treatment credit for bank filtration, as applicable, shall collect source water samples in the surface water prior to bank filtration.
    2. (ii) Systems that use bank filtration as pretreatment to a filtration plant shall collect source water samples from the well (i.e., after bank filtration). Use of bank filtration during monitoring shall be consistent with routine operational practice. Systems collecting samples after a bank filtration process may not receive treatment credit for the bank filtration.

14. (5) Multiple sources. Systems with plants that use multiple water sources, including multiple surface water sources and blended surface water and ground water sources, shall collect samples as specified in subparagraph (i) or (ii) of this paragraph. The use of multiple sources during monitoring shall be consistent with routine operational practice.

    1. (i) If a sampling tap is available where the sources are combined prior to treatment, systems shall collect samples from that tap.

    2. (ii) If a sampling tap where the sources are combined prior to treatment is not available, systems shall collect samples at each source near the intake on the same day and select one of the following options for sample analysis:

       1. (a) systems may composite samples from each source into one sample prior to analysis. The volume of sample from each source shall be weighted according to the proportion of the source in the total plant flow at the time the sample is collected; or
       2. (b) systems may analyze samples from each source separately and calculate a weighted average of the analysis results for each sampling date. The weighted average shall be calculated by multiplying the analysis result for each source by the fraction the source contributed to total plant flow at the time the sample was collected and then summing these values.

15. (6) Additional requirements. Systems shall submit a description of their sampling location(s) to the State at the same time as the sampling schedule. This description shall address the position of the sampling location in relation to the system’s water source(s) and treatment processes, including pretreatment, points of chemical treatment, and filter backwash recycle. If the State does not respond to a system regarding sampling location(s), the system shall sample at the reported location(s).

    (d) Reporting source water monitoring results.

16. (1) Systems shall report results from the source water monitoring no later than 10 days after the end of the first month following the month when the sample is collected.

17. (2) Systems shall report the following information, as applicable, for the source water monitoring samples required under subdivision (a) of this section:

    1. (i) Systems shall report the following data elements for each Cryptosporidium analysis: PWS ID; facility ID sample collection date sample type (field or matrix spike); sample volume filtered (in liters, to the nearest 0.25 liter); confirmation that 100 percent of filtered volume was examined; and the number of oocysts counted.

       1. (a) For matrix spike samples, systems shall also report the sample volume spiked and estimated number of oocysts spiked. These data are not required for field samples.
       2. (b) For samples in which less than 10 liters are filtered or less than 100 percent of the sample volume is examined, systems shall also report the number of filters used and the packed pellet volume.
       3. (c) For samples in which less than 100 percent of sample volume is examined, systems shall also report the volume of resuspended concentrate and volume of this resuspension processed through immunomagnetic separation.
    2. (ii) Systems shall report the following data elements for each E. coli analysis: PWS ID; facility ID; sample collection date; analytical method number; method type; source type; E. coli/100 mL; and turbidity. Systems serving fewer than 10,000 people that are not required to monitor for turbidity are not required to report turbidity with their E. coli results.

(a) Source water monitoring.