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17.38.215    BACTERIOLOGICAL QUALITY SAMPLES

(1) The board adopts and incorporates by reference the table in 40 CFR 141.21(a) (2) , which sets forth total coliform monitoring frequency requirements.

(a) The minimum monitoring frequency for total coliforms for community and nontransient noncommunity public water supply systems is based on the average daily population served by the system during the month of peak use, and must be in accordance with the table in 40 CFR 141.21(a) (2) .

(b) The supplier of water for a transient noncommunity water system shall sample according to the table in 40 CFR 141.21(a) (2) , except that a supplier of water for a transient noncommunity water system that uses only ground water that is not under the direct influence of surface water and serves a maximum daily population of 1,000 persons or fewer shall sample for coliform bacteria in each calendar month during which the system provides water to the public unless allowed to sample quarterly as provided in (1) (c) or (d) . The department may not, however, grant permission to sample quarterly pursuant to (1) (c) for a minimum of 24 months of system operation after a system initially becomes regulated under this rule.

(c) Upon the written request of the water supplier, the department may reduce the required sampling frequency for coliform bacteria for a transient noncommunity public water supply system that uses only ground water and serves a maximum daily population of 1,000 persons or fewer to once in each calendar quarter during which the system provides water to the public if the department determines that quarterly sampling is adequate to protect public health. This determination must be based upon the results of coliform bacteria samples from the past 24 months of system operation, sanitary surveys and any other information that indicates quarterly sampling is adequate.

(d) A water supplier who is allowed to sample quarterly pursuant to (1) (c) or who was authorized to conduct quarterly sampling on June 3, 1999, and is not required by the department to sample more frequently, may continue to sample quarterly except that:

(i) if E. coli bacteria or other microorganisms commonly found only in the intestinal tract of warm-blooded animals are detected in coliform bacteria samples taken under the requirements of this chapter, the supplier shall sample at least monthly, or more frequently if required by the department, until valid samples that do not contain coliform bacteria have been taken for at least 12 consecutive months of system operation. However, if the department determines before expiration of the 12-month period that the source of the contamination has been positively identified and removed, the department may allow the supplier to monitor in accordance with (c) .

(ii) if a maximum contaminant level violation occurs as a result of coliform bacteria samples taken under the requirements of this chapter, the supplier shall sample at least monthly, or more frequently if required by the department pursuant to (e) , until valid samples that do not contain coliform bacteria have been taken for at least 12 consecutive months of system operation. If the department determines before expiration of the 12-month period that the source of the contamination has been positively identified and removed, the department may allow the supplier to monitor in accordance with (c) .

(iii) a supplier who fails to submit the required routine or repeat samples in two or more quarters during any consecutive four calendar quarters of operation shall sample at least monthly for at least 12 consecutive months.

(iv) a supplier who constructs a system or system components without approval or who has modified a system without approval, in violation of 75-6-112 , MCA, and ARM 17.38.101, shall sample at least monthly, or more frequently if required by the department pursuant to (1) (e) , until the supplier has submitted plans and specifications in accordance with 75-6-112 , MCA, and ARM 17.38.101, the system modifications have been approved and the department has reduced sampling frequency pursuant to (1) (c) .

(v) if the department determines and notifies a supplier that its source or distribution system is vulnerable to contamination based upon the results of a sanitary survey, sample analyses, technical investigations or other scientifically defensible information, the supplier shall sample at least monthly, or more frequently if required by the department pursuant to (e) . If the department determines that the source of the contamination has been positively identified and removed, the department may allow the supplier to monitor in accordance with (c) .

(vi) a supplier that does not maintain or operate a system in accordance with the requirements of this chapter may be required to sample monthly, or more frequently if required by the department pursuant to (1) (e) , when the department determines that the violation may affect the microbiological quality of the water supply system. If the department determines that appropriate improvements in maintenance and operation have been implemented, it may allow the supplier to monitor in accordance with (1) (c) . A supplier shall implement any increase in sampling frequency immediately upon receipt of written notice from the department of the increase.

(e) The department may increase the required sampling frequency of any public water supply system based upon sampling results or other conditions that indicate a risk to the health of the water users. The department shall provide the supplier with a written explanation of any revised sampling requirements. A supplier shall implement any increase in sampling frequency immediately upon receipt of written notice of the increase from the department.

(2) The board hereby adopts and incorporates by reference 40 CFR 141.21, which sets forth monitoring and analytical requirements for coliform bacteria, except as modified in the sections that follow.

(3) 40 CFR 141.21(a) (2) is not adopted, except for the table adopted in (1) (a) . 40 CFR 141.21(a) (3) is not adopted.

(4) 40 CFR 141.21(a) (6) is replaced with the following: "A special purpose sample, including a sample taken to determine whether adequate disinfection has occurred after pipe placement or repair, may not be taken from a part of the public water supply distribution system that is actively serving the public. Repeat samples taken pursuant to 40 CFR 141.21(b) are not special purpose samples."

(5) 40 CFR 141.21(b) (5) is replaced with the following: "If a supplier who collects fewer than five routine samples per month has one or more total coliform-positive samples and the department does not invalidate the sample or samples under 40 CFR 141.21(c) , the supplier shall collect at least five routine samples during the next month the system provides water to the public. At least one of these routine samples must be collected from the site where the previous month's contaminated sample was taken unless that site was invalidated according to 40 CFR 141.21(c) (1) (ii) ."

(6) A supplier shall collect at least two samples that must be analyzed for coliform bacteria from any new source of water supply to demonstrate compliance with this subchapter before the source is connected to a public water supply system.

History: 75-6-103, MCA; IMP, 75-6-103, MCA; NEW, 1977 MAR p. 1187, Eff. 12/24/77; AMD, 1982 MAR p. 594, Eff. 3/26/82; AMD, 1987 MAR p. 311, Eff. 3/27/87; AMD, 1991 MAR p. 1492, Eff. 8/16/91; AMD, 1994 MAR p. 2131, Eff. 8/12/94; TRANS, from DHES, 1996 MAR p. 1499; AMD, 1998 MAR p. 1167, Eff. 5/1/98; AMD, 1998 MAR p. 1927, Eff. 6/26/98; AMD, 1999 MAR p. 1222, Eff. 6/4/99; AMD, 2000 MAR p. 3400, Eff. 12/8/00; AMD, 2004 MAR p. 3016, Eff. 1/1/05.

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