Section 810.30. Criteria for avoiding filtration for groundwater under the direct influence of surface water systems.

  A public water system that uses groundwater under the direct influence of surface water as a water supply source shall meet all of the conditions of subs. (1) and (2) , and is subject to sub. (3) , unless the department has determined, in writing, that filtration is required. If the department determines in writing that filtration is required, the water system owner shall install filtration and shall meet the criteria for filtered systems specified in ss. NR 810.29 and 810.31 (2) . Within 18 months of the failure of a public water system using a groundwater source under the direct influence of surface water to meet any one of the requirements of subs. (1) and (2) , the water system owner shall install filtration and shall meet the criteria for filtered systems specified in ss. NR 810.29 and 810.31 (2) .

(1)   Source water quality conditions.

(a) The fecal coliform concentration shall be equal to or less than 20/100ml, or the total coliform concentration shall be equal to or less than 100/100 ml, measured as specified in s. NR 809.311 (1) Table F, in representative samples of the source water immediately prior to the first or only point of disinfectant application in at least 90% of the measurements made for the 6 previous months that the system served water to the public on an ongoing basis. If a system measures both fecal and total coliforms, the fecal coliform criterion, but not the total coliform criterion, in this paragraph shall be met.

(b) The turbidity level may not exceed 5 NTU, measured as specified in s. NR 809.113 (1) Tables A and B, in representative samples of the source water immediately prior to the first or only point of disinfectant application unless both of the following apply:

1. The department determines that a turbidity "event" was caused by circumstances that were unusual and unpredictable. A turbidity "event" is a series of consecutive days during which at least one turbidity measurement each day exceeds 5 NTU.

2. There have not been more than 2 turbidity events in the past 12 months the water system served water to the public, or more than 5 turbidity events in the past 120 months the system served water to the public.

(2)   Site-specific conditions.

(a)

1. The public water system shall meet the disinfection requirements of s. NR 810.31 (1) (a) at least 11 of the 12 previous months that the system served water to the public, on an ongoing basis, unless the system fails to meet the requirements during 2 of the 12 previous months that the system served water to the public, and the department determines that at least one of these failures was caused by circumstances that were unusual and unpredictable.

2. The public water system shall meet the requirements of s. NR 810.31 (1) (b) at all times the system serves water to the public.

3. The public water system shall meet the requirements of s. NR 810.31 (1) (c) at all times the system serves water to the public unless the department determines that any failure was caused by circumstances that were unusual and unpredictable.

4. The public water system shall meet the requirements of s. NR 810.31 (1) (d) on an ongoing basis unless the department determines that failure to meet these requirements was not caused by a deficiency in treatment of the source water.

(b) The public water system shall maintain a department approved wellhead protection program which minimizes the potential for contamination by Cryptosporidium, Giardia lamblia cysts and viruses in the source water. The department shall determine whether the well head protection program is adequate to meet this goal. At a minimum, the program shall do all of the following:

1. Characterize the watershed hydrology, hydrogeology, and land ownership.

2. Identify watershed characteristics and activities which may have an adverse effect on source water quality.

3. Monitor the occurrence of activities which may have an adverse effect on source water quality.

(c) The public water system is subject to an annual on-site inspection to assess the well head protection program and disinfection treatment process. Either the department or a party approved by the department shall conduct the on-site inspection. The inspection shall be conducted by competent individuals and shall include all of the following:

1. A review of the effectiveness of the watershed control program.

2. A review of the physical condition of the source intake and how well it is protected.

3. A review of the system's equipment maintenance program to ensure there is low probability for failure of the disinfection process.

4. An inspection of the disinfection equipment for physical deterioration.

5. A review of operating procedures.

6. A review of data records to ensure that all required tests are being conducted and recorded and disinfection is effectively practiced.

7. Identification of any improvements which are needed in the equipment, system maintenance and operation, or data collection.

8. A review of the adequacy of the watershed control program to limit potential contamination by Cryptosporidium including: comprehensiveness of the watershed review, the effectiveness of the system's program to monitor and control detrimental activities occurring in the watershed, and the extent to which the water system has maximized land ownership or controlled land use, or both, within the watershed.

(d) The public water system may not have been identified as a source of a waterborne disease outbreak, or if it has been so identified, the system shall be modified sufficiently to prevent another occurrence, as determined by the department.

(e) The public water system shall comply with the maximum contaminant level (MCL) for total coliforms in s. NR 809.30 at least 11 months of the previous 12 months that the system served water to the public, on an ongoing basis, unless the department determines that failure to meet this requirement was not caused by a deficiency in treatment of the source water.

(f) The public water system shall comply with the requirements for total trihalomethanes, five haloacetic acids, bromate, chlorite, chlorine, chloramines and chlorine dioxide in s. NR 809.561 .

(3)   Treatment technique violations.

(a) A public water system that fails to meet any one of the criteria in subs. (1) and (2) , and for which the department has determined in writing that filtration is required, is in violation of a treatment technique requirement.

(b) A public water system that has not installed filtration is in violation of a treatment technique if either of the following apply:

1. The turbidity level in a representative sample of the source water immediately prior to the first or only point of disinfection application exceeds 5 NTU.

2. The system is identified as a source of a waterborne disease outbreak.

(4)   Additional circumstances when filtration would be required. The department may require a public water system to install filtration even when the system meets the requirements of subs. (1) and (2) if other water quality characteristics or site specific conditions present a threat to public health which could not be eliminated by disinfection alone.

History: CR 09-073 : cr. Register November 2010 No. 659 , eff. 12-1-10.