PURPOSE: This rule establishes monitoring requirements for lead and copper in source waters.

1. (1) Sample Location, Collection Methods and Number of Samples.

   1. (A) A water system that fails to meet the lead or copper action level on the basis of tap samples collected in accordance with 10 CSR 60-15.070 shall collect lead and copper source water samples in accordance with the requirements regarding sample location, number of samples and collection methods specified in 10 CSR 60-4.030 (inorganic chemical sampling).
   2. (B) Where the results of sampling indicate an exceedance of maximum permissible source water levels established under 10 CSR 60-5.040(2)(D), the department may require that one (1) additional sample be collected as soon as possible after the initial sample was taken (but not to exceed two (2) weeks) at the same sampling point. If the departmentrequired confirmation sample is taken for lead or copper, then the results of the initial and confirmation sample shall be averaged in determining compliance with maximum permissible levels. Any sample value below the detection limit shall be considered to be zero (0). Any value above the detection limit but below the practical quantification level (PQL) shall be as the measured value or be considered one-half (1/2) PQL.
2. (2) Monitoring Frequency After System Exceeds Tap Water Action Level. Any system which exceeds the lead or copper action level at the tap shall collect one (1) source water sample from each entry point to the distribution system within six (6) months after the exceedance.
3. (3) Monitoring Frequency After Installation of Source Water Treatment. Any system which installs source water treatment pursuant to 10 CSR 60-15.040 shall collect an additional source water sample from each entry point to the distribution system during two (2) consecutive six (6)-month monitoring 10 CSR 60-15

periods by the deadline specified in 10 CSR tions in samples collected from the new 60-15.040(1)(D). source during three (3) consecutive monitoring periods are below the maximum permis- (4) Monitoring Frequency After the Departsible lead and copper concentrations. ment Specifies Maximum Permissible Source Water Levels or Determines That Source AUTHORITY: section 640.100, RSMo Water Treatment is Not Needed. (1994).* Original rule filed Aug. 4,

1. (A) A system shall monitor at the follow- 1992, effective May 6, 1993. ing specified frequency in cases where the *Original authority 1939, amended 1978, 1981, department specifies maximum permissible 1982, 1988, 1989. source water levels under 10 CSR 60- 15.040(2)(D) or determines that the system is not required to install source water treatment under 10 CSR 60-15.040(2)(B):

   1. 1. A water system using only groundwa-

ter shall collect samples once during the three (3)-year compliance period in effect when the applicable department determination under subsection (4)(A) of this rule is made. Those systems shall collect samples once during each subsequent compliance period; and

1. 2. A water system using surface water

(or a combination of surface and ground water) shall collect samples once during each year, the first annual monitoring period to begin on the date on which the applicable department determination is made under subsection (4)(A) of this rule.

1. (B) A system is not required to conduct source water sampling for lead, copper, or both, if the system meets the action level for the specific contaminant in tap water samples during the entire source water sampling period applicable to the system under subsection (4)(A) of this rule.

1. (5) Reduced Monitoring Frequency.

   1. (A) A water system using only groundwater which demonstrates that finished drinking water entering the distribution system has been maintained below the maximum permissible lead or copper concentrations, or both, specified by the department during at least three (3) consecutive compliance periods under paragraph (4)(A)1. of this rule may reduce the monitoring frequency for lead, copper, or both, to once during each nine (9)- year compliance cycle.
   2. (B) A water system using surface water (or a combination of surface and ground waters) which demonstrates that finished drinking water entering the distribution system has been maintained below the maximum permissible lead and copper concentrations specified by the department for at least three (3) consecutive years may reduce the monitoring frequency in paragraph (4)(A)2. of this rule to once during each nine (9)-year compliance cycle.
   3. (C) A water system that uses a new source of water is not eligible for reduced monitoring for lead, copper, or both, until concentra-