NAC445A.454. Primary standards: Monitoring and analysis.

     1. The monitoring requirements for the primary standards set forth in NAC 445A.453 must be performed as required by 40 C.F.R. §§ 141.21 to 141.29, inclusive, 141.40, 141.41, 141.42, 141.74, 141.86 to 141.89, inclusive, 141.131, 141.132, 141.133, 141.172, 141.173, 141.174, 141.402, 141.530 to 141.564, inclusive, 141.605, 141.621 to 141.628, inclusive, and 141.701 to 141.709, inclusive, as adopted by reference in NAC 445A.4525.

     2. Any analysis conducted to determine compliance with the primary standards referenced in NAC 445A.453 must be performed by a laboratory that is certified pursuant to the provisions of NAC 445A.542 to 445A.54296, inclusive, in accordance with:

     (a) The method or methods listed in, or approved pursuant to, the provisions of NAC 445A.542 to 445A.54296, inclusive, for the selected contaminant or contaminants in the drinking water; or

     (b) Any method for the selected contaminant or contaminants in the drinking water approved by the United States Environmental Protection Agency as an acceptable alternative test procedure for drinking water.

     3. For water systems which are conducting water quality monitoring at a frequency greater than annually, compliance with the maximum contaminant levels for antimony, arsenic, asbestos, barium, beryllium, cadmium, chromium, cyanide, fluoride, mercury, nickel, selenium or thallium must be determined during normal operating conditions by a running annual average at any sampling point. A monitoring program identifying the sampling points must be submitted to the Division or the appropriate district board of health for review and approval. The monitoring program must demonstrate that the average quality of the water served to each customer in the distribution system is below the maximum contaminant level. The Division or the appropriate district board of health shall establish the number of samples the public water system must take for calculating the running annual average. The public water systems may not monitor more frequently than specified in the monitoring program by the Division or the appropriate district board of health to determine compliance unless approved in writing by the Division or the appropriate district board of health.

     4. As used in this section:

     (a) “Normal operating conditions” means the conditions that are achieved when the water system operates wells or treatment plants to supply water for seasonal demands.

     (b) “Running annual average” means the sum of the consecutive 12-month contaminant sample values divided by the total number of samples taken at one sample point. (Example: (Σx₁+ x₂+ x_n)/n = running annual average)

     (Added to NAC by Bd. of Health, eff. 7-16-92; A 10-22-93; 8-1-94; 3-28-96; 9-6-96; R048-99, 9-27-99; R203-99, 8-1-2001; R088-00, 8-3-2001; A by Environmental Comm’n by R126-05, 10-31-2005; R194-08, 10-27-2009; R061-10, 7-22-2010)