5 Colo. Code Regs. § 1002-11.18

Current through Register Vol. 47, No. 20, October 25, 2024

Section 5 CCR 1002-11.18 - NITRATE AND NITRITE RULE

11.18(1) Applicability

For all public water systems, the supplier must comply with the requirements specified in this rule.

11.18(2)MCL Requirements for Nitrate and Nitrite

(a) The nitrate and nitrite MCLs are as follows:

TABLE 11.18-I NITRATE AND NITRITE CHEMICALS MCLs
Chemical	MCL (mg/L)
Nitrate	10 (as Nitrogen)
Nitrite	1 (as Nitrogen)
Total Nitrate and Nitrite	10 (as Nitrogen)

(b) The cited detection limits for nitrate and nitrite are specified in 40 CFR 141.23(a)(4)(i).

(c) The BATs for achieving compliance with the MCLs for nitrate and nitrite are specified in 40 CFR 141.62(c).

(d)Elevated MCL Requirements for Nitrate

(i) For non-community water systems, the Department may allow an elevated MCL of 20

mg/L for nitrate, if the supplier can demonstrate to the satisfaction of the Department that:

(A) Such water will not be available to children under 6 months of age; and

(B) It will not result in any adverse health effects.

(ii) If the Department allows an elevated MCL for nitrate, the supplier must:

(A) Continuously post public notice stating that nitrate levels are greater than (>) 10 mg/L and include the potential health effects of exposure.

(I) The supplier must distribute Tier 1 public notice as specified in 11.33.

(B) Notify local and State public health authorities annually of nitrate levels greater than (>) 10 mg/L.

11.18(3)Sampling Requirements for Nitrate and Nitrite

(a)General Sampling Requirements for Nitrate and Nitrite

(i) To determine compliance with the MCLs for nitrate and nitrite, the supplier must comply with the sampling requirements specified in this section, 11.18(3).

(ii) The supplier may apply to the Department to sample more frequently than required.

(iii) The Department may:

(A) Require the supplier to sample more frequently than the minimum requirements specified in 11.18(3)(b) or 11.18(3)(c).

(B) Require the supplier to collect a confirmation sample for any sample result.

(C) Invalidate sample results based on sampling or analytical errors.

(D) Specify when the supplier must sample during each monitoring period.

(iv) If the system draws water from more than one source and the sources are combined before distribution, the supplier must sample during periods of normal operating conditions.

(b)Sampling Requirements for Nitrate

(i) To determine compliance with the MCL for nitrate, the supplier must comply with the sampling requirements specified in this section, 11.18(3)(b).

(ii) For new systems or new sources, the supplier must begin sampling at a routine frequency when the new system or source begins supplying water to the public.

(iii) For routine sampling, the supplier must collect one sample at each entry point:

(A) For community and non-transient, non-community water systems:

(I) For surface water systems, quarterly.

(II) For groundwater systems, annually.

(B) For transient, non-community water systems, annually.

(iv) For community and non-transient, non-community water systems, if the supplier is sampling annually and any sample result is greater than or equal to (>=) 50 percent of the MCL, the supplier must increase the sampling frequency at that entry point to quarterly for at least one year.

(v) If the supplier is required to sample quarterly, the Department may allow the supplier to reduce the sampling frequency at that entry point to annually if the sample results from four consecutive quarters are:

(A) For groundwater systems, reliably and consistently below the MCL.

(B) For community and non-transient, non-community surface water systems, less than (<) 50 percent of the MCL.

(vi) If the Department allows the supplier to reduce the sampling frequency to annually, the supplier must sample during the quarter that previously had the highest sample result.

(vii) If any sample result is greater than (>) the MCL, the supplier must collect a confirmation sample at that entry point no later than 24 hours after being notified of the original sample result.

(A) If the supplier is unable to collect a confirmation sample within 24 hours, the supplier must:

(I) Distribute Tier 1 public notice as specified in 11.33 no later than 24 hours after being notified of the original sample result.

(II) Collect and analyze a confirmation sample no later than 14 days after being notified of the original sample result.

(viii) If the Department allows an elevated MCL for nitrate, the supplier must sample at a Department-specified frequency.

(A) If any sample result is greater than (>) the elevated MCL, the supplier must:

(I) Notify the Department no later than seven days after being notified of the original sample result.

(II) Collect three confirmation samples at the same entry point no later than one month after being notified of the original sample result.

(c)Sampling Requirements for Nitrite

(i) To determine compliance with the MCL for nitrite, the supplier must comply with the sampling requirements specified in this section, 11.18(3)(c).

(ii) For new systems or new sources, the supplier must collect an initial sample at each entry point within the first year of operation.

(iii) After collecting the initial sample, if the sample result is less than (<) 50 percent of the

MCL, the supplier must sample at a routine frequency. For routine sampling, the supplier must sample at that entry point once during each nine-year compliance cycle.

(iv) If any sample result is greater than or equal to (>=) 50 percent of the MCL, the supplier must increase the sampling frequency at that entry point to quarterly for at least one year.

(A) If the sample results are reliably and consistently below the MCL, the Department may allow the supplier to reduce the sampling frequency at that entry point to annually.

(I) If the Department allows the supplier to reduce the sampling frequency to annually, the supplier must sample during the quarter that previously had the highest sample result.

(v) If any sample result is greater than (>) the MCL, the supplier must collect a confirmation sample at that entry point no later than 24 hours after being notified of the original sample result.

(A) If the supplier is unable to collect a confirmation sample within 24 hours, the supplier must:

(I) Distribute Tier 1 public notice as specified in 11.33 no later than 24 hours after being notified of the original sample result.

(II) Collect and analyze a confirmation sample no later than 14 days after being notified of the original sample result.

(d)Sampling Requirements for Consecutive Systems with Their Own Additional Sources

(i) For consecutive systems, the Department may change the nitrate and nitrite sampling requirements if the system meets all of the following criteria:

(A) The purchased water enters the distribution system separate from any additional sources owned by the consecutive system.

(B) The interconnection of the systems justifies the modification of sampling requirements.

(ii) The supplier must comply with the Department-specified schedule.

11.18(4)Compliance Determination for Nitrate and Nitrite

Compliance with the MCL is based on the individual sample result, unless a confirmation sample is required.

(a) If a confirmation sample is required, compliance will be based on the average of the original sample result and the confirmation sample result.

(b) If a sample result is less than (<) the cited detection limit, the sample result will be given a value of zero to calculate the average.

(c) If the supplier fails to collect the required number of samples, compliance will be based on the available sample results.

(d) If the Department allows an elevated MCL for nitrate and confirmation samples are required, compliance will be based on the average of the original sample result and the three confirmation sample results.

(i) The Department may determine compliance or initiate an enforcement action based on analytical results and other information gathered by Department-authorized representatives and agencies.

11.18(5)MCL Violation and Response for Nitrate and Nitrite

(a) If the average of any sample and its confirmation sample(s) is greater than (>) the MCL for nitrate and/or nitrite, an MCL violation occurs.

(b) In the event of a nitrate and/or nitrite MCL violation, the supplier must:

(i) Notify the Department and initiate consultation no later than 24 hours after the violation occurs.

(ii) Distribute Tier 1 public notice as specified in 11.33.

5 CCR 1002-11.18

38 CR 07, April 10, 2015, effective 4/30/2015

41 CR 11, June 10, 2018, effective 6/30/2018

41 CR 23, December 10, 2018, effective 12/30/2018

43 CR 07, April 10, 2020, effective 4/30/2020

43 CR 17, September 10, 2020, effective 9/30/2020

45 CR 24, December 25, 2022, effective 1/14/2023