Okla. Admin. Code § 252:628-11-5

Current through Vol. 41, No. 19, June 17, 2024

Section 252:628-11-5 - Action levels

(a)General. At a minimum, action levels shall protect beneficial uses and the criteria developed to protect them and consider rules regarding use of assimilative capacity in SWS-R waterbodies as outlined in OAC 252:730 and OAC 252:740-13.

(b)Statistical significance. Some action levels, such as the action levels for CECs, are based on a statistically significant increase. Determination of statistical significance is subject to DEQ approval. The determination of statistical significance may be determined by methods listed in this subsection, or by other DEQ-approved methods.

(1)The Student's t Test. The student's t test can be used to determine if two sets of data are significantly different from each other. A 95% confidence level shall be used when using the student's t test to determine statistical significance.

(2)Multiple range tests. Multiple range tests can be used to test for significant difference for a group of ranked means. Tests may include least significant difference or multiple t test, Student-Newman-Keuls test, Tukey's test based on allowances, and Duncan's multiple range test. A significance level of 5% shall be used.

(3)Distribution free methods. For parameters that will likely not be normally distributed, distribution free methods shall be used to determine statistical significance. Options include the Mann-Whitney test, Mood's Median test, and the Kruskal-Wallis test.

(c)Reporting. Permittee shall report results from statistical significance tests on the LMR forms as required by the permit.

(d)Actions and action levels by parameter group. The following requirements apply.

(1)In-Situ. Actions and action levels shall be determined by DEQ.

(2)Nutrients. The actions and action levels for nutrients are as follows:

(A)Accumulation of phosphorus. Actions and action levels shall be determined by DEQ; and

(B)Accumulation of nitrogen. Actions and action levels shall be determined by DEQ.

(3)Algal biomass. Actions and action levels shall be determined by DEQ.

(4)Minerals. The following requirements apply for minerals.

(A)Total Dissolved Solids. Requirements shall be placed in the permit to prevent the maximum ambient concentration exceeding the greater of 700 milligrams per liter or two (2) standard deviations above the mean background TDS value of the receiving waterbody prior to IPR Source Water discharge. Background levels can be established from any combination of scientifically defensible data, including historical data, segment averages, and baseline monitoring. Potential actions to control TDS shall include one or more of the following:

(i) Cease discharge;

(ii) Reduce discharge;

(iii) Increase treatment; and

(iv) Other appropriate action as approved by DEQ.

(B)Chloride and sulfate. Actions and action levels shall be determined by DEQ.

(5)Metals. Actions and action levels shall be determined by DEQ.

(6)Microorganisms. There are no action levels for this parameter group.

(7)Toxics. Actions and action levels shall be determined by DEQ.

(8)Constituents of Emerging Concern. When a statistically significant accumulation is identified at any monitoring site in the waterbody, the following actions may be required at DEQ's discretion:

(A) Investigate implications for public health and the environment. Permittee shall submit findings to DEQ.

(B) Increase effluent and/or waterbody monitoring frequency. Increased monitoring requirements shall be reflected in the OPDES permit. Additionally, the permittee shall not be eligible for reduced waterbody monitoring for the parameter of concern at the permit renewal.

(C) Pursue additional source delineation and submit findings to DEQ.

(D) Notification of PWS systems and any other entities as appropriate using the waterbody of the detected increase.

(E) Other appropriate action as approved by DEQ.

(9)Other drinking water parameters. Actions and action levels shall be determined by DEQ.

(10)Total Organic Carbon. There are no action levels for this parameter group.

Okla. Admin. Code § 252:628-11-5

Adopted by Oklahoma Register, Volume 35, Issue 24, September 4, 2018, eff. 9/15/2018

Amended by Oklahoma Register, Volume 40, Issue 6, December 1, 2022, eff. 10/25/2022

Amended by Oklahoma Register, Volume 40, Issue 24, September 1, 2023, eff. 9/15/2023