Okla. Admin. Code § 252:628-3-7

Current through Vol. 42, No. 7, December 16, 2024

Section 252:628-3-7 - IPR benchmarks for nutrients, chlorophyll-a, and algal biomass

(a)Water quality standards. IPR Source Water discharges shall not cause or contribute to an exceedance of narrative or numerical OWQS for nutrients, dissolved oxygen or chlorophyll-a. The evaluation of potential OWQS impacts shall be made using DEQ-approved effluent and receiving waterbody modeling.

(b)Eutrophication. IPR Source Water discharges shall not cause or contribute to excessive growth of algal biomass, periphyton, phytoplankton, cyanobacteria, or aquatic macrophyte communities, which impairs any existing or designated beneficial use.

(c)Mixing zones. No mixing zones or dilution factors shall be allowed for establishing effluent limitations for nitrate (as N) and nitrite (as N). Mixing zones or dilution factors shall be designated on a case-by-case basis for establishing effluent limitations for other nutrients, unless superseded by mixing zones or dilution factors established in OAC 252:740.

(d)Total nitrogen. Total nitrogen shall not exceed 8 milligrams per liter as a monthly average or 12 milligrams per liter daily maximum. More stringent effluent limitations representing enhanced nutrient removal technologies for nitrogen may be established where DEQ-approved modeling demonstrates that the IPR Source Water discharge may cause or contribute to an increase in ambient receiving waterbody concentrations of nitrogen to levels that would violate paragraph (a) or (b) of this Section, or of nitrate (as N) to levels that would exceed 10 milligrams per liter.

(e)Total phosphorus. Total phosphorus shall not exceed 0.2 milligrams per liter monthly average or 0.3 milligrams per liter daily maximum. More stringent effluent limitations representing enhanced nutrient removal technologies for phosphorus may be established where DEQ-approved modeling demonstrates that the IPR Source Water discharge may cause or contribute to an increase in ambient receiving waterbody concentrations of phosphorus to levels that would violate paragraph (a) or (b) of this Section.

(f)Chlorophyll-a. The following requirements apply:

(1)SWS-R Waterbodies. IPR Source Water discharges shall not cause or contribute to an increase in ambient receiving waterbody concentrations to levels that would exceed the aggregate long-term average concentration of chlorophyll-a at a depth of 0.5 meters below the waterbody surface of 0.010 milligrams per liter. Effluent limitations for nutrients to ensure compliance with this criterion shall be developed based on DEQ-approved modeling of the discharge and receiving waterbody.

(2)Non-SWS-R Waterbodies. IPR Source Water discharges shall not cause or contribute to an exceedance of narrative or numerical water quality standards for nutrients or chlorophyll-a. Effluent limitations for nutrients to ensure compliance with these criteria shall be developed based on DEQ-approved modeling of the discharge and receiving water.

(g)Effluent monitoring requirements. The following effluent monitoring requirements apply:

(1) Nutrient parameters which are included in the permit shall be monitored at a frequency of weekly during the period of May through October and twice a month during the period of November through April; and

(2) DEQ may increase the monitoring frequencies listed in (g)(1) of this Section for a period not to exceed two years during the initial permit cycle for the purpose of establishing the pattern and extent of variation for a given parameter.

(h)Harmful algal blooms. In the event HABs occur at an area of the receiving waterbody influenced by the IPR Source Water discharge, the permittee shall immediately cease discharge via the IPR Source Water outfall, and notify DEQ within 24 hours.

(1) A written report evaluating the size and extent of the HABs, the potential causes for the HABs, and the steps taken to eliminate the HABs shall be submitted to DEQ within ten (10) days.

(2) Discharge via the IPR Source Water outfall may resume after corrective action is completed, if necessary, the HABs are eliminated and written approval is received from DEQ.

Okla. Admin. Code § 252:628-3-7

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