15A NCAC 02B .0404      WATER QUALITY BASED EFFLUENT LIMITATIONS

(a)  Effluent limitations shall be developed by the staff for all existing or proposed discharges to the surface waters of the state. Water quality based effluent limitations shall be established for discharges that are found, through mathematical modeling of water quality impacts, statistical analysis of stream characteristics and effluent data or other appropriate means, to have a reasonable potential to cause or contribute to exceedance of applicable water quality standards; except that, if the discharge is subject to both technology based and water quality based effluent limitations for a parameter, the more stringent limit shall apply.

(b)  The staff may on a case‑by‑case basis develop seasonal limitations on the discharge of oxygen‑consuming wastes when a treatment facility complies with applicable limitations on these wastes in the summer season but does not consistently comply in the winter season due to the effects of cooler temperatures or other seasonal factors beyond its control. A discharger may request seasonal effluent limitations by submitting a written request to the Director with justification for such limitations. In no case shall seasonal limitations cause or be expected to cause a receiving water body to violate applicable water quality standards.

(c)  For the purpose of determining seasonal effluent limitations, the year shall consist of a summer and a winter discharge period. The summer period shall begin April 1 and extend through October 31. The winter period shall begin November 1 and extend through March 31. The summer oxygen‑consuming wasteload allocation shall be developed using the flow criteria specified in 15A NCAC 02B .0206. The winter oxygen‑consuming wasteload allocation shall not exceed two times the summer oxygen‑consuming wasteload limitations nor shall it be less restrictive than minimum treatment requirements.

(d)  No domestic sewage regardless of the treatment proposed and no other wastes that could adversely affect the taking of shellfish for market purposes shall be discharged into water classified "SA", into unnamed waters tributary to "SA" waters classified "C" or "SC" in accordance with 15A NCAC 02B .0301(i)(1)(B) and (C), or into other waters in such close proximity as to adversely affect such "SA" waters. Wastes discharged into other waters tributary to waters classified "SA" shall be treated in such manner as to assure that no impairment of water quality in the "SA" segments shall occur. No permits shall be issued for discharges into waters classified "SA" unless Shellfish Sanitation, Division of Marine Fisheries, Department of Environmental Quality, provides written concurrence that the discharge would not adversely affect shellfish water quality or the propagation of shellfish.

(e)  The discharge of wastewaters to the Atlantic Ocean shall follow the guidelines and requirements set forth in 40 CFR Part 125, Subpart M, Ocean Discharge Criteria.

History Note:        Authority G.S. 143-214.2(c); 143‑215; 143‑215.1; 143‑215.3(a)(1);

Eff. February 1, 1976;

Amended Eff. August 12, 1979;

Readopted Eff. May 1, 2020.