1. (a) Except as provided in (d) - (h) of this section, upon request of a discharger, the department may adjust technology-based effluent limitations and standards or water quality-based effluent limitations and standards to reflect net credits for pollutants in the discharger's intake water if

   1. (1) the applicable effluent limitations and standards contained in 40 C.F.R. Part 401 - 40 C.F.R. Part 471, adopted by reference in 18 AAC 83.010, specifically provide that those limitations and standards must be applied on a net basis; or
   2. (2) the discharger demonstrates that the control system it uses or proposes to use to meet applicable technology-based limitations and standards or water quality-based effluent limitations and standards would, if properly installed and operated, meet the limitations and standards in the absence of pollutants in the intake waters.
2. (b) If under (a)(2) of this section the department finds that an intake pollutant in the discharge does not cause, have the reasonable potential to cause, or contribute to an exceedance of an applicable water quality standard, the department may include a technology-based or water quality-based effluent limitation for the identified intake pollutant in the discharger's permit that specifies how compliance with the limits will be assessed.

3. (c) When the department evaluates a control system under (a)(2) of this section, the department may derive an effluent limitation reflecting the flow-weighted amount of each source of the pollutant if

   1. (1) intake pollutants are discharged from multiple sources that originate from the receiving water body and from other water bodies; and
   2. (2) the department determines that compliance can be established through adequate monitoring requirements that are included in the permit.
4. (d) The department will not grant net credits for generic pollutants such as biological oxygen demand or total suspended solids under this section unless the discharger demonstrates that the constituents of the generic measure in the effluent are substantially similar to the constituents of the generic measure in the intake water or unless the department places appropriate additional limits on process water pollutants either at the outfall or elsewhere.
5. (e) The department will grant net credits only to the extent necessary to meet the applicable limitation and standard, up to a maximum value equal to the influent value. The department may require additional monitoring to determine eligibility for credits and compliance with permit limits.
6. (f) The department will not grant net credits unless the discharger demonstrates that the discharge does not contribute to an increase in the concentration or mass of the identified pollutant for which a net credit is applied to the facility effluent.

7. (g) The department will grant net credits only if the discharger demonstrates that the intake pollutant is from the same body of water into which the discharge is made. The department may waive this requirement if it finds that environmental degradation will not result from a waiver. The department will consider an intake pollutant is from the "same body of water" into which the discharge is made if the department determines that

   1. (1) the intake pollutant would have reached the vicinity of the outfall point in the receiving water within a reasonable period had it not been removed by the discharger and the discharger demonstrates that:

      1. (A) the concentration of the pollutant in the receiving water, excluding any amount of the pollutant in the discharge, is similar to that in the intake water;
      2. (B) there is a direct hydrological connection between the intake and discharge points; and
      3. (C) water quality characteristics, including temperature, pH, and hardness, are similar in the intake and receiving waters;
   2. (2) site-specific factors relevant to the transport and fate of the pollutant indicate that the intake pollutant would have reached the vicinity of the outfall point in the receiving water within a reasonable period had it not been removed by the discharger; or
   3. (3) the intake pollutant originated from groundwater and would have reached the vicinity of the outfall point in the receiving water within a reasonable period had it not been removed by the discharger; for purposes of this paragraph, a pollutant is not from the "same body of water" if the groundwater contains the pollutant partially or entirely due to human activity, including industrial, commercial, or municipal operations, disposal actions, or treatment processes.
8. (h) This section does not apply to the discharge of raw water clarifier sludge generated from the treatment of intake water.
9. (i) In this section, "intake pollutant" means a pollutant that is present in waters of the state at the time it is withdrawn from state waters by the discharger or other facility supplying the discharger with intake water.

(Eff. 7/29/2006, Register 179)

Authority: AS 44.46.020, AS 46.03.020, AS 46.03.100, AS 46.03.010, AS 46.03.050, AS 46.03.110