WAC 246-291-340   Turbidity.  (1) The department shall determine monitoring requirements on a case-by-case basis. New surface water and GWI sources shall comply with applicable turbidity monitoring requirements in accordance with Part 6 of chapter 246-290 WAC.

     (2) MCLs.

     (a) The department shall consider standards under this subsection primary standards.

     (b) The MCLs for turbidity are:

     (i) 1.0 NTU, based on a monthly average of the maximum daily turbidity, where the maximum daily turbidity is defined as the average of the:

     (A) Highest two hourly readings over a twenty-four-hour period when continuous monitoring is used; or

     (B) Daily grab samples taken within one hour when daily monitoring is used.

     The department may increase the MCL to 5.0 NTUs if the owner can show the source is within a controlled watershed and the source meets the requirements under WAC 246-291-110.

     (ii) 5.0 NTUs based on an average of the maximum daily turbidity for two consecutive days.



[Statutory Authority: RCW 43.20.050. 94-14-002, § 246-291-340, filed 6/22/94, effective 7/23/94.]