Notes
Excerpt from Washington State Department of Ecology Permit Writer’s Manual (July 1999), AR024616–AR024618, covering Water Effect Ratio (WER) methodology sections 6.3 through 6.7. Topics include: Sample-Specific WER approach (EPA guidance pages 13–15), determining WERs for areas in or near plumes (Method 1, EPA page 17), freshwater and saltwater WER determination using upstream water, acute dilution factor, chronic dilution factor, and complete mix ratio; design flows for WERs including critical condition (7Q10), WET (Whole Effluent Toxicity) testing requirements, toxicity test species for freshwater (Ceriodaphnia sp., Daphnia magna, Rainbow Trout, Brook Trout) and saltwater (Holmesimysis costata, Mysidopsis bahia, Atherinops affinis, Menidia beryllina); acute vs. chronic WER determination; reasonable potential threshold; NPDES permitting. Handwritten notes on page 3 reference ‘IDF’ usage and ‘DOE’s position on stormwater mixing zones.’ Filed in PCHB Third Runway EIS administrative record.