Range-Finding Water-Effect Ratio Results Round 2

Notes

This draft memorandum summarizes range-finding toxicity test results conducted as part of a water-effect ratio (WER) study for copper in streams receiving Sea-Tac International Airport (STIA) stormwater. The tests used Daphnia magna as an indicator species to evaluate copper bioavailability in site waters compared to clean laboratory water, with samples collected from five locations including Miller Creek and Des Moines Creek during a storm event on April 15, 2000. The purpose was to determine whether final WERs would be robust enough to justify definitive studies, particularly in the event that mixing zones cannot be granted for the creeks.

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