The Port of Seattle v. the Pollution Control Hearings Board

Summary

The Washington Supreme Court upheld the reasonable assurance determination underlying Ecology's Clean Water Act § 401 certification for the SeaTac third runway project, holding that the PCHB must first find a certification inadequate in a particular respect before adding conditions, that Ecology's interpretations of water quality statutes and regulations receive great weight, that the PCHB's scope of review is truly de novo subject to discovery deadlines, and that reasonable assurance may rest on conditions, future submissions, NPDES permits, and monitoring with adaptive management. The court upheld the PCHB's mixing zone conclusion and Vacca Farm restoration credit but overturned PCHB conditions 5 (WER studies), 6 (1.0 cfs flow), 7 (fill criteria), 8 (SPLP prohibition), and 16 (water right) and the final sentence of condition 11 (out-of-basin mitigation), holding that retroactive Laws of 2003, ch. 210 validating the SPLP is constitutional and that detention and release of stormwater to mimic preproject flows is stormwater management, not a water right trigger.