EXH2112033725

TO: Gordon White, Paula Ehlers, Tom McDonald FROM: Tom Luster, 407-6918 RE: 401 Certification, Water Quality, and Stormwater This memo summarizes two issues that came up during Ecology's certification review for SeaTac airport. These issues have far-reaching implications, and will be a part of the Port's legal challenge to Ecology's ability to condition 401 certifications. I have included a discussion about each issue along with a recommendation and some implications. Some of this is based on my discussion two weeks ago with several folks from the Water Quality Program. Please let me know if you have questions or would like more information. Summary: Ecology's analysis of the Port's proposed stormwater treatment methods showed that the minimum BMPs in Ecology's Stormwater Manual were not adequate to allow the Port's stormwater discharges to meet water quality criteria. Additionally, it appears that even a combination of BMPs (i.e., going beyond the minimums) would not provide adequate treatment. Since the runoff from the Port is fairly typical of many urban stormwater discharges, it appears that the guidance provided in our Manual results in projects discharging urban stormwater not meeting the water quality standards. In fact, it appears that for many of those projects, even - going beyond the Manual will not result in their discharge meeting the standards. Our certification review also revealed some differences in the way the Water Quality Program and the 401 certification staff are interpreting and implementing the water quality standards. These differences may be appropriate, considering the type of…

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PSCAA Advisory Council Meeting Agenda
Add to CalendarMWednesday Mar 11, 9:00am - 11:35am
1904 3rd Avenue, Suite 105, Seattle, WA 98101
Call to order – Roll Call – Quorum Established – Land Acknowledgement We would like to acknowledge that our Agency operates in four present-day counties, which are the traditional lands of the Coast Salish people, past and present. This acknowledgement does not take the place of authentic relationships with indigenous communities in our jurisdiction and [...]