COMMISSION 
AGENDA MEMORANDUM                        Item No.          11b 
BRIEFING ITEM                            Date of Meeting      October 11, 2022 
DATE:     August 24, 2022 
TO:        Stephen P. Metruck, Executive Director 
FROM:    Sarah Ogier, Director-Maritime Environment & Sustainability 
Jon Sloan, Sr. Manager, Environmental Programs 
Danielle Butsick, Sr. Environmental Management Specialist 
SUBJECT:  Underwater Noise Mitigation and Management Plan 
EXECUTIVE SUMMARY 
Central Puget Sound is habitat for several species of threatened and endangered marine
mammals, birds, and fish—most notably southern resident killer whales, a “keystone” species for
conservation efforts.  Underwater noise impacts the southern resident killer whales’ ability to
feed, communicate, navigate, reproduce, and avoid danger. Without action, underwater noise
will continue to impact killer whales. The Port of Seattle (Port) is committed to help ensure that
commerce, communities, and killer whales can co-exist.  While the Port does not have direct
control over most port-related activities that generate underwater noise, it plays an important
role by providing support in the following areas: 
•       Leadership in environmentally responsible stewardship of marine facilities 
•       Advocacy for sound policy, regulations, and practices related to underwater noise 
•       Financial investments and studies to advance scientific knowledge 
•       Partnerships with industry, government agencies, tribes, and non-profits 
The Underwater Noise Mitigation and Management Plan (Plan) describes the Port’s approach to
reduce potential adverse effects of underwater noise on marine mammals and other sensitive
species. It focuses on two main port-related sources of underwater noise: vessel movement and
in-water construction. The Plan is designed to meet the Level 3 Criteria for the Green Marine
Underwater Noise Performance Indicator and will provide the framework for achieving Level 4
and Level 5 Criteria. 
ATTACHMENTS TO THIS BRIEFING 
(1) Presentation slides 
(2) Draft Underwater Noise Mitigation and Management Plan (UNMMP) 
PREVIOUS COMMISSION ACTIONS OR BRIEFINGS 
None. 

Template revised January 10, 2019.