Title
Briefing on Long-term Sea Level Rise Monitoring and Metrics for Adaptive Management
Recommended Action
Briefing only. No action requested.
Report
Issue:
Briefing on long-term sea level rise monitoring and metrics for adaptive management.
Staff Contact:
Natalie Weiss, Climate Resilience Coordinator, 360.570.5828
Presenter(s):
Natalie Weiss, Climate Resilience Coordinator
Justin Vandever, AECOM
Julia-Grace Sanders, AECOM
Background and Analysis:
In July 2025, the Collaborative Partners contracted with AECOM to develop a long-term sea level rise monitoring plan to track changing environmental conditions and support adaptive management. The key outcomes of the contract are a local evaluation of vertical land motion, updated sea level rise projections, and a long-term monitoring and metrics plan.
Assessed vertical land motion:
AECOM conducted an analysis of vertical land motion (VLM) in the Sea Level Rise Response Plan project area. Vertical land motion is the slow, long-term uplifting or sinking of land. In Olympia, we primarily experience sinking (or subsidence), which can influence flood risk as enhanced rates of subsidence can accelerate observed and future rates of relative sea level rise. AECOM assessed localized VLM and used those estimates to adjust regional sea level rise projections to local conditions. AECOM estimated a subsidence rate of -2 to -4 mm/yr.
Updated sea level rise projections:
Using the outputs of the VLM evaluation, AECOM developed projections for future sea level rise and maps showing the extent and frequency of sea level rise flood exposure. AECOM conducted a literature review of projections that have been published since the development of the Sea Level Rise Response Plan in 2019, and recommended using the NOAA (2022) regional sea level rise estimates. The updated projections, including VLM, show 12-18 inches of sea level rise by 2050, and 41-66 inches of sea level rise by 2100.
A long-term monitoring and metrics plan: The monitoring strategy provides a standardized, data-driven foundation for prioritizing future capital investments and ensuring timely construction of adaptation measures. The strategy creates a structure for Collaborative partners to evaluate when trigger points-specific, measurable thresholds in environmental or infrastructure conditions that signal when adaptation actions should be initiated-are reached. Project partners can use the trigger points to plan adaptation strategies based on observed changes, rather than fixed timelines. The report includes specific monitoring activities, metrics, and defined thresholds for action as well as templates for collecting data on a regular schedule and after episodic flood events.
The presentation will provide an overview and detail the key outcomes of the work, and an opportunity for questions and discussion with AECOM.
Climate Analysis:
The outputs of the work will allow project partners to be adaptive in our response to sea level rise. The updated sea level rise projections refine our understanding of what we are preparing for and helps to mitigate the impacts of sea level rise on critical infrastructure in downtown Olympia. Overall, the work advances a regional response to a key climate-related hazard.
Equity Analysis:
These initiatives will provide additional data and guidance on how to fund and implement sea level rise response strategies. When appropriate, staff will consider how data collection and analysis for these work items can be designed to improve our understanding of who may benefit and who will be impacted by future projects and funding.
Neighborhood/Community Interests (if known):
There is considerable community interest in sea level rise planning and implementation of flood protection measures in downtown Olympia.
Options:
Briefing only. No action requested.
Financial Impact:
The total cost of the consulting contract was $80,856.00. The outputs of the work will help guide future spending on sea level rise adaptation strategies, including but not limited to infrastructure investments and operational responses. The monitoring strategy also provides a way to track increasing financial impacts and risk to downtown Olympia and the Collaborative Partners.
Attachments:
Monitoring Plan Fact Sheet