COMMISSION 
AGENDA MEMORANDUM                        Item No.          8j 
ACTION ITEM                            Date of Meeting       April 16, 2024 

DATE :     March 21, 2024 
TO:        Stephen P. Metruck, Executive Director 
FROM:    Sarah Cox, Director Aviation Environment & Sustainability 
John Evered, Aviation Senior Environmental Compliance Manager 
SUBJECT:  Adoption of Resolution No 3821: SEA Land Stewardship Plan and Tree Replacement
Standards 
Amount of this request:                       $0 
Total estimated project cost:                   $0 
ACTION REQUESTED 
Request Commission adoption of Resolution No. 3821: a resolution adopting the SEA Land
Stewardship Plan and approval of proposed SEA tree replacement standards. No funding is
requested for this action at this time. 
EXECUTIVE SUMMARY 
This Request seeks authorization to adopt the SEA Land Stewardship Plan (LSP) and SEA Tree
Replacement Standards Policy Directive (STRS). Both the LSP and STRS are Strategies in the
Environmental Land Stewardship Principles (Principles) Order (Order 2023-10 ) approved by
Commission on July 11, 2023. The Principles offer a value statement and guidance for decisionmaking
that balance stewardship to improve the livability, accessibility, and environmental
health of the region with Port operations and development requirements. The Principles
emphasize  comprehensiveness; capital process   integration; consideration of equity and
community partnerships; and holistic ecology practices. 
The LSP is specific to SEA and establishes programmatic Objectives supported by measurable
Goals and Actions that integrate and balance environmental land stewardship with airport
operations, planning, and development. LSP Objectives support comprehensive application of 
the Principles using an approach tailored to SEA operations and land use. The Objectives include
maintaining a current natural resource inventory; restoring forest and other habitat; connecting
and expanding contiguous habitat; offsetting development and operational impacts to trees and
other habitat; applying an equity lens; providing benefits in support of community equity; and

Template revised January 10, 2019.

             COMMISSION AGENDA – Action Item No. 8j                                   Page 2 of 5 
Meeting Date: April 16, 2024 
supporting community partnerships that extend benefits into neighborhoods in the vicinity of 
SEA. 
The LSP also provides a baseline inventory of land use and land cover that is used to inform 
stewardship recommendations in partial achievement of the LSP Objectives. The LSP also
assesses site resources and opportunities in site-specific plans that can be used to inform capital
projects by identifying applicable regulatory, permitting and mitigation requirements; identify
potential locations for wetland mitigation and tree replacement; and supporting capital project
planning by informing preliminary scoping, design and cost estimates. 
Pursuant to the Principles and the LSP, tree replacement standards are being adopted for SEA
Airport Activity Area (AAA), as defined in the adopted (Resolution 3741) 2018 Port-SeaTac
Interlocal  Agreement  and  administered by the  Airport  Building Department.  Port-owned
property outside the AAA is subject to tree replacement standards established by the local
jurisdictions in which the properties are located. Currently certain Port-owned property within
the SEA AAA airport boundary is not subject to City of SeaTac tree replacement standards. The
tree replacement standards (i) exceed the minimum regulatory requirements of our neighboring
jurisdictions;  (ii)  ensure  continued  compliance  with  city,  state, and federal  development
standards for all operations and development activities; and (iii) ensure development and other
land use projects replace cleared trees and identify opportunities for additional types of
beneficial habitat such as pollinator meadows and wetlands. 
JUSTIFICATION 
The Port operates essential transportation infrastructure to ensure the efficient movement of
people and goods in the region and must utilize its land for development and operations, which
can include tree removal. At the same time, the Port recognizes the importance of balancing its 
operations and development with responsible use of economic, community, and natural
resources.
The Port understands that trees, forest and other habitat provide valuable benefits to the public
and the environment.  The Port continually strives to go beyond minimum regulatory
requirements to address environmental justice, improve environmental health, increase climate
resilience, and improve habitat for fish and wildlife.
The LSP and STRS, in line with the Port Equity Policy, will ensure in part that SEA responsibly
stewards  its  economic, community, and environmental resources  to further improve the
livability, accessibility, and environmental health of the region. 
DETAILS 
To support implementation of actions to achieve objectives and goals, the LSP provides planninglevel
information to inform decision-making for both Land Stewardship Program activities and
capital project development. Specifically, the LSP includes: 

Template revised June 27, 2019 (Diversity in Contracting).

             COMMISSION AGENDA – Action Item No. 8j                                   Page 3 of 5 
Meeting Date: April 16, 2024 
1)  Baseline inventory. Provides current landscape-scale and site-specific current information
on operational restrictions, existing/planned development; equity attributes; and natural
resources, including regulated stream, wetlands and buffers as wells as land (tree) cover. 
2)  Stewardship  recommendations.  Management Units  demarcated  based  on  common
planning and resource attributes are categorized into management recommendations.
Vegetation management in operational areas are highly restricted, and third-party
entities  are  responsible  for  maintaining  ground  lease  sites.  Stewardship  is  not
recommended for these areas. Stewardship at development sites focus on public safety,
including cleaning up illegal dumping; pruning vegetation to mitigate hazards  to 
infrastructure  (buildings)  and  human  safety  (publicly  accessible  areas;  roadways);
security; and operational safety (flight corridor safety; wildlife hazard management). 
Stewardship activities in ecological Management Units focus on improving forest health
through long-term stewardship of existing mitigation; construction of new wetland
mitigation to offset development impacts; and forest stewardship, including voluntary
actions and meeting regulatory requirements for tree replacement. 
3)  Site-specific stewardship potential.  Site-specific plans  are created summarizing site
condition and evaluating the extent and health of trees, forest, and other habitat within
each Management Unit. That information is used to evaluate potential for stewardship
and recommend specific actions for tree planting, tree protection, and restoration of
invasive areas. Evaluations also provide planning level information for capital projects to
identify applicable regulatory, permitting and mitigation requirements; identify potential
locations for wetland mitigation and tree replacement; and inform preliminary scoping,
design and cost estimates. 
4)  Site Prioritization. Prioritize ecological sites for stewardship based on relative potential
for ecological lift and increased benefits to community equity. Prioritization is based on
indexing for equity and ecological attributes. Equity criteria include the Port equity index;
urban heat island effects; and improving aesthetic of areas that are physically and/or
visually accessible to the public.  Ecological factors include potential for expanding
contiguous habitat, connecting existing isolated habitat, and restoring fish passage. 
Because most of SEA’s tree canopy is managed in large tracts of open space that is predominantly 
forested, the SEA Tree Replacement Standards apply a holistic ecological approach to tree
replacement that emphasizes improving forest health by increasing canopy, protecting existing
trees from invasive threats, and restoring invasive areas to native vegetation.  The standards
acknowledge the intensive land use the airport and requires retention of existing trees on
developing site to the extent practicable. 
Each tree removed will be replaced with four “stewardship credits”. This credit-based approach 
include the following actions that can generate “replacement credits” by enhancing forest health: 

Template revised June 27, 2019 (Diversity in Contracting).

             COMMISSION AGENDA – Action Item No. 8j                                   Page 4 of 5 
Meeting Date: April 16, 2024 
1)  Plant new trees to increase canopy. (1 tree planted = 1 credit) 
2)  Protect one existing tree from invasive threats to its life and vigor. (1 tree protected = 1
credit) 
3)  Clear invasive species and restore native understory. (200 square feet restored = 1 credit) 
These actions combined will increase overall canopy; ensure canopy is not lost due to invasive
threats; and improve structural and species diversity of restored areas. 
ALTERNATIVES AND IMPLICATIONS CONSIDERED 
The recommended alternative is required by Commission Order to adopt Environmental Land
Stewardship Principles so is required to be implemented. A range of ancillary factors are
considered for the alternatives analysis. 
Alternative 1 – Do not adopt SEA Land Stewardship Plan and SEA Tree Replacement Standards 
Pros: 
(1)   Does not increase operational and capital effort and costs. 
Cons: 
(1)   Does not achieve conditions of the Commission Order to adopt Environmental Land
Stewardship Principles. 
(2)   Does not support Port Mission and Values to responsibly steward resources and
improve regional quality of life. 
(3)   Does not balances SEA operations and development with environmental stewardship
to further improve the livability, accessibility, and environmental health of the region. 
(4)   Does  not  enable  a  programmatic  and  comprehensive  approach  to  SEA  Land
Stewardship. 
(5)   Does not establish a repeatable standard for avoiding and offsetting tree clearing
impacts, instead relying on ad hoc outcomes that vary across projects and activities,
which increases uncertainty and risk for projects and initiatives. 
This is not the recommended alternative. 
Alternative 2 – Adopt the SEA Land Stewardship Plan and adopt SEA Tree Replacement Standards 
Pros: 
(1)   Achieves  conditions  of  the  Commission  Order  to  adopt  Environmental  Land
Stewardship Principles. 
(2)   Supports Port Mission and Values to responsibly steward resources and improve
regional quality of life. 
(3)   Does not balance SEA operations and development with environmental stewardship to
further improve the livability, accessibility, and environmental health of the region. 
(4)   Enables for a programmatic and comprehensive approach to SEA Land Stewardship. 

Template revised June 27, 2019 (Diversity in Contracting).

             COMMISSION AGENDA – Action Item No. 8j                                   Page 5 of 5 
Meeting Date: April 16, 2024 
(5)   Establishes a repeatable standard for avoiding and offsetting tree clearing impacts,
which increases certainty and reduces risk for projects and initiatives. 
Cons: 
(1)   May increase operational and capital costs. 
This is the recommended alternative. 
ATTACHMENTS TO THIS REQUEST 
(1)   Resolution No. 3821 
o  Exhibit A: SEA Tree Replacement Standards 
o  Exhibit B: SEA Land Stewardship Plan (available online)
(2)   Presentation slides 
PREVIOUS COMMISSION ACTIONS OR BRIEFINGS 
February 20, 2024 – Briefed the Sustainability, Environment, and Climate Committee (SEAC)
Committee on SEA Tree Replacement Standards and SEA Land Stewardship Plan. 
February 16, 2024 – Briefed Commissioner Hasegawa on SEA Tree Replacement Standards
and SEA Land Stewardship Plan. 
November 6, 2023 – The Commission Sustainability, Environment, and Climate Committee
(SEAC) Committee received a briefing on SEA Tree Replacement Standards and SEA Land
Stewardship Plan. 
July  27,  2023  –  The  Commission  authorized  an  Order  to  implement  the  Port-wide
Environmental Land Stewardship Principles and Strategies. 
February 21, 2023 – The Commission Sustainability, Environment, and Climate Committee
(SEAC) received a briefing on the Port-wide Environmental Land Stewardship Principles
and Strategies. 






Template revised June 27, 2019 (Diversity in Contracting).