Seattle just released new zoning codes for former single-family neighborhoods, which detail how new housing will be built in most neighborhoods. Instead of following the science – which shows that trees and green space build climate resilience and save lives – Seattle is going in the opposite direction of most cities and drastically reducing tree canopy.
Here is how the new zoning harms Seattle’s climate resilience:
1: Fewer, smaller trees across Seattle
Current zoning requires developers to keep or plant two inches of trunk for every 1000 square feet of lot area. Under the new rules, this requirement is cut in half or removed for properties near public transit. Also under the new rule, four housing units get just one “tree point” for every 760 square feet of lot area. Each point only accounts for a small tree — such as a single decorative street tree — meaning many properties will see no meaningful shade. Lots with six or more housing units get no trees at all.
2: Much more pavement
Current zoning requires 65% of a given property to be free of structures, which usually leaves a small amount of green space, even if all trees are removed. The new zoning cuts this to just 20% and what little open space remains can be paved for parking and driveways, leaving almost no room for nature.
3: No room for street trees
Street trees need front-yard space to spread their canopy, since they are typically cut back on the street-side to make room for vehicle traffic, the sidewalk and powerlines. Current zoning gives street trees 20 feet in front yards, but new zoning cuts this to just 10 feet, meaning future street trees won’t have the space to provide meaningful shade.
4: Smaller lots, fewer trees
All residential lots will be reduced to 1,250 square feet with no mechanism to create space for trees. Wealthier neighborhoods with private covenants like Broadmoor and Sand Point Country Club will keep their green space, while all other neighborhoods will suffer from reduced tree cover. The wealth-tree gap will only grow larger under the new zoning plan.
Over two-thirds of Seattle’s trees grow in the affected residential zone (source). To reach 30% tree canopy, which science says is the minimum tree canopy needed to reap the majority of an urban forest’s benefits, we must maintain and grow trees in this zoning area. If we relied solely on public spaces to fill our tree canopy – with trees in all right-of-ways and even in baseball fields -- we’d only get to 18%, missing the mark.
No environmental impact analysis has been done, even though this plan proposes to eventually cover almost 40% of Seattle’s land with pavement and buildings. These new zoning codes were added to the comprehensive plan after the environmental impact analysis was done. That means we’re going into these new laws blind to environmental consequences.
This new zoning fuels heat islands and tree deserts in the name of adhering to the state Middle Housing law, but in actuality goes far beyond state guidelines. The middle housing law says cities can maintain their current environmental and tree regulations. The state does not require Seattle to cover lots with pavement and eliminate urban trees. In fact, the new zoning contradicts the spirit of middle housing legislation, and endangers Washington’s larger environmental goals such as salmon recovery and water quality.
How to do zoning right for housing and trees
Take it from Portland OR: there, the city dedicates space for trees where people live. On residential lots with four or fewer homes, 40% open space with trees or green space is required. On lots with five or more homes, it’s 20%.
The 3-30-300 rule: The 3-30-300 rule is a science-backed urban planning principle, which states that everyone should be able to see three trees from their home, neighborhoods should have 30% tree canopy, and everyone should live within 300 meters of a high-quality public green space.
Avoid lot sprawl: building densely, rather than spreading out housing across lots, is key to maintaining green space. Learn more at our blog post here.
Checkout more policy suggestions to build greener here.
Housing versus trees is a false dichotomy of the old way of unintelligent planning. We can grow with our trees, but not when city leaders encourage development that makes it impossible to plan for climate change.
How you can help
Attend info sessions: Join us to advocate for zoning that protects Seattle’s trees and climate. We’ll be attending OPCD’s upcoming info sessions and handing out flyers. Reach out by email or on our Instagram to let us know you’ll be there. All sessions are 5:30-7:30 pm.
Share this flyer: Print and share in your neighborhood, or let us know if you’d like printed copies.
Email city planners and elected officials: send this prewritten email to the writers of the new zoning code and elected officials. See the email text below if the link doesn’t work.
Subject: Protect Seattle’s Tree Canopy – Request for Zoning Code Revisions
Dear City Council Members, Mayor Harrell, and the Office of Planning and Community Development (OPCD),
I am writing to urge you to reconsider the recent zoning code updates, which will undermine Seattle’s climate resilience and lead to increased environmental inequity. The proposed changes significantly reduce space for trees both on private properties and streets, impacting two-thirds of Seattle’s existing tree canopy. This plan places Seattle on a path to fewer trees, less shade and higher temperatures. Please eliminate the following provisions:
Setback Reductions that limit essential space for both street and private-property trees.
Increased Hardscape Allowances that prioritize pavement over greenspace.
Reduced Tree Requirements on new developments, which are crucial for maintaining canopy as neighborhoods densify.
Look to Portland's tree code for how to build housing while retaining and planting large, climate resilient trees.
Seattle’s urban trees are critical to cooling our neighborhoods, improving air quality, and supporting biodiversity. Please revise the new zoning codes to protect Seattle’s trees and ensure a livable, climate-resilient city for all.
Yes, you read that right. Instead of having more protection, trees in Environmentally Critical Areas have even less protection than all other trees. Trees in ECAs are an essential bulwark against climate change impacts — help us raise awareness and change Seattle's code.
Towering evergreen trees sheltering homes define Seattle. They mean we can survive and even thrive in the face of growing climate impacts. But our roadmap to natural sustainability is under attack by developer interests who gain quick profits from “lot sprawl.”
We get a lot of questions from our elected officials and builders about if building housing and trees is possible — and if so, how we can do it. Here's Tree Action Seattle's expert-backed* guide to how we can build up and green Seattle.
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