Tacoma Urban Forestry

Executive Summary: Tacoma Urban Forest Manual 2025

Washington State Law: Combining Urban Forestry, Critical-Area Protection, and Public Benefit

The City of Tacoma's 2025 Urban Forest Manual (UFM) is one of the most detailed municipal plans in Washington State for combining tree care, landscaping standards, and stormwater compliance. The Planning and Development Services and Environmental Services Departments of the City of Tacoma created the UFM. It ensures that the city complies with the law (Tacoma Municipal Code (TMC 13.06.090B)) and that the state complies with the Growth Management Act (RCW 36.70A.172) by using Best Available Science (BAS) to protect critical areas and the health of ecosystems.

The manual redefines urban forestry as a vital public service, comparable to water, transportation, and energy infrastructure, grounded in objectives of achieving a 30% citywide tree canopy, enhancing climate resilience, and safeguarding watersheds.

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1. Keeping important places and waterways safe

Tacoma's plan puts trees first to protect against flooding, pollution, and erosion. TMC 13.11 (Critical Areas Preservation) says that the city's landscaping rules require plants to protect wetlands, steep slopes, and riparian areas.

• Roots of trees help keep slopes stable and stop sediment from washing into Puget Sound and Commencement Bay, which protects aquatic habitats.

• Canopy cover catches stormwater, which helps it soak into the ground and puts less stress on grey infrastructure. • The city makes sure that its tree-retention and Low Impact Development (LID) rules are in line with Tacoma's Stormwater Management Manual and the Shoreline Management Act (RCW 90.58). This directly links tree preservation to efforts to control flooding and improve water quality.

Tacoma ensures site-level compliance with hydrology and soil science by requiring Tree Protection Plans, Landscape Management Plans, and Certified Arborist reports.

2. Benefits for the environment and climate

Tacoma counts canopy as environmental capital.

• Canopy Credits: Tacoma's Tree Canopy Credit System gives each new or kept tree between 200 and 1,000 credits based on its size and species. These credits measure the tree's benefits for stormwater management, air quality, and carbon sequestration.

• Retention Incentives: Older trees (≥24” DBH) are given priority for preservation because they are better for air and water quality.

• Climate Mitigation: Trees take in CO₂, filter out pollutants, and lower the urban heat island effect, which can reduce the temperature by up to 10°F.

These benefits directly help the goals of RCW 70A.15 (Air Quality) and the State Clean Water Act. Tacoma's use of native and evergreen plants ensures that stormwater benefits persist year-round, supporting recovery goals for Puget Sound.

3. Health and Well-Being of the Community

Tacoma's UFM sees the canopy as a way to improve public health.

• Trees filter out fine particles (PM₂.₅) and take in ozone and nitrogen oxides, which make asthma and heart disease worse.

• Shaded corridors provide cool places to escape the heat, which is essential for seniors and other vulnerable groups.

• Tree-lined streets make it easier to walk, lower stress, and improve mental health.

The plan puts environmental justice into action by planting more trees in neighborhoods with significant differences, in line with RCW 43.70.820 (Health Equity Act).

4. Benefits for the economy and property values

Tacoma's canopy plan links environmental protection with economic benefits:

• For each dollar invested in planting trees, over $2.50 is saved on stormwater management, cooling, and energy expenses.

• Tree-lined commercial districts attract customers, and homes surrounded by mature trees can increase in value by as much as 10%.

• The city's flexible canopy-credit fee structure ($15 per credit or $3,000 per in-lieu tree) makes sure that private developers pay into the Urban Forestry Fund, which helps with fair replanting across watersheds.

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These results are in line with RCW 35.92.010, which allows people to invest in natural infrastructure for the public good.

 5. Tacoma, Washington: Laws that protect trees, make sure everyone has equal access to the canopy, and keep the climate healthy

Tacoma sees trees as public infrastructure that supports stormwater control, air quality, neighborhood health, and cooling. The city's code and planning documents state that tree canopy is linked to climate justice, public safety, and watershed protection. Tacoma's rules directly support Washington's statewide rules under the Urban and Community Forestry Act (RCW 76.15), the Water Pollution Control Act (RCW 90.48), the Shoreline Management Act (RCW 90.58), and the Growth Management Act (RCW 36.70A.172). City of Tacoma+2City of Tacoma+2

Tacoma also has a clear, measurable citywide goal: by 2030, the total canopy should go from about 20% to 30%, with a focus on neighborhoods that have been underserved in the past and are now hotter. City of Tacoma +2 City of Tacoma +2

TMC 9.20 — Urban Forestry Purpose and Scope:

Ordinance 28926, passed in December 2023, made Tacoma Municipal Code 9.20 (Urban Forestry), which sets rules for how trees in the public right-of-way can be planted, trimmed, and cut down. It gives the City official authority to manage and protect public trees as shared assets and establishes mechanisms to enforce that authority. Tacoma City

Important Points:

• Treats street trees and trees on other City-owned property as permanent landscaping, not as things that can be thrown away.

• Sets up a Heritage Tree Program that lets trees with historical, ecological, or cultural importance be officially named and protected.

• Requires that requests to prune or remove trees on public property be reviewed on a case-by-case basis to avoid losing unnecessary canopy and to keep mature trees in place whenever possible.

• Sets up a way to enforce the law and appeal decisions, including fines and other penalties, so that damaging trees in the right-of-way has legal consequences instead of being seen as "no harm done."

• Tells City staff to use best practices for pruning, spacing, and long-term health, not just short-term clearance.

Results of the policy:

TMC 9.20 changes the way we think about public trees as important infrastructure. This supports RCW 76.15 by providing the City with an operational urban forestry program. It also supports RCW 70A.15 (air quality) by preserving canopy in neighborhoods, where trees cool streets, filter particles, and reduce exposure to heat and vehicle emissions. City of Tacoma+2City of Tacoma+2

TMC 13.06.020.F and 13.06.090 — Tree Canopy Credits and Rules for Landscaping

Purpose and Scope: Tacoma's Urban Residential (UR) districts link tree canopy directly to zoning and development. The city's code requires new buildings and renovations to have a certain number of trees on their property, known as "Tree Credits." Tacoma CMS Key Provisions: Every development project in Urban Residential zones must have a canopy value of at least a specified amount.

·       UR-1 zones: the minimum canopy requirement is 30%.

·       UR-2 zones: 25% is the minimum.

·       UR-3 zones: 20% of the time.

·       The code lets specific bonuses and flexibilities lower those minimums, but there is still a floor, even with incentives, that is 10% in the lowest-density cases. Tacoma CMS

·       To get Tree Credits, you can: o Keep mature trees (keeping them is the best option because older trees provide more shade, cooling, stormwater interception, and habitat).

·       Putting new canopy trees in the ground on the property.

·       In some cases, approved off-site planting or contributions instead of a complete on-site canopy if it is not possible to build one on-site. Tacoma CMS

·       Landscaping and canopy layouts must be included in development plans from the beginning, not as an afterthought at the end of the permitting process. • Standards require species that can survive long term, provide shade, soak up stormwater, and stabilize soils, especially in paved, heat-prone neighborhoods that currently have the least canopy. Tacoma CMS+1

Policy Outcomes:

Tacoma is using zoning to push trees back into neighborhoods with paved roads. This directly connects private development to public health outcomes: areas that have historically been too hot and poorly served will have more shade, cooler streets, less flooding, and cleaner air. That structure is similar to RCW 36.70A.172 because it bases canopy requirements on mapped heat risk, differences in air quality, slope stability, and stormwater performance. CMS+1 in Tacoma

TMC 13.11—Preservation of Critical Areas Purpose and Scope:

The Critical Areas code in Tacoma protects wetlands, steep slopes, riparian corridors, areas likely to flood, and streams that support fish. RCW 36.70A.172 requires Tacoma, like other cities in Washington, to base these protections on the best available science.

Tacoma CMS Key Provisions:

• It limits the clearing, grading, or removal of vegetation—especially mature trees—in and near critical areas.

 • When work is proposed within a regulated buffer, qualified professionals must prepare vegetation management plans.

• When vegetation needs to be cut down for safety, utility work, or development, it must be restored, replanted, and stabilized.

 • Using native tree and shrub species helps keep slopes stable, slows down erosion, cools streams, and filters out pollutants before they get to Puget Sound and the Puyallup watershed. • These rules also fit with shoreline protections and stormwater rules, making sure that riparian canopy is seen as critical infrastructure for salmon recovery, flood control, and water quality, in line with RCW 90.58 "no net loss" and RCW 90.48 water-quality standards.

Results of the Policy:

TMC 13.11 establishes "no net loss of ecological function" as a rule in Tacoma's most sensitive areas, including salmon-bearing drainages and slopes prone to erosion. Not only are trees here a "nice habitat," they are also necessary natural armor against floods, landslides, and polluted runoff. Tacoma CMS+1

6. Vision and Strategy for the Future

The 30% canopy goal for Tacoma is both measurable and flexible. The UFM adds Tree Canopy Credits to measure benefits in different areas (UR, Commercial, Industrial).

• Canopy Loss Fees to make it less appealing to cut down mature trees (≥6" DBH).

• Tree banks that let people plant trees in the same watershed but not on their own property.

• Long-term benefits for stormwater BMP synergy (BMP L615, L633).

The city's vision shows that it wants to be strong in the long run:

"The trees in the cities depend on the health of the Puget Sound, and the cities depend on their trees."

Conclusion

Tacoma's Urban Forest Manual sets the standard for how cities in Washington should manage their environments. The plan changes the tree canopy from a pretty thing to an enforceable part of the environment that is important for clean water, public health, and climate resilience by combining land-use regulation, critical-area protection, and urban forestry science.