Seattle Urban Forestry Commission Raises Questions about Mandatory Housing Affordability Draft EIS

The Seattle Urban Forestry Commission has issued the following comments in response to the Mandatory Housing Affordability Draft EIS. Comments are due by August 7, 2017.

The letter below is the text of the letter dated August 2, 2017.

August 2, 2017.
Samuel Assefa
Director – Office of Planning and Community Development
600 4th Ave
Seattle, WA 98124


Dear Sam:
As the City of Seattle drafts policy that seeks to increase urban density and affordable housing to accommodate more people and jobs, protecting and enhancing Seattle’s urban forest is needed more than ever to abate the biological, visual, and health impacts of this measure.
The Urban Forestry Commission commends the MHA Draft EIS for stressing the importance of tree coverage for Seattle, specifically citing the goals outlined in the 2013 Urban Forest Stewardship Plan (UFSP), as well as incorporating the most recently published 2016 canopy cover assessment results.
The Commission, however, disagrees with the MHA Draft EIS determination of no significant impacts to the city’s tree canopy and requests clarification regarding methodology and mitigation measures proposed in the MHA Draft EIS, specifically:

1. What is the projected tree loss in the No Action Alternative of the MHA Draft EIS?
2. Please explain in more detail the methodology used to estimate the projected tree loss in
Alternatives 1 (No Action), 2 and 3 of the MHA Draft EIS.
3. How would a mitigation measure be actionable or enforceable when the UFSP is a policy
document and not a required ordinance?
4. Why is a 0.5% loss of tree canopy considered not significant? The MHA Draft EIS does not cite any authority or precedent for that conclusion.

In addition, the Commission requests a response to the following additional comments regarding the MHA Draft EIS:

Underestimation of tree canopy impacts:

The MHA Draft EIS states that there will be less than a 0.5% decrease in the tree canopy for both Alternatives 2 and 3 compared to the No Action Alternative. The Commission questions the methodology used in the MHA Draft EIS for calculating this assessment for the following reasons:

1. The MHA Draft EIS states, “Tree cover for a given zone was assumed to remain constant over time if the zoning designation stayed the same.” [Page 374] The Commission recommends that the MHA Draft EIS should account for some increase in tree canopy loss in zones that stay the same. MHA will likely incentivize developers to maximize gross floor area (GFA) on a 2  redevelopment sites, and one way a developer can maximize GFA is to develop the site to its fullest development potential.

The MHA Draft EIS does not take into account the effect (i.e. enhancement or increase) of the development potential of a lot in MHA areas when calculating tree canopy loss. We request that the final MHA EIS include a calculation of tree canopy reduction using the full development potential of each lot within MHA areas even if the zoning is not changing.

2. The MHA Draft EIS calculates that 0.5% decrease in tree canopy would result in up to a 5 to 16- acre loss in tree canopy associated with Alternatives 2 and 3. While a 0.5% reduction in canopy seems like a low percentage of loss, in real terms it would generally equate to a loss of 173-555 trees (assuming a typical tree canopy has a radius of 20 feet (1,256 square feet)), which is a potentially significant number of trees. Citing tree canopy loss using an estimated number of trees that are lost would more accurately communicate the likely impacts of the MHA policy to the neighborhood tree canopy.

The MHA Draft EIS does not cite any authority for the assertion that a loss of 0.5% tree canopy (i.e., 173-555 trees) is not significant. The Commission believes a loss of this many trees is a significant impact under Alternatives 2 and 3 that should be mitigated, and that the MHA Draft EIS is unsupported as written.

Inadequate Mitigation Measures:
The MHA Draft EIS states no significant, unavoidable adverse impacts to the tree canopy have been identified, but does list some mitigation measures that would help to avoid and minimize tree canopy loss. The Commission thinks the current mitigation measures are inadequate, and need to be expanded and strengthened.

1. The MHA Draft EIS recommends the City evaluate future urban forestry policies as part of the 2018 UFSP update, but does not include mitigation measures within the context of existing policies such as updating Seattle tree protection code, Seattle Green Factor guidelines, or the Seattle Street Tree Manual. Mitigation measures for tree canopy loss should deal with changing or updating existing regulations and not just recommending evaluation of future policy, which is not enforceable.

Specifically, the Commission recommends requiring mitigation for tree loss to include
replacement of equivalent canopy on- or off-site or paying into a City tree replacement and
maintenance fund.

2. A healthy urban forest can have an outsized impact on reducing the negative effects associated with increased development intensity, as trees (especially street trees) help to mitigate the visual impacts of density and create a more human-scaled environment, as well as providing important ecosystem and public health benefits. While the MHA Draft EIS documents multiple negative aesthetic impacts associated with increased development intensity, the plan does not recommend any mitigation measures focused on increasing or improving the urban forest to mitigate aesthetic impacts of density.

The Commission recommends including stronger, more binding requirements to promote and improve tree coverage in urban village areas. These recommendations could include but are not limited to the following:

1. Expand incentives and development standards to promote street trees in Urban Villages;
2. Update the interim tree protection ordinance to account for the impact MHA will have on
3. Reduce conflict between power lines and street trees;
4. Modify the Seattle Green Factor guidelines to give higher score to preserving healthy existing site vegetation;
5. Assess, monitor, and tally tree loss in the permitting process; and
6. Update the tree code to require retention, replacement, or payment into a City tree
replacement and maintenance fund for all removed trees, including hazardous trees, or trees which die as a result of development impacts or that are planted as project mitigation.

Thank you for your attention. The Commission looks forward to your response.


Seattle Urban Forestry Commission Raises Questions about Mandatory Housing Affordability Draft EIS — 1 Comment

  1. Stress the use of native trees and have a compleete careful assment of the invasive potential of non-native trees (Global Compendium of Weeds 2nd Addition, Randall). Make a real effort to provide healthy root system space for native trees, accomidate native trees in any way possible and come up with different ways of doing and thinking. Seattle has been ignoring the science of ecosystems and biodiversity with the ignorant attitude that a tree is an tree and canopy is canopy….. nope. The Seattle policies for more (native) trees and for more and better tree services needs to be accross all departments and needs to be funded for education of emploees and the public. We have people that are completely unaware of the long term consequences of decisions and actions that they have in their control. The people making decisions have a blind spot concerning sustaining biodiversity and they dismiss these elements when making tree decisions.