Seattle Needs to Require Developers to do Urban Forestry Canopy Impacts Assessments

The Seattle Urban Forestry Commission in 2014 recommended that its Department of Planning and Development require project developers to complete urban forestry canopy impact assessments. Seattle’s growth and property development and building is continuing at breakneck speed and impacting Seattle’s existing urban forestry infrastructure. Yet the city has done nothing to implement the Seattle Urban Forestry Commission’s recommendation. It should do so. Below is the text of the recommendation made on June 25, 2014.

June 25, 2014.
Mayor Ed Murray and Councilmember Sally Bagshaw
Seattle City Hall
600 4th Avenue
Seattle,WA 98124

Dear Mayor Murray and Councilmember Bagshaw,

As our city increases efforts to improve canopy coverage we have a gap in that even as we plant new trees, the number of trees removed from private land under development in the city is unknown. The Urban Forestry Commission would like to have better information on the number of trees removed from private land to obtain a metric which could be correlated to canopy cover assessments. This correlation would help articulate the need for a future tree code on private property. We would also be able to fulfill the monitoring called for in Seattle’s Urban Forestry Stewardship Plan and provide the City with data to judge how difficult a tree code on private property could be.

There are two specific requests we would like to make to comply with the monitoring efforts of the newly adopted Urban Forestry Stewardship Plan (UFSP).

1. Updated canopy assessment: Regular canopy coverage assessments are integral to the monitoring of the UFSP. The last canopy cover assessment was performed in 2009 with 2007 data. Please allocate funding for an updated canopy coverage assessment to the Office of Sustainability and the Environment per the short term action item (1-5 years) within the UFSP.

2. Quantify Tree Removals: Accurate tree planting and removal quantities are necessary for monitoring of the UFSP within the largest management unit in the city: single family residential areas. The table 8 (attached) is excerpted from page 73 of the UFSP. The last two columns show that we have a goal of raising the canopy cover substantially throughout the city. There currently is no data available to understand the impacts development has on canopy cover. In order to track our progress to reach our 2037 goal, we ask that DPD to:

a. Upgrade building permit applications within the single family zones to quantify tree removals; and
b. Report tree removals within the single family zones annually. Geographically located tally data would also be helpful for correlating development with tree canopy losses and gains.

Enclosed is a more detailed document explaining additional information that would be useful for the City to better manage the urban forest to accomplish the City’s goals.

Sincerely, Peg Staeheli, Chair Tom Early
Urban Forestry Commission Urban forestry Commissioner

cc: Council President Burgess, Councilmember Clark, Councilmember Godden, Councilmember Harrell, Councilmember Licata, Councilmember Rasmussen, Councilmember O’Brien, Councilmember Sawant,Jill Simmons, Diane Sugimura, Brennon Staley, Eric McConaghy

Urban Forest Canopy Impact Assessment

The Seattle Urban Forestry Commission is tasked with advising the Mayor and Seattle City Council on urban forestry issues. This includes implementing the Urban Forestry Stewardship Plan (UFSP) to achieve a 30% canopy goal by 2037. In addition, the current Seattle Comprehensive Plan states that the City needs to maintain no net loss of canopy as a baseline. As noted in our letter, the Commission considers two steps very important:

1. Perform a tree canopy assessment
2. Improve current submittal documentation for projects under development

The Commission has discussed several ideas to improve submittal documentation and final reporting for projects under DPD’s permitting.

• Currently, the City, through OSE and the Urban Forestry Interdepartmental Team, keeps track of the number of trees planted and removed on public property every year. The Commission recommends tracking trees lost on private property undergoing development to assist in determining where we are gaining or losing trees and canopy. This would add information to the overall city canopy coverage assessment data. By knowing more about canopy trends on different types of land, we can better direct policy and programming to ensure we are on track to meet our 30% goal.

• What would help the City better understand what is happening with tree canopy protection and enhancement is to require that all development projects submit an Urban Forest Canopy Impact Assessment prior to any construction project being approved. The Urban Forest Canopy Impact Assessment would include a map of the property with the trees numbered, canopy area of trees drawn, and trees to be removed clearly labeled. Under current guidelines it would minimally require that all trees 6 inches DBH (diameter at breast height) or larger be inventoried on the property. The suggested data points required would be :

  •  Species: speaks to size of canopy and amount of storm water benefit.
  •  DBH: speaks to age of tree and canopy coverage.
  •  Tree Height: speaks to canopy volume and amount of environmental benefit.
  •  Canopy Width (area): speaks to canopy volume and amount of environmental benefit.
  •  Tree Condition: speaks to overall forest health and environmental impacts.
  •  Photographs of the trees on the parcel and adjacent properties.
  •  Canopy coverage as a percent of area pre- and post-project development.

• Landscape Plan Requirements could include calculations for percent canopy coverage at 20 years and soils volume provided for each tree.

• The annual UFSP Progress Report to the Mayor and City Council could include canopy coverage for different development zones.

Implementing some or all of these operational steps would greatly help to evaluate whether or not we are doing enough to reach our 30% canopy goal by 2037. It would also allow some progress on clarifying tree requirements until DPD is able to put forward a new tree ordinance.

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