Better Ground


The Puget Sound region has become one of the fastest growing areas in terms of population and development. The expansion of impervious surfaces, often coupled with grading and tree removal, has increased stormwater runoff volumes, which contribute to flooding, erosion, and water pollution. Fortunately, tree canopy in urban areas can reduce stormwater volume and filter water, while also providing wildlife habitat, shade, and improved air quality, human health, and livability. What began (in Phase I) as a quest to accurately quantify the value of urban tree canopy for stormwater management in Puget Sound, the “Trees and Stormwater” project evolved to produce valuable resources for jurisdictions that go beyond stormwater. 

While the Technical Report from the tree canopy/hydrology modeling study demonstrates the effective role trees (especially conifers) play in stormwater management, the companion Handbook expands the conversation to consider an interdisciplinary approach to collaboration and co-design of green infrastructure and urban forest management for the compounding benefits provided to the community.

However, growth planning, management policies, and implementation practices rarely embrace trees as a part of the stormwater solution, let alone see them play a valuable role in community resilience. As this web-based Toolkit was being developed in Phase II to provide resources for more productive collaboration, the power of strong partnerships, influential champions, and public engagement were revealed as critical components for successful integration that can support a robust urban forestry element in a community’s agenda for resilience.

Phase I Resources: Puget Sound Urban Tree Canopy and Stormwater Management

This work would not have been possible without the support from our partners.

WA DNR Urban and Community Forestry 

Kathleen Wolf, PhD University of Washington

Heidi Siegelbaum, Washington Stormwater Center 

Pierce, King, Snohomish Counties – Surface Water

Pierce, King, Snohomish & Whatcom Conservation Districts

Phase I Pilot Cities of Kirkland and Tacoma

Cities of Snoqualmie and Edmonds

Stewardship Partners 

The Nature Conservancy – Washington

King County Cities Climate Collaboration (K4C)

The Keystone Concept 

This project has been funded wholly or in part by the United States Environmental Protection Agency under assistance agreement PC-01J18101 to the Washington State Department of Ecology. The contents of this document do not necessarily reflect the views and policies of the Environmental Protection Agency, nor does mention of trade names or commercial products constitute endorsement or recommendation for use.