Urban Tree Canopy for Stormwater Management

Studies have proven what many of us have suspected for a long time: planting trees in urban areas measurably improves quality of life and overall health of the residents living in those spaces. However, these trees have another secret benefit. Urban trees can also play a vital role in addressing stormwater problems. 

The Puget Sound region has become one of the fastest growing areas in terms of growth and development. The expansion of impervious surfaces, such as streets and roofs, has increased stormwater runoff volumes, which can lead to flooding, erosion, and water pollution. Planting trees in urban areas can reduce stormwater volume and filter water, while also providing wildlife habitat, shade, and improved air quality.

However, urban city planning, management policies, and implementation practices rarely embrace trees as a part of the stormwater solution. We want that to change!

In 2021, we completed The Puget Sound Urban Tree Canopy and Stormwater Management Handbook and its corresponding Technical Report in cooperation with King Conservation District. The goal of the Handbook is to promote tree planting and tree retention as a green stormwater infrastructure strategy.  

The Handbook includes information, incentives, tools, and other resources related to the many benefits of urban trees. It will help to support collaboration between urban forestry and stormwater management professionals and promote engagement with policy makers and implementers, builders and developers, and property owners.

We’ve also taken over management of the Urban Tree and Forest Canopy Cover Toolkit grant from King Conservation District and are leading the project in partnership with Whatcom Conservation District, cities, state agencies, and nonprofit partners. This web-based toolkit—to be completed in 2022—will help municipalities develop policies and implement community investment programs to enhance tree cover for stormwater management and habitat restoration, and to address equity disparities related to urban tree cover.