Bioswale Studies

Stormwater Trees

Tree condition and survival in street-side stormwater facilities ("bioswales")

Street-side stormwater infiltration basins (“green stormwater facilities”) planted with vegetation that often includes ornamental trees, are becoming increasingly common in cities. While bioswales can be effective in managing stormwater, very little is known about the performance of trees planted therein. The two projects described here evaluate tree survival, growth, and condition in stormwater facilities.

We use the city of Portland, OR (>10 years experience with trees in stormwater facilities) as a long-term comparison for cities in the San Francisco Bay Area (0-5 years experience). The studies will result in two products: a publication quantifying the initial results, and a standardized monitoring protocol for trees in stormwater facilities, to be used by cities that are installing their own bioswales with trees. The protocol will be informed by the study results as well as the suggestions from partner cities, and will include instructions, data collection templates and calculation sheets, as well as a discussion of lessons learned in the study.

Get involved: "Enroll" your bioswales in the study!

If you are a city in the greater Bay Area that has or is in the process of installing street-side stormwater facilities that contain trees, please contact me (ilacan "at" ucanr.edu) to "enroll" your stormwater trees in the study. There is no cost to the city, and depending on funding and site conditions, I might have soil instruments available to deploy in your bioswale!

Researchers, partners, and funders

Both projects are managed by Igor Lacan, UCCE San Mateo/San Francisco Urban Frestry advisor. My partners include City of Portland (Oregon); as well as Cities of Berkeley, El Cerrito, San Carlos, San Francisco, and San Jose.

The first phase of this research has been funded by the California Institute for Water Resources; the second phase is funded by a National Urban and Community Forestry Advisory Council matching grant.