An official website of the United States government.

This is not the current EPA website. To navigate to the current EPA website, please go to This website is historical material reflecting the EPA website as it existed on January 19, 2021. This website is no longer updated and links to external websites and some internal pages may not work. More information »

San Francisco Bay Delta

Fremont Tree-Well Filter

EPA awarded a $300,000 grant to install tree well systems to treat stormwater pollutants, including trash, from over 14,000 square feet in an industrial area. The San Francisco Estuary Institute is conducting pollutant reduction monitoring for the project. The city will develop a tree-well filter installation guide to direct future installation of the filters to treat stormwater.

Project Facts

Recipient: San Francisco Estuary Partnership/Association of Bay Area Governments
Funding: EPA = $300,000; Match/leverage = $67,668)
Project Period: February 2009 - December 2014
Partners: Architects for Humanity, San Francisco Estuary Institute

Environmental Results Summary: Fremont Tree-Well Filter

OUTPUTS (Activities, efforts, and/or work product during project period)

OUTCOMES (Environmental results)

(1-5 yrs)


Pilot two alternate full sized tree well filter designs to both treat stormwater in an industrial area of Fremont and incorporate NPDES trash capture requirements.

Treat stormwater from over 14,000 ft.² of impervious surface in an industrial area of Fremont.

Widespread use of LID to treat polluted stormwater and enhance aquatic ecosystems.

Full List of Project Summaries