In the summer of 2009, Urban Biofilter joined the Tijuana River National Estuarine Research Reserve and the Earth Island Institute’s Restoration Initiative on a bi-national project to restore the Tijuana River Estuary Watershed. Urban Biofilter hosted a 30-person workshop in the Tijuana neighborhood of San Bernardo to help restore the flow of water to the local river system. As is the case with many of the informal settlements in the area, San Bernardo does not have a centralized sewage treatment system. This means that wastewater from San Bernardo simply drains through the streets to the Tijuana River Estuary, one of the last 24 estuaries remaining in the country. Each side street becomes a tributary to the main street, Calle Amanecer, which eventually flows to the estuary, dramatically impacting the water quality and aquatic ecosystem. These open channels also pose a serious health concern as a vector for contamination, putting the local people at a greater risk of contracting hepatitis and staph infections, mosquito-borne diseases and diarrhea.

In the course of the workshop, participants lined the channel with gravel to reduce human exposure to the water and replanted the surrounding area with locally collected native willows to provide a natural air filter. The group also planted a small pilot crop of local bamboo.