The Urban Bioretention design specification covers special bioretention applications in highly urban areas, including stormwater planters, expanded tree pits and stormwater curb extensions. These designs differ from regular bioretention in that they rely primarily on filtering rather than infiltration, and are ideally suited for urban infrastructure (streets, sidewalks and buildings).

Most of the urban bioretention designs were originally developed in Portland Oregon and Seattle, WA, although several demonstration projects have been installed in Baltimore, MD. Comments are invited from the Network on how these special bioretention practices can be adapted for urban conditions in the Bay watershed would be most welcome. For example, does the same bioretention plant list work in these applications, or are more hardy species needed to withstand the tougher stressors found in ultra-urban areas?