With increasing concern about climate change, attention has turned towards cities for their capacity to enhance and use biogenic infrastructure, nature's services to remediate some of their own environmental impacts. Biogenic infrastructure encompasses urban tree planting, watershed restoration and green streets programmes to capture storm water and dry weather runoff through techniques such as bioswales and water infiltration zones. This chapter raises a set of issues about the retrofitting of green infrastructure that go beyond Los Angeles. Mayoral candidate Villaraigosa's 2004 campaign promise to plant a million trees was one of several programmes he put forward to make Los Angeles the greenest big city in the USA. It also shows that urban environmental management in the USA has a set of institutional contexts, and a path dependency that shapes current debates, expectations, and patterns. The chapter identifies the tensions they create with current city organisational structure for democratic accountability and participation and for equity.