The greening of streets in Southern California communities are increasingly resulting in both the beautification of public roadway infrastructure and direct improvements to (and within) the built environment.
Regional and watershed-based water quality management plans that address existing infrastructure and water quality needs have specifically identified green streets as a key opportunity (and Low Impact Development Best Management Practice) that can provide significant environmental benefit in a widely distributed manner. Benefits of distributed green street BMPs include the ability to provide wide coverage within virtually all land use types (a significant benefit in older, built-out urbanized areas). A second benefit is the ability to mitigate stormwater pollutants near the sources. Other environmental benefits include the addressing of heat island effects, restoration of water balance elements, aesthetic enhancement, habitat creation, and building a sense of neighborhood and community through environmental stewardship, social engagement, economic growth, and the experience of beauty. Development of green streets projects in Semi-Arid and Mediterranean environments with impaired water quality, however, provide a number of challenges. These challenges include engineering constraints (particularly geotechnical and geological constraints), more extreme hydrology, erosion potential, pollutant loading and accumulation, vegetation-specific requirements and tolerances, and local aesthetics. This paper/presentation describes green street design elements, with particular emphasis on those elements that are unique to Southern California environments. Examples of successes and challenges will also be provided.