Integrated Stormwater Management in Los Angeles, California: Best Management Practices and Evaluation of Ancillary Benefits

Abstract:

Best Management Practices (BMPs) and Low Impact Development (LID) have been the primary tools to address quantitative and qualitative surface runoff impacts. The City of Los Angeles (City) is evaluating plans for individual Total Maximum Daily Load (TMDL) pollutants in each of its major watersheds. However, it has yet to be studied if implementing individual BMP projects will adequately address water quality objectives for receiving (downstream) water bodies, such as Ballona Creek, Ballona Estuary and the Santa Monica Bay. In addition, there is significant uncertainty surrounding potential ancillary benefits (flood reduction, water supply, green space, etc.) from BMP/LID implementation. This presentation will overview our work with the City evaluating the influence of BMPs and LIDs in improving water quality at the watershed scale as well as quantifying other hydrologic benefits. Multiple BMP scenarios are considered to identify various pathways toward improved receiving water body quality in Ballona Creek and Dominquez watersheds. Specific study objectives are to: 1) identify suites of BMP scenarios which can lead to TMDL compliance, 2) quantify the multiple benefits provided by BMPs beyond their primary water quality improvement purpose, and 3) evaluate the success of using existing software for watershed-scale BMP modeling. Our goal is to provide realistic, implementable pathways that can be used by stakeholders to help plan for future education, outreach and capital improvement programs as well as determine feasible pollutant reduction objectives.