Development of watershed management modeling system: the Los Angeles County Flood Control District’s watershed based approach for urban runoff and stormwater quality

摘要

Improving the quality of urban runoff and stormwater in the Los AngelesCounty’s coastal watersheds is challenging. Thousands of separately permitteddischarges with multiple Total Maximum daily Loads flow into the samereceiving water bodies simultaneously. This makes it necessary and economicalto address many different pollutant sources concurrently. In order to helpovercome such challenges, the Los Angeles County Flood Control District isdeveloping a watershed modeling system (WMMS) that would ultimately identifycost-effective projects through an integrated, watershed based approach. UsingWMMS, collective impact of a variety of pollutant sources from point to nonpointis evaluated and thereby comprehensive, long-term strategies for overallwater quality improvement of the entire watershed will be planned. In addition,the WMMS will be used as an integrated watershed management tool for futureplanning of projects that achieve multiple benefits besides water quality such aswater conservation, flood control, and open space development. This wouldeventually allow for an effective stormwater resource management.