SAN DIEGO EMBRACES STORM WATER QUALITY MITIGATION FOR DEVELOPMENT PROJECTS

摘要

Urbanization generally results in an increase in pollutant sources and impervious surfaces. The increase in pollutant sources, such as parking lots, rooftops, and streets, contributes to increased pollutant loads found in storm water, while the increase in impervious surfaces prevents natural processes from filtering the same pollutant loads out of storm water runoff. In addition, urbanization’s impervious surfaces prevent storm water from infiltrating into the soil, directing increased runoff volumes onto downstream areas. What is the end result? Urbanized areas increase storm water runoff volumes and the quantities of pollutants carried in the runoff. Not surprisingly, these storm water flows from urban areas— urban runoff— impair the quality of downstream receiving waters: our creeks, bays, and the ocean. Addressing one or both of the factors affecting the quality of urban runoff during project design can reduce a development project’s negative impacts on the quality of runoff leaving the project site. These design strategies are often called post-construction, or permanent storm water best management practices (permanent BMPs), because they are designed to function throughout the life, or “use” phase of a project site. The notion that permanent BMPs can mitigate development’s negative impacts on the quality of urban runoff is widely accepted in urban storm water planning, and agencies and jurisdictions across the country are enacting new storm water development regulations affecting how projects are designed to mitigate the negative water quality impacts associated with development. However, the effectiveness of design strategies to reduce urbanization’s negative impacts on water quality continues to be hotly contested. Not surprisingly, how and to what degree to incorporate these design strategies into development projects continues to stir controversy in urban storm water planning. This area of contention often creates an atmosphere that is often an impediment to developing and implementing environmentally, socially, and economically optimal solutions in urban storm water planning.