Significant development has taken place in Riverside County in the last several decades resulting in the urbanization of many areas. Urbanization generally increases Urban Runoff volume and velocity of runoff and the amount of pollutants in the runoff.

As development occurs, natural vegetated pervious ground cover is converted to impervious surfaces such as highways, streets, rooftops and parking lots. Natural vegetated soil can both absorb rainwater and remove Pollutants providing an effective natural purification process. In contrast, impervious surfaces can neither absorb water nor remove pollutants, and the natural purification characteristics are lost.

Additionally, urban development can significantly increase pollutant loads as the increased population density causes proportionately higher levels of vehicle emissions, vehicle maintenance wastes, municipal sewage wastes, pesticide, household hazardous wastes, pet wastes, trash, and other anthropogenic pollutants.

To counteract the effects of urbanization, new developments and significant redevelopments follow Low Impact Development (LID) principles and utilize the Water Quality Management Plan (WQMP) template and guidance in the design of their site.

Low Impact Development

Low Impact Development (LID) is an approach to land development (or re-development) that works with nature to manage stormwater as close to its source as possible. LID employs principles such as preserving and recreating natural landscape features, minimizing effective imperviousness to create functional and appealing site drainage that treat stormwater as a resource rather than a waste product.

Developments in the City of Riverside are to implement LID; the City’s MS4 Permit specifically requires development projects to infiltrate, harvest and use, evapotranspire, and/or bio-treat stormwater on the development site. These four techniques can be realized through the design and construction of several types of Best Management Practices (BMPs).

The Riverside County Flood Control and Water Conservation District (RCFC&WCD) has developed a LID BMP Design Handbook to assist developers in their efforts to build quality, long lasting BMPs for their developments. This handbook, combined with the region’s Water Quality Management Plan guidance documents, provide the tools necessary to design and construct developments with minimal impact on water quality.

Water Quality Management Plans (WQMP)