Southern California LID Manual (PDF)

Southern California LID Manual Roadmap

Prepared for the Southern California Stormwater Monitoring Coalition, in cooperation with the State Water Resources Control Board, by the Low Impact Development Center, Inc.

Southern California is facing increased demands from urbanization, which can create adverse impacts to water quality and quantity. Water pollution not only impacts the beneficial uses of our receiving waters (e.g. aquatic life, recreation), but also represents a significant cost to cities as they strive to comply with increasingly stringent state and federal water quality regulations. The Southern California region, under the jurisdiction of three California Regional Water Quality Control Boards (RWQCBs), is faced with rapid population growth and continuous budget constraints. The region will meet the challenge of improving receiving water quality by incorporating low impact development (LID) stormwater techniques.

Stormwater is increasingly being managed through the strategies and principles of Low Impact Development, which is defined as an ecosystem-based approach to designing a built environment that remains a functioning part of an ecosystem rather than existing apart from it. LID is a design strategy that utilizes decentralized, small-scale source control structural and/or non-structural stormwater practices to meet certain technical requirements of federal, state, and local government stormwater management regulations, as well as natural resource protection and restoration goals. Targeted watershed goals and objectives can be addressed through the use of structural and non-structural LID techniques in order to reduce the discharge of pollutants and the effects of changes to runoff patterns caused by land use modifications (hydromodification).

The purpose of this LID Manual is to serve as a resource that can be used to guide communities in the development of design, construction, and maintenance standards and specifications, as well as codes and ordinances, which can support their water quality management and regulatory compliance programs. It is intended to complement evolving local stormwater management requirements driven by the adoption of new municipal separate storm sewer system (MS4) permits under the Clean Water Act. New MS4 permits are increasingly requiring the adoption of LID techniques to minimize increases in runoff volume and peak discharge rates resulting from land development. Local permits are discussed in Appendix B

This manual provides site planning and design guidance, but given the varying site conditions and regulations throughout the region it is not practical to provide suggestions and guidance for every possible situation. The recommendations in this manual are not intended to supersede any local regulations. The manual consists of concepts and techniques presented in a format that will facilitate dialogue between developers, engineers, and local governments to encourage adaptation and integration of these strategies and techniques into local regulatory and watershed protection programs.