Low Impact Development Manual for Southern California: Technical Guidance and Site Planning Strategies
Southern California is facing increased demands from urbanization, which can create adverse impacts to water quality and quantity. The region will meet the challenge of improving receiving water quality by incorporating low impact development (LID) stormwater techniques.
Download the complete Southern California LID Manual (PDF), or skim its contents.
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.
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).
Section 1: The Impacts of Development and How LID Can Help
This section provides a summary of the potential environmental, economic, and community benefits associated with the use of LID. It also describes how LID can be used to address major water quality and regional environmental challenges.
Section 2: The LID Site Design Process
This section outlines the LID site design process that informs all stages of planning and design. The process includes an emphasis on specialized site planning methods that are intended to be integrated into the overall site design rather than implemented as an afterthought.
Sec 2, Step 1: Comprehensive Site Assessment
Serves as the fundamental starting point in the development of and LID site design. This step includes information on a variety of data sources ranging from on-site visual inspection to professional surveys and geotechnical reports.
Sec 2, Step 2: Define Goals
Describes how LID fits into the regulatory environment and how it can be used in green building. This step outlines common regulatory requirements for water quality and hydromodification.
Sec 2, Step 3: Implement LID Principles
Outlines specific LID strategies that can be selected and implemented to address the potential impacts of development. The LID strategies are divided into two types: LID Principles (minimize impacts) and LID BMPs (mitigate impacts).
Sec 2, Step 4: Use LID BMPs to Mitigate Impacts
Emphasizes that LID Principles alone may not completely address potential impacts of development and subsequently meet minimum project goals. This step includes descriptions, basic design guidance, and selection criteria for the most commonly used LID BMPs.
Sec 2, Step 5: Evaluation Design
Identifies methods for assessing the successful application of LID to a given site. This includes technical guidance on the estimation and control of stormwater runoff quality and quantity.
Section 3: Case Studies
This section presents four case studies showing how LID is applied in various contexts including retrofit of existing commercial, retrofit of existing residential development, new commercial development design, and new residential development design.
Appendix A: Lists of Plants Suitable for LID in Southern California
This appendix provides lists of plants suitable for general landscaping, bioretention, and green roofs in Southern California. The plant lists included in this manual are intended to serve as a general guide for identifying plants likely to be suitable for use in LID.
Appendix B: California Planning and Regulatory Framework for LID
This appendix serves as an overview of how LID fits into California’s regulatory environment. This includes a discussion of LID in NPDES Stormwater Permits and municipal permits within the region have contained specific LID and hydromodification requirements.
Appendix C: LID, LEED, and the Sustainable Sites Initiative
This appendix outlines how LID can be used to achieve LEED or Sustainable Sites Initiative Certification. Three tables are provided to display some of the options for achieving LEED credit points through LID: LEED for New Construction Credit Options, LEED for Neighborhood Development Credit Options, and Sustainable Sites Initiative Prerequisite and Credit Options.
Prepared for the Southern California Stormwater Monitoring Coalition, in cooperation with the State Water Resources Control Board, by the Low Impact Development Center, Inc. The recommendations in this manual are not intended to supersede any local regulations.