Low Impact Development (LID)  is a stormwater management and design strategy that is integrated into the design of the development project. Use of LID in project design is a requirement of the current MS4 Permit.  When designing for low impact development, consider the following: 

 
Principles of Low Impact Development (LID)

• Conserve natural resources that provide valuable natural functions associated with controlling and filtering Stormwater 
• Minimize & disconnect impervious surfaces 
• Direct runoff to natural and landscaped areas conducive to infiltration 
• Use distributed small-scale controls or integrated Best Management Practices (BMPs) to mimic the site’s pre-project hydrology, preventing additional runoff 
• Stormwater education leads to pollution prevention 

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Strategies of Low Impact Development (LID)
Required as part of a project’s WQMP Site Design BMPs. Ten practices are:

1. Bioretention & Rain Gardens 
2. Rooftop Gardens 
3. Sidewalk Storage 
4. Vegetated Swales, Buffers & Strips; Tree Preservation 
5. Roof Leader Disconnection 
6. Rain Barrels and Cisterns 
7. Permeable Pavers 
8. Soil Amendments 
9. Impervious Surface Reduction & Disconnection 
10. Pollution Prevention & good Housekeeping

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Resources for Low Impact Development (LID)

Riverside County Flood Control has released its LID BMP Design Handbook, it can be accessed via the following link:

http://rcflood.org/NPDES/LIDBMP.aspx
   
LID measures have been recognized by US EPA as a preferred method for stormwater treatment (compared to many conventional treatment devices). This handbook reflects the findings of the District's research of LID BMP guidance and installations from across the country and has been developed to ease the transition to LID by providing standard recommendations and guidance for the design of a specific sub-set of LID BMPs in a manner that maximizes their effectiveness in semi-arid environments.

For each of 7 different BMPs included, this handbook includes relevant information such as siting considerations, setbacks, design procedures, inspection and maintenance guidelines and design calculation worksheets. It also includes various appendices including one dedicated to discussing infiltration testing requirements.

It is not required to use this handbook to meet the LID Permit requirements, however we hope you find this manual helpful.

• Low Impact Development Manual for Southern California - California Stormwater Monitoring Coalition, in cooperation with the State Water Resources Control Board, by the Low Impact Development Center, Inc., April 2010                
• BMP Handbook for New Development and Redevelopment, California Stormwater Quality Association (CASQA).
• California EPA, State Water Resources Control Board 

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