The amount of impervious surfaces – roads, parking lots, driveways, sidewalks, patios, and rooftops – increases as land is developed. As naturally pervious areas are replaced by impervious surfaces, a greater percentage of rainfall flows off the land as stormwater runoff instead of infiltrating into the ground. The increased volume and velocity of runoff flowing off of impervious surfaces may harm natural resources. Stormwater runoff also picks up pollutants – including car oil, fertilizers, pesticides, sediment, pet waste, and trash – and carries these pollutants to waterways and the ocean.

Low Impact Development (LID) is an approach to stormwater management that aims to replicate the site’s natural hydrologic balance. LID emphasizes site design strategies that protect the site’s natural capacity to retain stormwater, supplemented by small-scale distributed Best Management Practices (BMPs) to retain stormwater on-site (via infiltration, evapotranspiration, or harvesting stormwater for later use). Coastal Commission Water Quality Program staff recommends giving precedence to an LID approach to stormwater management in all development.

Examples of LID site design strategies include minimizing impervious surface area, preserving natural vegetation, conservation and use of natural drainage features, maintaining the infiltration capacity of the soil, and directing runoff from impervious surfaces into pervious areas. Examples of LID BMPs include rain gardens, grassy swales, permeable pavements, rain barrels, green roofs, soil amendments, planting native plants, and bioretention systems.

Low Impact Development Design Information

Low Impact Development Presentations

Additional Resources on Low Impact Development

  • Review of Low Impact Development Policies: Removing Institutional Barriers to Adoption (2007). Greg Gearheart, California State Water Resources Control Board’s Stormwater Program and the Water Board Academy. Prepared by the Low Impact Development Center, Beltsville, MD

    This report provides an analysis of the State of California’s primary mechanisms for regulating stormwater runoff, and a good overview of the LID approach to stormwater management. Explains the importance of minimizing changes in a site’s pre-development runoff flow regime (hydromodification) by addressing runoff volume and duration in addition to peak flows. California’s LID regulations have continued to be strengthened in recent years compared to the example state policies and permits in this report.
  • NOAA Webpage on Adapting Stormwater Management for Coastal Floods(Last modified 05/08/2024.) NOAA Office for Coastal Management.

    Coastal flooding may hamper a community’s stormwater management today or in the not-too-distant future. This webpage presents actions and case studies to increase the long-term resilience of a community’s stormwater management systems.
  • U.S. EPA Webpage on Nonpoint Source: Urban Areas. (Last updated 11/30/2023). Provides a list of LID Resources and Publications, including:

    • Green Streets Handbook

      (November 2023). This handbook informs practitioners about the latest approaches for LID bioretention system design, construction, inspection, and maintenance.
    • Bioretention Design Handbook

      (March 2021). This handbook provides guidance on how to select, design, and implement LID site design strategies and green infrastructure practices to protect water quality when developing roads and parking lots.
    • LID “Barrier Buster” Factsheet Series

      (March 2012). These factsheets are primarily intended for state and local decision makers considering an LID approach to stormwater management.