Low Impact Development

Stormwater Mitigation Plans / SUSMP

Low Impact Development

For questions related to projects required to comply with the Low Impact Development ordinance, please call (213) 482-7066 or visit the LA Stormwater Public Counter at 201 North Figueroa Blvd, 2nd Floor, Suite 280, Los Angeles, CA  90012 (new location as of January 14, 2019).

Low Impact Development (LID) is a leading stormwater management strategy that seeks to mitigate the impacts of runoff and stormwater pollution as close to its source as possible. Urban runoff discharged from municipal storm drain systems is one of the principal causes of water quality impacts in most urban areas. It can contain pollutants such as trash and debris, bacteria and viruses, oil and grease, sediments, nutrients, metals, and toxic chemicals that can negatively affect the ocean, rivers, plant and animal life, and public health.

LID comprises a set of site design approaches and best management practices (or BMPs) that are designed to address runoff and pollution at the source. These LID practices can effectively remove nutrients, bacteria, and metals while reducing the volume and intensity of stormwater flows.

Los Angeles’ LID ordinance became effective in May 2012. The main purpose of this law is to ensure that development and redevelopment projects mitigate runoff in a manner that captures rainwater at its source, while utilizing natural resources. Project applicants are required to prepare and implement a stormwater mitigation plan when their projects fall into any of these categories:

  • Single-family hillside residential developments
  • Housing developments of 10 or more dwelling units (including single family tract developments)
  • Industrial /Commercial developments with one acre or more of impervious surface area
  • Automotive service facilities*
  • Retail gasoline outlets*
  • Restaurants*
  • Parking lots of 5,000 square feet or more of surface area or with 25 or more parking spaces
  • Projects with 2,500 square feet or more of impervious area that are located in, adjacent to, or draining directly to designated Environmentally Sensitive Areas (ESA)

* Developments of less than 5,000 square feet in these categories are only subject to the prescriptive method described in the City of Los Angeles Best Management Practices Handbook Part B, 3rd Edition.

Project applicants will be required to incorporate stormwater mitigation measures into their design plans and submit the plans to the City for review and approval. Plan check appointments are available at two locations – Downtown Los Angeles and the Valley District Office. Any project that cannot comply with the Low Impact Development Ordinance requirements shall be required to comply with, at a minimum, all applicable Standard Urban Stormwater Mitigation Plan requirements in order to maximize onsite compliance.