skip navigation

Low Impact Development - Runoff Reduction


Low impact development (LID) is a stormwater management strategy that emphasizes conservation and use of existing natural site features integrated with distributed, small-scale stormwater controls to more closely mimic natural hydrologic patterns in residential, commercial, and industrial settings. LID employs principles such as preserving and recreating natural landscape features and minimizing impervious surfaces to create functional and appealing site drainage that treat stormwater as a resource rather than a waste product. Practices that adhere to these LID principles include bioretention facilities, rain gardens, vegetated rooftops, rainwater harvesting (rain barrels and cisterns), and permeable pavements.

This webpage includes information on two LID practices: rain gardens and rainwater harvesting, including associated stormwater rate reductions.

General Information

The following resources address low impact development techniques.

Sample Local Government Provisions

This section includes sample regulations and information on LID from Washington cities and counties.

Washington Cities

  • Bellingham Low-Impact Development - Includes native plant guide and information on rain gardens and rain barrels
  • Bothell Low Impact Development Report, 2011 - This document is intended to help identify barriers for LID implementation and establish goals and metrics to promote and measure the use of LID techniques
  • Edmonds Sustainability Low Impact Development - Links to several LID-related documents
  • Fife Green Factor, Low Impact Development - Includes ordinance and Green Factor worksheets
  • Kirkland Low Impact Development, Surface Water - Includes tools and requirements for surface water development and LID elements, such as pervious pavement, green roofs, rain barrels, and rain garden
  • Mercer Island Low Impact Development - Basic LID information
  • Port Angeles Municipal Code Ch. 17.44 - Planned Low Impact Development Overlay Zone
  • Redmond Low Impact Development - Information about LID policies and projects
  • Spokane Ordinance No. C35021, adopted 09/03/2013 - Regarding low impact development provisions

Washington Counties

Rain Gardens

A rain garden is a shallow planted area in the landscape where rainwater is allowed to collect and absorb back into the soil. A rain garden mimics the undisturbed conditions of the natural environment. This section includes information on rain garden design.

Rainwater Harvesting

Rainwater harvesting for irrigation involves collecting the water that falls on a roof in a rain barrel or cistern and using it for watering lawns and gardens. Rainwater harvesting conserves water and can reduce the impact of heavy storm flows on streams, lakes, bays, and watersheds. The following is some information from communities in Washington State.

Statutes Allowing Reduction of Stormwater Charges

The following state statutes allow for possible rater reductions for new or remodeled commercial buildings that use permissive rainwater harvesting systems.

Sample Ordinances - Stormwater Rate Reductions for Rainwater Catchment Systems

  • Kitsap County Ordinance No. 315-2004 - Amends Kitsap County Code Sec.12.40.050 to establish a surface and stormwater management program rate reduction for permissive rainwater harvesting systems, infiltration systems, and direct discharge systems, passed 04/12/2004
  • Snohomish County Ordinance Nos. 05-102 and 05-103 provide reductions in surface water management rates and charges for commercial properties with approved rainwater harvesting systems, passed 10/2005

Additional Resources


Last Modified: December 17, 2019