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Low Impact Development

What is LOW IMPACT DEVELOPMENT?

Low Impact Development (LID) is a cost-effective and innovative solution to prevent polluted runoff from entering surface and ground water sources. Polluted runoff, also known as stormwater, is a significant threat to water quality in the Spokane River.

LID emphasizes site conservation and uses natural features to filter and retain urban runoff as close to where it falls as possible. It is a cost effective storm drainage and landscape management system that protects the Spokane River, other surface water streams in the Spokane River Basin, and Spokane Valley- Rathdrum Prairie Aquifer. Instead of piping stormwater directly to streams or to facilities located at the bottom of drainage areas, LID addresses stormwater through cost-effective landscape features. The City of Spokane is involved and invested in finding solutions to water quality threats in our area.

The City of Spokane is involved and invested in finding solutions to water quality threats in our area. View or print the Low Impact Development brochure that the City of Spokane and Spokane Riverkeeper produced as part of a collaborative effort to inform the public of polluted runoff in Spokane.

Ways Low Impact Development Benefits You

  • Removes pollutants from stormwater
  • Reduces size of swales and evaporation ponds
  • Reduces flooding
  • Allows projects to be constructed on less land
  • Preserves open space
  • May result in construction and maintenance cost savings
  • Replenishes streams, wetlands, and the aquifer
  • Improves appearance of neighborhoods
  • May store snow to help keep sidewalks clear in winter

Low Impact Development Methods

Storm Gardens Open Conveyance
Storm gardens feature organic soils, mulch, drought-tolerant plantings, and when necessary, underdrains and overflow features. Open conveyance may reduce the size of or entirely eliminate conventional underground piped conveyance systems.


Clustered Development Site Conservation
Cluster homes and units to minimize building footprints, reduce road and driveway lengths, and maximize open space. Preserve native landscapes where possible. Amend soils and revegetate when not.


Stormwater Reuse Permeable Pavement
Capturing roof runoff in a cistern or rain barrel allows for reuse for irrigation. Pavement that allows water to move through it. Some options include interlocking concrete pavers, pervious concrete, and porous asphalt. Permeable pavement is applicable to low-traffic areas such as parking areas and sidewalks.


Reduced Lawn Limit Paved Surfaces
Replacing lawn with drought-tolerant plantings where appropriate may save money on irrigation and maintenance and reduce runoff pollution. Narrowing street widths, using pervious pavement, and reducing building footprints may result in smaller storm drainage facilities for planned unit development and parking lots.


Street Design
Traffic calming measures may be combined with specific LID methods, including storm gardens, narrower streets, and drought-tolerant landscaping.

Recent Projects

Nevada-Lidgerwood Parking Lot

Location: Intersection of Broad Avenue and Addison Street

As part of a parking expansion for the Nevada-Lidgerwood Council / C.O.P.S. Shop, a pervious walkway and storm gardens were used to treat stormwater runoff.


Lincoln St.

Location: Lincoln Street from 29th Avenue to Cannon Hill Park

The storm gardens were installed as part of a street repair projet. The storm gardens capture and treat street runoff and drain to the Cannon Hill Park Pond.


Broadway Ave.

Location: Broadway Avenue from Elm to Oak Streets

This street revitalization project uses storm garden planters to recharge the Spokane-Rathdrum aquifer.


Low Impact Case Study

This case study demonstrates two approaches to a high density residential development. The site is characterized by shallow depth to bedrock requiring evaporative ponds to manage stormwater on-site. Through a low impact approach, the size of the evaporation ponds can be reduced, allowing for more flexible use of the site.

Conventional Approach Low Impact Approach
The conventional design includes paved parking lots, walkways, and patios. Stormwater management is provided by infiltration basins, grass-lined swales, filter strips, and a large evaporation pond. The LID design includes the same mix of uses, but uses permeable paving, vegetated roofs, roof rainwater harvesting, and storm gardens for stormwater management and storage. By using low impact strategies the size of the project’s evaporation pond is significantly reduced.

Eastern Washington Regional LID Guidance Manual

Recognizing the need for low impact development design guidelines applicable to the region, Spokane County secured grant funding from the Department of Ecology to produce an Eastern Washington Low Impact Development Guidance manual. Spokane County collaborated with many Eastern Washington municipalities, including the Cities of Spokane and Spokane Valley, and the Washington Stormwater Center. AHBL and HDR were selected as the project consultants. The manual is available for download at the Washington Stormwater Center's website, www.wastormwatercenter.org.

The manual has provided a technical framework for the City of Spokane's LID Ordinance. It was adopted as an optional design reference for low impact development projects.

Meeting Notices and Documents

LID Ordinance

SEPA LID Ordinance Determination of Non-Significance

Plan Commission Workshop May 22, 2013 Agenda and LID Packet

Wednesday, January 16th 2013 Stakeholder Meeting Presentation

Wednesday, September 19th 2012 Stakeholder Meeting Presentation

This web page was developed in coordination with the Spokane Riverkeeper.

Photos and images by AHBL, Inc.