Low Impact Development

Low Impact Garden image

The City of Kirkland requires the use of low impact development (LID) techniques as feasible on new development and redevelopment projects.

  • The PW Pre-Approved Plans include a section related to LID Storm facilities. The section includes policies, design criteria, and details for LID techniques.
  • In 2016, the City of Kirkland adopted the 2016 King County Surface Water Design Manual (KCSWDM). As required by this manual, development projects that create more than 2,000 sf of new and/or replaced impervious surface must evaluate LID facilities to the maximum extent feasible and include amended soil in all landscaped areas.

Low Impact Development Elements

Pervious pavement

Pervious pavement can be used for walkways, parking areas, driveways, and patios. The pervious pavement reduces the amount of storm runoff by allowing rain to infiltrate through the surface and into the ground. Examples are pervious concrete, pervious asphalt, permeable pavers, and grass pavers.

Green roofs

Green roofs can be used on residential or commercial development. The thin layer of soil and installation of plants can reduce the amount of storm runoff by absorbing the rain.


Disconnecting downspouts

Disconnecting downspouts reduces the amount of storm runoff into the public surface water system. Runoff can be routed to a grass or gravel area and infiltrated. This replenishes groundwater and helps reduce the increase flow to small creeks during rain events. Be careful not to route runoff directly onto a neighbor’s property, or in a place that could cause drainage problems.


Rain barrels and cisterns

Rain barrels and cisterns capture roof runoff to be used later for irrigation. This reduces the increase in summer water usage.


Rain gardens and bioretention areas

Rain gardens and bioretention areas can be used to collect runoff from hard surfaces. Pollutants are removed by the plants and a large portion of the runoff is infiltrated.



Amending soils

Amending soils with compost will increase infiltration and absorption. Nutrients in the composted soils work to break down and remove pollutants from the runoff.