In the Garden Gate development, a permeable pavement sidewalk allows rain water to infiltrate, and a rain garden treats stormwater runoff from the street.

A colorful rain garden that attracts birds and butterflies; a roof that is alive with plants; a creative way to save on your water bill.  Who knew managing stormwater runoff could be a thing of beauty?

Low impact development, also known as LID, is an environmentally sensitive approach to managing stormwater runoff created by development.  Instead of conveying rainwater off-site, LID uses small-scale landscape features that manage rainfall at the source.  LID features mimic the natural hydrologic processes that occurred prior to development; such as allowing stormwater runoff to soak into the ground, and filtering out sediment and other pollutants.  This type of development protects aquatic resources, water quality, and the natural hydrology of a watershed while development takes place.

As of January 2010, the City of Kirkland requires most development projects to incorporate stormwater LID features if it is feasible.  Development applicants are asked to consider full dispersion and infiltration for runoff, and if that is not feasible then at a minimum applicants are asked to install one stormwater LID feature for a portion of the runoff from the site.  Examples of stormwater LID features are listed below:

• Rain Gardens are shallow depressions filled with plants.  Runoff from hard surfaces is directed into the rain gardens where pollutants are removed by the plants and runoff is infiltrated.
• Permeable Pavement is strong enough to be used for walkways, parking areas, driveways, and patios, yet porous enough to allow rain to flow through it into the ground.
• Rainwater Harvesting captures roof runoff to be used later for irrigation or other uses; reducing the amount of potable (drinkable) water used (thus saving your cost of water).
• Vegetated Roofs contain a thin layer of soil and plants on top of a building.  The soil and vegetation soak up rain water and contribute significantly less runoff than a typical impervious roof.

Now that LID features are required on most projects, you may see more of them in your neighborhoods.  And once installed, we need to protect these features so they can function as intended; not fill them in or pave over them.  For more information on this new requirement, look at:  http://www.ci.kirkland.wa.us/stormwaterupdate or contact Stacey Rush, Surface Water Utility Engineer, at (425) 587-3854 with questions.