Shoreline, WA Landscaping Rules: Artificial Turf (2026)

The Development Code's hardscape definition at SMC § 20.20.024 governs how much of a lot's artificial turf counts toward impervious lot-coverage limits. Ordinary hardscape includes decks, patios, and paved or graveled surfaces, but the code carves out a specific 50/50 split for turf: artificial turf installed with a subsurface drain field, or over a deck that drains to the soil below, is counted as only 50 percent hardscape and 50 percent pervious for lot-coverage purposes. Products that let vegetation grow between components and drain to the soil underneath get a pervious percentage that the Director sets case by case, based on manufacturer specifications the applicant must supply.

That credit only applies where a project is not inside one of the city's special drainage areas. SMC § 13.10.230 lets the director designate special drainage areas where flooding, drainage, or erosion conditions threaten the surrounding community; the Deer Creek Wellhead Protection Buffer Area is named as one such area. Within a special drainage area, several activities are flatly prohibited regardless of the hardscape credit available elsewhere in the code, including deep underground injection wells, greywater irrigation and infiltration, hydrocarbon extraction, and the use of crumb rubber (styrene-butadiene rubber) infill for artificial turf installations.

Development applications must identify whether the project sits in a special drainage area, and where it overlaps a wellhead protection buffer, the applicant must notify the water purveyor and provide drainage and geotechnical reports.