Shoreline, WA Water Use Rules: Turf Replacement Rebates (2026)

The Shoreline Development Code regulates how much of a lot can be covered in impervious surface through zone-by-zone maximum hardscape percentages set in the SMC § 20.50 dimensional standards tables, and SMC § 20.20.024 supplies the definition that decides what counts. "Hardscape" is defined broadly to include structures, decks, patios, and paving of gravel, concrete, or asphalt, but the definition carves out a specific allowance for artificial turf: turf installed with subsurface drain fields, and decks that drain to soil underneath, are valued at 50 percent hardscape and 50 percent pervious rather than counted as fully impervious.

The same definition extends a similar partial credit to other permeable coverings, letting the director set the pervious percentage for products that allow vegetation growth between components based on the manufacturer's specifications the applicant provides. Retaining walls, narrow gravel or paver paths under four feet wide with open spacing, and the first 18 inches of roof eaves are excluded from the hardscape count entirely. Because maximum hardscape percentages are a hard numeric ceiling per zone under Title 20 SMC, this credit directly affects whether a homeowner or developer replacing natural lawn with drained artificial turf can still meet the applicable coverage limit, effectively rewarding turf systems designed to drain to soil rather than pool water on an impermeable base.

The rule is a definitional standard rather than a permit requirement, so no separate approval is needed to install draining artificial turf; the pervious value simply feeds into the lot's hardscape calculation reviewed with any building or land-use permit application.