Bellevue, WA Environmental Rules: Grading & Drainage (2026)

Bellevue regulates grading and drainage through Land Use Code 20.25H (Clearing and Grading) and Bellevue City Code 24.06 (Storm and Surface Water Utility Code). A clearing and grading permit is required when moving more than 50 cubic yards of earth, clearing over 2,000 square feet, or conducting any grading on slopes steeper than 15 percent or within critical areas. Drainage review is triggered when new or replaced hard surface exceeds 2,000 square feet, or when land-disturbing activity exceeds 7,000 square feet. Bellevue follows the Washington State Department of Ecology's Stormwater Management Manual for Western Washington (2022 edition), which mandates flow control, water quality treatment, and low impact development (LID) techniques such as permeable pavement, bioretention, and rain gardens for small projects. Drainage from driveways and downspouts cannot be directed onto neighboring properties or the public right-of-way in sheet flow. Violations of drainage rules can lead to civil infractions with penalties up to 500 dollars per day. Call Development Services at 425-452-6800 before any grading work.