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

BMC Chapter 15.42 incorporates by reference the Ecology Stormwater Management Manual for Western Washington and applies the SWMMWW's nine Minimum Requirements to development and redevelopment projects. Redevelopment projects involving 5,000 square feet or more of land-disturbing activity must comply with Minimum Requirements No. 1 (Preparation of Stormwater Site Plans) through No. 5 (On-Site Stormwater Management). Projects that add 10,000 square feet or more of new impervious surface and discharge directly or indirectly to fresh water trigger the full nine Minimum Requirements including Flow Control and Runoff Treatment, sized to the SWMMWW. BMC Chapter 15.40 (Drainage) administers the city's drainage system: 'The authority and responsibility for administration of this chapter is vested in the department of public works or its successor agency,' and BMC 15.40.140 requires all dedicated drainage facilities to be constructed under contract with the city to design and construction standards. BMC 15.42.060 sets approval standards for stormwater site plans, and BMC 15.42.070 provides for maintenance, inspection and enforcement. Grading itself is reviewed under the building code adopted by BMC Title 17 (IBC Appendix J as adopted in WAC 51-50, with IRC R401.3 requiring minimum positive drainage of 5% for the first 10 feet away from foundations for residential structures). Inside the Lake Whatcom watershed, BMC Chapter 16.80 layers additional requirements: BMC 16.80.080 development standards for residential single development and the BMC 16.80.120 seasonal restriction limiting ground disturbance to June 1 through September 30. Public Works engineering review is the primary venue; the city's adopted SWMMWW design standards control where the BMC is silent.