Spokane County, WA Environmental Rules: Erosion Control (2026)

185 of the Spokane County Code sets erosion and sediment control (ESC) standards for land-disturbing activity in the unincorporated county. The chapter applies to all 'major land-disturbing activities,' defined as disturbing one acre or more, or adding 5,000 square feet or more of impervious surface, plus any 'minor land-disturbing activity' that's part of a larger common plan of development or sale or that itself needs a county permit. Applicants must prepare and implement a stormwater pollution prevention plan (SWPPP) using structural and non-structural best management practices (BMPs) consistent with the Spokane Regional Stormwater Manual and the Washington Department of Ecology's Stormwater Management Manual for Eastern Washington, with the stricter of the two controlling any conflict.

The county engineer or public works director, or the director of whichever department issued the underlying permit, administers and enforces the chapter and may enter any permitted or permit-pending site to inspect. Even a major land-disturbing project that needs no county permit still must meet the chapter's performance standards. 020, forest practices under WAC Title 222 (except Class IV conversions from timberland), emergency utility or government work to restore service or reopen a road, and permits with no physical ground disturbance, such as interior remodels or paper land divisions. 185.