Grading, Drainage, & Storm Water is a section within the Engineering and Construction division that reviews and issues permits related to grading, drainage and storm water for properties in unincorporated Sonoma County.

Drainage is the collection, conveyance, containment, and/or discharge of storm water runoff. A drainage system includes constructed and/or natural features that work together to collect, convey, channel, hold, inhibit, retain, detain, infiltrate, divert, treat, or filter storm water runoff, including detention and retention basins, overland flow paths, pipes, channels, and the inlets and outlets to these features.

Grading is the removal or deposition of earth material by artificial means. Earth material is defined as any rock or natural soil or combination thereof. Grading is generally a combination of excavation (cuts) and placement (fill) of soil. Common examples of grading include, but are not limited to, construction of driveways, building pads, site improvements or reservoirs, and restoration/stabilization of hillsides, slopes or stream banks. Grading does not include routine farming practices.

A grading permit is required prior to commencing any grading or related work, including preparatory site clearing and soil disturbance, except where exempted from permit requirements by Sonoma County Code section 11.04.010.A.

Grading and Drainage Ordinance (Sonoma County Code Chapter 11)

Storm water is any storm water runoff, snow melt, or surface runoff. Generally, storm water runoff occurs when rainfall flows over the ground.

Storm Water Quality Ordinance (Sonoma County Code Chapter 11A)