A drainage permit is required prior to commencing any drainage improvement or related work, including preparatory site clearing and soil disturbance, except where exempted from permit requirements in Sonoma County Code section 11.04.010.A. A separate drainage permit is required for each site.
Projects with new drainage features require a drainage report submission that indicates the nature and extent of proposed drainage improvements. Drainage improvements must demonstrate no adverse impacts to existing and proposed structures and to adjacent properties.
A civil engineer must prepare drainage reports for engineered grading projects. Drainage reports for regular grading and all other permit applications may be prepared by the property owner, a civil engineer or an architect (if that architect also designed and prepared the grading or site plans for the same development).