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Department of Planning and Development
Department of Planning and Development

Apply for a Drainage Permit

A Drainage Permit is required if a project:

  • creates more than 2,000 square feet of new impervious area; or 
  • changes the existing drainage pattern on the property; or 
  • requires cuts or fills between 75 and 150 cubic yards within the Special Flood Hazard Area; or 
  • is for any work within the floodway.

Note: Drainage work conducted pursuant to a grading permit is not required to obtain a drainage permit (drainage will be reviewed under the grading permit).

Submittal Requirements

Copies of the following items are required to be submitted digitally. You may submit these documents on the Public Permit Portal . We can also help you in-person at the Permit Center.

  • Drainage plans, sized 24”x36”, and prepared by a Licensed Civil Engineer. The County’s standard cover sheet should be used in the plan preparation, with PDF and DWG formatted templates linked. Erosion Control Plans, including 24”x36” copies of the erosion control template EC-1 and EC-2, shall be included in the plan set.
  • Drainage calculations prepared by a Licensed Civil Engineer.
  • The minimum Drainage Permit fee. If Staff hours exceed the minimum fees collected additional funds will be required at the time of permit issuance.
  • Signed copy of the San Francisco Bay Watershed or C.3 Questionnaire for sites draining to San Francisco Bay or Low Impact Development Worksheet for sites draining to Monterey Bay.

The approved drainage plan will be sealed with an approved stamp and placed in the record. Drainage improvements must be inspected and approved by the Land Development Engineering Inspector.

For additional information, see our drainage manual​.​