Sonoma County Municipal Code Art. 12 Agricultural Drainage Permits

A. Permit required. An agricultural drainage permit shall be required prior to commencing any agricultural drainage involving construction or modification of drainage facilities or related work, including preparatory land clearing, vegetation removal, or other ground disturbance, except where exempted from permit requirements by Subsection C. A separate agricultural drainage permit shall be required for each site.

B. Designation and performance. All agricultural drainage involving construction or modification of drainage facilities shall be designated "engineered agricultural drainage," and shall be performed in compliance with approved plans and specifications prepared by a civil engineer.

C. Exemptions from permit requirements. The following agricultural drainage activities are exempt from the provisions of this section and may be conducted without obtaining an agricultural drainage permit, provided that these activities shall still be subject to the standards in Article 20 and the department's best management practices for new vineyard and orchard development, vineyard and orchard replanting, and agricultural grading and drainage.

1. Drainage facilities for new vineyard and orchard development, vineyard and orchard replanting, or agricultural grading. Construction or modification of drainage facilities for new vineyard and orchard development, vineyard and orchard replanting, or agricultural grading where authorized by a valid new vineyard and orchard development, vineyard and orchard replanting, or agricultural grading permit.

2. Emergency agricultural drainage. Construction or modification of drainage facilities necessary to protect life or property, or to implement erosion prevention or control measures, where a situation exists that requires immediate action. Only the work necessary to abate an imminent hazard may be performed prior to obtaining an agricultural drainage permit. The person performing the emergency work or the property owner shall notify the agricultural commissioner and provide evidence acceptable to the agricultural commissioner of the scope and necessity of the work on or before the next business day after the onset of the emergency situation. The property owner, an authorized agent of the property owner, or other person with the written consent of the property owner shall apply for an agricultural drainage permit within ten (10) days after the commencement of the emergency work. The agricultural commissioner may order work to be stopped or restricted in scope based upon the nature of the emergency.

3. Existing private drainage facilities. Maintenance, repair, or replacement of existing, lawfully constructed private drainage facilities where the location and design capacity are not changed. The agricultural commissioner shall be notified in writing at least thirty (30) days prior to the commencement of the work.

4. Minor pipe and vee-ditch swale systems. Construction or modification of pipe and vee-ditch swale systems that meet all of the following criteria:

a. The drainage area is less than one-half (½) acre for a smooth-walled pipe or vee-ditch swale system, or less than one-quarter (¼) acre for a corrugated pipe system.

b. The pipe or vee-ditch swale system is not in the flood-prone urban area.

c. The pipe system is a single run, with a minimum diameter of eight inches (8") and installed slopes between two percent (2%) and four percent (4%), or the vee-ditch swale system is lined with grass or rock, with side slopes no greater than two feet (2') horizontal to one foot (1') vertical [fifty percent (50%)], maximum depth of nine inches (9"), and installed slopes between two percent (2%) and four percent (4%).

5. Resource conservation, restoration, or enhancement projects. Construction or modification of drainage facilities for soil, water, wildlife, or other resource conservation, restoration, or enhancement projects where a public agency takes full responsibility for the work. The agricultural commissioner shall be notified in writing at least thirty (30) days prior to the commencement of the work.

6. Seasonal drainage swales. Construction or modification of seasonal drainage swales that meet all of the following criteria:

a. The flowline slope of the drainage swale does not exceed four percent (4%).

b. The drainage swale does not exceed one hundred fifty feet (150') in length.

c. The drainage swale is lined with grass, with side slopes no greater than two feet (2') horizontal to one foot (1') vertical [fifty percent (50%)], and maximum depth of nine inches (9").

d. The outlet for the drainage swale is protected to prevent erosion.

(Ord. No. 6338, § I(Exh. A), 3-16-2021)