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Sonoma County Vineyard Erosion and Sediment Control Ordinance Recommendations and Review

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One of our junior geologists conducting a vineyard project site assessment.

In January 2012, the Board of Supervisors for the County of Sonoma (County) adopted an urgency ordinance to establish a temporary moratorium on vineyard and orchard site development on ridgetops and on any land where development would include the removal of trees. The existing County code did not include vineyard or orchard development standards for projects proposing the removal of trees, and there was public concern around environmental impacts related to tree removal.

 

The County Agricultural Commissioner retained LACO to accomplish the following:

  • Preparation of a scientific analysis of erosion and sedimentation for vineyard development involving tree removal
  • Support for revisions to the County Grading and Drainage Ordinance through research, analysis, document preparation, and public outreach
  • Development of new best management practices (BMPs) for agricultural erosion and sediment control applicable to vineyard and orchard developments

 

The Board of Supervisors acknowledged that trees provide stability to natural drainage features of the land, and are an important habitat component of the watersheds and watercourses; tree removal for vineyard and orchard site development on ridgetops and sloped land may impair the habitat value of watersheds and watercourses, and could potentially harm aquatic species. At the time of the urgency ordinance, seven applications for new vineyard projects involving tree removal were pending. To prevent construction delays for the pending projects, the County needed to develop a revised ordinance and new BMPs before the oncoming dry season when new vineyard construction is allowed (June through September).

 

LACO assembled a multidisciplinary team from our offices in Santa Rosa, Ukiah, and Eureka to address the complexities of new public policy. Our project team included professionals with expertise in geotechnical engineering, hydrology, engineering geology, CEQA processes, governmental affairs, and forestry. Through collaborative research, analysis, and a technical vetting process, our project team provided science-based documentation to justify County code modifications that require projects proposing tree removal to calculate predicted soil loss and to design projects with no net increase in soil loss.

 

During an intense 60-day meeting and response schedule, our project team attended numerous stakeholder meetings to address questions and obtain feedback. Despite multiple challenges, including threats of third-party lawsuits and intense pressure from political, environmental, and industry stakeholders, our project team met a looming construction season deadline by providing scientifically-defensible recommendations in a timely, responsive manner. The Board of Supervisors unanimously approved the adoption of our proposed changes to the Grading and Drainage Ordinance, and authorized our recommended new BMPs advanced by the County Agricultural Commissioner. The North Coast Regional Water Quality Control Board reviewed the proposed changes to the ordinance and BMPs, and indicated that a project built under the new code would achieve substantial compliance with the pending waste discharge requirements for irrigated lands. 

 

Subsequently, the County retained LACO to provide engineering and geologic review of proposed vineyard and orchard developments with tree removal, to confirm compliance with the new ordinance and BMPs.

 
LACO provided engineering and geologic review of proposed vineyard and orchard developments with tree removal, to confirm compliance with the new ordinance and BMPs.