A Case Study in Agricultural Stormwater Management Along the Laguna de Santa Rosa

Purpose of the Study: The purpose of this paper is to document stormwater management practices, noting the challenges, successes, and lessons learned on this 400+ acre agricultural site that could be relevant for similar sub-watershed sites. It should be used as a reference for BMPs implemented if a site with similar topography and proximity to the Laguna de Santa Rosa were to be developed and or managed in a similar fashion. The assumptions made with each BMP for long-term outcome on most agricultural operations are rarely noted for those practices. The documentation of those expectations will be a valuable reference to those who study this site in the future to confirm or deny the assumptions expressed. Procedure: A systematic review was performed of the lessons learned from 3 distinct phases of watershed management over a 30 year period on this agricultural site adjacent to the Laguna de Santa Rosa. Interviews were conducted with internal management, regulatory officials, and NGO's; coupled with the review of both legal and internal documents from the property owners as to how the Adaptive Management Approach (AMA) was used from each phase to achieve continuous improvement. Findings: Management recognized improvement opportunities in each phase and adapted their management approach to ensure stormwater management improvements were realized during each phase. Conclusions: The final development phase showed significant improvement over the first development 30 years earlier. The reduction of non-point source sedimentation through sheet flow and no-till operations were documented. Vegetative filter strips bordering creek setbacks were the first of their kind in the area and adopted as part of the requirements into the Sonoma County General Plan for agricultural operations. A seasonal wetland constructed next to the Laguna de Santa Rosa acts as a protective buffer zone between the Laguna and agricultural operations on the site. Continuous improvement to stormwater quality through improved land management practices over the last thirty years on this property was evident by the use of the AMA during each development phase.