Preservation Ranch Development Project EIR, CA

Client: Sonoma County

Location: Sonoma County, California

Summary: ENTRIX is currently assisting Sonoma County in conducting an environmental assessment for a proposed timberland-to-vineyard conversion project. The Preservation Ranch project proposes to convert 1,600 acres of second growth coastal forest to wine vineyards. ENTRIX provided technical review of the applicant’s materials, developed a project description to serve as the basis for CEQA review, and performed the Initial Study. ENTRIX is currently preparing the administrative draft EIR, with the public draft and final EIR documents to be completed in the near future. We are conducting environmental impact assessments, analyzing alternatives, developing mitigation measures and coordinating public hearings.

Of the several resource areas, ENTRIX performed a hydrologic and geomorphic study of the potential project effects from modifying the hydrologic and sediment yield conditions by changing forest to managed vineyard. ENTRIX developed a calibrated HEC-HMS model in two one-thousand acre watersheds, for both the existing condition as well as the proposed project condition. The model was used to evaluate changes in the hydrologic water balance, changes in land runoff, stormwater conveyance, function of stormwater storage and detention basins, and changes in stream flow.

ENTRIX performed a geomorphic study of the receiving waters (creeks) and evaluated the effects of changed stream flows on flooding, channel stability (erosion) and habitat conditions. Pre and post-project sediment transport modeling was used to study channel erosion and sediment loads, and evaluate potential impacts on channel stability and features important for riparian habitat health.

ENTRIX performed an impacts assess on water quality and addressed the sediment TMDL of the watersheds main river – the Gualala River. The relative contribution of different sediment sources were evaluated using results from the applicant’s studies. ENTRIX evaluated the performance of the proposed water quality and sediment control BMPs, studied the effects of proposed housing and septic systems on nearby springs and drinking water source. And finally, ENTRIX evaluated the applicant’s management plan for the storage and use of agricultural chemicals, such as fertilizers, pesticides, herbicides.