Matthes Vineyard Conversion Agricultural Erosion Control Plan #P21-00047-ECPA

The Matthes Vineyard Conversion Agricultural Erosion Control Plan #P21-00047-ECPA involves the development of approximately 13.2 gross acres of vineyard on a 40-acre property in St. Helena, California. The project scope includes vegetation clearing, earthmoving, land contouring, and the installation of erosion control measures across three vineyard blocks. The development area features average slopes between 18% and 28%, with some non-contiguous areas exceeding 30%. To minimize environmental impact, the plan includes a 7.3-acre Preservation Area and specific mitigation measures to protect roosting bats, nesting birds, and ephemeral streams. The project also involves the removal of 17 oak trees and one Ponderosa pine tree, while preserving intact coast live oak woodland. Managed by Napa County Planning, Building and Environmental Services, the project requires strict adherence to CEQA guidelines, Napa County Code, and Regional Water Board Best Management Practices. Key technical deliverables include drainage analyses to ensure no increase in peak stormwater runoff, water availability assessments for groundwater use, and soil erosion modeling using the Universal Soil Loss Equation. Performance is subject to field inspections at the Meadowood Lane site to verify that post-construction ground cover reaches a minimum of 90%. The project timeline indicates a planting stage occurring between April and October 2026, with full operational status beginning in 2027.