Maxville Vineyard Conversion Agricultural Erosion Control Plan (ECP) - P23-00130

The project involves the conversion of approximately 56.2 gross acres of sloped land, ranging from 5% to 37% gradient with an average slope of 20%, into a vineyard across three contiguous parcels in St. Helena, California, identified by APNs 025-020-023-000, 025-020-027-000, and 025-020-028-000. The development will consist of 42 net planted acres organized into ten blocks, reducing from the original proposal of 83.5 acres and 14 blocks. The site lies within the Napa River Watershed and the Sacramento River Watershed, specifically within the Lake Hennessey Sensitive Domestic Water Supply Drainage, and encompasses diverse native ecosystems including coast live oak, Oregon white oak, blue oak woodlands, wild oat grassland, and ruderal land, with minor areas of walnut orchard. In conjunction with vineyard development, 32.4 additional acres are designated for permanent preservation, augmenting the 520 acres already protected under a Forever Wildland Conservation Easement managed by the Napa County Land Trust. The Environmental Review addresses land-disturbing activities including vegetation clearing, earthmoving, and installation of erosion control measures required under Agricultural Erosion Control Plan P23-00130, ensuring compliance with CEQA, Napa County grading and conservation codes, and California Fish and Game Code Section 1603 for streambed alterations. All work must comply with stringent environmental and land use regulations, including a 50-foot setback from wetlands and 35-foot setback from ephemeral drainages, mandatory maintenance of 80% vegetative cover density, and restricted use of federally and state-approved chemicals. Erosion control must include mulch application, specific seed mixes, and proper fertilizer use as defined in County standards. Construction is scheduled in phases: pre-planting activities from April 1 to October 15, 2025, followed by planting from April 1 to June 1, 2026, with final operations concluding by October 15, 2026. A qualified professional must oversee implementation and certify compliance prior to final approval. Napa County’s Planning Division acts as the primary regulatory authority, with Dana Morrison serving as the contracting officer and Scott Garvey