Regulatory Framework for ECPAs

The Conservation Regulations affect the development and maintenance standards of new and replanted vineyards on land slopes greater than 5%. Prior to the development of new vineyards on slopes greater than 5%, an engineered Erosion Control Plan and Approval (ECPA) must first be reviewed and approved by the Director of Planning, Building and Environmental Services (PBES). Ongoing environmental benefits of the Conservation Regulations go far beyond the soil loss issue protecting valuable natural resources. Specifically, they provide for stream setbacks based on a sliding scale directly correlated to the slope of the land adjacent to the stream or waterway. These setbacks are primarily intended to be protective of water quality, aquatic habitats, and special-status fish species, but they also provide for significant terrestrial habitat preservation and wildlife movement.

The Conservation Regulations provide for enhanced protections and benefits for the project within sensitive domestic water supply drainages. Such protections include the retention of 40 to 60% of the vegetation existing on June 16, 1993, preparation of a geotechnical study to help ensure slope stability, the requirement for drainage facilities to be designed to the 100-year storm event, and direct notification to the water purveyor. Protecting drinking water through these requirements also accomplishes habitat preservation and other environmental benefits.

California Environmental Quality Act (CEQA)

The CEQA generally requires state and local government agencies to inform decision-makers and the public about the potential environmental impacts of proposed projects, and to reduce those environmental impacts to the extent feasible. In general, if a project subject to CEQA will not cause any adverse environmental impacts, a public agency may adopt a brief document known as a Categorical Exemption or Initial Study/Negative Declaration (IS/ND). If the project may cause adverse environmental impacts, the public agency must prepare a more detailed study called an Initial Study/Mitigated Negative Declaration (IS/MND) or Environmental Impact Report (EIR). These more detailed documents contain in-depth studies of potential impacts, measures to reduce or avoid those impacts, and in the case of an EIR, an analysis of alternatives to the project. A key feature of the CEQA process is the opportunity for the public to review and provide input on both Negative Declarations and EIRs.

Numerous resource topics are required to be analyzed as part of an IS/ND or IS/MND or EIR. The significant resource topics that are often associated with vineyard ECPAs generally include groundwater, hydrology/water quality, biological resources, soils and geology, archaeology, traffic, air quality, and greenhouse gases.

In general, agriculture activities are not subject to County discretionary approval.  However, the grading, vegetation removal, and land disturbance activities on slopes greater than 5% necessary to install the vineyard require the preparation and approval of an ECPA, which is subject to review under CEQA. The CEQA documents that are typically prepared in support of the review and approval of vineyard ECPAs are 1) Categorical Exemption, 2) IS/ND, 3) IS/MND, and 3) EIR.

Categorical Exemption

In order for a project to qualify for a categorical exemption, the following criteria must be met:

  1. Disturb less than 5½ acres of land and have an average slope of 15% or less
  2. Located in a drainage 5½% or less of which is known to have been converted to the vineyard since 1993
  3. No increase in overall groundwater use on the parcel, if the parcel is within a groundwater deficient area. In all other areas would not consume in total with all other uses on the parcel groundwater exceeding the Phase 1 groundwater standard determined by the Department of Public Works
  4. Located more than half a mile from a designated Mineral Resource Area, or an active or potentially active mine or quarry

There are no public noticing requirements or comment periods associated with a categorical exemption. However, pursuant to Section 15300.2 of the CEQA Guidelines a categorical exemption shall not be used for an activity where there is a reasonable possibility that the activity will have a significant effect on the environment due to unusual circumstances. By way of example, if a project meets the required criteria, but it happens to be located within an area containing special status species, the presence of those species would constitute a significant and a categorical exemption could not be used. In this case, an IS/ND or IS/MND would need to be prepared.


A public agency shall prepare or have prepared a proposed negative declaration or mitigated negative declaration for a project subject to CEQA when:

  1. The initial study shows that there is no substantial evidence, in light of the whole record before the agency, that the project may have a significant effect on the environment
  2. The initial study identifies potentially significant effects, but:
    1. Revisions in the project plans or proposals made by or agreed to by the applicant before a proposed mitigated negative declaration and initial study are released for public review would avoid the effects or mitigate the effects to a point where clearly no significant effects would occur
    2. There is no substantial evidence, in light of the whole record before the agency, that the project as revised may have a significant effect on the environment

There is a 20-30 day public comment period required as part of the process. A 30-day review period is required if the project involves the jurisdiction of a state agency.


If the Planning Director finds during preliminary review or based on an Initial Study that there is substantial evidence in the record as a whole that a project may have a significant adverse effect on the environment, or if an EIR is required by statute, the Planning Director shall notify the project sponsor in writing within 30 days that an EIR must be prepared. The Planning Director’s decision may be appealed pursuant to Napa County Code Chapter 2.88. There is a 45-day public comment period required for EIRs.

CEQA documents requiring a formal public review period require a formal response to comments document, which is included as part of the overall approval package. For Negative Declaration or Mitigated Negative Declaration, the responses are more informal and included as part of the overall application approval package. For EIRs, the response to comments is contained within the Final EIR.

General Plan Goals & Policies

The majority of the County’s General Plan Goals and Policies related to vineyard development are contained within the Conservation Element of the General Plan. The Conservation Element provides goals, policies, and action items related to open space conservation as well as a wide range of other topics that together comprise the natural environment of Napa County, including its natural resources and water resources. The goals and policies contained in the element also address climate change and sustainable practices for environmental health-related to water, energy conservation, air pollution, greenhouse gas emissions, clean energy generation, and related issues.

While there are numerous General Plan Goals and Policies relevant to new vineyard development, the following policies are those that tend to have a significant influence on the review of new vineyard ECPAs:

Policy CON-13

The County shall require that all discretionary residential, commercial, industrial, recreational, agricultural, and water development projects consider and address impacts to wildlife habitat and avoid impacts to fisheries and habitat supporting special-status species to the extent feasible. Where impacts to wildlife and special-status species cannot be avoided, projects shall include effective mitigation measures and management plans including provisions to:

  1. Maintain the following essentials for fish and wildlife resources:
    1. Sufficient dissolved oxygen in the water.
    2. Adequate amounts of proper food.
    3. Adequate amounts of feeding, escape, and nesting habitat.
    4. The proper temperature through maintenance and enhancement of streamside vegetation, the volume of flows, and velocity of the water.
  2. Ensure that water development projects provide an adequate release flow of water to preserve fish populations.
  3. Employ supplemental planting and maintenance of grasses, shrubs, and trees of like quality and quantity to provide adequate vegetation cover to enhance water quality, minimize sedimentation and soil transport, and provide adequate shelter and food for wildlife and special-status species and maintain the watersheds, especially streamside areas, in good condition.
  4. Provide protection for habitat supporting special-status species through buffering or other means.
  5. Provide replacement habitat of like quantity and quality on- or off-site for special status species to mitigate impacts to special-status species.
  6. Enhance existing habitat values, particularly for special-status species, through restoration and replanting of native plant species as part of discretionary permit review and approval.
  7. Require temporary or permanent buffers of adequate size (based on the requirements of the subject special-status species) to avoid nest abandonment by birds and raptors associated with construction and site development activities.
  8. Demonstrate compliance with applicable provisions and regulations of recovery plans for federally listed species.

Policy CON-17

Preserve and protect native grasslands, serpentine grasslands, mixed serpentine chaparral, and other sensitive biotic communities and habitats of limited distribution. The County, in its discretion, shall require mitigation that results in the following standards:

  1. Prevent removal or disturbance of sensitive natural plant communities that contain special-status plant species or provide critical habitat to special-status animal species.
  2. In other areas, avoid disturbances to or removal of sensitive natural plant communities and mitigate potentially significant impacts where avoidance is infeasible.
  3. Promote protection from overgrazing and other destructive activities.
  4. Encourage scientific study and require monitoring and active management where biotic communities and habitats of limited distribution or sensitive natural plant communities are threatened by the spread of invasive non-native species.
  5. Require no net loss of sensitive biotic communities and habitats of limited distribution through avoidance, restoration, or replacement where feasible. Where avoidance, restoration, or replacement is not feasible, preserve like habitat at a 2:1 ratio or greater within Napa County to avoid significant cumulative loss of valuable habitats.

Policy CON-24

Maintain and improve oak woodland habitat to provide for slope stabilization, soil protection, species diversity, and wildlife habitat through appropriate measures including one or more of the following:

  1. Preserve, to the extent feasible, oak trees and other significant vegetation that occur near the heads of drainages or depressions to maintain the diversity of vegetation type and wildlife habitat as part of agricultural projects.
  2. Comply with the Oak Woodlands Preservation Act (PRC Section 21083.4) regarding oak woodland preservation to conserve the integrity and diversity of oak woodlands, and retain, to the maximum extent feasible, existing oak woodland and chaparral communities and other significant vegetation as part of residential, commercial, and industrial approvals.
  3. Provide replacement of lost oak woodlands or preservation of like habitat at a 2:1 ratio when retention of existing vegetation is found to be infeasible. Removal of oak species limited in distribution shall be avoided to the maximum extent feasible.
  4. Support hardwood cutting criteria that require retention of adequate stands of oak trees sufficient for wildlife, slope stabilization, soil protection, and soil production be left standing.
  5. Maintain, to the extent feasible, a mixture of oak species that is needed to ensure acorn production. Black, canyon, live, and brewer oaks as well as blue, white, scrub, and live oaks are common associations.
  6. Encourage and support the County Agricultural Commission’s enforcement of state and federal regulations concerning Sudden Oak Death and similar future threats to woodlands.

Policy CON-30

All public and private projects shall avoid impacts to wetlands to the extent feasible. If avoidance is not feasible, projects shall mitigate impacts to wetlands consistent with state and federal policies providing for no net loss of wetland function.

Policy CON-48

Proposed developments shall implement project-specific sediment and erosion control measures (e.g., erosion control plans and/or stormwater pollution prevention plans) that maintain pre-development sediment erosion conditions or at a minimum comply with state water quality pollution control (i.e., Basin Plan) requirements and are protective of the County’s sensitive domestic supply watersheds. Technical reports and/or erosion control plans that recommend site-specific erosion control measures shall meet the requirements of the County Code and provide detailed information regarding site-specific geologic, soil, and hydrologic conditions and how the proposed measure will function.

Policy CON-50(c)

The County shall require discretionary projects to meet performance standards designed to ensure peak runoff in 2-, 10-, 50-, and 100-year events following development is not greater than predevelopment conditions.

Soil loss and Hydrologic Studies are required to demonstrate a given project meets the County’s no net increase in erosion and runoff standards are met. The Universal Soil Loss Equation (USLE) is the model used to measure and quantify pre- and post-project soil loss rates. Similarly, pre- and post-project changes in runoff are measured using Technical Release 55 (TR-55). The procedures related to the application of hydrologic modeling are fairly standard. Guidance documents for the preparation of these analyses are currently being drafted.