Water Availability Analysis


Update to Water Availability Analysis (WAA) Policy for Discretionary Groundwater Permit Applications

Changes to the County’s WAA policy were adopted by the Board of Supervisors on May 13, 2015. Changes to the policy were based upon public input, the Groundwater Resources Advisory Committee (GRAC) in April 2014, work by the County’s groundwater consultant, Luhdorff &Scalmanini Consulting Engineers, and comments received at the January 7, 2015 County Planning Commission meeting.

If you have questions, need information about WAA policy, please email the Planning Building and Environmental Services (PBES) staff or call them at 707-253-4417.

WAA Background & Application

Napa County is required by the California Environmental Quality Act (CEQA) (Public Resources Code 21000-21177 and California Code of Regulations, Title 14, Division 6, Chapter 3, Sections 15000-15387) to conduct an environmental analysis of all discretionary permits submitted for approval. CEQA requires analysis of dozens of environmental aspects; including: “Would the project substantially deplete groundwater supplies or interfere substantially with groundwater recharge such that there would be a net deficit in aquifer volume or a lowering of the local groundwater table level (e.g., the production rate of pre-existing nearby wells would drop to a level which would not support existing land uses or planned uses for which permits have been granted)?” 

The purpose of the WAA Policy is to provide guidance and a procedure to assist applicants, neighbors, county staff, decision-makers, and other interested parties to gather the information necessary to adequately answer that question. The WAA is not an ordinance, is not prescriptive, and project-specific conditions may require more, less, or different analyses in order to meet the requirements of CEQA. The WAA Policy is used procedurally as the baseline to commence groundwater analysis of any given discretionary project.


A WAA is required for any discretionary project that may utilize groundwater or will increase the intensity of groundwater use of any parcel through an existing, improved, or new water supply system (Napa County Groundwater Conservation Ordinance, Section 13.15.010). As such, it is most commonly used for discretionary development applications using groundwater such as wineries and commercial uses. Since CEQA is not applicable to non-discretionary (“ministerial”) projects, the WAA Policy does not apply to projects such as building permits, single-family homes, track II replants, etc. 

While discretionary vineyard projects are welcome to borrow from the WAA, such vineyard projects, due to their size and scope, generally receive a much more exhaustive analysis under longstanding processes managed by the Conservation Division of the PBES Department. The WAA may also apply when a discretionary Groundwater Permit is required by the Groundwater Conservation Ordinance, Section 13.15.010 of the Napa County Code.

Project Information

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  • Project Class: Other
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  • Address: County Unincorporated

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