TO: Technical Advisory Group for the Napa County Groundwater Sustainability Agency
FROM: Brian D. Bordona, Director of Planning, Building and Environmental Services
REPORT BY: Jamison Crosby, Natural Resources Conservation Manager
SUBJECT: Updates on Napa Valley Integrated Hydrologic Model Refinements
RECOMMENDATION
title
The TAG will receive a presentation from Nick Newcomb (LSCE) describing current refinements to the Napa Valley Integrated Hydrologic Model (NVIHM) used to support the development and implementation of the Groundwater Sustainability Plan.
body
Procedure
Staff introduces.
Questions and answers with the TAG.
Public comments.
BACKGROUND AND DISCUSSION
The TAG will receive a presentation from Nick Newcomb (LSCE) describing current refinements to the Napa Valley Integrated Hydrologic Model (NVIHM) used to support the development and implementation of the Groundwater Sustainability Plan. Key elements include:
1. Changes to the model to accommodate the modified Subbasin boundary;
2. Refinement to the Streamflow Routing Package used to simulate streamflow;
3. Updates to representation of land use and evapotranspiration;
4. Updates to the distribution and construction of groundwater pumping wells; and
5. Coordination with the model code developers to incorporate soil moisture storage.
This is intended to provide the TAG an opportunity to spur discussion, questions, and provide feedback to staff and participants.
ENVIRONMENTAL IMPACT
ENVIRONMENTAL DETERMINATION: The proposed action is not a project as defined by 14 California Code of Regulations 15378 (State CEQA Guidelines) and therefore CEQA is not applicable.
SUPPORTING DOCUMENTS
A. Napa Valley Integrated Hydrologic Model Refinements Presentation (LSCE, June 2026)