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: Presentation on Interconnected Surface Water (ISW) and Groundwater Dependent Ecosystem (GDE) Workplan implementation and 2025 Monitoring Results
RECOMMENDATION
title
Provide an update on the Interconnected Surface Water (ISW) and Groundwater Dependent Ecosystem (GDE) Workplan implementation with a focus on 2025 monitoring results.
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Procedure
Staff introduces.
Questions and answers with the TAG.
Public comments.
BACKGROUND AND DISCUSSION
Monitoring groundwater dependent ecosystems for Napa Valley Subbasin Groundwater Sustainability Plan (GSP) implementation occurs through a combination of shallow monitoring wells and remotely sensed vegetation health. To address data gaps and better characterize the interconnection between surface water and groundwater dependent ecosystems, the NCGSA installed additional dual-completion ISW monitoring wells and developed a workplan that included biological field assessments, review of existing data, investigations of stream habitat conditions, and evaluation of listed species. The Interconnected Surface Water and Groundwater Dependent Ecosystems Workplan (Workplan) was completed in March 2024 with implementation beginning in May 2024. The Workplan identified six intensive survey sites: four on the Napa River (Napa River at Calistoga, Napa River at St. Helena, Napa River at Yountville, Napa River at Oak Knoll) and two tributary sites (Sulphur Creek and Bale Slough).
Surveys conducted in 2025 include:
* flow connectivity studies;
* fish population and fish habitat;
* continuous water quality monitoring for temperature and dissolved oxygen;
* up to four visual encounter surveys for aquatic wildlife;
* environmental DNA (eDNA) sampling for northwestern pond turtle and foothill yellow-legge...
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