Napa County to Implement New Groundwater Sustainability Fees Beginning FY 2026–27

Photo by Sarah Anne Risk

What Growers Need to Know
Napa County is moving forward with a new groundwater sustainability fee program to support long-term implementation of the Napa Valley Subbasin Groundwater Sustainability Plan (GSP), as required under California’s Sustainable Groundwater Management Act (SGMA).

Beginning in fiscal year 2026–27, groundwater users within the Subbasin will begin paying regulatory fees to fund monitoring, planning, and compliance activities that protect groundwater resources for the long term. These fees are designed to ensure Napa Valley maintains local control of groundwater management while meeting state sustainability requirements.

Program Cost and County Support
The Groundwater Sustainability Agency (GSA) has adopted a proposed annual program budget of approximately $2.47 million. To help reduce the financial burden on groundwater users, Napa County will contribute $500,000 annually to the program, including:

• $300,000 to broadly reduce the overall revenue requirement and lower fee rates for all users
• $100,000 dedicated to self-supplied domestic well users
• ​$100,000 reserved for hardship fee waivers and to support a program reserve fund

After applying the County contribution, approximately $2.17 million per year will be recovered through user fees.

How Fees Are Allocated
Program costs are divided into two main categories:

• Common costs, which provide broad benefits to all groundwater users, including administration, monitoring, data systems, reporting, and regulatory compliance
• Applied groundwater use costs, which are assigned only to large-volume groundwater users, primarily agriculture and public water systems, based on pumping levels

Costs are allocated across three user classes using a five-year average of groundwater pumping:

• Agriculture: approximately 74% of total pumping
• Self-supplied users (mostly domestic wells): approximately 18%
• ​Public water systems: approximately 8%

Agricultural Rates
Agricultural parcels will be billed based on planted acreage using Napa County Assessor crop records. The fee structure includes two components:

• A base rate of $38.58 per acre applied to all planted acres
• ​An additional groundwater irrigation rate of $60.16 per acre

For acreage irrigated primarily with groundwater, the total rate is $98.74 per acre. Dry-farmed acres, or acreage supplied by surface water or recycled water, will pay only the base rate of $38.58 per acre.

The GSA currently assumes that 90% of planted acreage uses groundwater unless growers provide documentation showing otherwise. Growers will have the opportunity in 2026 to report dry-farmed acreage or acreage supplied by alternative water sources before final bills are calculated.

Other User Rates

• Public water systems will be charged $129.87 per acre-foot of groundwater pumped
• Self-supplied domestic well users will be charged $62.58 per parcel

Domestic well owners may apply for hardship waivers, which will be funded through the County’s $100,000 assistance allocation.

Collection and Timing
Fees will begin in fiscal year 2026–27. For agricultural and domestic users, charges will appear on property tax bills starting in December 2026. Public water systems will be billed directly.

Before fees are imposed, Napa County will conduct a formal public notice and hearing process in accordance with California Water Code §10730.

What Growers Should Do Now
To prepare, growers should plan to:

• Review planted acreage records for accuracy
• Identify blocks that are dry-farmed or supplied by surface water or recycled water
• ​Be ready to submit documentation to the GSA when the reporting window opens in 2026

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NVG will continue to monitor the implementation process and share updates to help growers navigate these changes. Protecting groundwater while keeping management local is a shared responsibility, and informed participation will be key to ensuring a fair and effective program for Napa Valley agriculture.

We want to hear from you! If you have questions or concerns, please comment below.