Napa County Well Statistics 2026: 44 Facts & Data
Napa County Well Overview
Napa County, world-renowned for its wine industry, relies heavily on groundwater for vineyard irrigation and rural domestic supply. The Napa Valley Subbasin is carefully monitored to ensure sustainable use alongside the county's $2+ billion wine industry.
Source: Napa County PBES, Napa County Groundwater Resources Advisory Committee
Well Population by Type
| Well Type | Number | % |
|---|---|---|
| Domestic/Residential | 3,900 | 56.9% |
| Agricultural/Vineyard | 2,200 | 32.1% |
| Monitoring | 385 | 5.6% |
| Public Supply/Winery | 265 | 3.9% |
| Industrial | 100 | 1.5% |
Key Napa County Facts
- 45,000+ acres of vineyard in Napa County
- ~60% of vineyards rely on groundwater for irrigation
- Medium Priority Basin under SGMA (Napa Valley Subbasin)
- 754 square miles county area
- 140,000 county population (2025)
- Groundwater levels generally stable on the valley floor
- Local groundwater ordinances for vineyard development
- Napa County Groundwater Resources Advisory Committee provides oversight
Wells by Community
Top Areas by Well Count
| Area | Wells | Avg Depth |
|---|---|---|
| St. Helena Area | 1,180 | 275 ft |
| Calistoga | 920 | 245 ft |
| Yountville/Oakville | 850 | 265 ft |
| Napa City Outskirts | 780 | 295 ft |
| Angwin/Howell Mountain | 680 | 385 ft |
| Rutherford | 620 | 255 ft |
| Pope Valley | 540 | 320 ft |
| American Canyon Area | 480 | 215 ft |
| Carneros | 420 | 195 ft |
Napa Valley Groundwater Data
Source: Napa County Groundwater Monitoring Program
Basin Information
| Characteristic | Napa Valley Subbasin |
|---|---|
| Priority Level | Medium (SGMA) |
| Basin Area | ~80 square miles |
| Primary Aquifer | Alluvial deposits |
| Typical Yields | 10-100 GPM |
| GSA | Napa County |
Groundwater Level Trends
| Area | 5-Year Change | Status |
|---|---|---|
| Central Valley Floor | -1.8 ft | Stable |
| Calistoga Area | -2.5 ft | Stable |
| Northeastern Napa (uplands) | -8.2 ft | Declining in some areas |
| Carneros | -0.5 ft | Stable |
| Howell Mountain | -5.8 ft | Variable |
Notable Findings
- Valley floor: Generally stable with good recharge
- Hillside/mountain areas: More variable, deeper wells needed
- Northeastern subarea: Some wells showing declines
- Newer hillside wells: May be deeper for dependable rates
- High seasonal variability in some areas
Permit Statistics
Permit Types (2026)
| Type | Count | % |
|---|---|---|
| New Domestic | 78 | 50.0% |
| New Agricultural/Vineyard | 48 | 30.8% |
| Replacement | 18 | 11.5% |
| Deepening | 8 | 5.1% |
| Monitoring | 4 | 2.6% |
Permit Requirements
- Permit fee: $1,650 domestic, $2,100 agricultural (2026)
- Processing time: 10-21 business days
- Vineyard wells: May require erosion control and CEQA review
- Hillside wells: Additional geologic assessment may be required
- 100-foot setback from septic systems
Drilling Costs (2026)
Costs by Area
| Area | Low | Avg | High |
|---|---|---|---|
| Valley Floor (Napa, Yountville) | $32,000 | $42,000 | $68,000 |
| Calistoga/St. Helena | $35,000 | $48,000 | $75,000 |
| Howell Mountain | $48,000 | $65,000 | $98,000 |
| Pope Valley | $42,000 | $55,000 | $85,000 |
| Carneros | $28,000 | $38,000 | $58,000 |
Vineyard/Agricultural Well Costs
Vineyard irrigation wells (high capacity) typically cost $75,000-$145,000 for complete systems with variable frequency drives and automation.
Cost per Foot
- Alluvium (valley): $45-60/ft
- Volcanic formations: $55-75/ft
- Hard rock (mountains): $70-95/ft
Water Quality
Common Issues
| Issue | % Affected |
|---|---|
| Hard water | 35% |
| Boron (natural) | 8% |
| Iron/Manganese | 12% |
| Arsenic | 3% |
| Geothermal influence (Calistoga) | 5% |
Calistoga Geothermal
The Calistoga area has natural geothermal activity. Some wells tap hot water, and mineral content may be elevated. Proper well construction and depth selection is important.
We service all major pump brands including Franklin Electric, Grundfos, Goulds (Xylem), and Sta-Rite (Pentair). Our trucks carry common parts and components for same-day repairs.
Frequently Asked Questions
How many wells are in Napa County?
Napa County has approximately 6,850 registered wells, including 3,900 domestic and 2,200 vineyard/agricultural wells.
What is the average well depth?
Domestic wells average 285 feet; agricultural wells average 385 feet. Hillside areas may require depths of 400-600 feet.
Are groundwater levels declining?
Valley floor levels are generally stable. Some hillside and northeastern areas show declines and may require deeper wells.
How much does a well cost?
Average domestic cost is $48,500 (2026), ranging from $28,000 in Carneros to $98,000 on Howell Mountain.
Are there special regulations for vineyard wells?
Yes, Napa County has local groundwater ordinances for vineyard development, including potential CEQA review and groundwater availability assessments.
Need Well Information?
For Napa County well services, contact Napa County PBES at (707) 253-4417.
For San Diego/Riverside: (760) 440-8520
Related Articles
Continue learning about well maintenance and troubleshooting
