Mendocino County Well Statistics 2026: 38 Facts & Data
Mendocino County Well Overview
Mendocino County is one of California's most rural counties, with vast stretches of forest, vineyard, and agricultural land. Most rural properties rely on private wells due to limited municipal water systems. The county has two SGMA-regulated basins in the Ukiah area, with most wells drawing from fractured rock aquifers.
Source: Mendocino County Environmental Health, California DWR
Well Population by Type
| Well Type | Number | % |
|---|---|---|
| Domestic/Residential | 11,400 | 80.3% |
| Agricultural/Vineyard | 1,850 | 13.0% |
| Public Supply | 420 | 3.0% |
| Monitoring | 350 | 2.5% |
| Industrial | 180 | 1.2% |
Key Mendocino County Facts
- 65,000+ residents rely on private wells
- 75% of county population depends on groundwater
- 3,509 square miles county area (3rd largest in CA)
- 87,000 county population (2025)
- 2 SGMA basins: Ukiah Valley and Big Valley (both Medium Priority)
- Majority of county: Fractured rock aquifers (Franciscan Complex)
- Wine grape acreage: ~18,000 acres (Anderson Valley, Redwood Valley)
- Coastal areas: Often challenging well drilling due to geology
Wells by Community
Top Areas by Well Count
| Area | Wells | Avg Depth |
|---|---|---|
| Ukiah Valley | 3,450 | 185 ft |
| Willits | 2,180 | 245 ft |
| Redwood Valley | 1,650 | 265 ft |
| Anderson Valley | 1,280 | 285 ft |
| Fort Bragg Area | 1,150 | 195 ft |
| Mendocino Coast | 980 | 235 ft |
| Laytonville | 750 | 345 ft |
| Potter Valley | 620 | 175 ft |
| Covelo (Round Valley) | 580 | 155 ft |
| Hopland | 520 | 225 ft |
Groundwater Data
Source: California DWR Bulletin 118
Groundwater Basins
| Basin | Priority | Area |
|---|---|---|
| Ukiah Valley | Medium | ~25 sq mi |
| Big Valley | Medium | ~10 sq mi |
Aquifer Types
- Ukiah Valley: Alluvial deposits, good yields (50-500 GPM)
- Interior valleys: Mixed alluvium and fractured rock
- Mountain/Forest areas: Franciscan Complex fractured rock (1-20 GPM typical)
- Coastal: Franciscan mélange, variable and often challenging
Groundwater Level Trends
| Area | 5-Year Change | Status |
|---|---|---|
| Ukiah Valley | -3.5 ft | Stable |
| Willits | -5.2 ft | Slight decline |
| Anderson Valley | -2.8 ft | Stable |
| Coastal Areas | Variable | Highly seasonal |
Permit Statistics
Permit Types (2026)
| Type | Count | % |
|---|---|---|
| New Domestic | 92 | 71.9% |
| New Agricultural | 18 | 14.1% |
| Replacement | 12 | 9.4% |
| Deepening | 4 | 3.1% |
| Monitoring | 2 | 1.5% |
Permit Requirements
- Permit fee: $1,245 domestic (2026)
- Processing time: 7-14 business days
- 100-foot setback from septic systems
- Cannabis cultivation: Additional water source assessment may be required
Drilling Costs (2026)
Costs by Area
| Area | Low | Avg | High |
|---|---|---|---|
| Ukiah Valley | $24,000 | $32,000 | $52,000 |
| Willits | $30,000 | $42,000 | $68,000 |
| Anderson Valley | $32,000 | $45,000 | $72,000 |
| Coastal Areas | $38,000 | $55,000 | $88,000 |
| Remote Mountain | $45,000 | $62,000 | $98,000 |
Cost per Foot
- Alluvium (valleys): $40-55/ft
- Franciscan rock: $60-85/ft
- Hard rock (remote): $75-100/ft
Remote Access Considerations
Mendocino County's remote properties may incur additional costs for:
- Equipment mobilization on unpaved roads
- Water trucking for drilling operations
- Helicopter drilling for extreme sites (rare)
Water Quality
Common Issues
| Issue | % Affected |
|---|---|
| Iron/Manganese | 22% |
| Hard water | 18% |
| Low yield | 15% |
| Arsenic (natural) | 5% |
| Bacteria (older wells) | 4% |
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 Mendocino County?
Mendocino County has approximately 14,200 registered wells, with 11,400 domestic wells serving rural properties.
What is the average well depth?
Domestic wells average 295 feet, varying from 155 feet in Round Valley to 400+ feet in mountainous areas.
How much does a well cost?
Average cost is $42,500 for a complete system, ranging from $24,000 to $98,000 in remote areas.
Is well drilling difficult on the coast?
Coastal areas can be challenging due to Franciscan Complex geology. Yields are often low and variable. Hydrogeological surveys are recommended.
What about cannabis cultivation wells?
Cannabis cultivation in Mendocino County may require water source assessments and proof of adequate water supply as part of permitting.
Need Well Information?
For Mendocino County well services, contact Mendocino County Environmental Health at (707) 234-6625.
For San Diego/Riverside: (760) 440-8520
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