SC By SCWS Team | February 2, 2026 | 16 min read
Groundwater Rights in California Explained
If you own property with a well or are considering drilling one in California, understanding groundwater rights is essential. California's groundwater law has evolved dramatically—from the "Wild West" days of unlimited pumping to today's SGMA-regulated landscape. This guide explains traditional water rights doctrines, how SGMA has changed the game, and what it all means for property owners and well users in 2026.
⚠️ Important Disclaimer
This article provides general educational information about California groundwater law. It is not legal advice. Water rights issues can be complex and situation-specific. For questions about your specific water rights, consult a qualified water rights attorney.
The Basic Framework: Do You "Own" Groundwater?
Let's address the fundamental question: Do you own the groundwater under your property?
The short answer: No, not exactly. Under California law, groundwater is considered a public resource. However, as a landowner, you have certain rights to use groundwater. This distinction matters—you don't own the water molecule itself, but you have legal rights to extract and use groundwater under specific conditions.
California recognizes several types of groundwater rights, which developed through common law (court decisions) over the past 150+ years. SGMA (2014) added a regulatory layer on top of these traditional rights but didn't replace them.
Types of Groundwater Rights
1. Overlying Rights (Most Common for Landowners)
If you own land above a groundwater basin, you have overlying rights—the most common and often most valuable type of groundwater right.
✅ Key Features of Overlying Rights
- • Automatic: Exists simply by owning land over the basin
- • For use on overlying land: Must be used on the land above the basin
- • Reasonable use: Limited to "reasonable beneficial use"
- • Superior to appropriative rights: Satisfied before appropriators
- • Shared among overliers: All overlying users share during shortages
- • Attached to land: Transfers with property sale
Example: You own a 10-acre farm above the San Diego Formation basin. You have overlying rights to pump groundwater for use on that 10 acres—for your home, livestock, and irrigation. You don't need a "water right" document; it comes with land ownership.
2. Appropriative Rights
Appropriative rights allow use of groundwater on land that doesn't overlie the basin (transporting it elsewhere) or use of "surplus" water beyond what overlying users need.
📋 Key Features of Appropriative Rights
- • Junior to overlying rights: Cut back first during shortages
- • For non-overlying use: Water transported away from basin
- • Priority system: "First in time, first in right" among appropriators
- • Can be lost: Non-use for extended periods may forfeit rights
- • Typically held by: Water districts, municipalities, export users
3. Prescriptive Rights
Prescriptive rights can be acquired through prolonged, open, and notorious use of water that exceeds what's legally available to the user. This is similar to adverse possession for land.
- Requires 5+ years of continuous "wrongful" use
- Use must be open and known to affected parties
- Difficult to establish and prove
- SGMA may limit the ability to acquire new prescriptive rights
4. Pueblo Rights (Historical, Limited)
Some California cities (Los Angeles, San Diego) inherited pueblo rights from Spanish and Mexican law, giving them superior rights to groundwater within their original pueblo boundaries.
The Hierarchy of Rights
When there isn't enough water for everyone, California law establishes a hierarchy for who gets water first:
📊 Groundwater Rights Priority (Highest to Lowest)
1. Pueblo Rights
Historical municipal rights (rare, limited areas)
2. Overlying Rights
Landowners using water on their overlying land
3. Appropriative Rights (by priority date)
Older rights senior to newer rights
4. Prescriptive Rights
Rights acquired through prolonged adverse use
Important: Among overlying users, rights are "correlative"—all overlying users share equally during shortages, proportional to their overlying acreage or beneficial use. One overlying user can't claim all the water to the exclusion of others.
How SGMA Changed the Game
The Sustainable Groundwater Management Act (SGMA), passed in 2014, fundamentally changed how groundwater is managed in California—without directly changing the underlying water rights doctrines.
What SGMA Did
- Created local governance: Groundwater Sustainability Agencies (GSAs) manage basins
- Required sustainability plans: GSAs must develop plans to achieve sustainability
- Set deadlines: Critically overdrafted basins by 2040, others by 2042
- Authorized management tools: GSAs can limit pumping, charge fees, require metering
- Didn't eliminate rights: Traditional water rights still exist but are now regulated
Practical Impact on Water Rights
⚖️ SGMA's Effect on Different Users
Domestic/De Minimis Users
Wells producing <2 acre-feet/year generally exempt from fees and metering, but still subject to general sustainability measures.
Agricultural Users
May face metering, pumping fees, and allocations. Overlying rights still exist but practical pumping may be limited by GSA.
Municipal/Industrial Users
Often appropriative rights holders. Subject to full GSA management and potentially significant pumping restrictions.
New Users
May face difficulty establishing new pumping in overdrafted basins. Some basins have moratoriums on new wells.
🚨 Key Point
Your overlying right to pump groundwater still exists under SGMA, but the GSA can now regulate how much you can pump if necessary to achieve sustainability. You have a "right" to water, but that right may be subject to allocation limits in practice.
Adjudicated Basins: A Different System
Some California groundwater basins have been "adjudicated"—meaning a court has determined the rights of all users and assigned specific pumping allocations.
How Adjudicated Basins Work
- Court-determined rights: A lawsuit (often decades ago) established who can pump and how much
- Specific allocations: Each party has a defined annual pumping amount
- Watermaster: A court-appointed manager tracks pumping and enforces allocations
- Tradeable: Water rights in adjudicated basins can often be bought and sold
- Penalties: Exceeding your allocation results in fees or penalties
Major Adjudicated Basins in Southern California
- Mojave Basin: One of the largest, covers much of the High Desert
- Raymond Basin: Pasadena area
- Main San Gabriel Basin: San Gabriel Valley
- Chino Basin: Inland Empire
- Orange County Basin: Northern Orange County
💡 Buying Property in an Adjudicated Basin?
If you're purchasing property in an adjudicated basin, water rights may or may not be included. Ask specifically whether water rights (allocation) convey with the property, and verify with the watermaster. You may need to purchase rights separately, which can cost thousands to hundreds of thousands of dollars depending on the basin and amount.
Common Water Rights Questions
Can My Neighbor's Pumping Affect My Well?
Yes, and this is one of the most frustrating aspects of California groundwater law. Under the traditional doctrine of "reasonable use," if your neighbor is making reasonable beneficial use of groundwater, you generally have no legal claim against them even if their pumping lowers your water table.
Potential remedies:
- Deepen your well to access lower water
- In SGMA basins, report concerns to the GSA (they can address cumulative impacts)
- If pumping is "unreasonable," legal action may be possible (expensive, uncertain)
- In adjudicated basins, watermaster enforces allocations
Do Water Rights Transfer When Property Sells?
Overlying rights: Yes, they're attached to the land and transfer automatically with property sale.
Adjudicated basin allocations: Not necessarily. These may be severable from land and sold separately. Check carefully before purchasing.
SGMA allocations: Varies by GSA. Some allocations may be tied to historic use, not land ownership. Check with your GSA.
Can I Sell My Groundwater?
This is legally complex:
- Overlying rights: Are for use on your land, not for sale. Selling water may convert your right to appropriative (making it junior)
- Adjudicated basins: Allocations are often tradeable. Contact the watermaster.
- Some SGMA basins: May allow allocation transfers. Check with GSA.
- Consult an attorney: Before attempting to sell groundwater, get legal advice
What If I'm Pumping More Than My Allocation?
Consequences vary by basin type:
- Adjudicated basins: Penalties, fees, possible legal action. Must purchase additional allocation.
- SGMA basins with allocations: Fees, penalties, enforcement actions by GSA. Severity increasing as basins approach deadlines.
- Unmanaged basins: Currently fewer consequences, but this is changing as more basins come under SGMA management.
Protecting Your Water Rights
Document Your Historical Use
As SGMA implementation continues, historical pumping records may become important for establishing allocations. Keep records of:
- When your well was drilled (Well Completion Report)
- Estimated annual pumping (electricity records, meter readings)
- Crops grown, livestock watered, other beneficial uses
- Any correspondence with water agencies
Engage with Your GSA
If you're in a SGMA basin, participate in the GSA process:
- Attend public meetings
- Comment on Groundwater Sustainability Plan updates
- Understand how allocations might be determined
- Join agricultural or domestic user stakeholder groups
Consider Water Efficiency
In a constrained future, using water efficiently protects your ability to continue beneficial use:
- Install efficient irrigation (drip vs. flood)
- Fix leaks promptly
- Choose water-efficient landscaping
- Consider rainwater harvesting as a supplement
Due Diligence When Buying Property
If you're purchasing property and planning to rely on groundwater, investigate water rights carefully:
Water Rights Due Diligence Checklist
- ☐ Identify the groundwater basin (DWR basin maps)
- ☐ Determine basin priority and SGMA status
- ☐ Check if basin is adjudicated (watermaster records)
- ☐ Contact GSA for any restrictions or moratoriums
- ☐ Review existing well records and pumping history
- ☐ Verify water rights convey with property sale
- ☐ Understand any allocation limits or pumping fees
- ☐ Consider well testing for yield verification
- ☐ Get water quality testing results
- ☐ Consult water rights attorney if significant investment
Frequently Asked Questions
Do I own the groundwater under my property in California?
In California, you don't technically "own" groundwater, but as a landowner you have overlying rights to use a reasonable amount of groundwater on your overlying land. This right exists simply by virtue of land ownership, but it's a right to "use," not ownership of the water itself. SGMA has added regulatory limits to this right in managed basins.
What is the difference between overlying and appropriative groundwater rights?
Overlying rights allow landowners to use groundwater on their overlying land and are generally considered superior to appropriative rights. Appropriative rights allow use of groundwater on non-overlying land (transporting it elsewhere) but are junior to overlying rights. During shortages, overlying users are satisfied first.
How has SGMA changed groundwater rights in California?
SGMA hasn't eliminated traditional groundwater rights but has added a regulatory framework on top of them. In managed basins, Groundwater Sustainability Agencies can now limit pumping even by overlying users to achieve sustainability. GSAs can require permits, metering, fees, and allocations—effectively creating practical limits on previously unlimited overlying rights.
What is an adjudicated groundwater basin?
An adjudicated basin is one where a court has determined water rights and assigned specific pumping allocations to users. These basins have a watermaster who manages allocations. Examples include Mojave Basin and Raymond Basin. To pump in an adjudicated basin, you typically need to purchase or lease water rights.
Can my neighbor's pumping affect my well?
Yes, excessive pumping by neighbors can lower groundwater levels and affect your well. Traditionally, California followed the rule of "reasonable use"—if pumping is reasonable, you generally have no legal claim even if it affects your well. SGMA may provide some protection as GSAs work to prevent undesirable results including declining water levels.
Do water rights transfer when I sell my property?
Overlying groundwater rights are attached to the land and generally transfer with property ownership. However, in adjudicated basins, water rights may be separable from land and could be sold separately. Check property records and any basin management agreements before assuming water rights are included with a property purchase.
Can I sell my groundwater to others?
In most unadjudicated basins, selling groundwater is legally complex. Overlying rights are for use on your land, not sale. Converting to appropriative use for sale may put you at the bottom of the rights hierarchy. In adjudicated basins and some SGMA basins, water allocations may be transferable. Consult a water rights attorney before attempting to sell groundwater.
What happens if I'm pumping more than my allocation?
In adjudicated basins, exceeding allocations results in penalties and may require purchasing additional rights. In SGMA basins with allocations, exceeding limits can result in fees, penalties, or enforcement actions by the GSA. Some basins are still developing enforcement mechanisms as of 2026, but penalties are becoming more common.
Questions About Your Well or Water Rights?
While Southern California Well Service isn't a law firm and can't provide legal advice on water rights, we can help you understand your groundwater basin, navigate the well permitting process, and ensure your well is properly constructed and documented. Our 20+ years of experience in San Diego and Riverside County means we know the local water landscape. Contact us for a consultation about your well project.
