Central Valley Drinking Water
Nitrate Well Water Contamination Claims
If your private well or community drinking water in the Central Valley has been contaminated with nitrate, your family may have a claim against the agricultural operations responsible. This page explains how these claims work. The firm is not accepting new matters in this area — the State Bar of California’s Lawyer Referral Services, (866) 442-2529, can connect you with a lawyer who is.
Please read first: this page is kept online for general information. The Law Offices of David L. Milligan, APC is not accepting new environmental or toxic-exposure matters. If you need a lawyer for a matter like this, please contact the State Bar of California’s Lawyer Referral Services at (866) 442-2529 — they will connect you with an attorney who handles these cases. Please do that now rather than waiting to hear from this office. Legal deadlines apply and can be short; delay can forfeit rights.
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Why this matters
Nitrate contamination of Central Valley groundwater is not theoretical. It is documented, repeatedly, by published scientific research and by community water organizations. Many rural Central Valley families rely on private wells. Many of those wells exceed the federal drinking-water standard for nitrate. The likely sources are tied to specific land uses — large dairies and concentrated animal feeding operations, manure lagoons and corrals, and fertilizer-intensive agriculture.
The legal question, when these conditions affect your household, is whether the operations responsible should bear the costs you are bearing — bottled water, treatment systems, hauled water, lost property value, and in some situations, health-related concerns.
The pattern is documented
These figures come from peer-reviewed scientific work in the San Joaquin Valley and from community water organizations. The federal drinking-water standard (MCL) for nitrate is 10 mg/L.
Source: Harter et al., San Joaquin Valley nitrate research; Kings Water Alliance. Sample populations and methodologies vary by study; the consistent finding across sources is that a substantial share of Central Valley domestic wells exceeds the nitrate MCL.
What nitrate is, in plain English
Nitrate is a chemical compound (NO3−) that can move easily through soil and into groundwater. It is invisible, tasteless, and odorless in well water. Common sources include:
- • Manure lagoons and corrals at dairies and concentrated animal feeding operations.
- • Heavy synthetic fertilizer use on row crops and orchards.
- • Septic systems in some rural settings.
- • Historical land use that left a residual loading of nitrogen in shallow groundwater.
The U.S. EPA Maximum Contaminant Level (MCL) for nitrate in drinking water is 10 mg/L (as nitrogen). The MCL was set primarily to protect infants from methemoglobinemia, sometimes called “blue baby syndrome.” Long-term exposure has been studied for other potential health concerns; the science continues to evolve and any specific health claim depends on facts and expert review.
Where the problem is showing up
Documented nitrate concerns are concentrated in the San Joaquin Valley counties listed below. These are not the only counties potentially affected; they are the ones with the strongest published evidence base.
Fresno County
Significant nitrate exceedances in domestic wells in agricultural areas.
Kings County
High exceedance rates documented in monitoring data.
Tulare County
Among the most heavily affected counties for domestic well contamination.
Merced County
Substantial exceedances near dairy and agricultural operations.
Stanislaus County
Documented contamination patterns linked to land use.
Other Central Valley areas
If you are outside these counties but have a nitrate test result above the MCL, the same framework may apply — talk to a lawyer.
Who may have a potential claim
A nitrate claim is fact-specific. Some categories of people commonly come forward:
- • Well owners with confirmed test exceedances. If your well has been tested and the result is above 10 mg/L for nitrate, you have the strongest objective starting point.
- • Families who stopped drinking their well water. If you have switched to bottled water, hauled water, or installed a treatment system because of contamination concerns, that is a documented cost.
- • Residents near likely nitrate sources. Proximity to dairies, concentrated animal feeding operations, manure lagoons, or heavily fertilized fields raises questions worth investigating.
- • Households with infants or young children. The MCL exists primarily to protect infants. Particular care is taken in these cases, and any health-related component is reviewed carefully and conservatively.
- • Tenants and mobile-home-park residents. You do not have to own the well or the property to have been harmed.
Who may be responsible
Source identification is technical work that requires testing, hydrogeology, land-use history, regulatory records, and expert review. Nobody should point a finger before the evidence is there. That said, the categories of potentially responsible parties commonly include:
- • Large dairies and concentrated animal feeding operations
- • Operators of manure lagoons and storage facilities
- • Fertilizer-intensive agricultural operators
- • Landowners and property operators with relevant land-use history
- • In some situations, water providers or public agencies that failed to act on known risks
Reporting in 2026 indicates that nitrate pollution remains an active regulatory issue, including a proposed California Water Board order aimed at bringing dairies into long-term nitrogen balance. This is not a closed historical problem.
How a lawyer investigates a nitrate claim
These cases live or die on the science. The work proceeds in roughly this order:
Water testing
Confirming nitrate concentrations from a properly collected sample at a certified lab. If you do not yet have a test, this page covers how to get one.
Land-use history
Identifying nearby agricultural operations, dairies, manure lagoons, and historical uses that could explain the loading.
Regulatory records
Pulling Regional Water Board, County Environmental Health, and Department of Pesticide Regulation files for nearby operators.
Hydrogeology and source tracing
Working with experts to evaluate groundwater flow, depth, and isotopic markers that distinguish manure-derived nitrate from fertilizer-derived nitrate.
Damages documentation
Capturing what your family has already spent on bottled water, treatment, hauled water, lost property value, and other measurable costs.
Legal evaluation
Determining whether the facts support a claim, who the right defendants are, and whether your matter belongs in an individual case or a coordinated proceeding.
Common questions
What if I do not know the source?
That is normal. Source identification is part of what counsel and experts do. You do not have to identify the responsible operator before talking to a lawyer. A confirmed exceedance and a description of nearby land use are usually enough to start.
What if I do not own the well?
You do not have to own the well to have been harmed by the water. Tenants, family members, and others who used the water may have claims depending on the facts.
What if I live in a rental or a mobile-home park?
Renters and mobile-home-park residents are sometimes the most affected. Park-owned wells and small water systems have their own regulatory and contractual issues. A lawyer can review the details with you.
What if my contamination has been going on for years?
Long-running contamination is common and is part of the legal story, not a barrier. Whether your specific claim is timely depends on the facts and on how recent your discovery, harm, or testing is. A lawyer can look at it with you.
What if I am already getting bottled water?
Then you have already paid real, documentable costs. Save your receipts and any communications about why you switched. That documentation often strengthens a claim.
What if I do not know whether my community qualifies?
Talk to a lawyer. Even if your specific area is not on a public exceedance list, a recent test result above the MCL or a documented water notice is often enough to begin.
What level of nitrate is unsafe in drinking water?
California's maximum contaminant level is 45 mg/L measured as nitrate — equivalent to the federal 10 mg/L as nitrogen (State Water Board). Above that level, infants face methemoglobinemia (“blue-baby syndrome”), and pregnant women are advised not to drink the water.
How widespread is the problem in the Central Valley?
The State Water Board's Drinking Water Needs Assessment has estimated that nearly a third of California domestic wells are at high risk of exceeding safe-water standards, with nitrate concentrated in agricultural basins like the Tulare Lake Basin. The Central Valley is the epicenter of the state's nitrate problem.
Can I get my well tested for free?
Often yes. The State Water Board's GAMA program offers free domestic-well testing in many high-risk areas, county programs exist, and in an investigation counsel typically arranges certified-laboratory testing. Never rely on taste — nitrate is colorless and odorless.
What is CV-SALTS and why does it matter to a claim?
CV-SALTS is the Central Valley regulatory program requiring nitrate dischargers in priority basins to notify affected users and supply replacement drinking water (Nitrate Control Program). Its studies and permittee data help identify who contaminated a basin — evidence a civil case builds on.
What deadlines apply to a water-contamination claim?
Personal-injury claims generally run two years from discovery of the injury and its cause; property claims can refresh under the continuing-nuisance doctrine; public-entity defendants require a government claim within six months. Deadlines are heavily litigated in these cases — get advice early.
What information helps
You do not need all of the following before reaching out. Anything you have is enough to start a conversation.
- • Address or community name and county.
- • Whether your home uses a private well, a small water system, or a community water supply.
- • Any test results you have, even if you do not understand them.
- • Approximate date(s) of any water notices, advisories, or correspondence.
- • Receipts or records of bottled water, hauled water, or treatment system costs.
- • A general sense of nearby agricultural operations, dairies, or manure lagoons if you know of any.
- • Whether anyone in the household has had health concerns you connect to the water.
Where to get help
The Law Offices of David L. Milligan, APC is not accepting new environmental or toxic-exposure matters, and this office cannot review or respond to inquiries about them. Lawyers do handle these cases, and the State Bar of California’s Lawyer Referral Services will connect you with one:
Lawyer Referral Services: (866) 442-2529
Please act promptly — legal deadlines apply and can be short, and waiting can forfeit rights.
Important: The information on this page is provided for general educational purposes only and does not constitute legal advice. This firm is not accepting new matters of this kind and cannot review inquiries about them; contacting the firm about this subject does not create an attorney–client relationship. Past results do not guarantee future outcomes, and no specific recovery is promised. Health-related statements describe regulatory standards and published research; whether a specific health concern is causally linked to nitrate exposure depends on the facts and on expert review. The Law Offices of David L. Milligan, APC is licensed in California.