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Nitrate pollution in groundwater is a widespread water quality problem that can pose serious health risks to pregnant women and infants if consumed at concentrations above the Maximum Contaminant Level (MCL) of 45 milligrams per liter (mg/L) nitrate as nitrate. Nitrate contaminated groundwater can be found in many areas of California, but is a particularly significant concern in the Tulare Lake Basin and Salinas Valley areas.
It is the goal of the State Water Resources Control Board (State Water Board) and the Regional Water Quality Control Boards (Regional Water Boards), collectively Water Boards, to protect surface and groundwater resources and to ensure safe drinking water for all California residents.
In response to nitrate concerns, the Legislature enacted Chapter 1 of the Second Extraordinary Session of 2008 (SBX2 1, Perata). SBX2 1 required the State Water Board to develop pilot projects focusing on nitrate in groundwater in the Tulare Lake Basin and Salinas Valley. SBX2 1 also required the State Water Board to submit a report to the Legislature on the scope and findings of the pilot projects, including recommendations, within two years of receiving funding.
In response to SBX2 1, the State Water Board contracted with the University of California, Davis (UC Davis) in 2010 to conduct an independent study on nitrates in the Tulare Lake Basin and the Salinas Valley. The UC Davis Nitrate Report, comprised of volumes 1-8, was delivered to the State Water Board in March 2012. The key findings of the report are summarized below.
UC Davis Key Findings
- Nitrate problems will likely worsen for decades. For more than half a century, nitrate from fertilizer and animal waste have infiltrated into Tulare Lake Basin and Salinas Valley aquifers. Most nitrate detected in drinking water wells today was originally applied to the surface decades ago.
- Agricultural fertilizers and animal wastes applied to cropland are by far the largest regional sources of nitrate in groundwater. Other sources can be locally important.
- Nitrate loading reductions are possible, some at modest cost. Large reductions of nitrate loads to groundwater can have substantial economic cost.
- Traditional pump and treat remediation to remove nitrate from large groundwater basins is extremely costly and not technically feasible. Instead, “pump-and-fertilize” and improved groundwater recharge management are less costly long-term alternatives.
- Drinking water supply actions such as blending, treatment, and alternative water supplies are most cost-effective. Blending will become less available in many cases as nitrate pollution continues to spread.
- Many small communities cannot afford safe drinking water treatment and supply actions. High fixed costs affect small systems disproportionately.
- The most promising revenue source is a fee on nitrogen fertilizer use in these basins. A nitrogen fertilizer fee could compensate affected small communities for mitigation expenses and effects of nitrate pollution.
- Inconsistency and inaccessibility of data prevent effective and continuous assessment of California’s groundwater quality. A statewide effort is needed to integrate diverse water-related data collection activities by many state and local agencies.
The State Water Board considered input and findings from various sources to make specific recommendations for addressing nitrate contaminated groundwater. In developing their Report to the Legislature, the State Water Board relied on the UC Davis report as a foundation, and obtained significant input from the Interagency Task Force (ITF), which included representatives from the California Department of Public Health (CDPH), the California Department of Food and Agriculture (CDFA), the Department of Pesticide Regulation (DPR), California Environmental Protection Agency (CalEPA), and local environmental health agencies. Recommendations were also informed by public input, and the findings of a task force convened by the Governor’s office to address safe drinking water issues. The State Water Board made 15 recommendations to address the issues associated with nitrate contaminated groundwater. These recommendations are reflected in the table below:
|State Water Board Recommendations||Status of Recommendation||Lead Agencies/Participants|
|Providing Safe Drinking Water
An impediment to providing safe drinking water to small Disadvantaged Communities (DACs) impacted by nitrate contamination is the lack of a stable, long-term funding source. A stable funding source integrated with institutional changes is critical in providing long-term safe drinking water infrastructure and interim solutions for the small DACs impacted by nitrate contamination.
|1. (a) The most critical recommendation in this report is that a new funding source be established to ensure that all Californians, including those in DACs, have access to safe drinking water, consistent with AB 685. The Legislature should provide a stable, long-term funding source for provision of safe drinking water for small DACs. Funding sources include a point-of-sale fee1 on agricultural commodities, a fee on nitrogen fertilizing materials, or a water use fee.
(b) In addition, the Legislature also should authorize the Water Boards* to assess a fee in lieu of interest on Safe Drinking Water State Revolving Fund loans, or to assess other fees associated with these loans, to generate funds for expanded assistance to water systems.
|(a) Underway - A long-term, stable funding source that can address operation and maintenance costs is still being pursued. The Governor's 2015-16 Budget proposal calls for working with local government, communities, and dischargers on strategies to achieve affordable, safe drinking water for disadvantaged communities.
(b) Completed - The legislature has given the State Water Board authority to assess an in lieu fee to generate funds for expanded assistance. The State Water Board is using this authority and funds will accrue and be available within several years.
Water Boards*, California Department of Food and Agriculture (CDFA), and Local Government Agencies
|2. The State Water Board and Regional Water Quality Control Boards (collectively referred to as “the Water Boards”) will use their authority under the Porter-Cologne Water Quality Control Act (Porter-Cologne) (Water Code,§13000 et seq.) to order parties responsible for nitrate contamination to provide replacement water to impacted communities, as appropriate.||Ongoing - Since 2014, the State Water Board Office of Enforcement (OE) has assisted the Central Valley, Central Coast, and Lahontan Regional Water Boards with negotiating replacement water orders, including bottled water and reverse-osmosis treatment, for nitrate-impacted drinking water. This effort is expanding in 2015 to include additional regions and improved screening methods.||Water Boards*|
3. The Legislature should enact legislation to establish a framework of statutory authorities for Water Boards*, regional organizations, and county agencies to have the regulatory responsibility to assess alternatives for providing safe drinking water and to develop, design, implement, operate, and manage these systems for small DACs impacted by nitrate2.
|There is currently no legislation to address this recommendation.||Water Boards*,
|4. State funding agencies should continue to increase access to safe drinking water funding sources for small DACs by streamlining funding applications, providing planning grants, and providing technical assistance.||
Completed - The State Water Board (Division of Financial Assistance) has combined all drinking water assistance programs into a one-application process using its FAAST online application tool.
|Water Boards*, Department of Water Resources (DWR)|
5. DWR should give preference in the Proposition 84 Integrated Regional Water Management (IRWM) Grant Program to proposals with IRWM Plans that include an evaluation of nitrate impacts, including the access of safe drinking water to small DACs, for areas that have been identified as nitrate high-risk areas.
|Completed - DWR's IRWM Grant Program's Statewide Priority to Protect Surface Water and Groundwater Quality now includes access of safe drinking water to small DACs for areas identified as nitrate high-risk.||DWR|
|Monitoring, Assessment, and Notification
A groundwater monitoring and assessment program is a critical element in effectively managing groundwater quality.
|6. The Water Boards will define and identify nitrate high-risk areas in order to prioritize regulatory oversight and assistance efforts in these areas.2||
Ongoing - An interactive map,
|7. The Legislature should enact legislation that establishes a framework of statutory authority for the Water Boards, in coordination with other state and local agencies, to improve the coordination and cost effectiveness of groundwater quality monitoring and assessment, enhance the integration of monitoring data across departments and agencies, and increase public accessibility to monitoring data and assessment information.2||
a) Ongoing - Water Board staff is performing outreach efforts to various state and local agencies to discuss GAMA's mission, vision, and proposed future enhancements to increase inter-agency communication and groundwater quality and quantity data availability on the GeoTracker/GeoTracker GAMA Information System.
b) Underway-Water Board staff is working with the Division of Financial Assistance to require that groundwater information collected for grant and loan projects is submitted to the Water Board in a format compatible with GeoTracker. Water Board staff is also developing a tool for GeoTracker GAMA that compiles sampling plans to avoid overlap of sampling efforts, and working with environmental justice groups to house their data in GeoTracker.
|Water Boards, other State and local agencies, grantees, borrowers, and stakeholders.|
|8. The Legislature should enact legislation that establishes a funding source for the State Water Board’s Groundwater Ambient Monitoring and Assessment (GAMA) Program.||Completed - The State Water Board passed Resolution 2014-0063 to authorize GAMA Program contracts not to exceed $3,102,690 from the Waste Discharge Permit Fund, including funding based on 2014 emergency drought legislation and the Budget Act of 2014.||Water Boards|
9. The Legislature should require state and local agencies to notify groundwater users in nitrate high-risk areas and recommend that the well owners test their wells to evaluate drinking water quality. The Water Boards* and local public health agencies will coordinate in identifying private domestic wells and small, unregulated water systems in nitrate high-risk areas.2
|There is currently no legislation to address this recommendation.||Water Boards*, local public health agencies|
|10. The Legislature should require property owners with private domestic wells or other unregulated groundwater systems (2 to 14 service connections) to sample their well as part of a point of sale inspection before property title transfer or purchase.||There is currently no legislation to address this recommendation.||Water Boards*, local public health agencies|
|Nitrogen Tracking and Reporting
According to the UC Davis Nitrate Report, nitrogen fertilizing material application is the main source of nitrate in groundwater. A system to track the application of nitrogen fertilizing materials is a critical element in managing groundwater quality.
|11. CDFA, in coordination with the Water Boards, should convene a Task Force to identify intended outcomes and expected benefits of a nitrogen mass balance tracking system in nitrate high-risk areas. The Task Force should identify appropriate nitrogen tracking and reporting systems, and potential alternatives, that would provide meaningful and high quality data to help better protect groundwater quality.||
Completed - This Task Force has convened and provided their recommendations in the Nitrate Tracking and Reporting Task Force Final Report.
CDFA, Water Boards, county agriculture commissioners, local agencies
Contaminated groundwater results in treatment, well closures, or new well construction, which increases costs for consumers and the public. Regulating groundwater is essential in maintaining a safe drinking water supply.
|12. The Water Boards should continue to provide technical assistance for CDFA’s ongoing work with University of California Cooperative Extension (UCCE) and other experts in establishing a nitrogen management training and certification program that recognizes the importance of water quality protection.2||Completed - CDFA and UC ANR have established a Nitrogen Management Training Program (NMTP) for Certified Crop Advisors (CCAs). As of 2025, a total of 800 CCAs have been trained throughout California. The NMTP materials developed are annotated and available as online modules on the UC ANR website.
Ongoing - CDFA, UC ANR, and grower coalitions are currently developing curricula for grower self-certification and accompanying 'Train the Trainers' programs.
|13. CDFA should maintain the mill fee on fertilizing materials at its fully authorized amount to support and develop crop-specific nutrient application rates, Best Management Practices (BMPs), and nutrient management programs via the Fertilizer Research and Education Program (FREP). The information should continue to be made available on-line.||
Completed - CDFA has increased the mill fee to the fully authorized amount.
|14. The Water Boards will convene a panel of experts to assess existing agricultural nitrate control programs and develop recommendations, as needed, to ensure that ongoing efforts are protective of groundwater quality. The Water Boards and CDFA will use the findings to inform ongoing regulatory and non-regulatory efforts.2||
Completed - The Expert Panel has convened and provided their recommendations in the Agricultural Expert Panel Final Report.
|Water Boards, CDFA|
|15. The Water Boards will evaluate all existing Waste Discharge Requirements to determine whether existing regulatory permitting is sufficiently protective of groundwater quality at these sites. The Water Boards will use the findings to improve permitting activities related to nitrate.2||In Progress||Water Boards|
*Including the Division of Drinking Water, formerly the CDPH Drinking Water Program.
1. Although the term 'fee' is used throughout this report, it is beyond the scope of this report to assess whether the fee is a fee or tax under Proposition 26. The term is simply used for convenience and consistency.
2. Additional funding will be required to adequately implement these strategies.
- Frequently Asked Questions
- State Actions to Address Drinking Water Quality Fact Sheet
- California Department of Public Health (CDPH) Nitrate Fact Sheet
- Is My Property Near a Nitrate-Impacted Water Well?
- Ashley Zellmer
Phone: (916) 341-5911