Elevated and Dangerous
Stanford experts provide comments presenting preliminary public health research concerning elevated nitrate in California’s dairy-dominated communities
In late December, the Climate and Energy Policy Program (CEPP) and Environmental and Natural Resources Law & Policy Program’s (ENRLP) Sustainable and Humane Food Systems team submitted a letter to the California Water Resources Control Board (State Water Board) regarding the State Water Board's proposed revisions to Central Valley dairy manure regulations. The comment letter highlights preliminary research by Stanford Professor Dr. Jenny Suckale and her lab suggesting a geographic correlation between dangerously high nitrate concentrations in domestic wells near dairies, and babies with MediCal billing codes for the potentially deadly blue baby syndrome or its dominant symptom, cyanotic attacks.
The Central Valley dairy requirements cover how and which dairies must monitor, report, and manage cow waste (termed cow manure when applied to agricultural land for fertilizer). Such requirements have a significant impact since about 89% of California's cows, and 81% of our dairy farms are in the Central Valley. Furthermore, one dairy cow emits about a pound of nitrogen a day, that is, 365,000 pounds of nitrogen a year on a 1,000-cow dairy.
Comment Letter Context
Pursuant to the Clean Water Act and California’s Porter-Cologne Water Quality Control Act, the State Water Board is tasked with preserving and protecting clean water throughout California. The State Board does so in part, by overseeing nine semiautonomous Regional Water Quality Control Boards (Regional Water Boards). The Regional Water Boards develop local rules to enforce the State Water Board’s water quality objectives.
The recent State Water Board Draft Dairy Order is part of a long saga dating back to the Central Valley Regional Water Board’s early 2000s waste discharge requirements (WDRs). In 2007 environmental justice organizations petitioned the State Water Board to review those WDRs given ongoing dairy waste water pollution. By 2012, the appellate court finally agreed that the dairy regulations were inadequate, and, on October 3, 2013, the Central Valley Board adopted revised WDRs for the region's milk cow dairies. However, water quality continues to degrade and the 2013 WDRs may now change in light of the State Water Board's latest review.
Reviewing the 2013 WDRs: State Water Board’s Draft Dairy Order
Among other things, the State Water Board's October 2024 Draft Dairy order focuses on a need to fundamentally shift how we think about liquid dairy manure crop application. Rather than treating land applications as a desired crop fertilizer, the Draft Dairy Order frames it primarily as a waste management tool. This shift in regulatory perspective largely resulted from several state-commissioned UC Davis studies that identified manure land application as the second largest source of the Central Valley’s groundwater nitrate. Indeed, the estimated average annual land application rate for silage corn, one of the main crops “fertilized” with dairy manure, exceeds the federally recommended rate for beneficial crop production by a factor of four.
Encouragingly, the Draft Dairy Order explains that “going forward, we must regulate dairies’ land application practices primarily as a method of disposing of dairy waste that has secondary benefits of fertilizing crops.” Unfortunately, the Draft Dairy Order lacks strong immediate interventions and focuses on long-term structural changes with significant leeway in deadline deferral.
Enter: The CEPP and ENRLP Comment Letter.
One cause of infantile methemoglobinemia, commonly termed “blue baby syndrome,” is the ingestion of nitrate-contaminated drinking water. When consumed, nitrate enters the bloodstream and oxidizes hemoglobin into methemoglobin, preventing it from transporting oxygen. As a result, the bloodstream becomes less able to supply oxygen to tissues. Unaddressed, this causes a blue-grey discoloration of the skin, and in extreme cases, death.
California's Central Valley has approximately 92,000 households that rely on unregulated domestic wells. While data on the location and water quality of many of these wells is significantly lacking, the publicly available information draws a worrisome picture.
Dr. Suckale’s findings suggest that there may be elevated rates and counts of both blue baby syndrome and its predominant symptom, cyanotic attacks, in the Central Valley near dairies. Given the State Water Board's recognition of the many nitrate-linked public health concerns, the comment letter shares Dr. Suckale’s preliminary findings and urges the State Water Board to expeditiously provide safe drinking water to vulnerable communities.
A few preliminary findings from Dr. Suckale’s work:
90% of coded cases are clustered around dense urban areas or agricultural regions, including the Central Valley.
Of coded cyanotic attacks and methemoglobinemia, many are from repeat patients–suggesting clusters of high-risk areas.
In the Central Valley, and often clustered in zip codes near dairies, domestic well water tests report nitrate levels over 50 mg/L (EPA’s maximum contaminant level for groundwater nitrate is 10 mg/L).
Dr. Suckale’s lab emphasized the need for more robust data on these issues. The lab was limited to using 2011-2019 MediCal beneficiary billing codes for cyanotic attacks and methemoglobinemia. There are several complications with using such data as a proxy for estimating how many methemoglobinemia or cyanotic attacks occurred. For instance, billing codes indirectly suggest that a doctor saw methemoglobinemia-like symptoms or a cyanotic attack, but do not confirm a final diagnosis, thus likely overestimating the number of true cases. It also takes time for a baby to get a unique beneficiary ID. In the meantime, billing codes may be linked to the parent-beneficiary, thus potentially undercounting infant reports. Lastly, MediCal data only captures about 38% of the 2019 California population, likely contributing to an undercount of total cases.
Well-water data is also significantly lacking. Researchers were limited to the public Groundwater Ambient Monitoring and Assessment (GAMA) domestic well water dataset. This means researchers only have a partial picture of where, and how widespread, nitrate contamination is in the Central Valley.
The Draft Dairy Order recognizes that blue baby syndrome is a potentially deadly illness caused by excess nitrate, but lacks any information regarding its potential presence in the Central Valley despite numerous anecdotal reports of the syndrome. Our comment letter provides the State Board with a preliminary study suggesting such cases are reflected in the medical records. Given the public health risks associated with nitrate, our comment letter emphasizes that immediate fresh-water access and further community awareness are warranted.
See the full comment letter and preliminary study by Dr. Suckale’s lab here!
Gina Hervey is a legal fellow whose work centers around building more sustainable and humane food systems. With a focus on the public health impacts of concentrated animal feeding operations and closed-loop farming systems, Gina’s work intersects law, policy, agricultural sciences, and equity.
Great example of the power in correlating across diverse datasets and thanks in explaining the history, challenges, and preliminary findings.