Skip to main content.

California's nitrate woes

California's nitrate woes

Picture of Julia  Scott

This week, several newspapers across California published my investigative series focusing on the threats posed by nitrates in groundwater. The full stories with accompanying sidebar can be read here, along with multimedia resources that include video, photo slideshows, and a three-part series on nitrates by KQED Radio.

This yearlong investigative collaboration between California Watch and KQED began when I learned that there were people in the Central Valley who were unable to drink their well water because of nitrates. A byproduct of nitrogen fertilizer, animal manure, leaky septic tanks and some wastewater treatment plants, nitrates are the most ubiquitous groundwater contaminant in California and across the U.S., and scientists call it the biggest threat to California's future drinking water supply.

I discovered that nitrates - which can cause methemoglobinemia, or "blue baby syndrome", in infants when consumed at levels that exceed public health limits - don't just affect the Central Valley. The Central Coast and the Imperial Valley are also struggling with a heavy legacy of nitrate contamination, chiefly from a history of commercial farming and dairies in particular regions. In the end, I reported that The water supply of more than two million Californians has been exposed to harmful levels of nitrates over the past 15 years.

Many Californians are lucky enough to live in urban area that treat the water and remove nitrates before they reach the tap - although some cities, like those in Southern California, have spent hundreds of millions of dollars to make their water drinkable.

The Bay Area also struggles with nitrate problems to a lesser extent. Just this week, 100 migrant workers were evicted from their farm labor camps when officials in Pescadero, California discovered they had been drinking nitrate-contaminated water at six times the legal limit.

This is an important story that can be told from a local angle most anywhere in California. The State Water Resources Control Board has compiled a handy searchable interactive map that allows users to look up their cities or towns and drill down to see which wells have been affected by high levels of nitrates. (Unfortunately, the map will not tell you the exact address of the well, only an approximation within one square mile). Tips on using this search tool can be found here. You can use this same database to search for other groundwater pollutants, from perchlorate to benzene.


Picture of Rebecca Plevin

Thanks for writing this important story and for sharing some of your reporting tools! I'm a reporter in Fresno, and think it's a true injustice that many Central Valley residents don't have access to safe, clean drinking water.

Picture of Leah Beth Ward

My series on nitrates in Washington state's Yakima Valley -- Hidden wells, dirty water -- spurred an EPA investigation that's now ongoing. They are doing DNA sampling on the water to identify the source of the contamination, which is also turning up e.coli. Dairies and fertilizer are the leading suspects. This is an environmental justice issue as many of the rural well owners are Latino farmworkers.

Picture of Angilee Shah

Leah Beth Ward shared her investigative report on here on ReportingonHealth -- it's a great read.


Leave A Comment


In this webinar, we'll look at how journalists can tell urgent stories as states reopen and workers are potentially forced to choose between their health and their economic survival. Sign-up here!

The Center for Health Journalism is dedicated to supporting journalists covering two of the biggest stories of our time — the twin pandemics of COVID-19 and systemic racism and inequities in America. We provide reporters with intensive training instituteswebinars and tips about craft and content and are providing deep and sustained support for reporters and their newsrooms in this historic and difficult moment. You can donate through the USC web portal at this link. Pressed for time? You can also text to donate! No amount is too small; just send a text to 41-444 and type the message CHJ for further instructions.


Follow Us



CHJ Icon