Water – whether too much of it or too little – is a perennial problem in California. According to the U.S. Drought Monitor, over 90% of the state was in a severe drought or worse for most of 2021 and 2022. Additionally, moderate or worse drought conditions impacted over one-third of California’s land area for much of 2025. That same year, December brought record-breaking rainfall to parts of Los Angeles, prompting flooding, multi-county emergency declarations, and mass evacuations.
While threats posed by natural disasters such as floods and drought are often well publicized, water in California also presents a lesser-known, invisible threat – nitrate contamination.
Nitrate is an inorganic pollutant contained in fertilizer, and in many parts of the country, agricultural runoff can contaminate ground and surface water. A recent report from the the Environmental Working Group found that more than 22.7 million people in California, by far the most of any state, have likely been exposed to tap water containing at least 3 milligrams of nitrate contaminants per liter – a level of concentration that can increase the risk of certain types of cancer, including thyroid and colorectal. According to EWG, as many as 10.7 cancer cases for every 100,000 people in the state could be attributed to such exposure…