Water quality is a pressing concern for many Modesto residents. Recent reports have highlighted issues such as PFAS contamination and elevated nitrate levels in the city’s water supply.
PFAS Contamination
Per- and polyfluoroalkyl substances (PFAS) have been detected in Modesto’s groundwater wells. Sampling at Well 16 in September 2024 revealed PFOS levels at 4.6 parts per trillion (ppt) and PFOA at 4.1 ppt, both exceeding California’s notification level of 4.0 ppt. The city is in the process of installing granular activated carbon (GAC) treatment systems at affected wells to mitigate this contamination. However, as of 2026, not all wells have dedicated treatment in place. Residents are advised to stay informed about the status of their local water sources and consider using filtration systems if concerned. Source
Nitrate Levels
Nitrate contamination, primarily from agricultural fertilizers and dairy operations, is another significant issue. The San Joaquin Valley, including Modesto, has experienced elevated nitrate levels in groundwater. This contamination poses health risks, especially to vulnerable populations. Residents relying on private wells are encouraged to test their water regularly for nitrates and other contaminants. Source
City Initiatives
In response to these challenges, Modesto has undertaken several initiatives. The city approved a nearly $144 million investment to overhaul the River Trunk sewage pipeline system, aiming to prevent future sewage spills and improve overall water quality. Additionally, community workshops have been organized to educate residents on air quality and environmental advocacy, reflecting a broader commitment to environmental health. Source Source
Residents are encouraged to participate in community surveys and workshops to voice their concerns and stay informed about ongoing efforts to improve water quality in Modesto.