Facts about the Boil Water Orders issued in the Village of Mendocino on April 29, 2025

At the end of April, the County of Mendocino and the State Water Resources Control Board Division of Drinking Water sent out an alarming public health advisory notice warning residents who live west of Highway 1 to boil their water. The advisory also said three restaurants in the area were under “boil water notices,” suggesting that their water was not safe.

It turned out there was no immediate risk, however. The notices were issued as part of an enforcement action to compel the restaurants to install multibarrier water treatment in addition to existing treatment methods, which included ultraviolet treatment, ozonation, and chlorine. While there is no urgent public health emergency, the notices revealed that raw well water in the Village Mendocino has tested positive for E. coli in winter months. While treated water has tested clean, adding filtration treatment will further strengthen water safety.

KZYX News reviewed the citations and compliance orders, as well as test results. We also interviewed Stefan Cajina, Zachary Rounds and Matt Foster of the State Water Resources Control Board, and Marlayna Duley, environmental health director for the County of Mendocino, along with Sarah Bradley of Dark Gulch Environmental Consulting, Donna Feiner of Feiner Fixings, and Jaime Placido of JP Waterman.

Here are the facts you need to know:

1. All restaurants affected by the order are currently using potable water. The “boil water notices” posted in the window are an enforcement mechanism to encourage prompt adoption of filtration technology.  All three restaurants were cited for not including “filtration treatment” as an additional treatment method, for groundwater under the influence of surface water.
2. The restaurants cannot resume using well water until they adopt filtration technology or another mitigation method is reviewed and approved by the state.
3. The restaurants can choose the filtration technology they want to adopt and they can propose other mitigation measures.
4. The wells associated with the restaurants are compliant with Mendocino County Department of Environmental Health regulations. 
5. Bacteria, including E. coli, has been detected in groundwater in Mendocino County and in the Village of Mendocino particularly during the months of heavy winter rains (November through February). No level of E. coli is safe. During heavy rains, a highly alarming measurement of 65.0 MPN/100mL of E. coli was taken at a well that was subsequently disinfected. Anything above 1 MPN/100mL is considered a violation and unsafe for drinking without treatment. Everyone who drinks well water should test their water to ensure it is safe from undesirable contaminants and treat it if necessary.
6. The California State Water Resources Control Board Division of Drinking Water became aware that restaurants in the village of Mendocino were not connected to a community water system during the drought in 2021. 
7. Because the restaurants are not connected to a community water system, each restaurant is considered its own transient water system based on the fact that it provides water for human consumption.
8. All California restaurants that serve water to 25 or more individuals on their 60th busiest day and that rely on a well are required to submit monthly water samples to ensure compliance with potable water standards, maximum levels of contaminants, specific treatment techniques, and monitoring and, reporting requirements as specified in regulations adopted by the State Water Board.
9. Mendocino restaurants who received citations are compliant with state monitoring and reporting requirements.
10. The treated well water, otherwise known as tap water or drinking water was not contaminated at the restaurants who received boil water notices in April 2025 before the notices were issued. The raw water at the restaurants also tested clean for at least two months prior to the sending of the notices.
11. The state inspected transient water systems in the Village of Mendocino in 2022 and issued reports that included concerns that some wells were under the influence of surface water, which could lead to fecal contamination.
12. According to the citation and compliance orders issued in April 29, 2025, the water in the wells used by these restaurants meets the definition of “ground water under the direct influence of surface water,” which requires “multibarrier treatment.“ 
13. The definition of groundwater under the influence of surface water is “any water beneath the surface of the ground with significant occurrence of insects or other macroorganisms, algae or large diameter pathogens such as Giardia lamblia or Cryptosporidium, or significant and relatively rapid shifts in water characteristics such as turbidity, temperature, conductivity or pH which closely correlate to climatological or surface water conditions.”
14.  All three restaurants were cited for not including “filtration treatment” as an additional treatment method, for groundwater under the influence of surface water.