State Water Fluoridation Law Supercedes City’s Anti-Fluoride Ordinance

In City of Watsonville vs. State Department of Health Services, 2005 WL 2769514, Cal. App. 6 Dist., Oct. 26, 2005, a California Court of Appeal considered whether the city’s newly enacted ordinance banning fluoridation of city water supplies conflicted with state laws requiring fluoridation, and if so, which law should prevail. The court found that the laws did directly conflict, and that the state’s interest in regulating its water supply clearly superceded the city’s interest in the subject. It concluded that the city law is therefore preempted by state law.


In the fall of 2002, voters in Watsonville passed Measure S, which prohibited introducing any substance into the City’s drinking water, and brought a halt to the City’s planned water fluoridation project. The State Department of Health Services (DHS) ordered the city to fluoridate anyway, citing Health and Safety Code Section 116410, which requires fluoridation of public water systems having at least 10,000 hookups, as Watsonville’s did. The City, unable to comply with the order without violating Measure S, sued, asking that Measure S be found valid and enforceable, and that DHS be enjoined from enforcing its order. The trial court ruled that Measure S was preempted by state law and that the city must comply with state law. The city appealed.

Appellate Court Decision

The court ruled that the only issue before it was whether Measure S is preempted by state law. It first concluded that a state law regulating a statewide concern can preempt local ordinances and regulations. It then found that Measure S clearly did conflict with state law because the area of water fluoridation was already fully occupied by state law. Furthermore, it noted, in Health and Safety Code Section 116409, the Legislature expressed specific intent to preempt any conflicting local measures restricting fluoridation.

The court then found that fluoridation of public water systems is a matter of statewide concern. While the city has a valid interest in controlling its water quality, the State’s interest is more compelling because water standards apply generally to all users of water statewide, the court said, citing Paredes vs. County of Fresno. All citizens of the state are entitled to water that conforms to public health standards, which a patchwork of inconsistent local measures can’t provide, the court said.

The court concluded, therefore, that the state’s fluoridation law affects the statewide interest of promoting public health and ensuring quality drinking water, and has no significant effect on other municipal affairs. Measure S therefore conflicted with state law and was void and without effect, the court ruled.

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