The Utah Supreme Court recently reversed a decision of the Utah 3rd District Court requiring the City of Holliday to fluoridate its water pursuant to a regulation adopted by Salt Lake County.
The Supreme Court found that recently passed Utah Senate Bill 29, which exempted "corporate public water systems" from having to comply with the county's fluoridation regulation, made the case moot because Holliday operated a "corporate public water system" and was thus exempt. The Supreme Court remanded the case to the district court for dismissal on that basis.
As noted in the court's opinion, Holliday may still have a contractual obligation to Salt Lake County to fluoridate its water based on a prior contract between the two municipalities. A case is currently pending in the district court to determine that issue.
The Utah Supreme Court's ruling in Salt Lake County v. Holliday Water Company can be found in pdf format at this link.