The Gilbert water manager who was fired last fall amid a controversial shutdown of the town’s fluoridation system will likely have his job back after a hearing officer on Tuesday declared his dismissal “arbitrary and capricious.”

Chris Ochs was terminated in September after upper management discovered voter-mandated fluoridation had been halted at the town’s North Water Treatment Plant for more than a year. Ochs said he shut off the system in July 2011 because of safety concerns brought on by visible corrosion and a white powder apparently being spewed by the main pump.

Prolonged exposure to hydrofluoric acid, a hazardous chemical added to drinking water to help fight tooth decay, can cause bone changes, ulcers, shock, coma and death, according to chemical distributor ClearTech Industries.

Ochs reported the problems to his superior, Public Works Director Lonnie Frost, but could not gain traction in getting the system repaired and back online, documents show.

The lengthy stoppage went unreported to Town Manager Patrick Banger until last August, when a Town Council member received a constituent e-mail inquiring about the status of the fluoridation system.

Frost and Ochs were immediately put on administrative leave during an investigation, and Frost was later allowed to retire after 28 years with the town. Ochs, on the other hand, was given a pink slip for “failure to ensure compliance … as it relates to fluoridation,” according to a notice of dismissal.

That disparity in treatment, along with the fact that the town apparently did not mete out punishment to other administrators who knew of the shutdown, provided grounds for overturning the decision to fire Ochs, mediator Steven Guttell said in a decision released Tuesday.

Guttell, a Scottsdale attorney specializing in employment and labor law, ordered the town to reinstate Ochs as water manager and grant him full pay retroactive to Sept. 6 at his annual salary of $96,000.Guttell’s statement describes his decision as final and binding.

Gilbert spokeswoman Dana Berchman said the town is reviewing the decision but does not comment on personnel matters.

Guttell was selected as a mediator in November, and a one-day hearing was held on Dec. 19 at Gilbert Town Hall. The parties called multiple sworn witnesses, including Deputy Town Manager Marc Skocypec, Risk Manager Leland Frische and Ochs.

During his testimony, Skocypec characterized Ochs’ failure to go over Frost’s head to report the shutdown as “an egregious violation of the public trust,” according to Guttell’s statement.

Skocypec insisted that Ochs did not have to fear retaliation for reporting the problem because he would have been afforded the protections of a whistle-blower, according to Guttell’s statement.

Guttell said, however, that fluoridation is not included in the water manager’s job description and that the town was posing a “unique argument” in using whistle-blower protections as “a sword rather than a shield.”