Navarro has been a school board member since 2006, and in November was elected to a seat on the water district board that he took Jan. 8.
In December, county counsel Jean-Rene Basle drew from a previous attorney general opinion that said representing a water district and school district could lead to a "significant clash of duties and loyalties," for instance because the water district sets wholesale prices that retail water agencies then pass on to school districts.
Even a potential future significant clash means the first office must be resigned, according to the attorney general's website.
But the school board voted 4-1 on Monday - with Navarro abstaining - to ask the attorney general whether the offices were compatible.
"This is a legal matter that needs to be resolved, and the proper channel is to go through the attorney general," Board President Bette Harrison said in a statement from the county superintendent's office.
Navarro said he supported that decision, although he expected a backlog of cases in the attorney general's office would mean it would take a year and a half to get an opinion, which he said would have to be followed by a lawsuit in Superior Court.
"I have no problem with the process other than it's a waste of taxpayer dollars," Navarro said.
Navarro's school board seat, which represents schools in San Bernardino and Rialto, is up for election in November 2014.