The Stinson Beach County Water District is formulating a lease agreement with AT&T to allow the cellular company to build a 65-foot-tall 5G cell tower disguised as a pine tree at a tank site in the highlands. District general manager Kent Nelson said the tower—which would be visible across town—would boost reception, save the district tens of thousands of dollars a year on meter inspections and provide needed funds.

Mr. Nelson said the lease could…