Rainbow and Fallbrook water districts are free to join a water system in Riverside County, after a split decision by regional policymakers Monday that would slightly lower costs for ratepayers in those districts but may raise water rates in other areas across San Diego County.

The San Diego County Local Agency Formation Commission, or LAFCO, which is responsible for approving and managing changes to local jurisdictions, voted 5-3 to authorize Fallbrook Public Utility District and Rainbow Muncipal Water District to separate from the San Diego Water Authority. They plan to join Eastern Municipal Water District, which serves southern Riverside County, said Jack Bebee general manager for the Fallbrook district.