The state water board has unanimously approved emergency regulations behind a move to halt Russian River diversions for up to 2,400 water right holders, part of a wider effort to conserve dwindling supplies in Lake Sonoma and Lake Mendocino.

The 5-0 vote of the State Water Resources Control Board late Tuesday came over the objections raised by agricultural interests and allies who argued the new rule was too blunt a tool to use to address the worsening drought.