Signaling a cutback in water supplies for farming and cities, California regulators on Wednesday issued a new scientific analysis that proposes overhauling the management of the Sacramento River and devoting more water to Northern California’s dwindling fish populations.The State Water Resources Control Board, in a widely anticipated report crafted by its staff, said it’s considering allowing much more of the flow from the Sacramento River and its tributaries to wash out into the ocean.The board avoided issuing a specific recommendation on how much additional water should go to fish.