The framework of a plan for the Sacramento River watershed released Friday by the state Water Resources Control Board calls for an increase in the amount of water running into the Sacramento-San Joaquin Delta and out to sea, but it leaves the question of where that water would come from largely unanswered. It’s a good chunk of water. According to the framework, the target of letting 55 percent of “unimpeded flow” run downstream amounts to a reduction of 17 percent of the current average surface water supply available in the Sacramento River and its tributaries, plus the three rivers that run directly into the delta from the east.