Splitting California into three new states would scramble nearly every segment of government that touches residents’ lives, from taxes to Medi-Cal to driver’s licenses. New agencies would have to be created to operate prisons, highways and universities. CalPERS, CalSTRS, Cal Fire and the California Highway Patrol, to name a few, would have to be reconfigured and replaced. But of all the gargantuan tasks facing Californians should they choose to divide themselves by three — a proposal that has qualified for the November ballot — none is arguably more daunting than carving up the state’s water supply.