Les Grober, deputy director of the State Water Resources Control Board, said his agency had done “more than was required” in studying the impacts of the state’s water grab on our rivers. But what became clear during a daylong public session in Modesto was that his agency hasn’t done as much as it should have.Rod Smith, who earned his doctorate in economics at the University of Chicago, had some pointed questions for the bevy of state officials who attended Friday. He started by asking about the state’s assumptions on volatility and reliability.