Water moves quickly but water policy slowly. For decades, Gov. Jerry Brown has wanted to shore up the State Water Project, the system of canals, pipelines and reservoirs that his father helped create and that now carries Northern California water to Southern California. In 1982, during Brown’s first stint as governor, he pushed for a big open canal to help ensure water would continue flowing south. Voters didn’t like that idea. Now, toward the end of his career, he’s backing a plan to build a pair of 35-mile underground tunnels instead.