Still swirling in controversy, Gov. Jerry Brown’s proposed $15.5 billion re-engineering of the troubled Sacramento-San Joaquin Delta is heading into a critical phase over the next year that could well decide if the project comes to fruition. Crunch time starts Tuesday. The State Water Resources Control Board begins months of grueling public hearings on the details of Brown’s plan to burrow a pair of massive tunnels beneath the heart of the Delta, a grand public works project designed to shore up the reliability of water deliveries to millions of Southern Californians and San Joaquin Valley farmers.