Gov. Jerry Brown’s massive Delta tunnels project is moving forward through a series of state and federal environmental reviews. But it still faces an array of major hurdles including public opposition, financing and approvals by state water contractors. The $15 billion project, known as California Water Fix, is on track to finish the state environmental impact report and federal environmental impact statement by the end of the year, said Cindy Messer, assistant chief deputy with the state Department of Water Resources.