While campaigning for president in 2016, Donald Trump promised a cheering Fresno crowd he would be “opening up the water” for Central Valley farmers who’d been victimized by “insane” environmental rules to protect fish. Trump took one of the most aggressive steps to date to fulfill that promise Tuesday by proposing to relax environmental regulations governing how water is shared between fish and human uses throughout the Central Valley. The U.S. Bureau of Reclamation released an 871-page “biological assessment” of conditions in the Delta that it said is designed to “maximize water supply and delivery” while maintaining protections for fish.