The Trump administration, teeing up a fight with California regulators, is trying to pump more water through the fragile Sacramento-San Joaquin Delta to the southern half of the state despite fresh evidence of the estuary’s shrinking fish population. A proposal by the U.S. Bureau of Reclamation to “maximize water deliveries” represents the administration’s first concrete effort to make good on a promise Donald Trump made while campaigning for the presidency in Fresno, where he vowed to deliver more water to San Joaquin Valley farmers and derided protections for endangered fish species.