The drought may be over in the minds of urban Californians, quite literally washed away by huge accumulations of rain last year that filled reservoirs and left the state’s mountains covered with snow even now. But the farmers and others in the Central Valley, veterans of multiple drought-and-flood cycles, know the reprieve is only temporary. On Wednesday they pressed new U.S. Sen. Kamala Harris to work to ensure a more reliable source of water for the nation’s most bountiful farming region.