More rain is coming to the Sierra Nevada, adding to a bountiful spring that’s left the snowpack at twice its historical average for this time of year. The mountains are holding more snow than they were two years ago, when Northern California was coming off a historically wet winter that officially ended the drought. But the heavy spring runoff is frustrating some hikers, campers and rafters. And it’s left farmers in part of the Central Valley frustrated that they aren’t getting full allocations of irrigation water despite one of the wettest winters in years.