MAMMOTH LAKES, Calif. (KABC) -- Skiers and snowboarders, rejoice! Officials at Mammoth Mountain say there's been so much snow this winter that its slopes will stay open until summer.The main lodge at Mammoth has already seen 35 feet of powder -- and counting.Mammoth says that's enough snow to keep the lifts running until at least July 4.More than 20 feet fell during January alone, and more snow is predicted for the weeks to come.