(Corrects spelling of river in third and fourth paragraphs to Bulkley from Buckley) VANCOUVER, British Columbia, June 7 (Reuters) - Canadian forecasters said flooded rivers in northwest British Columbia rose again on Thursday, but officials said the threat of major problems on the Fraser River east of Vancouver had eased. Officials said the mountain snow pack that threatened to cause major spring flooding along the Fraser and Thompson rivers has now largely melted, but they remain concerned about potential problems if there are heavy rains. The unusually heavy winter snows had kept British Columbia on edge about flooding for weeks, but only the high levels of the Skeena and Bulkley rivers in the northwestern area of the Pacific coast province have caused major problems. Melting snow has produced the biggest waterflow in the Bulkley since officials started keeping records more than 70 years ago, and water levels in both it and the Skeena were expected to continue rising through the weekend. Flooding closed the only major highway through the region to the port city of Prince Rupert, and prompted evacuation orders and alerts in several communities. High water also caused Canadian National Railway Co. <CNR.TO> to stop service to Prince Rupert, which handles both grain and coal exports. The railway said it was talking to the Canadian Grain Commission about diverting traffic to Vancouver. Passenger rail service along the CN line has also been halted.