HOPE, British Columbia, Nov 19 (Reuters) - The flood-battered Canadian province of British Columbia received some good news at last on Friday when Canadian Pacific Railway (CP.TO) said it should restore service in the middle of next week. Massive floods and mudslides caused by extreme rainfall destroyed roads, bridges and homes and cut two critical east-west rail lines owned by CP and Canadian National Railway Co (CNR.TO) that lead to Canada"s busiest port in Vancouver. read more CP said work to repair damaged infrastructure and restore service to the rail corridor between Kamloops and Vancouver would continue non-stop. "Barring any unforeseen issues, we currently estimate service will be restored mid-week," spokesperson Salem Woodrow said in an email. The disaster looks set to be the costliest natural disaster to ever hit Canada. The railway shutdowns have left exporters of commodities scrambling to divert shipments away from Vancouver and underscored the vulnerability of Canada"s supply chains to climate change. read more The restoration of rail service is a first step in what will be a massive effort to restore smashed infrastructure across a giant mainly mountainous province that covers some 360,000 square miles (925,000 square km) - the same size as Nigeria. Water pumps are still working flat out in the city of Abbotsford to the east of Vancouver. If they fail, officials said all 160,000 residents may have to leave. Bruce Banman, a provincial lawmaker who represents the area, surveyed the damage from a helicopter on Friday and said about 50% of agriculture-rich Sumas prairie remains underwater. "The damage is significant, it"s catastrophic," he said. "It"s heartbreaking to see. There are farmers still trying to save livestock." He said infrastructure repairs alone would cost more than C$1 billion ($790 million) and that did not cover the loss of crops. "I was talking with a farmer who had cabbage and Brussels sprouts yet to be harvested and he figures he"s lost a million tonnes of produce," he said. ($1 = 1.2648 Canadian dollars)