In early May, Bureau of Reclamation officials gathered the world’s top builders and bankers for a meeting at the Sheraton West hotel conference room in Lakewood, Colorado, a Denver suburb that abuts Rocky Mountain foothills. Reclamation faces a conundrum. The assets of the federal agency that operates many of the largest dams and canals in the American West are aging. Maintenance costs are rising. Rural water supply systems and other projects authorized by Congress decades ago are tens of billions of dollars away from completion.