Federal regulators have granted Native American tribes more power to block hydropower projects on their land after a flurry of applications were filed to expand renewable energy in the water-scarce U.S. Southwest. Previously, the Federal Energy Regulatory Commission granted developers approval to move ahead with planning even if tribes objected. Now, a new commission policy allows tribes to quickly veto proposals, forcing businesses to cooperate if they want the federal government to grant them exclusive rights to their hydropower projects.