President Barack Obama is creating more controversy over the proposed Keystone XL Pipeline.
The president said the project should only be approved if it does not increase carbon pollution.
Supporters for the $7 billion pipeline argue it would create jobs.
Environmentalists said they are worried about the carbon-intensive oil it would carry from Canada.
According to the report from State Department, other methods of oil transportation contribute 8 percent more greenhouse gases than the Keystone Pipeline would.
The southern half of this project is already under construction, stretching from Cushing, Oklahoma, to the Gulf of Mexico.