The Environmental Protection Agency again is raising objections to the proposed Keystone XL pipeline that would carry oil from western Canada to the Texas Gulf Coast.

The EPA said that despite more than four years of study, the State Department still has not done sufficient analysis of the project’s environmental impact

In a letter to the State Department on Monday, the EPA urged State to conduct a more thorough analysis of oil spill risks and alternative pipeline routes, as well as greenhouse gas emissions associated with the pipeline.

The concerns are similar to objections the EPA raised about the project in 2011. The State Department has authority over the pipeline because it crosses a U.S. border. A draft report in March said the project would not create significant environmental impacts.