In the report, known as an environmental impact statement, staff at the Federal Energy Regulatory Commission (FERC) concluded construction and operation of the project would result in some adverse environmental impacts, but most of these would be reduced to less-than-significant levels with mitigation measures.

FERC acknowledged some impacts would be significant, however.

Construction of the project would "temporarily, but significantly impact housing in Coos Bay," it said, adding that the project would "permanently and significantly impact the visual character of Coos Bay."

The project could also have a significant impact on the Southwest Oregon Regional Airport operations, FERC said. Additionally, constructing and operating the project was likely to adversely affect 18 federally-listed or proposed threatened and endangered species, it said.

Jordan Cove is designed to produce 7.5 million tonnes per annum (MTPA) of LNG, equivalent to around 1 billion cubic feet per day (bcfd) of natural gas.

One billion cubic feet is enough gas to supply about five million U.S. homes for a day.

It would include five liquefaction trains, two LNG storage tanks and the 229-mile (369-kilometer) Pacific Connector pipeline that would be capable of transporting up to 1.2 bcfd of gas.

As proposed, the LNG terminal would be called upon by about 120 LNG carriers per year, FERC said in a release.

Earlier this year, Pembina said the project would cost about $10 billion and could enter service in 2025.

Officials at Jordan Cove said they were reading the federal report and could not immediately comment on it.

Jordan Cove is one of more than three dozen LNG export projects under development in the United States, Canada and Mexico.

Just looking at the projects under construction, U.S. LNG export capacity is expected to rise to 6.9 bcfd by the end of 2019 and 9.6 bcfd by the end of 2020 from 6.8 bcfd now.

That keeps the United States on track to become the third biggest LNG exporter in the world in 2019, behind Qatar and Australia, and the biggest supplier of the fuel in 2024.

(Reporting by Scott DiSavino; Editing by Tom Brown)