(Salem, OR) -- The Federal Energy Regulatory Commission has completed an environmental impact statement on a plan to increase capacity of a natural gas pipeline that runs from Canada to Oregon. It supplies natural gas to Washington, Oregon and California. The environmental review finds it would result in limited adverse impacts on the environment. Gas Transmission Northwest wants to modify compressor stations to boost capacity. They say it's necessary to meet demand. Attorneys general in Oregon, Washington and California say the additional gas that would be burned undermines efforts to fight climate change. FERC plans a final decision next year.