Here are facts on Central Maine Power’s proposed transmission line:

• Its power comes from a new dam (250 megawatts), generation upgrades at existing dams (500 to 750 MW) and flowage currently being spilled by Hydro-Quebec because it lacks profitable long-term purchase agreements. That’s all new and emits much less carbon than the natural gas it will replace.

• Opponents say that Hydro-Quebec may divert hydropower now going to Ontario and New York state into the CMP line, increasing carbon-based generation in New York and Ontario. Both have strict green power portfolio requirements: New York is committed to 100 percent green power by 2040, and Ontario currently has 94 percent green power. Assuming Hydro-Quebec tried to divert hydro from New York and Ontario, their green power requirements would keep them from replacing hydro with carbon generation.

• According to an independent expert retained by the Maine Public Utilities Commission, the project will reduce annual carbon emissions in Massachusetts by over 3 million metric tons. Global warming is a global problem, and carbon reductions in Massachusetts benefit Maine just as much as reductions here in Maine do.

• Maine renewables will not be hurt by the project. CMP will upgrade a transmission bottleneck in Pownal that limits renewable transmission into southern New England and take steps to relieve the remaining bottleneck at the New Hampshire border.

The CMP project impacts Maine, but also benefits Maine by large-scale reductions in regional greenhouse-gas emissions. I support Gov. Mills’ decision to endorse the CMP project as part of her comprehensive climate change initiative.

Dan Amory

trustee, Conservation Law Foundation

Portland