DOE and Montana release Final Environmental Impact Statement for 422-mile North Plains Connector transmission line

The U.S. Department of Energy and the Montana Department of Environmental Quality jointly released the Final Environmental Impact Statement for the proposed North Plains Connector Project on August 28. Acting as Joint Lead Agencies, the two bodies cleared a major milestone in the federal and state review process for the project—a 422-mile, 525-kV high-voltage direct current transmission line planned to run between Colstrip, Montana, and western North Dakota, linking the country’s eastern and western power grids.

Federal and state agencies publish final environmental review

The August 28 release of the Final Environmental Impact Statement marks a real step forward for the North Plains Connector. DOE and the Montana Department of Environmental Quality coordinated the review together as Joint Lead Agencies, rather than running separate tracks. That kind of joint federal-state setup is relatively rare—and it signals the institutional weight behind this project.

The FEIS is the product of an extensive environmental review process, examining the potential impacts of building and operating a 422-mile, 525-kV HVDC overhead transmission line between Colstrip, Montana, and western North Dakota. The corridor is long, the voltage is high, and the infrastructure is substantial. A rigorous review had to happen before anything moves forward.

It would provide 3,000 MW of bidirectional transfer capacity between the Eastern and Western Interconnections—a connection that currently has very limited capacity.

Why the project is being pursued

The short answer is demand. Electricity use is rising in Montana, North Dakota, and across the country, and the grid infrastructure serving those regions wasn’t built with today’s load in mind. The gap between what the system can handle and what consumers need keeps widening.

There’s also a structural problem underneath all of this. The U.S. power grid isn’t one unified system—it’s two. The Western Interconnection covers the western states; the Eastern Interconnection covers most of the rest. These two grids have very limited ability to move power between them, so if one side has a surplus and the other has a shortage, there’s no easy way to balance things out.

The North Plains Connector is designed to fix exactly that. By physically linking the two interconnections, it creates a pathway for electricity to flow based on where demand is highest or where generation is most available—flexibility that doesn’t exist at scale right now.

Capacity and grid reliability benefits

The NPC would provide 3,000 megawatts of bidirectional transfer capability. To put that in perspective, 3,000 MW is enough to power millions of homes, depending on regional consumption patterns. The bidirectional design means electricity can flow either direction along the line—east to west or west to east—depending on conditions at any given moment.

That flexibility matters for reliability. When a heat wave drives up air conditioning demand on one side of the grid, or a cold snap strains heating systems on the other, pulling power from wherever it’s available can prevent outages. Catherine Jereza, DOE’s Deputy Assistant Secretary for the Office of Electricity, said the project would help communities “safeguard against outages and ensure reliable power when demand is at its peak.”

Weather-driven outages have become more frequent and more costly, and aging infrastructure in many parts of the country leaves the grid more exposed. Long-distance, high-capacity transmission lines like the NPC are among the primary tools federal energy planners are using to address that vulnerability—a priority that’s only grown in recent years.

Context: The role of the environmental review process

A Final Environmental Impact Statement is a legal requirement, not a formality. Under the National Environmental Policy Act, any major federal infrastructure project must go through a structured environmental review before receiving federal approval. The FEIS is the culmination of that process—it documents the analysis, identifies potential impacts, and evaluates alternatives.

Releasing the FEIS doesn’t mean the project has been approved. It’s a necessary step, but additional federal and state permitting decisions typically follow before construction can begin, each carrying its own reviews, public input opportunities, and regulatory sign-offs.

The North Plains Connector sits within a broader national push to expand long-distance transmission infrastructure. Rising electricity demand, the growth of renewable energy generation in remote areas, and the need for greater grid flexibility have all made transmission expansion a federal policy priority. Projects like the NPC are central to that strategy—moving large amounts of power across long distances, connecting generation where it exists to load centers where it’s needed.

525 kV using direct current technology

The release of the FEIS for the North Plains Connector is a concrete step forward for a project that’s been in development for some time. A few things are worth keeping in mind.

The line would run 422 miles between Colstrip, Montana, and western North Dakota, operating at 525 kV using high-voltage direct current technology. It would provide 3,000 MW of bidirectional transfer capacity between the Eastern and Western Interconnections—a connection that currently has very limited capacity. The Department of Energy and the Montana Department of Environmental Quality acted as Joint Lead Agencies in producing the FEIS, released on August 28.

Publishing the FEIS doesn’t mean the project is approved, and additional permitting steps remain. But clearing this milestone moves the North Plains Connector meaningfully closer to a final decision on whether it gets built.

Kelly Lippke

Kelly is an experienced writer with 15 years of experience exploring the big stories that shape our world, from tech breakthroughs and space exploration to climate, energy, and the fascinating quirks of science. She has a talent for turning complex ideas into sharp, memorable insights that stay with readers long after they’ve finished reading.