A political action committee opposing the creation of a hydropower transmission corridor in Maine has been fined over a $100,000 donation.

According to the Portland Press Herald, Mainers for Local Power was fined $2,500 Monday for violating state campaign finance law. The Maine Ethics Commission voted unanimously to impose the fine.

The group didn’t notify Texas energy company Calpine, which donated more than $100,000, that it would need to file a major contributor report with the commission.

The $1 billion transmission project, which is already underway, still faces some legal hurdles, with a judge recently vacating a lease for the project.

A referendum on the ballot in November will also ask Mainers if they approve of a law change that could put the corridor in jeopardy.