metal towers stand on land recently cleared on an existing Central Maine Power power line corridor on April 26, 2021, near Bingham. 

Energy companies gave more than $6.8 million to groups on both sides of the fight over the Central Maine Power Co. corridor ahead of a November referendum in three months as total spending in the past two years surpassed $42 million.

Pro-corridor spending continued to far outpace anti-corridor money, but the flow on both sides highlights how the project aiming to bring hydropower from Quebec through western Maine stands to benefit business interests and hurt others. The fight about the corridor has extended for more than 18 months after a ballot question last year was declared unconstitutional.

The spending between April and the end of June was led by NECEC Transmission LLC, the company responsible for constructing the corridor that is affiliated with CMP’s parent company, Avangrid. It gave $4.9 million to Clean Energy Matters, the chief pro-corridor political committee, according to filings submitted to the Maine Ethics Commission on Thursday.

Clean Energy Matters also spent more than $5.5 million during that same period, with advertising and outreach making up the bulk of its spending. A second group affiliated with the provincial energy company Hydro-Quebec, which will supply power to the corridor, spent $2 million more during the quarter, likewise with the majority of its spending on advertising.

Hydro-Quebec’s continued presence in the referendum fight is dependent in part on Gov. Janet Mills’ decision last month to veto a bill that would have blocked companies with foreign government ownership from spending on referendum campaigns.

A group opposing the corridor, Mainers for Local Power, got a $1.6 million contribution from NextEra, the Florida energy company that owns the oil-fired Wyman Station plant in Yarmouth and was accused by CMP last year of impeding the corridor’s development. The group also got smaller in-kind contributions from Calpine and Vistra, two companies that own natural gas plants in Maine, and primarily spent money on ads during the second quarter.

Construction on the CMP corridor is ongoing despite a planned November referendum that could require the Legislature to assess the project’s permit. The fight has made for odd political allies within Maine, as both business and labor groups have mostly supported the corridor while environmental groups and lawmakers from both parties have split.