(Reuters) – Mainers voted on Tuesday to reject a $1 billion project to bring hydropower from Quebec into New England, after a years-long battle that pitted clean energy advocates against locals seeking to preserve the state’s pristine woodlands.

New England Clean Energy Connect’s fight for the project is an example of the challenges developers across the country face when laying new transmission lines. Many more of these must be built in the coming decades to modernize the nation’s creaking grid systems and connect farflung renewable energy sources to population centers.

According to local media, 59% of Maine voters opposed the project. Nearly 90% of poll stations reported by Wednesday morning.

NECEC, a project of energy company Avangrid (NYSE:), was meant to bring some 1,200 megawatts of Quebec hydropower to New England along a new 145-mile transmission line through Maine’s northern forests. Avangrid reported last week that the corridor is now cleared to more than 35% with approximately 100 poles being installed.

HydroQuebec and Avangrid utilities Central Maine Power supported the project. They argued that it would help New England state and country combat climate change. Hydropower production produces no greenhouse gases.

But opponents, supported by U.S. power company NextEra which has competing generating projects in New England, argued that the line would cause permanent damage to Maine’s north woods and hurt the region’s tourism industry.

The fight for votes cost both sides combined nearly $100 million, making it the most expensive referendum question in Maine’s history.

This project was originally proposed in Maine in 2017, after an earlier proposal to run a transmission cable through New Hampshire was rejected by the local opposition. The project received several state and federal permits from 2019 to 2021, and construction began in the early part of 2021.