PORTLAND, Maine — Workers are installing hundreds of utility poles and stringing power lines on them as construction proceeds on a much-delayed project to bring Canadian hydropower-generated electricity to 1 million homes in New England.

A report filed with state regulators this week indicates that construction crews have erected 441 poles for the 145-mile  line, with wires installed on 178 of them, and that progress is being made other parts of the New England Clean Energy Connect, which has been plagued by delays, litigation and a referendum in which Maine voters rejected it.

Avangrid, which partnered with Hydro Quebec on the project, expects it to be completed by late next year. Avangrid, parent of Central Maine Power, declined to comment when reached.

The cost of the project grew from $1 billion to at least $1.5 billion because of inflation and delays caused by opponents, requiring the Massachusetts Legislature to give its approval for most of the additional costs to be passed on to ratepayers. Negotiations are continuing in Massachusetts on how the added costs will be divvied up.

Supporters of the project say the 1,200 megawatts of electricity it provides would lower rates across the region and reduce carbon pollution. Critics contend that it will destroy woodlands and fail to deliver on promised environmental benefits.