Following an engineering assessment of New England’s power system that highlighted southwest Connecticut as an area of concern for power transmission reliability, the region’s power grid operator, ISO New England, said it needs $900 million in transmission upgrades to maintain system reliability. More than 4,500MW of new generation capacity has been added to the region’s power system over the last three years, but a similar investment in the transmission system has yet to be made.

ISO said electricity produced in Maine, southeastern Massachusetts, and Rhode Island could help alleviate the problem in energy-strapped areas like Connecticut, but weak power lines can’t carry the load.

The grid operator approved a plan for more than 30 transmission projects planned or proposed throughout New England. Proposed projects in southwestern Connecticut and northwestern Vermont account for almost $750 million of the expected upgrade costs.