A D.C. agency approved a $6.8 billion merger between Pepco and Exelon on Wednesday, becoming the last regulator needed to clinch the deal.
The Federal Energy Regulatory Commission and commissions in four states -- Virginia, Maryland, Delaware and New Jersey -- had already approved it.
On Wednesday, D.C.'s Public Service Commission (PSC) approved the merger by a vote of two to one, with one abstention.
But DC Mayor Muriel Bowser accused the PSC of favoring government and commercial rate-payers over D.C. residents. She said there could be a rate hike as early as this summer.
Pepco and Exelon said in a news release that integration efforts are well underway.
Atlantic City Electric, Delmarva Power and Pepco will remain as separate companies and retain their local headquarters in Mays Landing, N.J., Newark, Del., and Washington, D.C., respectively, the release said.
“We remain focused on operational excellence, environmental sustainability, customer service and support for the communities we serve,” Chris Crane, president and CEO of Exelon, said. “We now have a larger, more diverse team with more knowledge and best practices to share, and we will leverage our combined strengths and talents to deliver world-class performance for customers.”
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Earlier this month, the power companies had undertaken a last-ditch effect to save the merger, which some D.C. leaders and civic groups had opposed, saying they were worried about the possibility of higher rates set by a large, out-of-state corporation.
In an attempt to save the deal, Pepco and Exelon had formally asked the D.C. Public Service Commission (PSC) to reconsider conditions it put on the merger last month, warning that failure to reconsider could "derail" the merger.
Chicago-based Exelon also said it would give $20 million to the D.C. PSC for customer discounts to help low-income customers or to modernize the grid. That's on top of the $25.6 million Exelon has previously to agreed to pay for customer discounts.
The effect of that money would hold down residential power rates until 2019.
Business groups had sought the merger, saying they believe a larger utility would be better managed and more reliable.
However, the Community Power Network, a group that promotes local renewable energy projects, released a statement Wednesday stating it was "profoundly disappointed and saddened" about the deal.
"By approving the merger, the PSC has exposed our city to decades of higher rates, weakened its own ability to guide our city's energy future, and helped ensure that DC will fall behind the rest of the US on clean, efficient energy," the group's statement said in part.