WASHINGTON (AP) — Pepco is apologizing to customers in the Washington region for widespread power outages and pledges to make improvements in a full-page newspaper advertisement.

Pepco Chairman and CEO Joseph Rigby issued a letter Feb. 7 in The Washington Post. The apology comes as D.C. Council member Tommy Wells holds a hearing on winter storm problems.

Maryland Sen. Barbara Mikulski also requested a hearing on setting a federal reliability standard, citing the Pepco outages.

Rigby writes that no utility can guarantee against power outages. But he says the company must do better. He writes, “We will not make excuses. We will make improvements.”

Pepco says it’s committing $574 million to upgrade infrastructure and protect power lines from trees. Rigby says he will speed up that work.