PORTLAND, Ore.—Nearly 150,000 customers remained without power Wednesday in and around Portland, Oregon, nearly a week after a massive snow and ice storm swept into the Pacific Northwest, taking out hundreds of miles of power lines as ice-laden trees toppled. The damage wrought by the storm to the power system was the worst in 40 years, and more than 2,000 power lines—about 208 miles in total—were still down, said Maria Pope, CEO of Portland General Electric. At the peak of the storm, more than 350,000 customers were without power, and 5,000 power lines and three substations were down. “These are the most dangerous conditions we’ve ever seen in the history of PGE,” said Dale Goodman, director of utility operations, who declined to predict when all customers would have power restored. “Hopefully in the next day or two we’ll get ahead of this thing and start making more and more progress—as …