1. Two decades after the Exxon Valdez disaster, a tugboat working to prevent another oil spill in Alaska's Prince William Sound ran aground on the same reef and left a three-mile sheen of fuel oil on the water. The 136-foot tug Pathfinder had just finished checking for dangerous ice and was heading back to port in Valdez when it hit Bligh Reef. The boat is part of the Ship Escort Response Vessel System that was created after the Exxon Valdez ran aground in 1989 and spilled nearly 11 million gallons of crude oil - the worst ever U.S. spill. The Coast Guard said Thursday that two of its tanks - containing an estimated 33,500 gallons of diesel fuel - were damaged and there was a fuel sheen on the water about 3 miles long and 30 yards wide.