The possible environmental repercussions of oil production became clear in the "Exxon Valdez" oil spill of 1989. On March 24, the tanker "Exxon Valdez" ran aground in Prince William Sound, releasing 11 million gallons of crude oil into the water, spreading along 1,100 miles (1,800 km) of shoreline. According to the U.S. Fish and Wildlife Service, at least 300,000 sea birds, 2,000 otters, and other marine animals died because of the spill. Exxon spent US$2 billion on cleaning up in the first year alone. Exxon, working with state and federal agencies, continued its cleanup into the early 1990s. Government studies show that the oil and the cleaning process itself did long-term harm to the ecology of the Sound, interfering with the reproduction of birds and animals in ways that still aren't fully understood. Prince William Sound seems to have recuperated, but scientists still dispute the extent of the recovery. In a civil settlement, Exxon agreed to pay $900 million in ten annual payments, plus an additional $100 million for newly discovered damages. In a class action suit against Exxon, a jury awarded punitive damages of US$5 billion, but as of 2008 no money has been disbursed and appellate litigation continues.