Environment News Service: Today is the 20th anniversary of the massive Exxon Valdez oil spill, but the federal and state governments have yet to collect millions of dollars that the oil company agreed to pay. A final $92 million claim for harm to wildlife, habitat and subsistence users filed in 2006 has gone unanswered by the Exxon Corporation, now ExxonMobil. Early in the morning on March 24, 1989, the oil tanker Exxon Valdez struck Bligh Reef in Prince William Sound spilling more than 11 million …