_The fight over oil drilling in the Arctic National Wildlife Refuge heated up Tuesday over the possibility that a new management plan could put the refuge and its billions of barrels of crude off-limits for good. At issue is the refuge's 1.5-million-acre coastal plain and whether an updated plan would designate the oil-rich area as wilderness. The coastal plain ˜ believed to contain an estimated 11 billion barrels of recoverable oil ˜ has been a battleground for decades between environmentalists who don't want drilling and oil companies and Alaska officials that see a large, untapped resource that could ease the country's dependence on foreign oil. Production at Prudhoe Bay, North America's largest oil field, is declining by about 10 percent a year. The refuge's coastal plain, and its large pool of oil just to the east, is enticingly close. It's also onshore.