(Astoria, OR)  --  The Coast Guard is working to clean up a major oil spill on the Columbia River near Astoria.  Coast Guard officials say the spill sprang from a 20-foot-long tank underneath the Cannery Pier.  The tank has a maximum spill potential of 42-hundred gallons, and Coast Guard officials aren't yet sure how much oil has already spilled into the river.  Crews are currently working to minimize the environmental impacts.