The tanker barge Na-Kao went aground in Nushagak Bay off Dillingham, Alaska.   The tug Seneca who was towing the Na-Kao had become entangled with a gill net in its starboard prop disabling the tug.   The Na-Kao was loaded with 249,958 gallons of jet fuel, 349,958 gallons of gasoline and 612,238 gallons of diesel fuel.    The Coast Guard was alerted, but the owners were able to refloat the Na-Kao later the same day by transferring some fuel to another barge.  No pollution was released.