Some 135 years after New York state's first marketable oil for sale started flowing from a hole in western New York, the state's producers are trying to suck the last drops from wells producing on average a quarter of a barrel a day. Now, the few hundred people still employed in the industries face a threat that they say could bring the long history of New York state oil production to an end. State environmental authorities are requiring them to spend thousands of dollars a well plugging holes that in many cases have been abandoned for decades.