If I were in that situation I would have got a good discription of the guy got off the water tried to get a vehicle lic number then called the county sherriff.

A pellet gun can count just as much as a reel gun as far as the law goes. Pellet guns can kill and it seems that he had intent to shoot you, (even if he didnt intent to kill you it dosent really mater) with it from what you described. So I would see it as a 2nd degree felony assault. Pretty seriouse charge and Im not jokeing. And obviosly he wasnt either.

Your situation meets the elements of Second Degree assault.