Wikipedia tells me it is the 64th ball hit into the cove since AT&T Park opened in 2000. Barry Bonds hit 35 of those 64 homers. Needless to say, Jones hitting a ball into the water is damn impressive.
Know what is more impressive? Hitting a homer into two different natural bodies of water in the same season. Back on June 2, Jones became the second player ever to hit a ball into the Allegheny River beyond the right field stands at PNC Park:
I could be wrong, but I don't think there's another reachable natural body of water in the big leagues. The pool at Chase Field in Arizona and the fountains at Kauffman Stadium in Kansas City don't count. I guess the Ohio River outside the Great American Ballpark in Cincinnati is reachable if you use a metal bat or something.
I don't know about historically, but it's safe to say Jones is the first guy to homer into two different natural bodies of water in the same season in a long, long time. That will go right on his Hall of Fame plaque.
(h/t Jackie Moore)