I know I'm going to kick myself when I see the answer but for some reason, just can't get my head around any of the left hand side of todays grid so no guarantees the 3 letters I've entered are correct.
Thanks sir.prize, got Utica when you gave 1d. Worked just as well for Haifa - 1 between Hawaii and Florida, but still stumped by 16ac. Can't think of any abbreviated rivers (or plants) which are 'obvious'