Sir, I beg to differ. The free water at the Steel Bridge - immediately adjacent to the Waterfront Park - is 773.4 feet.
Please feel free to check.
tac
Funny, I looked it up online before I posted, since I didn't know how wide it was. I didn't find the number you quoted. The source I found online must have been no good. I just pulled up another source that says "the main stem of the Willamette varies from about 100 to 200 meters (330 to 660 ft) in width". I never could find a listing for the exact width measurements - if you know where to look, I'd definitely be interested in seeing them for pure curiosity's sake.