Just looking at google maps the stretch between power lines (with no markers on them) and the new tall foot bridge would be somewhere around 1600m, add 100m to the old Victoria bridge if we are to go back to that claim from a decade ago.
Claims I can find online mention around 1400m for a CL415 to get from 15m, scoop and get back to 15m...be one sporty pilot near kissing the wires on the way down just to see a 30 odd meter tall bridge structure coming up rather fast through the window!
You have to remember that the Canadair study was done 30 years ago. I cannot remember the exact date.
From the same study;
The total distance required from a height of 15m on the approach to 15m during climb out is 1,200m. Water-borne distance is 564m. Scoops have been made, however, from significantly smaller water areas. Normal speed for scooping is 70kts and scooping time is about 10 seconds. The safe water depth for scooping is less than 2m and excellent water handling characteristics permit the use of narrow bodies of water only 100m wide.
The paper shows what could have been done then, when we had a chance of buying the CL415s.
We blew it back then.