FarmerPete,
Aren't there are number of water sking races along the Murray such as the Southern 80? Boats travelling at average speeds of over 150km/hr for 80 k's or so between Torrumbarry and Echuca ? There would have to be dozens of spots along that section of the river that could be used for scooping. I've never been able to read water conditions or depths from photos - the only things that work for me are local knowledge interpreted by the pilot and the trained mark one eyeball.
Best constructed break for a fire that I've ever seen was the one to the east of Gillantipy in the Gippsland Fires of about 2003 - the break was about the same width as the Hume Highway.
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notmyC150v2
Very unlikley to have made much of a difference - it would have saved some houses and possibly a few lives. In extreme fire conditions that only thing that will stop a developed fire in Victoria is a change in the weather or Bass Strait. The Gippsland Fires mentioned above were a classic example - they'd build a control line, hold it for a few days, the north westerlies would pick up again and then the fire would jump the control lines and they'd start again. After about a month the weather patterns changed and they got it under control.
However, where aircraft have a big advantage is in slowing a fire which has only just started, giving ground crews a chance to get to the scene and contain the fire. It's going back a few years, but I think the advice was if you don't have a fire under control in thirty minutes (can't remember the actual time, but it was damn short) on an extreme fire danger day it's time to start mobilising some serious resources including from a long distance away. The fire that is held by an aircraft might otherwise turn into a very destructive fire with loss of life - there have been many killer fires that started days before the loss of the first life, and from tiny beginnings.