Canadair and National Jets produced a study last century dispelling that theory.
Reading that bit and living right near the Nepean in Penrith I'd be very interested in where they think scooping water could be done, 90% upstream from Penrith has the river running through a narrow winding gorge and downstream from the Penrith weir it's rather damn shallow! Especially in a drought like we are having right now, flow downstream of the weir is near nil.
Sure you might be able to squeeze one down between the M4 bridge and the Victoria bridge, near 3 km stretch of wide enough river between the bridges...with a few lots of power lines going across.