I am the proud owner of not one, but two bright orange river pumps. They are made by a Pennsylvanian company called Rife, and float in the water race just downstream of Rooster Bridge.
In my garden the river pumps are used to pump water down a little wriggling stream in the Wattle Woods. The water collects at the bottom of the slope in a small pond, which is surrounded by green Phormiums and pink Azaleas.
Paths follow the stream and little arched footbridges cross the slowly trickling water. I've lined the little stream with black polythene and filled it with river stones, to give it a natural look.
The Rife river pumps are very low-tech and work with nature, not needing much maintenance. I just have to keep each propeller free of any debris that's floated down and jammed it. And when the nearby Waimakariri River is in flood, the intake is shut and the water level in the race gets really low. Then the river pumps just rest gently on the bottom, no problem.
River Pump Propeller
Rife River Pumps Website
To quote Rife's website: 'The RIFE River Pump is a self supporting system for pumping water. It is completely mechanical and operates without electricity or fuel. The power to drive is provided by flowing water.'