The structure in the right background is for raising and lowering the intake gates to the penstocks. There is a long wooden handle attached to a rake on top of the intake screen for removing debris.
On the left hand side of the structure are two Yagi UHF aerials for remote monitoring. In the back centre can be seen the two low pressure concrete penstocks.
In the middle foreground there are floats roped together to warn the occasional canoeist not to approach the intake too closely.
The canal is lined with a heavy plastic (butyl rubber?) membrane to prevent leakage. The light volcanic soil on which it is built erodes very easily.
Len states (August 2018) - the screen cleaner is a recent upgrade around $500,000 and replaces an old model, which did half the screen at a time, and had to be pushed manually from one side to the other. I suppose it did its job for 40 years. but a lot more weed now comes in hence the modernisation.