The picture at the top is from the Ashlu River, a very similar situation to the one in Petawawa. Water is diverted through a huge pipe and returned to the river once the gradient is gone. The water that remains in the riverbed is coming out of that small tube. Seriously. That is what is left over.
As you see in the second picture, the Developer would take water from Railroad Rapid and return it BELOW Catwalk rapid. Thanks. Green energy my ass.
Even the Squamish town council fought to prevent this dam and lost. Don't let it happen to the Petawawa.