While we are talking about rivers this is the fate of the streams of Christchurch that I used to float down in an inflatable dinghy as a child. No doubt the water was quite potable and certainly had fish in them.
This is a combination of human greed (taking water throughout Canterbury for dairying) and an abrupt climate change- induced drought.
Christchurch's vanishing streams worry residents
11 March, 2016
Now they are completely empty, save for the discarded beer bottles, plastic bags and an occasional puddle of stagnant water, which attract swarms of mosquitos.