February 23, 2011
Craig Somerville from Castabroad in New Zealand have sendt me this little amazing story about a recovering river.
Mother nature can be very powerful - but also very generous!!
Recovering of a favorite River
By Craig Somerville
At 4:40am on the 29th August 2007, the North branch valley of a river near Lake Wanaka, New Zealand, suffered a landslide subsequently blocking the river’s path.
A wall of approximately 11million cubic meters of rock formed a dam creating a new lake 500m wide, 2 km long and 70m deep. This makes for a lake volume of around 23 million cubic meters.
The location of the lake is near the source of the river affecting the several kilometers of pristine water downstream. The river was a well known favourite fishery amongst local fly fishing guides and recreationals alike, and with the landslide the river turned from an incredibly clear freestone paradise to a silt coated suffocated and tempremental spillway remoulded by a single destructive act of God.
The fishing of course was completely wiped out for several years due to the aluvial silt and debris. The fly life dwindled unable to sustain itself with the once loose riverstones now being smothered. All in all a soul destroying moment for those of us that love what the river provided once upon a time.
Well good news!... This year on one of our regular country-wide fly fishing reconnaissance missions we managed to find many (average 3-4lb) wild rainbow trout back in the damaged yet recovering river system. They were strong fighting fish happily feeding on cicadas falling from the overhanging NZ Beech trees. This was of course a great day to have but even more so a relief that the river was on track to recovery. Never (used loosely), will the river return to it’s original glory but there is hope.
Unfortuanately, for you the reader that is, we will not reveal the name of the river because we think it in the best of interests for it to have as good a chance as possible at this slow recovery without increased angling pressure. I’m sure you will agree this is for the best?
Potentially, there is a risk of the dam failing and the consequent flood would again destroy the river’s progress but maybe then the silt will be washed out. On the reverse side, the dam could hold forever, who knows?
Craig Somerville of Castabroad New Zealand – www.castabroad.com
Acknowledgements for factual material:
Gavin Palmer (Otago Regional Council), Paul Hellebrekers (Department of Conservation),TimDavies (Canterbury University), Oliver Korup (Swiss Federal Institute for Snow andAvalanche Research)