The Young River Landslide occurred on the North Branch of the Young River, near Lake Wanaka, New Zealand, at 4:40am on 29 August 2007.
The debris avalanche occurred in closely jointed schist, forming a dam 70m high across the valley. Water began impounding behind the dam and then overtopped, scouring an outflow channel on the downstream face of the dam. The impounded lake is approximately two kilometres in length and 500m at its widest point. Water first overtopped the dam on 5 October 2007, approximately 5 weeks after its formation. Water continues to flow over the dam crest and has scoured material from along the outflow channel after periods of high rainfall and associated outflows.
Further Information: The Young River Landslide (pdf)