New Zealand's newest lake expected to burst dam

New Zealand’s newest lake is threatening to overflow and flood connecting rivers in the South Island’s Mount Aspiring National Park.

The 2km-long lake formed in September after a massive landslide in the northern branch of the Young River. The slip sent hundreds of thousands of tonnes of rock plunged 900m to the valley floor, creating a dam 70m high.

Heavy rain and snowmelt has built the lake up to within 1m of the naturally formed dam, said Department of Conservation Wanaka area manager Paul Hellebrekers. It is inevitable the lake will overflow within the next few days. ''What will then happen is that it may come over the top and form its own channel through the dam and there will be no great flow, or it may cause a collapse of part of the dam.''

The Department of Conservation and local councils are monitoring the lake and have formed contingency plans for the large flows of water expected down the river.

The Institute of Geological and Nuclear Sciences has installed a time-lapse camera to record the anticipated breach. A radio system is also in place that will alert authorities.

Residents and visitors are being informed of the risk of collapse, and possible flooding hazards by Civil Defence staff. Authorities have closed the area to trampers.