Quake lakes emerge in St Arnaud?

The sudden appearance of two small lakes on the waterfront at St Arnaud was ‘‘almost certainly’’ caused by the Kaikoura earthquakes, the Department of Conservation says.

The miniature lakes near the shore of Lake Rotoiti, south of Nelson, formed following the 7.8-magnitude quake and subsequent aftershocks that rattled most of the country on November 14 last year.

Heavy rain has flooded Lake Rotoiti and filled the new lakes with water since then.

DOC Nelson Lakes operations manager John Wotherspoon said the water would usually drain away. But the new lakes have remained throughout summer, making him think they’re there to stay.

Wotherspoon said the precise cause of the lakes was a mystery, but they were ‘‘almost certainly’’ connected to the November earthquakes.

‘‘The timing of it would be too coincidental to not be related to the earthquake, but we don’t know how it formed,’’ he said.

‘‘When we get heavy rain sometimes the area can turn into a bit of a lake and then it dries up and goes away again.

He said a wetland-type of environment had formed in the lakes, which had attracted wading birds to the area for the first time.

‘‘A lot of the plants around it are native. There are some reedy weeds and other things we want to get rid of as well. It’s a mix.

‘‘Also we’ve had visits from pied stilts and white herons that we haven’t seen here before. That was pretty amazing.’’

St Arnaud resident Pete Rainey said flooding was common at Lake Rotoiti, but ‘‘this is the first time it hasn’t really drained away’’.

‘‘We’ve had some pretty huge lake level rises over summer, both jetties being completely covered.’’

Wotherspoon said DOC would be investigating.

‘‘What’s actually happened underneath the ground, we don’t know. No one’s looked at it from a science point of view.’’

This week it was reported that trampers may have discovered a new lake in the Tararua Ranges, which GNS Science says may have been caused by the November earthquakes.

A massive slip into the seldomvisited upper headwaters of the Tauherenikau River, west of Masterton, has dammed the river, creating a lake up to 100 metres long and 18m wide.