Worlds clearest freshwater discovered, yet again, in Nelson

December 19th, 2011

Ironic that I’m talking about water this week in Nelson isn’t it?

Looks like another world record is about to be broken, and it appears at first that Nelson, New Zealand is the loser. But Nelson, New Zealand is also the winner.

Confused, let me explain.

I’ve previously reported here, that Te Waikoropupu Springs (“Pupu Springs”) in Golden Bay, holds at 63m, the current world record for underwater visibility. In other words the clearest water in the world.


Well it looks like the Nelson region is about to lose its world record title to another part of the globe with a press release from NIWA today 18th December 2011.

This new discovery, as reported by NIWA today says;

Nelson-based NIWA hydrologist Rob Merrilees first recognised that Blue Lake might be optically outstanding, having observed on tramping trips that this water body appeared broadly similar to Te Waikoropupu, in which a visibility of 63 metres has been reported. He mentioned his suspicions to NIWA aquatic optics specialist, Dr Rob Davies-Colley, who had led the original work on Te Waikoropupu Springs. On a preliminary tramping visit to Blue Lake in March 2009, the two Robs were surprised to find that the visibility of Blue Lake exceeded that of Te Waikoropupu.

They subsequently organised a scientific study of the lake with involvement of NIWA scientist Mark Gall, an expert in ocean optics instrumentation. Several visits by helicopter (six in all) established that the horizontal visibility in the lake typically ranges from 70–80 metres.

That’s right, didn’t just beat 63m, they really trumped it!

“The theoretical visibility in distilled water is about 80 metres, as estimated from the best available instrumental measurements in the laboratory,” says Dr Davies-Colley. “So Blue Lake is a close approach to optically pure water”.

Where, well it just so happens that its at Nelson’s Blue Lake, up at the Nelson Lakes National Park so although we lose one title, we just picked up another.

That now means that here in little ole Nelson, the “Top of the South” of the South Island, of New Zealand (“Middle Earth” to many) now holds the Gold, and Silver when it comes to the clearest water in the world.

You can visit this area yourself, and stay overnight in the region, something that NIWA & DOC (NZ’s Department of Conservation) have stated;

  • Blue Lake is a side trip off the popular Travers Sabine Circuit multi day tramp.
  • The Blue Lake Hut receives in excess of 700 trampers a year, mainly through the summer months.
  • Numbers will be monitored to see if visitation increases.
  • The clarity of the lake will remain monitored to establish if there are any changes in the next year or two.
  • The waters of Blue Lake/ Rangimairewhenua are sacred to Ngāti Apa ki te Rā Tō iwi. The significance to them was acknowledged in their Treaty of Waitangi settlement signed in 2010.
  • The Department of Conservation would ask that the waters are respected and that people don’t wash themselves or their clothes or dishes in the lake.

Courtesy of it being the clearest, it could also be the cleanest water in the world?

Maybe not at present as NIWA mention in their press release today that;

“Because of the heavy rain in the Nelson region over the last few days, the lake is likely to be murky right now, but may be expected to clear within a few days.”

They also mention another couple of factoids that may greatly assist this body to have the clearest water on the planet.

The spring-fed source of the water, and its altitude above sea level (1200m), just below the tree line of stunted mountain beech, ensures that Blue Lake is always cold, ranging between 5 and 8°C.

SOURCE:  NIWA Press Release – Nelson’s Blue Lake – The clearest freshwater ever reported


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Where is the clearest water in the World?

 20th Dec 2011 UPDATE

NZ Media website picks up the story, but I believe, goes one better in releasing an outstanding photo (again from NIWA) which hints at illustrating the cleanest water on the globe at present. Just breath takingly beautiful I suggest.


Although at first the Nelson Mail didn’t quite see the gravity of the situation…


…. The Press did recognize the significance of the occasion.