Officially it's known as Blue Lake, but to the scientists studying it, it has taken on a new name: God's Bathtub.

Blue Lake sits on North Stradbroke Island in the Australian state of Queensland. The tiny lake with crystal-clear waters was already known as one of the country's most beautiful sites, but new research reveals something even more remarkable: the lake has been relatively unaffected by changes in climate or the effects of humans for more than 7,000 years.

"Blue Lake is one of those rare, beautiful lakes in Australia," Dr. Cameron Barr of the University of Adelaide said in a news release this week. "It's unusual because it's more than 10 meters deep, but it's so clear you can see to the bottom. We didn't realize just how unique and unusual this lake is until we started looking at a wide range of environmental markers."

Barr and his fellow researchers looked at records kept about the lake for the past 117 years as well as fossil information about pollen and algae. By looking at photographs and a great deal of other data, they came to a remarkable conclusion: the depth and water chemistry of Blue Lake has remained almost unchanged for millennia.

The research was published April 26 in the journal Freshwater Biology.

"We know that there have been variations in climate in the region including North Stradbroke Island over recent decades," Barr said, "but during that time ... Blue Lake has displayed little variation. We also know that the region experienced a significant shift towards a drier climate around 4000 years ago. Again, Blue Lake has demonstrated little variation over this period. This is in stark contrast to other changes in the region due to shifts in climate."

Barr told the Australian Broadcasting Company that the freshwater system of Blue Lake is unique. It is refreshed by an aquifer and it drains into a nearby swamp, a process that completely replenishes the lake every 35 days or so. This constant system of refreshment allows the lake to remain consistent in size, depth and chemistry regardless of changes in climate around it.

Barr called the lake a "climate refuge" for the freshwater algae and other life in the region, and says the lake could remain untouched for thousands of years in the future if it is properly managed. The main threats to that future are human usage of freshwater on the island or the introduction of chemicals into the water.

Although Blue Lake is unique in Australia, that it has remained so stable over such a long period of time could provide clues for managing freshwater resources in other places.

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