Aquifer Blue Lake Tours (at Mt Gambier) with Keith Conlon

Last week's visit to the Blue Lake City, Mt Gambier, included a trip down to the surface of its famous lake. Apologies for omitting it from my look around the city last week, because the tour was well worth taking.

Joining Gary Turner's Tourism Award winning, Aquifer Tour is as easy as turning up on the hour to the pumping station entrance at the top of the Blue Lake crater. He's an enthusiastic guide, full of information about the pumping system, the lakes dimensions and its marine life.

Gary would admit, though, that the star of his show is the lake itself - and its magic, mysterious deep blue. The descent to the surface has its attraction, too. In the 1880's a well about 1 metre in diameter was cut through the old ash, volcanic basalt and limestone evident in the crater's sides to supply the town nearby with water. It took 5 months to dig and another 2 months to line with hand-cut stone. In a recently installed elevator we drop thirty metres to the next viewing level in a minute!

The colour of the water close below becomes even more fascinating. Gary Turner emphasises his explanation is still in theory. Scientists seem to agree now on the origins of its vivid blue. It is important to note that this is only evident from November to March. Warmer surface water encourages calcite in the aquifer under the region - and exposed in the Blue Lake - to precipitate into tiny crystals. They absorb all other colours in the spectrum, leaving that marvellous blue.

Tour groups walk down steps on the water supply structure to a pontoon floating on the water. Just below them, the ancient water is clear, sparkling - and yes, even at close quarters, it's still blue! The views across the lake to the crater walls are impressive.

Gary's fountain of information still flows. The water level is nearly nine metres below its high point. It's a 'window on the acquifer', or ground water absorbed in the limestone underlying the region. A big drainage scheme in the region, forestry, farming and lower rainfall are likely reasons for the drop in level.

At the lake level, visitors are nearly thirty metres below the central Mt. Gambier level. The water creeps through the aquifer towards the Southern Ocean, and so the sample we saw was thousands of years old.

It's a fact-filled tour which only takes an hour, but the one thing ALL Gary's customers are definitely going to talk about when they get home is the magic of that Blue Lake BLUE!!

Tour details from Aquifer Blue Lake Tours, Mt. Gambier, phone 8723 1199 or email info@postcards.sa.com.au Tours run hourly from 9 am every day, but the closing time varies seasonally.