Lake Fidler

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Lake Fidler
Location	Tasmania
Lake type	meromictic
Basin countries	Australia

Lake Fidler is a meromictic lake beside the Gordon River in the Wilderness World Heritage area of the west coast of Tasmania, Australia. The lake has a layer of fresh water overlying an anoxic salt water layer.

The meromictic lakes and ponds of the Gordon River were discovered by D.A. Hodgson and Professor Peter Tyler (reported 1996).

It became evident that, following the establishment of a hydro-electric power industry on the Gordon River, the flows of fresh water into the lake were disturbed and the anoxic salt layer was declining in depth. Previously, low river flows at certain times of the year allowed salt water to migrate upriver and occasionally spill into Lake Fidler through a narrow channel joining it to the river, thus recharging the salt water layer.

In 2004, Hydro Tasmania gained state and federal approval to recharge the lake with seawater drawn from the sea outside Macquarie Harbour at the mouth of the Gordon River. This involved having a sea-going tug draw up around 1.4 million litres of salt water in lots of around 100,000 litres, and discharge the water through a diffuser that allowed the seawater to settle into the lower salt layer. (See diagrams at Hydro Tasmania press release, 18 June 2004) This was completed and the results confirmed in April 2005. However, it was noted that, if no natural recharging occurs, the process of recharging may need to be repeated in about 10-15 years.

[edit] References

Hodgson, D.A. and Tyler, P.A., 1996. The impact of a hydro-electric dam on the stability of meromictic lakes in south west Tasmania, Australia. Arch. Hydrobiol. 137 (3): 301-323.
Hodgson, D., Tyler, P.A. and Vyverman, W., 1996. The paleolimnology of Lake Fidler, a meromictic lake in south-west Tasmania and the significance of recent human impact. Journal of Paleolimnology 18: 313-333.
Hodgson, D., Wright, S., Tyler, P. and Davies, N., 1998. Analysis of fossil pigments from algae and bacteria in meromictic Lake Fidler, Tasmania, and its applications to lake management. Journal of Paleolimnology 19: 1-22.
Hodgson, D., 1999. The formation of flocculated clay laminae in the sediments of a meromictic lake. Journal of Paleolimnology 21: 263-269.