Lake Fidler is a

meromictic lake A meromictic lake is a lake which has layers of water that do not intermix. In ordinary, holomictic lakes, at least once each year, there is a physical mixing of the surface and the deep waters. The term ''meromictic'' was coined by the Austri ...

beside the

Gordon River The Gordon River is a major perennial river located in the central highlands, south-west, and western regions of Tasmania, Australia. Course and features The Gordon River rises below Mount Hobhouse in the Franklin-Gordon Wild Rivers National ...

in the

Tasmanian Wilderness The Tasmanian Wilderness World Heritage Area, abbreviated to TWWHA, is a World Heritage Site in Tasmania, Australia. It is one of the largest conservation areas in Australia, covering , or almost 25% of Tasmania. It is also one of the last ex ...

World Heritage Site A World Heritage Site is a landmark or area with legal protection by an international convention administered by the United Nations Educational, Scientific and Cultural Organization (UNESCO). World Heritage Sites are designated by UNESCO for h ...

area of the west coast of

Tasmania ) , nickname = , image_map = Tasmania in Australia.svg , map_caption = Location of Tasmania in AustraliaCoordinates: , subdivision_type = Country , subdi ...

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

. The lake has a layer of

fresh water Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does include ...

overlying an

anoxic The term anoxia means a total depletion in the level of oxygen, an extreme form of hypoxia or "low oxygen". The terms anoxia and hypoxia are used in various contexts: * Anoxic waters, sea water, fresh water or groundwater that are depleted of diss ...

salt water Saline water (more commonly known as salt water) is water that contains a high concentration of dissolved salts (mainly sodium chloride). On the United States Geological Survey (USGS) salinity scale, saline water is saltier than brackish water, ...

layer. The meromictic lakes and ponds of the Gordon River were discovered by D. A. Hodgson and Professor Peter Tyler.

Description

It became evident that, following the establishment of a

hydro-electric Hydroelectricity, or hydroelectric power, is electricity generated from hydropower (water power). Hydropower supplies one sixth of the world's electricity, almost 4500 TWh in 2020, which is more than all other renewable sources combined an ...

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 Federal or foederal (archaic) may refer to: Politics General *Federal monarchy, a federation of monarchies *Federation, or ''Federal state'' (federal system), a type of government characterized by both a central (federal) government and states or ...

approval to recharge the lake with

seawater Seawater, or salt water, is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% (35 g/L, 35 ppt, 600 mM). This means that every kilogram (roughly one liter by volume) of seawater has appro ...

drawn from the sea outside

Macquarie Harbour Macquarie Harbour is a shallow fjord in the West Coast region of Tasmania, Australia. It is approximately , and has an average depth of , with deeper places up to . It is navigable by shallow-draft vessels. The main channel is kept clear by the ...

at the mouth of the Gordon River. This involved having a sea-going tug draw up approximately of salt water in lots of approximately , 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.

References

External links

Hydro Tasmania press release, 18 June 2004Hydro Tasmania proposal to Australian Department of Environment and Heritage
under Environment Protection and Biodiversity Conservation Act 1999; DOC file, with maps {{DEFAULTSORT:Fidler Lakes of Tasmania Meromictic lakes Tasmanian Wilderness World Heritage Area hu:Fiedler (egyértelműsítő lap)#Fidler

Description

See also

References

Further reading

External links