Ewens Ponds (South Australia)

Infobox lake
lake_name = Ewens Ponds
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location = South Australia
coords = coord|38|01|S|140|47|E|region:AU-VI_type:waterbody|display=inline,title
type = Cenotes
inflow = Eight Mile Creek
outflow =
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basin_countries = Australia
length =
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max-depth = 10 metres (30 feet)
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Ewens Ponds are a series of three limestone sinkholes on Eight Mile Creek km to mi|25 south of Mount Gambier and km to mi|5 east of Port Macdonnell, South Australia. The ponds are popular with scuba divers, with underwater visibility of up to 80 metres (264 feet) and a large fish population including the endangered golden pygmy perch.

History

The original inhabitants of the land were Aborigines of the "Boandik" tribe, part of a larger "Bunganditj" clan. The first European identified with the area was Thomas Ewens, whose dog chased a kangaroo into one of the ponds.cite book |title =Ewens Ponds Conservation Park Management Plan | first = | last = | coauthors= | month =February | year =1999 | publisher =Department for Environment, Heritage and Aboriginal Affairs, South Australia | pages =p5 | url =http://www.environment.sa.gov.au/parks/pdfs/PARKS_PDFS_EWEN_PONDS_MP_AMEND.PDF | isbn =0730858472] The land surrounding the ponds was gradually cleared for agriculture and dairy farming and a drainage system built to draw water from the ponds for land sold for soldier settlement programs post-World War Two.

In 1978 a trout farm was established utilising the waters flowing through Ewens Ponds. Although the ponds themselves are now part of a conservation park, the farm continues to operate. Water for the farm is drawn from the second pond, and wastewater discharged back into Eight Mile Creek downstream from the pond system. [cite book |title =Ewens Ponds Conservation Park Management Plan | first = | last = | coauthors= | month =February | year =1999 | publisher =Department for Environment, Heritage and Aboriginal Affairs, South Australia | pages =p8 | url =http://www.environment.sa.gov.au/parks/pdfs/PARKS_PDFS_EWEN_PONDS_MP_AMEND.PDF | isbn =0730858472]

Geography

Each pond is a basin-shaped limestone cenote approximately ten metres (30 feet) deep and connected to the others by shallow watercourses.cite web| title =Ewen Ponds Conservation Park | publisher =Department of Environment and Heritage, South Australia | month =June | year =2008 | url =http://www.environment.sa.gov.au/parks/sanpr/ewenponds/index.html | accessdate =2008-09-10 ] The beds are covered with a fine silt layer and the floor of the third pond also contains a natural shallow cave. [cite web| title =Piccaninnie Ponds | publisher =Getaway, Nine Network | month =September | year =2000 | url =http://getaway.ninemsn.com.au/article.aspx?id=16993 | accessdate =2008-09-10] The ponds are located in a narrow band of native bush land, surrounded by cleared terrain. The landscape is characteristic of karst topography, shaped by the gradual dissolution of soluble limestone to form hollows and small caves. [cite book |title =Ewens Ponds Conservation Park Management Plan | first = | last = | coauthors= | month =February | year =1999 | publisher =Department for Environment, Heritage and Aboriginal Affairs, South Australia | pages =p3 | url =http://www.environment.sa.gov.au/parks/pdfs/PARKS_PDFS_EWEN_PONDS_MP_AMEND.PDF | isbn =0730858472]

The ponds' excellent water quality allows underwater visibility of up to 80 metres (264 feet), [cite web| title =Ewen Ponds Conservation Park | publisher =AboutAustralia Pty Ltd | month = | year =2008 | url =http://www.about-australia.com/travel-guides/south-australia/limestone-coast/attractions/natural/ewens-ponds-conservation-park/ | accessdate =2008-09-10] and sufficient natural light for plant growth on the pond beds to reach up to six metres in height. The ponds are occasionally affected by blue-green algae, [cite news| last = |first = |coauthors = |title =EPA probes possible Ewens Ponds algae outbreak | work =ABC News | pages = | publisher =Australian Broadcasting Corporation | date =2008-02-05 | url =http://www.abc.net.au/news/stories/2008/02/05/2154874.htm | accessdate =2008-09-10 ] though testing has found no evidence of health risks. [cite press release| title =Ewens Ponds algae no risk to public | publisher =Department of Environment and Heritage, South Australia | date =2008-02-18 | url =http://www.environment.sa.gov.au/data/press/ewenPonds.pdf | accessdate =2008-09-10 ] In 2007 the South Australian Environmental Protection Agency suggested the algal blooms may be a result of continued concentrations of soluble nitrogen in both the ponds and the adjoining Eight Mile Creek, arising from infiltration of the groundwater by fertilisers, animal waste or wastewater. [cite web| title =Eight Mile Creek: Archived water quality assessments | publisher =Environmental Protection Agency, South Australia | month =September | year =2007 | url =http://www.epa.sa.gov.au/eight_mile_archive.html | accessdate =2008-09-10 ]

Fauna

The ponds are one of only three recorded locations for the golden pygmy perch ("Nannoperca variegata"). [cite web| title =Nannoperca variegata in Species Profile and Threats Database | publisher =Department of the Environment, Water, Heritage and the Arts, Australia| month = | year =2008 | url =http://www.environment.gov.au/cgi-bin/sprat/public/publicspecies.pl?taxon_id=26178 | accessdate =2008-09-10 ] Other fish life includes schools of short-finned eel, river blackfish, pouched lampreys, mullet and common galaxias . [cite book |title =Ewens Ponds Conservation Park Management Plan | first = | last = | coauthors= | month =February | year =1999 | publisher =Department for Environment, Heritage and Aboriginal Affairs, South Australia | pages =p10 | url =http://www.environment.sa.gov.au/parks/pdfs/PARKS_PDFS_EWEN_PONDS_MP_AMEND.PDF | isbn =0730858472] The ponds are also home to populations of flatworms, freshwater crayfish and mussels, and the larva of the carnivorous caddis fly.cite web| title =Ewens Ponds | publisher =Australian Network | month =February | year =2008 | url =http://australianetwork.com/nexus/stories/EWENSPONDS.htm | accessdate =2008-09-10 ]

Recreational activities

The pond beds are formally owned by the South Australian Department of Water, Land and Biodiversity Conservation and managed as a conservation park by the Department of Environment and Heritage. [cite journal | last =Tedder | first =G. | coauthors = | title =Management of Piccaninnie Ponds and Ewens Ponds | journal =Australian Society for Limnology Congress | volume = | issue = | pages = | publisher =Australian Society for Limnology | location =Caulfield East | date = | url =http://www.aanro.net/dbtw-wpd/exec/dbtwpub.dll?XC=/dbtw-wpd/exec/dbtwpub.dll&BU=&QB0=AND&QF0=linkid@ccmaaanro&QI0=ca00866&TN=ccmalink&AC=QBE_QUERY&FG=000000&DF=webdisplay&RF=webdisplay&DL=0&EL=0&RL=0&NP=1&BAF=1 | doi =1984-05-19 | accessdate =2008-09-10 ] Plant and animal species in the ponds are protected and may not be removed.

High visibility and a substantial fish population have made the Ponds popular with scuba divers. [cite web| title =Scuba Diving in South Australia | publisher =Outdoors SA | month = | year =2008 | url =http://www.outdoorssa.com.au/Scuba%20Pages/freshwater_diving.htm | accessdate =2008-09-10 ] . Of particular interest in these clear waters is the actual observation of photosynthesis. Water plants can be seen releasing thin trails of bubbles as they convert sunlight into oxygen. However divers are prohibited from entering caves or crevices on the pond beds and strongly discouraged from disturbing the silt layer as the resulting turbidity may harm plant life. Of particular concern is the practice of divers returning through the channel linking the three ponds, thereby disturbing the water plants lining the channel. Water temperatures range from 10 to 15 degrees.cite web| title =Guidelines for SCUBA Diving and Snorkelling in Ewens Ponds | publisher =Department of Environment and Heritage, South Australia | month = | year =2008 | url =http://www.environment.sa.gov.au/parks/pdfs/PARKS_PDFS_EWENSPONDS_GUIDE.PDF | accessdate =2008-09-10 ]

ee also

*Piccaninnie Ponds Conservation Park

References

External links

* [http://www.slv.vic.gov.au/pdoak/inter/160705.shtml Images of Ewen Ponds, from the State Library of Victoria]