The Lake George Mine is located at Captains Flat, approximately 50 kilometres south east of Canberra. The mine operated from 1892 until 1962, producing lead, zinc, copper, pyrite, silver and gold.

Extensive rehabilitation works have been carried out since the mine closed to manage erosion, improve safety and control tailings pollution from the site. Current and ongoing issues include seepage of Acid Mine Drainage (AMD) and heavy metal contaminants spreading from the site, with zinc being the primary contaminant of concern.

Current Site Description

Lake George Mine covers approximately 100 hectares with the main mine infrastructure extending underground to a depth of 619 metres. Numerous shafts and adits are present at the surface, and structures for ore storage, processing, loading and transport remain at the site. There are two large mine tailings dump areas (northern and southern).

Rehabilitation Works

Initial rehabilitation works to reduce pollution were carried out in 1966 and 1968 by the NSW Department of Mines but were only partially successful.

Further, significant works were the carried out in 1976, which included stabilisation of mine waste dumps to prevent ongoing erosion and leaching, and to minimise the risk of major collapse. Works also included drainage modifications to Forsters Creek to minimise the inflow of water into the mine.

The 1976 works were primarily to protect and upgrade water quality of the Molonglo River for drinking and agricultural use, and of Lake Burley Griffin.

Since the early 1990s other significant works on various sections of the site have included:

  • 1993 – erosion control works
  • 1999-2002 – survey and Remediation Action Plan (RAP)
  • 2000/01 – contaminated materials removal
  • 2002/03 – relocation of waste slag
  • 2004 – RAP preparation
  • 2005/06 – erosion control/structure safety
  • 2005/06 – heritage assessment
  • 2007/08 – sediment control and de-silting
  • 2009/10 – drainage mill/load out site and safety fencing
  • 2012 – design for stabilisation of the northern face of the south tailings dump
  • 2012 – erosion control at the north face of the south tailings dump
  • 2013 – site safety works to rectify subsidence issues
  • 2014 – silt (from dam) disposal, spillway repair and stabilisation
  • 2017 – Review effectiveness of previous works at the site and determine required future rehabilitation works
  • 2018/19 – Detailed investigation into capping, revegetation design and water treatment options
  • 2019 - Safety fencing delivered around New-Keatings area, and fence repairs to the north and south tailing dumps
  • 2020 - Bench scale testing (a form of water analysis) to better inform water treatment facility design.

The next phase of works will involve capping bare areas on the mine site and pursuing options to treat water coming from the mine.

Mine History and Heritage Value

During both periods Captains Flat was one of the largest towns in the southern mining region, having a considerable impact on the development and settlement of the area.

Mining operations in Captains Flat were carried out during two periods: 1882-1889 and 1937-1962. The site was closed in 1962 due to the depletion of economic grade ore.

Cross section of part of Captains Flat mine

During the second period of operation (1939-1962), more than 4 million tonnes of complex copper-lead-zinc ore was processed to produce approximately 243,000 tonnes of lead, 406,000 tonnes of zinc, 27,000 tonnes of copper, 7.4 million ounces of silver and 220,000 ounces of gold.

All of the workings of the mine were underground, with the lowest levels reached being 619 metres. At this level, drives were extended a number of times to locate the ore bodies but in 1960, the diamond drilling at the end of the drives failed to locate any ore of economic importance.

While dwarfed in size by the Broken Hill field (which was one of the largest in the world), Lake George Mine at Captains Flat was one of the largest base metal mining fields in NSW, if not Australia. The Mt Isa and Mt Lyell fields were larger but primarily produced copper.

The highly complex mineralogy of the ore body and consequently the varied and changing processing technology was a unique aspect of mining of Captains Flat.

The Captains Flat mining field is significant for its contribution to base metal mining in Australia, and NSW in particular, over a period of 80 years. It was the major mining site in southern NSW in the 1890s and again during its second period of operation in 1937-1962.

During the four decades of the 1930s-1960s, Captains Flat was one of the most important mining sites in Australia as a producer of lead, silver, zinc and sulphur, and to a lesser extent, copper and gold. Its production was particularly valuable during World War 2.