Captains Flat is a town in the Southern Tablelands of rural New South Wales, Australia, in Queanbeyan-Palerang Regional Council.

The town formed as a result of mining for gold, silver, lead, zinc, copper and iron pyrites in the hills surrounding the upper reaches of the Molonglo River.

The impact on European markets due to World War II meant mining operations were subsidised by the government through power and freight concessions as the foreign revenue was seen as important to the Australian economy.

The company also built a theatre, hospital, tennis courts and a swimming pool, and paid for the medical staff, the provision of street lighting, electricity and water.

The mine closed on 11 March 1962 due to the lack of viable ore. To that point men had worked in tunnels extending 840 metres (2,800 feet) below the ground.

Immediately after the closure the Lake George Mines dismantled and sold the infrastructure including removing many of the cottages.

The impact of sulphur and acid rain produced by the smelting has resulted in the area around the mines having a stark and somewhat alien landscape reminiscent of Queenstown in Tasmania.

The resulting pollution severely damaged the ecological communities of the Molonglo River downstream from the mine site, and eradicated all native fish populations.

Despite Federal and NSW government funded remediation programs of $2.5m in 1976, toxic leachates still enter the river from the Captains Flat mine site.

[9] In February 2021 the NSW Environment Protection Authority carried out precautionary testing of surface soils in public and community spaces.

When the Captains Flat Community Preschool was made aware of these results the management committee and staff took immediate measures to ensure that the children could continue to attend in a safe manner.