It is one of the three main water sources for Metro Vancouver, and part of the Coquitlam watershed.

It is also a part of BC Hydro's power generation system.

[1] Construction of the tunnel between Coquitlam Lake and Buntzen Lake began in 1902 and finished in 1905, supplying water to powerhouses on Indian Arm, which supplied electricity to Vancouver.

[2] The first Coquitlam Dam, built to raise the water level by 5 feet (1.52 m), was begun in April 1904 and completed in 1905.

It formed during the Little Ice Age and is shrinking as the last Ice Age ends and, potentially, due to the effects of climate change.