A view from the south lake on the Vartry Reservoir in Roundwood, Co. Wicklow as the Sun Sets.

An earthen dam was built over the Vartry River between 1862 and 1868 to construct the Lower Reservoir which holds 11.3 billion litres of water and goes to a depth of 18.3 metres. The smaller Upper Reservoir was built later in 1923, holding 5.6 billion litres of water.

These lakes provide the drinking water to the population of Dublin.