The Darwin River Dam is an earth- and rock-filled embankment dam across the Darwin River, located in the eponymous settlement, in the Northern Territory of Australia. Completed in 1972, the dam was built to supply potable water for the city of .
The earth and rock-filled dam wall is high and long. At full capacity, the resultant reservoir can hold , covering a surface area of that is drawn from a catchment area of . The reservoir is eleven times bigger than the Manton Dam.
The dam relies on the annual wet season to be replenished. It is ungated with no spillway regulation, and toward the end of the wet season the dam can overflow. Most years spilling occurs and is considered normal. Depending on the amount of rainfall, this overflow can last from days to weeks.
The dam was officially opened by Prime Minister William McMahon on 29 June 1972, and the construction cost was .
The water in the Darwin River Dam reservoir is considered to be one of the most pristine on Earth. In order to preserve this quality, the catchment and reservoir policy prohibits recreational use with substantial penalties imposed for trespassing. The reservoir is free of Cabomba, an aquatic weed genus that can affect water quality.