From the earliest days of European and Chinese settlement in the Darwin region, securing a reliable water supply was an issue.
In the mid-1930s, to meet the demand of Darwin’s growing civilian population and increased military presence as the war drew closer, several potential dam sites were surveyed. Manton Gap, 42 miles from Darwin, was chosen as the most suitable location. With funding from the Royal Australian Navy, the construction of the dam wall and its 300mm pipeline began in 1939.
Manton Dam under construction around 1940-1941
While the dam was built, an interim water supply was pumped from Howard Springs, mainly for Defence establishments. The dam wall was completed in January 1942 and the first water flowed to Darwin on 11 March. The water quality was initially poor, partly due to the low water levels in the dam.
The entry of Japan into World War II in December 1941 upgraded the strategic value of the dam. Military units and anti torpedo nets were assigned to guard the structure. The Japanese raids of 1942 and 1943 partly damaged the Manton Dam pipeline, but water supply was maintained throughout the war. A second 375mm pipeline and upgraded storage facilities were laid in 1945 to increase flow and distribution.
Construction of the original pipeline between Manton Dam and Darwin around 1940-1941
The dam, pumping stations, pipelines and storage facilities were handed over to Northern Territory administration after the war. The dam remained Darwin’s main source of water until Darwin River Dam was constructed in 1972. Kept as an emergency back-up , it was put twice in service: in 1974 after Cyclone Tracy and again in 1992 when a fire halted pumping operations at Darwin River Dam.
For more information read the brochure Manton Dam, One of Darwin's best kept secrets.