Located up in the mountains of Central Province in the Koiari LLG, the dam is the only source of water that supplies the residents of Port Moresby and parts of Central.
PNG Power Limited (PPL) measurement recording on Tuesday stands at 100 Mm3, 29.6 percent of the dam capacity.
The dam is designed to hold 340 Mm3 of water.
PPL last recording on Monday January 25, the measurement tipped the scale at 102 Mm3, which is 30% of the spill level.
PPL owns the dam and had dropped its hydro-electricity generating as an option to save water.
Water supplier, Eda Ranu have an agreement with PPL that when the water level hit the 50 Mm3 mark, power generation will totally stop.
Caption: File Picture of Sirinumu dam captured in December 2015