Mahakam River

Mahakam River is the largest river in East Kalimantan, these 980-km-long river flows from the district of Long Apari in the highlands of Borneo, to its mouth at the Makassar Strait. The river originates in Cemaru from where it flows south-eastwards, meeting the River Kedang Pahu at the city of Muara Pahu. From there, the river flows eastward through the Mahakam lakes region, which is a flat tropical lowland area surrounded by peat land.

There are about 76 lakes spread in the Mahakam river basin and about 30 lakes are located in the middle Mahakam area including the three main lakes (Lake Jempang 15,000 Ha; Lake Semayang 13,000 Ha; Lake Melintang 11,000 Ha). The lakes levels are seasonally fluctuated from 0.5m – 1m during dry period to seven meters during rainy season.Downstream of the connection with the Semayang and Melintang lakes, the Mahakam meets three other main tributaries - the rivers Belayan, Kedang Kepala, and Kedang Rantau - and flows south-eastwards through the Mahakam delta distributaries, to the Makassar Strait.

Mahakam River has great flora and Fauna diversity, a total of 147 indigenous freshwater fish species had been identified. The Mahakam hosts the freshwater dolphin Irrawaddy Dolphin (Orcaella brevirostris; called Pesut by local people) a critically endangered fish species. The Mahakam river basin is also an important breeding and resting place for 298 bird species, among them 70 protected and five endemic species: Borneo Dusky Mannikin (Lonchura fuscans), Borneo Whistler (Pachycephala hypoxantha), Bornean Peacock-pheasant (Polyplectron schleiermacheri), Bornean Blue-flycatcher (Cyornis superbus) and Bornean Bristlehead (Pityriasis gymnocephal).

Mahakam is also the main river system on where the indigenous Dayak are resides for generations while preserved their very native way of life and culture.