The Lilajan River (Niranjan River and also mentioned as Nilanjan River) flows through the Chatra and Gaya districts in the Indian states of Jharkhand and Bihar. Some people refer to this river as the Falgu River.The Lilajan begins its journey north of Simaria in Chatra district on the Hazaribagh plateau, the western portion of which constitutes a broad watershed between the Damodar drainage on the south and the Lilajan (also called Niranjan) and Mohana rivers on the north. It flows through a deep and rocky channel until it reaches the neighbourhood of Jori.
The water falls into a dah or natural reservoir in the Lilajan River. It is 11 kilometres (6.8 mi) west of Chatra – about half the distance is motorable, the rest has to be on foot.