Aruṇāsarasvatīsaṅgama (Aruna-saraswatisangamatirtha) is a nadī-tīrtha (nadi-tirtha; river-pilgrimage)). Aruṇā(Aruna) is actually another name for the river Sarasvatī (Sarasvati).
Great sages once relieved the river Sarasvatī of the curse of carrying the blood of Viśvāmitra (Viswamitra), and made its flow clear again. For the redemption of the Rākṣasa(s), these great sages again invoked Sarasvatī in the name of Aruṇā. Since Sarasvatī here emerged as Aruṇā, this site has been named Aruṇā-Sarasvatīsaṅgama. The Rākṣasa(s) (Rakshasa; one kind of Demons), after taking bath in this Aruṇā, left their mortal existence and went up to heaven. Learning this attribute of Aruṇā, Indra also took a bath in this river, and got redeemed of the sin of killing Namuci (Namuchi). Prajāpati (Prajapati; Lord of the people)Brahmā(Brahma) sent Indra to this tīrtha, to get relieved of sin. Valarāma (Valarama), too, received the fruits of puṇya (punya; virtue) by taking a bath in this site, and performing donations.