Canto 1 - Boyhood
Bāla-kāṇḍa
Chapter 35: The History of Gaṅga
Text 1.35.4

अयं शोणः शुभजलो गाधः पुलिनमण्डितः।
कतरेण पथा ब्रह्मन्सन्तरिष्यामहे वयम्॥

ayaṁ śoṇaḥ śubha-jalo gādhaḥ pulina-maṇḍitaḥ
katareṇa
pathā brahman santariṣyāmahe vayam

ayam śoṇaḥ = Śoṇā; śubha-jalaḥ = auspicious water; gādhaḥ = is shallow; pulina-maṇḍitaḥ = and decorated with sand; katareṇa = by which; pathā = path; brahman = O brāhmaṇa; santariṣyāmahe = shall cross over this river; vayam = we.

Śoṇā of auspicious waters is shallow and decorated with sand. O brāhmaṇa, by which path shall we cross over this river?

Because Śoṇā is shallow and filled with sand, it could be crossed over without a boat.