Water is a defining feature of Nagaon's geography, shaping its culture, agriculture, and daily life.
* **Kolong River**: A major tributary of the Brahmaputra, the Kolong flows directly through the heart of Nagaon city, dividing it from the commercial hub of Haibargaon. * **Samaguri Beel**: An oxbow lake formed by the abandoned path of the Kolong river, renowned for its serene beauty and as a habitat for migratory birds. * **Wetlands**: The district is dotted with numerous *beels* (wetlands) that serve as crucial ecological zones for aquatic flora and fauna and support local fishing communities.