| River | Length in Bihar | Districts Covered | Entry Point | Confluence / Exit | Key Facts |
|---|---|---|---|---|---|
| Ganga | ~445 km | Buxar, Bhojpur, Saran, Patna, Vaishali, Samastipur, Begusarai, Munger, Khagaria, Katihar, Bhagalpur, Lakhisarai | Chausa (near Buxar) after Karmanasa | Sahibganj (Jharkhand) | Longest stretch in Patna – 99 km; Largest tributary Ghaghara |
| River | Origin | Length | Entry / Flow Area | Confluence Point | Important Notes |
|---|---|---|---|---|---|
| Ghaghara | Mapapachuchango (Tibet) | — | Bihar–UP boundary | Revelganj (Saran) | Largest tributary of Ganga |
| Gandak (Narayani) | Nepal | ~640 km | Valmikinagar (Triveni Canal) | Pahleja Ghat | Major Himalayan river |
| Burhi Gandak | Chautarwa (Nepal) | ~320 km | N. Bihar plains | Khagaria | Tributaries: Masan, Pandai, Sikta etc. |
| Kosi (Saptakosi) | Arun + Sun Kosi + Tamur | — | Hanumannagar (Supaul) | Kursela (Katihar) | Sorrow of Bihar, transboundary |
| Bagmati | Shivpuri Range (Nepal) | ~589 km | Sitamarhi | Badla Ghat (Kosi) | Sacred to Hindus & Buddhists |
| Kamla | Mahabharat Range (Nepal) | — | Jainagar (Madhubani) | Bagmati | Tributaries: Tao, Balan, Trisula |
| Punpun | Chhota Nagpur Plateau (Palamu) | — | S. Bihar | Fatuha (Patna) | Mentioned in Vayu & Padma Purana |
| Son | Maikal Range (Amarkantak) | — | S. Bihar | Near Patna | Perennial river |
| Karmanasa | Kaimur Plateau | — | SW Bihar | Chausa (Buxar) | GT Road bridge, dams present |
| River | Origin | Entry District | Confluence | Special Feature |
|---|---|---|---|---|
| Bagmati | Shivpuri Range (Nepal) | Sitamarhi | Kosi | Transboundary |
| Burhi Gandak | Chautarwa (Nepal) | West Champaran | Ganga | Flood-prone |
| Gandak | Nepal | Valmikinagar | Ganga | Triveni Canal |
| Kamla | Nepal | Madhubani | Bagmati | Himalayan river |
| Kosi | Tibet–Nepal | Supaul | Ganga | Sorrow of Bihar |
| River | Origin | Districts | Confluence | Notes |
|---|---|---|---|---|
| Son | Amarkantak | Rohtas, Patna | Ganga | Perennial |
| Punpun | Palamu | Gaya, Patna | Ganga | Religious importance |
| Phalgu (Niranjana) | Lilajan + Mohana | Gaya | Punpun | Vishnupad Temple |
| Karmanasa | Kaimur | Kaimur, Buxar | Ganga | Chandraprabha Dam |
| Kiul | Giridih (Jharkhand) | Lakhisarai | Harohar | Jh–BR boundary |
| River | Countries Involved | Notes |
|---|---|---|
| Kosi | China–Nepal–India | Saptakosi |
| Mahananda | India–Bangladesh | Flows via Kishanganj |
| Bagmati | Nepal–India | Religious river |
| Kamla | Nepal–India | Tributary of Bagmati |
| River | Religious Significance |
|---|---|
| Phalgu | Vishnupad Temple, Bodh Gaya |
| Punpun | Mentioned in Puranas |
| Bagmati | Sacred to Hindus & Buddhists |