The river basins under this Organisation are Upper reaches of Ganga Basin (excluding Yamuna Basin) up to Ballia in Uttar Pradesh and lies in the states of Uttaranchal, Uttar Pradesh and part of Madhya Pradesh, Chhattisgarh including the main Ganga river and its tributaries Ramganga, Sharda, Gomti, Rapti, Ghaghra, Tons, Sone etc.

Major Tributaries of the River Ganga under Upper Ganga Basin Organization:

1. Bhagirathi

It flows for about 193 km before merging with the Alaknanda at Deoprayag. Various tributaries joining Bhagirathi are: Bhilangana, Jalangi River, Chor-Mana, Jalandri, Huini and Kaldigad.

2. Alaknanda

The River Alaknanda rises at the confluence and fed of Satopath and Bhagirathi Kharak glacier in Uttarakhand and meets River Bhagirathi at Deoprayag. Various tributaries of River Alaknanda are - Dhauliganga, Pindar, Mandakini, etc. It meets River Bhagirathi at Deoprayag.

After the confluence of River Bhagirathi and Alaknanda the stream is called as Ganga.

3. Ramganga:

The River Ramganga originates from Doodhatoli ranges in the district of Pauri Garhwal, Uttarakhand state of India. It is the first major tributary joining Ganga on its left bank near Kannauj in Fatehgarh district. The total length of River in 596 Km and having a catchment of 32,493 Sq Km This River flows from Almora, Pauri, Kalagarh, Bijnore, Moradabad, Rampur, Bareilly, Shahjahanpur and it joins the Ganga from left near Kannauj

4. Ghaghara:

It is the largest tributary of River Ganga. The River Ghaghara is called Karnali or Manchu in upper reaches and has its source in Himalayan glaceir about 60 km south-west at Mansarovar at an elevation of 4800 m. The total length of Ghaghara River upto its confluence with Ganga at Doriganj in Bihar is 1080 Km. Various tributaries are Saryu, Sarda, Rapti, Kwano, Little Gandak, Seti etc.

5. Gomati:

The Gomati originates from Gomat Taal also known as Fulhaar Jheel near Madho Tanda, Pilibhit, India. It flows for about 900 km through Uttar Pradesh and meets River Ganga near Saidpur, Kaithi at Ghazipur. Various Tributaries of River Gomati are Sai, Kalyani, Kadu etc.

6. Tons:

Tons River emanates at Tamaskund, in the Kaimur range of hills in Satna district of Madhya Pradesh. River Satna joins it on left bank. It enters Uttar Pradesh at Deoria, in Allahabad district and after receiving Belan, major tributary on its right, flows to join the River Ganga on right bank at 31 km downstream of the confluence of the River Ganga and Yamuna. Ther River has total length of about 264 Km and catchment area of 16,860 Sq Km

7. Sone:

The River Sone emanates at Sonebhadra in Maikala range of hills in the district Bilaspur in Chhattisgarh. The River in its initial reach flows in cascades through a maze of hills and valleys of the Vindhya Range. The River follows north easterly course and enters Mirzapur district in Uttar Pradesh after joining with the River Banas and Gopad on its right bank. Other tributaries joining River Sone are Rihand, Kanhar, North Koel etc. The River then takes north easterly course and joins the River Ganga at about 16 km upstream of Danapur in Patna district, Bihar.