The Satluj River (Urdu: درياۓ ستلُج), (alternatively spelled as Sutlej River) (Bengali: শতদ্রু,Punjabi: ਸਤਲੁਜ, Sanskrit: शुतुद्रि, Śutudri, and Hindi: सतलज) is the longest of the five rivers that flow through the historic crossroad region of Punjab in northern India and Pakistan. It is located north of the Vindhya Range, south of the Hindu Kush segment of the Himalayas, and east of the Central Sulaiman Range in Pakistan.
The Sutlej is sometimes known as the Red River. It is the easternmost tributary of the Indus River. Its source is from Lowangko Co, Tibet near Lake Rakshastal in Tibet, China, near Mount Kailas, and it flows generally west and southwest entering India through the Shipki La pass in Himachal Pradesh. In Pakistan, it waters the ancient and historical former Bahawalpur state. The region to its south and east is arid, and is known as Cholistan a part of Bahawalpur Division. The Sutlej is joined by the Beas River in Hari-Ke-Patan, Amritsar, Punjāb, India, and continues southwest into Pakistan to unite with the Chenab River, forming the Panjnad River near Bahawalpur. The Panjnad joins the Indus River at Mithankot. Indus then flows through a gorge near Sukkur, flows through the fertile plains region of Sindh, forming large delta region between border of Gujarat, India & Pakistan and finally terminates in the Arabian Sea near the port city of Karachi in Pakistan.
Contrary to the claims of Punjab state in India, small part of Haryana state lying north of Chandigarh city is part of Sutlej river basin area in addition to Punjab, Himachal Pradesh and Chandigarh in India (refer Google earth). Thus Haryana is also a riparian state of Indus river basin.
The waters of the Sutlej are allocated to India under the Indus Waters Treaty between India and Pakistan, and are mostly diverted to irrigation canals in India. There are several major hydroelectric projects on the Sutlej, for example, the 1,000 MW Bhakra Dam, the 1,000 MW Karcham-Wangtoo and the 1,530 MW Nathpa Jhakri Hydroelectric Dam. There has been a proposal to build a 214-kilometre (133 mi) long heavy freight canal, known as the Sutlej-Yamuna Link (SYL), in India to connect the Sutlej and Yamuna rivers. However, the proposal met obstacles and was referred to the Supreme Court.
The Sutlej was known as Śutudri in the Vedic period.