Step 1: The Indira Gandhi Canal is the longest canal of India. It is meant to irrigate the arid districts of north-western Rajasthan such as Sri Ganganagar, Bikaner, Jaisalmer and Barmer. Step 2: It takes off from the Harike Barrage, built at the confluence of the Sutlej and Beas rivers in Punjab. Step 3: The canal passes through Punjab and Haryana before entering Rajasthan, and ends near Mohangarh in Jaisalmer district. Step 4: Bhakra is a dam on the Sutlej and Okhla is on the Yamuna near Delhi; neither feeds this canal directly. Answer: Harike Barrage.