The Ottu barrage, sometimes spelled as the Otu barrage and also known as Ottu Head, is a masonry weir on the Ghaggar-Hakra River in Sirsa, Haryana state of India that creates a large water reservoir out of the formerly-small Dhanur lake, located near the village of Ottu, which is about 8 miles from Sirsa City in Haryana, India.

[3] The Ottu barrage was constructed in 1896-97 using low-cost labor that was available due to a famine in the region at that time.

[1] Prior to the construction of the barrage and its associated reservoir and canals, agriculture in the then princely state of Bikaner had come under pressure from fluctuating water-supply in the monsoon season caused by diversions in the Ghaggar by riparian farmers further upstream.

[4] It was once assumed by some historians that Ottu lake was the site where Timur had encamped after overpowering Bhatnair fort in Hanumangarh (Rajasthan) during his invasion of India in 1398-99 CE.

However, it is now known that the actual site of his camp, which he described as being Kinar-e-Hauz (i.e. on the banks of a tank or lake), was at the banks of Talwara Lake, which is further 40 km downstream in Hanumangarh district between Ellenabad and Hanumangarh town.