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. It is a feeder for the two Ghaggar canals that carry irrigation water to northern Haryana state. In 2002, a new tourist complex was inaugurated at the barrage, and it was given the honorary name of "Chaudhary Devi Lal Weir" to commemorate the former Chief Minister of Haryana state, Chaudhary Devi Lal. The Dhanur lake reservoir is now often referred to simply as the Ottu reservoir.

The Ghaggar-Hakra River is an intermittent river in India and Pakistan that flows only during the monsoon season. The river is known as Ghaggar before the Ottu barrage at 29.4875°N 74.8925°E, and as Hakra downstream of the barrage in the Thar Desert. In pre-Harappan times the Ghaggar was a tributary of the Sutlej. It is still connected to this paleochannel of the Sutlej, and possibly the Yamuna, which ended in the Nara River, presently a delta channel of the Indus River joining the sea via Sir Creek.