The Mount Crosby Weir is a heritage-listed weir on the Brisbane River at Mount Crosby and Chuwar, both in City of Brisbane, Queensland, Australia. The project was instigated by John Petrie at the end of the 19th century. The town of Brisbane was expanding and seeking more reliable sources of drinking water than Enoggera Dam and Gold Creek Dam could provide. In conjunction with the Mount Crosby Pumping Station, it was listed on the Queensland Heritage Register on 25 October 2019.