Great Sheffield Flood - Collapse of Dale Dyke Dam

Collapse of Dale Dyke Dam

On the night of 11 March 1864, assisted by a strong south-western gale, the newly built dam known as the Dale Dyke Dam at Low Bradfield on the River Loxley, collapsed while it was being filled for the first time. An estimated 3 million m3 (700 million imperial gallons) of water swept down the Loxley Valley, through Loxley village and on to Malin Bridge and Hillsborough, where the River Loxley joins the River Don. The flood continued south down the Don into Sheffield centre, around the eastward bend of the Don at Lady's Bridge, then to Attercliffe, past the sites of today's Don Valley Stadium, Sheffield Arena and Meadowhall Shopping Centre and on to Rotherham. A wall of water moved swiftly down the valley, destroying everything in its course. It was said that within an hour the whole reservoir was emptied. Most people at the time were set on the idea that an error in the design caused the collapse, and after a visit from an engineer, who pointed out the flaws, it became a definite answer. The company’s consultant engineer John Towlerton Leather and resident engineer John Gunson were working closely together during the construction of the dam. Leather designed the dam and oversaw its construction where Gunson directed and supervised the construction of the dam. Gunson was on site the night of the collapse and stated that there was a worrying crack in the outer slope of the embankment. For some reason Gunson convinced himself that the crack was not dangerous, but took precautions anyways by opening up the valves on the middle of the embankment to let more water through. Unfortunately these precautions did not prevent the already disturbing crack in the embankment.