This weir is one of many barriers to fish migration in the River Darwen catchment, and like many of the weirs, it was built to supply water to a mill. Maps of Lower Darwen from 1845 seem to indicate that this weir supplied a mill race for Ewood Cotton Mill. By 1895 the mill race had been modified and although it still supplied Ewood Mill, it first supplied water to Scotshaw Brook Paper Mill. In 1945 both of the mills were demolished, although the redundant weir remained standing.
The section of river which the mill lies in is relatively secluded, although it is adjacent to a leisure centre, nursery, and industrial estate. It can also be seen from the River Darwen Parkway Local Nature Reserve. The weir is concrete faced over stone sets, the structure itself is concave with an irregular gradient and step at the toe.
Studies showed that even partial removal would be too high risk for this site and so a rock ramp bypass channel was created around the left hand side of the weir.
The path of the overspill from the river during high flows is beginning to erode a channel behind the weir. The rock ramp will follow the path of the overspill and help to stabilise the banking at this point and reduce the chances of weir failure.