Craig Goch Dam is a masonry gravity structure built between 1897-1904. The dam is 36.5 m high above the river bed, 119 m long, 32 m thick at the base and the foundation extend 3 m below the river bed. Craig Goch reservoir has a capacity exceeding 9 billion litres covering an area of 217 acres. The primary purpose of the dam and other reservoirs in the area is to supply Birmingham with water.
Purely for intellectual interest, Dr Mothersille and his 26-year-old son Reiss visited the structure and were fortunate enough to witness it spilling and conveying thousands of litres of water downstream.