Derby is the small town with a big story. For a time it was the richest tin mine in the world. Water was the energy source, and to keep it coming, the company built water races and then a dam above the town. The inspectors said the dam would never fail. But in April 1929 it rained for five days straight, culminating in a final downpour of 5 inches in just two hours. 

Derby was the richest mine in the North East, but one of the few not worked by the Chinese.
As the largest, it was also the mine most thirsty for water. To get it the mine operarators built the longest water race in the North-East: 48 kilometres long, weaving its way from the headwaters of the Ringarooma through the hills to the mine in the valley. In dry summers, however, there was still not enough water to keep the mine going.

Construction began on a dam above the town, on the Cascade River. Completed three years later, it was declared ‘safe for its purpose’.

Then in April 1929, five days of torrential rain ended with a furious downpour: ‘a cloudburst’. The dam failed. A billion litres of water hurtled down the valley, taking everything with it. Derby would never be the same.