The contract included the making of a large stone dam at the southern end of the reservoir site, and the various feeders which would collect the water and deliver it to the canal.

With traffic on the canal less than expected, surplus was sold, with Manchester Corporation buying 200 million imperial gallons (910 Ml) between 1844 and 1846, to top up Gorton Reservoir.

With the growth of leisure traffic on the canal and the disuse of the water-saving side ponds on the locks, this capacity was proving inadequate by 1984, and a programme of raising the dam to prevent overtopping and erosion by wave action was started.

When a new concrete overflow was completed in 1987, it allowed the level to be raised again by 5.5 feet (1.7 m), increasing the capacity to 321 million imperial gallons (1,460 Ml).

The team produced a digital map of the lake surface, which was then divided up into 98-foot (30 m) squares, and used to guide a survey boat, which spent two days taking depth soundings using a multi-beam sonar.

The valve house, which controls the discharge of water from the dam to the canal and the Bosley Brook, is built of buff gritstone, with cyclopean stonework and a semi-circular entrance.

It is the original structure built in 1831 and is grade II listed,[7] as is the bridge with an elliptical horseshoe arch which carries the road across a stream at the eastern end of the dam.