Gartmorn Dam Pump House

In 1710 George Sorocold, a hydraulic and mining engineer from Derby, was commissioned by the 6th Earl of Mar to advise on the drainage of his coal mines at Sauchie north of Alloa. Sorocold recommended that the reservoir with its earth embankment which had been rebuilt by the Earl as early as 1694, now known as Gartmorn Dam (NS99SW 90.03), and which was fed with water from a small burn, should have its power capacity increased by means of a substantial additional feeder from Forest Mill on the River Black Devon about two miles to the east.

At Forest Mill, water from the river was diverted for the mill and feeder to Gartmorn Dam at a horseshoe shaped masonry weir some 10 ft high. Construction of the feeder along the north flank of the river valley, and requiring several rock cuts, was a considerable challenge in 1710. Sorocold set it out using a large wooden quadrant with a plummet set on a tripod. The feeder was cut soon afterwards (NS99SE 16, from NS9539 9386 to NS9291 9412).

His advice for improved pumping at the mines seems to have been disregarded as an earlier chain and bucket arrangement continued in use. In 1767 Smeaton was consulted about improving the transport of coal from Sauchie and reported on making the Devon navigable to the Forth.

In 1785 the dam (NS99SW 90.03) was heightened and surfaced with rough hewn stone, and in 1827 was repaired for £300. The weir at Forest Mill (NS99SE 16) was rebuilt in 1835 for £248 (see Paxton and Shipway, 2007, 340). From 1820 onwards some of the water was led to Alloa for domestic use through wooden pipes and since 1860 the system has been used solely for this purpose. In 1894 the dam (NS99SW 90.03) was given a stone face and its crest was raised by a further 2 ft increasing the water area to about 160 acres. A pump house was also built which is now the Visitor Centre (NS99SW 90.06).

The dam itself is believed to be the oldest in Scotland still in use for water supply. It is now located in a country park giving public access to all surviving features of the system.

R Paxton and J Shipway 2007

Reproduced from 'Civil Engineering heritage: Scotland - Lowlands and Borders' with kind permission from Thomas Telford Publishers.