Derry Dam (historic)
Derry Dam (historic) is the (ruined) artificial dam build across the breach in Derry Dam (prehistoric) through which the Uisge an Doire continues to flow. Derry Dam (historic) stood a short distance upstream from Derry Dam Footbridge.
It would be relatively easy to recreate the prehistoric 'Loch Doire' by building an artificial dam across the breach, and apparently that’s exactly what was done in the early 19th century by Alexander 'Sandy' Davidson.
About 1828 Alexander 'Sandy' Davidson - built an artificial dam across the breach in the Derry Dam (prehistoric) during the earlship of James, 4th Earl Fife. Alexander 'Sandy' Davidson, was a very real, and larger than life Deeside character. 'Sandy' would have been about 28 years old at the time, and evidently rebuilt the dam to produce a man-made flood on Uisge an Doire, Laoigh to float logs down to the Dé. A full account of ‘Sandy’ Davidson’s life appears in Michie (1872) where the author refers to the construction writing :
… about a mile above its [Gleann Doire] opening into Glenlui are to be seen some very manifest and undisturbed specimens of terminal moraines. Here we may suppose the ice made its final stand as a glacier, here deposited its last burden - Sandy Davidson was no geologist, and did not visit Glen Derry for the purpose of making observations on glacial action, but of purchasing Scotch fir from the Earl of Fife, [sic] and bring it to market in Aberdeen. He accordingly took advantage of these terminal moraines, to construct a dam of sufficient size to make a large lake in a long hollow which the ice had scooped out behind them, and thus give him the water power to float his timber to the Dee
- Michie (1872) (p206-207)
The knowledge of this Derry Dam survived into the 20th century - in Gordon (1925) the author refers to its foundations in passing - writing :
The Derry burn is crossed by a bridge a little below the foundations of the old Derry Dam. A hundred years ago this dam regulated the artificial floods that floated the timber down the Dee : it was demolished by the great spate of 1829
- Gordon (1925) (p46)
Clear physical evidence of the historic Derry Dam survived into the 1950s. A storm in August 1956 resulted in a flood that undermined the Luibeg Footbridge ; that flood may also be responsible for the removal of the last physical evidence of the historic Derry Dam