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Leinster Leader 15th April 2010
Flooding the valley … 70 years of Poulaphuca

Seventy years ago this Spring a sluice gate was dropped on the flow of the river Liffey at Poulaphuca (south of Blessington) and the landscape on the Kildare/Wicklow boundary was changed for ever. The sluice gate operation was part of the construction of the Poulaphuca dam and reservoir which harnessed the Liffey.  In the seventy years since the scheme has provided a source of environmentally friendly power and a reliable supply of water for the metropolis of Dublin and adjoining districts.  The name Poulaphuca (translated as ‘cave of the evil one’) echoes superstitions that a hideous supernatural creature lived in the sheer-sided gorge where the Liffey poured through a chasm in the hills east of Ballymore Eustace. However any lingering fear that there was something sinister in the deep gorge was literally blown away when the drills, compressors and excavators of the ESB’s contractors moved on to the site in 1937 to begin work.  This was a massive civil engineering project for its time and was one of the few new projects to bring hope to the nation during the grey years leading to the second world war.
The Leinster Leader’s West Wicklow notes correspondent was among the first to record the beginning of work in an issue of November 1937: ‘The erstwhile lonely, silent conditions at Poulaphuca waterfall have suddenly been displaced with extraordinary hum and activity. Fifty men have already started work on the scheme. Houses, including a new Garda station, are springing up rapidly and before long the entire district included in the scheme will see a little army of workers employed there.’
The Poulaphuca scheme was a joint project between the ESB and Dublin Corporation, the latter providing additional employment in the making of a box culvert for sixteen miles through East Kildare from Poulaphuca to the city reservoirs at Saggart.
The main contract for the massive dam construction work had been awarded to the Francois Cementation company, based in Doncaster, England. The company had patented a method of sealing porous stone against water seepage – an important consideration given that the dam was wedged in a gorge of Wicklow rock. Their contract for the construction of the dams, tunnels, and structures at both the Poulaphuca dam, and its little brother downstream, the Golden falls dam, had a value of £300,000 out a total scheme budget for the dam and reservoir of £750,000 (1937 prices).  A more distant cousin, the Leixlip dam, was built to control the Liffey flow before it reached the city.
Employment on the scheme grew spectacularly at Poulaphuca as the construction tempo accelerated. From the fifty workmen who had moved on site in November 1937 the workforce had grown to 200 by July 1938. Another 120 were employed by Bray based contractor C.S.Downey on the construction of three new bridges facilitating a roads system to link communities cut off by the flooding of the valley.
An Irish Times reporter who visited the site in February 1939 was clearly impressed by the dynamism of the construction operation at Poulaphuca: ‘High up on the rock face, drills were preparing for fresh charges of gelignite and when I was in the neighbourhood I heard several explosions … Near the face of the dam, which is being treated with a special preparation which ensures it is water tight, the tunnel which will carry the water to the power-house is being bored.’ By that time 12,000 tons of concrete had been poured into the dam; the same quantity again would be required to complete it.
The prelude to the scheme had not been without its problems; the dwellers and farmers of the valley had to be compensated and relocated. Some left under protest; others anticipated a new beginning on Land Commission farms in the Mullacash and Donadea areas of Co. Kildare.
Yet by early 1940 all was in readiness to begin flooding. The dam had been completed; and some 5,500 acres of the Liffey valley between Blessington, Lacken and Valleymount had been vacated by man and beast. While it would be another four years before the heavy turbine plant was in place to generate the first current, all was now ready for flooding the valley. The sluice gate was dropped on the river flow at 10am on 3rd March 1940. The mountain waters of the Liffey began to pool behind the dam, extending to an area as large as the Phoenix Park by autumn of that year.  Seventy years later the Poulaphuca lakes appear as if they were part of nature’s gift to West Wicklow. Instead they are the product of inspired planning and hard work by the generation that literally shaped Ireland in the middle decades of the twentieth century.  Series No: 173.

In his regular column 'Nothing New Under the Sun' Liam Kenny  reflects on the Poulaphuca dam and reservoir which harnessed the Liffey 70 years ago.  Our thanks to Liam.

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