Poulaphouca Reservoir, officially Pollaphuca (), is an active reservoir (for both water supply and electricity generation) and area of wild bird conservation in west

County Wicklow County Wicklow ( ; ) is a Counties of Ireland, county in Republic of Ireland, Ireland. The last of the traditional 32 counties, having been formed as late as 1606 in Ireland, 1606, it is part of the Eastern and Midland Region and the Provinces ...

Ireland Ireland (, ; ; Ulster Scots dialect, Ulster-Scots: ) is an island in the North Atlantic Ocean, in Northwestern Europe. Geopolitically, the island is divided between the Republic of Ireland (officially Names of the Irish state, named Irelan ...

named after the Poulaphouca waterfall on its south-western end where the water exits the lake. The lake is also commonly known as the

Blessington Blessington, historically known as Ballycomeen (, from the Irish surname ''Ó Coimín''), is a town on the River Liffey in County Wicklow, Ireland, near the border with County Kildare. It is around 25 km south-west of Dublin, and is situat ...

Lakes, even though there is just one. It holds 166 billion litres (43.8 billion gallons, or 0.2 cubic km) and has a surface area 22.26 km², making it the largest artificial reservoir in Ireland by capacity and surface area. It has a 44.3 km (27.5-mile) shoreline, and is 39.6 km (24.6 miles) from the sea.

History

It was created between 1937 and 1947, with flooding beginning at 10:00 on 3 March 1940 by

dam A dam is a barrier that stops or restricts the flow of surface water or underground streams. Reservoirs created by dams not only suppress floods but also provide water for activities such as irrigation, human consumption, industrial use, aqua ...

ming the

River Liffey The River Liffey (Irish language, Irish: ''An Life'', historically ''An Ruirthe(a)ch'') is a river in eastern Ireland that ultimately flows through the centre of Dublin to its mouth within Dublin Bay. Its major Tributary, tributaries include t ...

at Poulaphouca as part of the

Electricity Supply Board The Electricity Supply Board (ESB; ) is a state owned (95%; the rest are owned by employees) electricity company based in Ireland with operations worldwide. While historically a monopoly, the ESB now operates as a commercial semi-state concer ...

project to build a second

hydroelectric Hydroelectricity, or hydroelectric power, is Electricity generation, electricity generated from hydropower (water power). Hydropower supplies 15% of the world's electricity, almost 4,210 TWh in 2023, which is more than all other Renewable energ ...

station in

Ardnacrusha Ardnacrusha () is a village in County Clare, Ireland, located on the northern bank of the River Shannon. By road, it is north of Limerick. The name derives from the phrase ''Ard na Croise'' meaning "the height of the cross", due to a large cro ...

on the

River Shannon The River Shannon ( or archaic ') is the major river on the island of Ireland, and at in length, is the longest river in the British Isles. It drains the Shannon River Basin, which has an area of , – approximately one fifth of the area of I ...

being the first. Kaplan Turbine Pollhaphuca

The reservoir is one of two major sources of

Dublin Dublin is the capital and largest city of Republic of Ireland, Ireland. Situated on Dublin Bay at the mouth of the River Liffey, it is in the Provinces of Ireland, province of Leinster, and is bordered on the south by the Dublin Mountains, pa ...

water supply Water supply is the provision of water by public utilities, commercial organisations, community endeavors or by individuals, usually via a system of pumps and pipes. Public water supply systems are crucial to properly functioning societies. Th ...

, the other major supply being

Vartry Reservoir Vartry Reservoir () is a reservoir at Roundwood in County Wicklow, Republic of Ireland, Ireland. The water is piped from Vartry to a large open service reservoir in Stillorgan in the southern suburbs of Dublin. The reservoir is operated by Iris ...

in east Wicklow. Between 1938 and 1940, 76 houses were demolished, and the bridges at Humphreystown, Baltyboys, and Burgage blown up, in anticipation of the flooding of the valley for the Poulaphouca hydroelectric power station. In 1947, the recently flooded reservoir appeared in scenes of the film '' Captain Boycott'', parts of which were filmed in the lakeside villages of Lacken and Ballyknockan.

Technique

The Poulaphouca Reservoir supplies the three power stations along the River Liffey, which are located in Poulaphouca, Golden Falls and

Leixlip Leixlip ( or ; , ) is a town in north-east County Kildare, Ireland. Its location on the confluence of the River Liffey and the Rye Water has marked it as a frontier town historically: on the border between the ancient kingdoms of Leinster and ...

. Poulaphouca has the largest capacity with two 15 MW generators driven by

Kaplan turbine The Kaplan turbine is a propeller-type water turbine which has adjustable blades. It was developed in 1913 by Austrian professor Viktor Kaplan, who combined automatically adjusted propeller blades with automatically adjusted wicket gates to a ...

s, the other two stations have a capacity of 4 MW each, so the total capacity of the power stations on the River Liffey is 38 MW. The Kaplan turbines of the Poulaphouca station were delivered by the Swiss manufacturer Ateliers des Charmilles from

Geneva Geneva ( , ; ) ; ; . is the List of cities in Switzerland, second-most populous city in Switzerland and the most populous in French-speaking Romandy. Situated in the southwest of the country, where the Rhône exits Lake Geneva, it is the ca ...

Switzerland Switzerland, officially the Swiss Confederation, is a landlocked country located in west-central Europe. It is bordered by Italy to the south, France to the west, Germany to the north, and Austria and Liechtenstein to the east. Switzerland ...

. Each turbine has a capacity of 25,300 horsepower at a

hydraulic head Hydraulic head or piezometric head is a measurement related to liquid pressure (normalized by specific weight) and the liquid elevation above a vertical datum., 410 pages. See pp. 43–44., 650 pages. See p. 22, eq.3.2a. It is usually meas ...

of 50.5 m. The contract was executed in collaboration with

English Electric The English Electric Company Limited (EE) was a British industrial manufacturer formed after World War I by amalgamating five businesses which, during the war, made munitions, armaments and aeroplanes. It initially specialised in industrial el ...

from

London London is the Capital city, capital and List of urban areas in the United Kingdom, largest city of both England and the United Kingdom, with a population of in . London metropolitan area, Its wider metropolitan area is the largest in Wester ...

Nature

The reservoir is sometimes known as "lakes" due to its shape, which arises because it lies in not one but two river valleys - that of the Liffey and, primarily, that of the King's River. The King's River joined the Liffey at Baltiboys, at which point it was the larger flow, and when the Liffey was dammed upstream of the confluence, the King's River Valley was flooded far to the south. A ridge of land, on which the village of Valleymount lies, divides the southern part of the reservoir. The goosander, recently arrived as a breeding species in Ireland, can sometimes be seen here.

Blessington Greenway

Th
Blessington Greenway
walk is 6.5 km in length and links the historic town of Blessington with the Palladian mansion at Russborough House. The trail starts in Blessington village and leads south to the Avon Ri Activity Centre at the southern end of the town and weaves its way along the lake shores and forestry, crosses an ancient medieval Ringfort, and then uses the footpath along part of the N81 before turning back into the forest at Burgage Moyle lane. The Greenway follows the lakeshore and phase 2 is underway, with the goal of a 30 km greenway around the reservoir for walking, cycling and other recreational activities.

Gallery

File:Wicklow Mountains topographic map-fr.svg, Map of Wicklow detailing the lake File:Blessington Lake, County Wicklow 01.jpg, The lake in 1988 File:Moanbane, Silsean, Wicklow, Ireland.jpg, Moanbane hill overlooking the lake File:Sandy beach - geograph.org.uk - 904360.jpg, Baltyboys Lower Bridge crossing the lake File:Jan1985, frost by Blessington Lake 05.jpg, A frosty day by the lake File:Season 4 filming..jpg, Filming for ''

Vikings Vikings were seafaring people originally from Scandinavia (present-day Denmark, Norway, and Sweden), who from the late 8th to the late 11th centuries raided, pirated, traded, and settled throughout parts of Europe.Roesdahl, pp. 9� ...

'' on the lake in 2015 File:Mist on Blessington Lake - geograph.org.uk - 1615577.jpg, Mist on the lake

References