| Lough Derg | |
|---|---|
| Loch Deirgeirt | |
 | |
  Lough Derg Lough Derg (County Clare) Show map of County Clare Lough Derg Lough Derg (County Galway) Show map of County Galway | |
.png) Location in Ireland | |
| Coordinates | 52°59′N8°19′W / 52.983°N 8.317°W /52.983; -8.317 |
| Type | Freshwater lake |
| Primary inflows | River Shannon |
| Primary outflows | River Shannon |
| Basin countries | Ireland |
| Max. length | 38.6 km (24.0 mi) |
| Max. width | 12.9 km (8.0 mi) |
| Surface area | 130 km2 (50 sq mi) |
| Average depth | 7.6 m (25 ft) |
| Max. depth | 36 m (118 ft) |
| Water volume | 0.887 km3 (0.213 cu mi) |
| Residence time | 0.15 years |
| Shore length1 | 179,000 m (587,000 ft) |
| Surface elevation | 33.5 m (110 ft) |
| Settlements | Garrykennedy,Portumna,Killaloe &Ballina,Dromineer,Terryglass |
| 1 Shore length isnot a well-defined measure. | |
Lough Derg, historicallyLough Dergart (Irish:Loch Deirgeirt),[1] is a freshwaterlake in theShannon River Basin, Ireland. It is the third-biggest on the island of Ireland (afterLough Neagh andLough Corrib) and the second largest lake in the Republic of Ireland.
It is a long, narrow lake, with shores in countiesClare (south-west),Galway (north-west), andTipperary (to the east). It is the southernmost of three large lakes on theRiver Shannon; the others beingLough Ree andLough Allen. Towns and villages on Lough Derg includePortumna,Killaloe &Ballina,Dromineer,Terryglass,Mountshannon andGarrykennedy.
The lake's name evolved from the IrishLoch Deirgdheirc.[1] This was one of the names ofThe Dagda, the father of gods and men inIrish mythology, and literally means "red eye".[2]
Lough Derg has many islands includingInis Cealtra or Holy Island.
At its deepest, the lake is 36 m (118 ft) deep and covers anarea of 130 km2 (50 sq mi).[3] Close downstream from where Lough Derg empties into the Shannon are the falls of Doonass, the largest fall on the otherwise gently sloping river. Nearby is the location of thehydroelectric power plant atArdnacrusha, which, when built in 1927 was the world's largest.
In the nineteenth century, Lough Derg was an important artery from the port atLimerick toDublin through the canals in themidlands of Ireland. Navigable over its full 38.6 km (24.0 mi) length, Lough Derg is today popular with cruisers and otherpleasure craft, as well assailing andfishing. TheUniversity of Limerick has an activity centre by the lake, just north of Killaloe, where there arecanoes,kayaks,windsurfing, sailing dingies, and other recreations.
Lough Derg is home to anRNLI Lifeboat which is based at Dromineer, the first inland station in Ireland.[4] In June 2013, 35 people were brought to safety when a major rescue effort was undertaken after an international rowing event was hit by severe weather.[5]
Dublin City Council published a plan in 2011 for apipeline to supply up to 350 million litres of water a day from Lough Derg to Dublin city and region. In 2016 theParteen Basin at the south of lough was chosen as the proposed site of extraction. Water would be pumped to a break pressure tank atKnockanacree nearCloughjordan in County Tipperary and gravity fed from there to Dublin.[6][7][8][9]
A breeding pair ofwhite-tailed eagles first nested on an island in Lough Derg in 2012. This marked a great success for the Irish reintroduction programme started in the summer of 2007.[10][11][12]
Nitellopsis obtusa, an invasivealga in the familyCharaceae (stoneworts), was first recorded in Ireland in this lough in 2016.[13] In 2021, invasivequagga mussels were discovered in the lake and inLough Ree by a research team fromUCD.[14]
The North-East Shore is listed as a Special Area of Conservation.[15]
