Rahasane Turlough () is a turlough (an intermittent lake), west of

Craughwell Craughwell (historically ''Creaghmoyle'', from ) is a village and townland in County Galway, Republic of Ireland, Ireland. As of the 2022 census of Ireland, 2022 census, the village had a population of approximately 1,000 people. Craughwell is ...

in southwest

County Galway County Galway ( ; ) is a Counties of Ireland, county in Republic of Ireland, Ireland. It is in the Northern and Western Region, taking up the south of the Provinces of Ireland, province of Connacht. The county population was 276,451 at the 20 ...

. It is the largest surviving turlough in Ireland. A turlough is a

karst Karst () is a topography formed from the dissolution of soluble carbonate rocks such as limestone and Dolomite (rock), dolomite. It is characterized by features like poljes above and drainage systems with sinkholes and caves underground. Ther ...

lake, which has no surface outlet and is surrounded on all sides by rising land. At Rahasane the drainage has been modified in that since the 19th century the Dunkellin River has followed an artificial channel downstream of the turlough, but part of the flow continues to go underground, via a natural sink, into the underlying limestone. Rahasane consists of two basins which are connected at times of flood but separated as the waters decline. It covers at an altitude of above sea level. The site comprises marshes, and seasonally flooded

wet meadow A wet meadow is a type of wetland with soils that are Solubility, saturated for part or all of the growing season which prevents the growth of trees and brush. Debate exists whether a wet meadow is a type of marsh or a completely separate type of ...

s, with limestone outcrops and scrub at its margins. In the summer the lake empties and the basin is grazed by cattle, horses and sheep. The southern basin is the more impressive feature, with high rocky sides above an undulating base, strewn with boulders. There is a low hill on the south side of the main basin, and another on the northeast, near Shanbally Castle.

Ecology

It has been designated a

Special Protection Area A special protection area (SPA) is a designation under the European Union Directive on the Conservation of Wild Birds. Under the Directive, Member States of the European Union (EU) have a duty to safeguard the habitats of migratory birds and cer ...

and a

Special Area of Conservation A special area of conservation (SAC) is defined in the European Union's Habitats Directive (92/43/EEC), also known as the ''Directive on the Conservation of Natural Habitats and of Wild Fauna and Flora''. They are to protect the 220 habitats and ap ...

. It is an important location for migrating birds, and wintering ground for the

Greenland white-fronted goose The greater white-fronted goose (''Anser albifrons'') is a species of goose, closely related to the smaller lesser white-fronted goose (''A. erythropus''). The greater white-fronted goose is migratory, breeding in northern Canada, Alaska, Gre ...

. It is one of the few known breeding grounds in Ireland of the

Eurasian wigeon The Eurasian wigeon or European wigeon (''Mareca penelope''), also known as the widgeon or the wigeon, is one of three species of wigeon in the dabbling duck genus ''Mareca''. It is common and widespread within its Palearctic range. Taxonomy T ...

. The

garganey The garganey (''Spatula querquedula'') is a small dabbling duck. It breeds in much of Europe and across the Palearctic, but is strictly bird migration, migratory, with the entire population moving to Africa, India (in particular Santragachi), Ban ...

can be seen on occasion. It is a very good place to spot accidental visitors from America, such as the

American wigeon The American wigeon (''Mareca americana''), also known as the baldpate, is a species of dabbling duck found in North America. Formerly assigned to ''Anas'', this species is classified with the other wigeons in the dabbling duck genus ''Mareca'' ...

, and from Europe, such as the

black tern The black tern (''Chlidonias niger'') is a small tern generally found in or near inland water that breeds in Europe, Palearctic, Western Asia and North America. In winter the birds migrate to coastal areas of Africa and South America. Taxonomy T ...

. The

fairy shrimp Anostraca is one of the four orders of crustaceans in the class Branchiopoda; its members are referred to as fairy shrimp. They live in vernal pools and hypersaline lakes across the world, and they have even been found in deserts, ice-covered mou ...

'' Tanymastix stagnalis'' was first recorded in Ireland from the southern basin at Rahasane.

References

{{reflist Lakes of County Galway Karst Important Bird Areas of the Republic of Ireland Protected areas of County Galway Special Areas of Conservation in the Republic of Ireland Special Protection Areas in the Republic of Ireland Endorheic lakes of Europe