Grćndalur valley in the Ölfus area merits maximum environmental protection according to the Icelandic Institute of Natural History, and the institute considers its conservation of international significance. There have nevertheless been proposals for a 120 MW power plant in the valley.
The Hengill Area and Ölkelduháls
The Hengill Area is one of Iceland‘s largest geothermal areas, approximately 100 km˛ in size. That is not to say it is all one and the same cauldron, but rather a composite of the Hveragerđi volcano (Grćndalur), Ölkelduháls and the geothermal area of the Henglafjöll mountains.
Considerable power plant construction has already taken place in the area, including power plants at Hengill and Nesjavellir. In the 2nd phase of the Master Plan for Hydro and Geothermal Energy Resources, further proposals for power plants at Grćndalur and Bitra are classified as protected, proposals at Gráuhnúkar, Hellisheiđi, Hverahlíđ and Meitillinn are classified as exploitable, while projects at Innstidalur, Ölfusdalur and Ţverárdalur await further assessment.
The hot springs and geysers with siliceous sinter deposits at Hveragerđi and Reykjar are characteristic of the Grćndalur area, along with the numerous natural springs that are formed during rockslides. Steam fumaroles are common in the area and often coincide with cracks formed in the large earthquakes that periodically hit South Iceland.
At Ölkelduháls, there is a lot of geothermal activity of various kinds. Numerous large mudpots, muddy hot springs and fumaroles are dotted around the area. In several places, vestiges of powerful steam explosions can be found. Mineral salt and sulphuric deposits predominate. At Klambragil canyon at the bottom of Reykjadalur valley, great bubbling hot springs can be found, from which a hot stream runs before joining a colder current and creating an optimal bathing spot in the river Reykjadalsá.
A large portion of the area is on the Nature Conservation Register, i.e. the drainage basin of Grćndalur valley, Reykjadalur valley and Hengladalir valleys. There are several popular hiking routes in the area.
Grćndalur valley is home to luxuriant vegetation and several rare plant species that in Iceland can only grow in geothermal areas are found there. Amongst these species, Water Speedwell and Redshank are listed as endangered species. The area‘s hot springs foster a uniquely varied ecosystem.
Grćndalur valley lies almost directly inland from Hveragerđi but the entrance to the valley is narrow and inconspicuous. The valley is also named Grendalur but the appellation Grćndalur (literally "green valley") is most appropriate due to the valley‘s abundant and verdant vegetation.
Signs of geothermal activity are very widespread, along the sides as well as in the innermost part of the valley. The underlying rock stratum is dense and absorbs a limited amount of surface water. As a result there are signs of flooding along the sides of the valley and small springs form there.
Geothermal activity in the valley is unusually varied. Fumaroles are especially common, but there are also mudpots, small explosive craters, hot patches, hot springs, as well as small streams that meander down the slopes.
Grćndalur valley is one of Iceland's largest untouched hot spring areas in the vicinity of urban areas. The Icelandic Institute of Natural History and the Environment Agency of Iceland have proposed that Grćndalur be afforded protected status. Grćndalur is easily accessible by driving north from Hveragerđi to where the road ends.
Photo © Sóley Stefánsdóttir
Proposals exist for a 120 MW power plant at the mouth of Grćndalur valley. Permission has been granted for experimental drillings and other geothermal research in the area.
Photo © Hlynur Stefánsson