Three dams on the Jökulsá á Dal; the Kárahnjúkar Dam (), the Desjará Dam () and the Sauðárdalur Dam () create the Hálslón Reservoir. At tall and long, the Kárahnjúkar Dam is the largest dam in the project and the largest of its type in Europe as well. The tall and long Desjará Dam and the tall and long Sauðárdalur Dam are saddle or auxiliary dams that maintain the desired height of the Hálslón Reservoir. Water from the long, capacity Hálslón Reservoir (about the size of Manhattan island in New York) is diverted down a long, diameter headrace tunnel towards the Fljótsdalur Power Station.