Þverá, a clear river into which all the streams from Fljótshlíð flow. Previously this river got a good share of glacial water from Markarfljót, which would turn Þverá into a menace that often broke down the fertile land of the district. A series of protective rock barriers was built in order to keep Markarfljót in its own course and since then grasslands are being recultivated.