The sources of Þverá & Kjarrá in Borgarfjörður come from lakes on Tvídægra by Kvíslamót, but from the lakes it is only a stones throw to the source of Núpsá in Miðfjörður. From Tvídægra the river runs through Kjarrárdal and there the tributaries Krókavatnsá og Lambá merge into it. Þverá & Kjarrá are in fact the same river, even though anglers sometimes talk about them as two separate ones. Kjarrá is the upper part of the river but Þverá the lower part, below the grazing fence above Örnólfsdalur. About 18 km above the confluence of Þverá and Hvítá, below the farm Guðnabakki, the river Litla-Þverá joins river Þverá. The fishing in recent years has been great, from about 1000 salmon up to around 3700 (2010). The best fishing was in the summer 2005, when 4165 salmon were caught.