Hjaltadalsá is a river in Hjaltadalur valley in Skagafjörður, Iceland.

[1] It originates from Hjaltadalsjökull glacier and runs the full length of the valley, before many tributaries and lakes flow into it.

Further down the river there are lots of rapids and small waterfalls and the current is strong and rough in many places.

A little past the town of Sleitustaðir, the Hjaltadalsá and Kolka rivers run together.

Hjaltadalsá often contains outwash, but Kolka has much more of it, which results in a significant color difference where the rivers converge.