The River Blackwater (Irish: Abhainn Dubh) rises in the Cuilcagh Mountains, in the townland of Gowlan, Parish of Killinagh, Barony of Tullyhaw, County Cavan.
It then flows in a south-east direction and ends in Ballymagauran Lough.
[1] It has a fish population of brown trout, pike and perch.
[2] The earliest mention of the river is in poems in the Book of Magauran dating to the 1350s.
This article related to the geography of County Cavan, Ireland is a stub.