The Ballymascanlan rises on Slieve Gullion and runs some fourteen miles to Dundalk Bay. It holds a modest stock of brown trout, but its summer salmon and sea trout are the draw, and the best of that lies in the pools below Ballymascanlan Bridge. This is a spate river: fish it after a flood, when fresh fish have run up on the rising water. Work the pools at night from July to September. Dundalk Brown Trout Anglers hold the day permits.
A flashy Slieve Gullion spate stream where stoneflies and terrestrials outweigh upwings; hatches are sparse and flood-driven, with night sedges the key food once sea trout run in summer.
- Mixed

