The name means a wet and mucky area and its also known to locals as Pixies Paradise. It is sourced up on Cairntogher Mountain, one of the major peaks of the Sperrins and flows into the Clady. It is regarded as a good fishing river by locals of Maghera, Swatragh and the Clady And District Angling Club. It also flows through the nature reserve of Drumnaph Woods, making it a major checkpoint in the forest reserve. It is known as the salmon's kingdom in the forest because of the many fish species — including salmon, Rainbow Trout, Brown Trout, Dollaghan on occasion , and other smaller fish that is caught from time to time the tend to hide in the rocks or deep under the water the best method on this river for those who are anglers is spin fishing with mepps or Z or even toby lures — these fish migrate upriver to spawn and lay eggs. Often dippers are spotted around the old bridges, where they dive to the bottom in order to feed on a range of aquatic invertebrates.The river itself is a spate river during the winter; it is fast flowing with white rapids. In the summer, the river is a lot lazier, and collects a lot of green algae, especially around culnady downwards making it difficult for deeper fishing at these times. The river itself is about 5 to 7 metres in the upper reaches and about 10 metres on its lower course The Grillagh Empties Into The Clady River