With the hills often shrouded in clouds, it is not surprising that they have a wide range of freshwater habitats. These vary from bog pools and damp ‘flow bogs’ at the summits, to small mountain streams. The streams become larger wooded rivers and waterfalls, finally feeding urban rivers down to the River Lagan and Belfast Lough, or west through countryside to Lough Neagh. Water is also supplied from groundwater sources which bubble up as springs and which have been used by people and businesses in the hills for centuries. In addition there are quarry ponds, old millponds and reservoirs scattered along the hillsides.
Each of these freshwater habitats, from stagnant to fast moving water comes with its own mix of plants, insects, amphibians, fish, birds and mammals. Upland ponds attract dragonflies and damselflies as well as newts and frogs. The fast flowing streams are home to dippers, caddis flies and mayflies. The rivers of the Belfast Hills are visited by otters looking for salmon and trout, which rely for survival on the clean waters flowing down from the hills.