Llyn Alaw is a large man-made reservoir near the village of Llannerchymedd, on Anglessey, North Wales, which was built in the 1960s. It supplies water to the northern side of the island. It has a length of 4.3 km (2.7 miles), a surface of 3.6 square km (2.2 square miles) and a maximum depth of 5.2 m (17 feet). It is designated a Site of Special Scientific Interest, being the home of a variety wild fowls, especilally overwintering birds such as whooper swan. It supports a recreational trout fishery, where permits are available. This reservoir stands in an open landscape and has a wide parking area.