River LennonThe River Lennon or Leannan is a river in County Donegal, Ireland.CourseThe River Lennon rises in the Glendowan Mountains and flows through Gartan Lough and Lough Fern. It continues through Kilmacrennan and enters Lough Swilly at Ramelton.WildlifeThe River Lennon is a noted brown trout fishery. Salmon numbers are recovering after a UDN outbreak in the 1970's. Other species found in the river include the freshwater pearl mussel, European otter and slender naiad.