Most of the river and its corridor have been identified as Local Biodiversity Sites (LBS) and several protected species live along its course. The wooded river-banks are host to carpets of wildflowers and many dramatic trees, including patches of ancient woodland. Often peat-stained, the water is still of a high quality both chemically and biologically, so many species of invertebrate and fish flourish.
Notable bird species resident on the river include: kingfisher, dipper, grey wagtail, heron, cormorant, goosander, swan and moorhen. Great spotted woodpecker, long tailed tits, mistle and song thrush, sparrow hawk and tree creeper are frequently spotted in the woodlands.
Mammals resident around the river include; otter, badger, roe deer, grey squirrels, stoats, foxes and bats (common and soprano pipistrelle, and daubentons).
Up to fourteen species of fish have been recorded in the river. However, the 2009 survey only noted nine species including brown trout, European eel and various species of Lamprey.
Balerno Common and Bavelaw Marsh is the only Site of Special Scientific Interest (SSSI) within the catchment and is adjacent to Harlaw Reservoir. There is a Special Protected Area (SPA) for the Tern colony in Leith Docks close to where the Water of Leith flows into the Firth of Forth SPA.
The river flows from upland grassland and heathland, past wetland reservoir habitats, through agricultural grassland and forestry into the almost continuous riparian woodland between Balerno and Leith. In urban areas, it passes several city parks, numerous private gardens, meadows, community gardens, allotments and some living landscape areas. Extensive biological records and habitat maps are available – contact us for details.