A wide variety of invertebrates live in river and streams including worms, snails, leeches, fly larvae, crayfish and shrimp. These invertebrates differ in their tolerance to different pollutants, so by identifying which species are present we can determine how clean the water is. Their common characteristics of limited mobility, relatively long life cycle, presence throughout the year and specific tolerances to changes in environmental conditions make them powerful biological indicators to monitor water quality.

The Riverfly Partnership is a network of organisations and groups that regularly monitor river fly populations, coordinated by the Freshwater Biological Association. The river fly partnership concentrates on mayfly larvae, stonefly larvae and caddisfly larvae which require clean water to survive.

Find out more about the scheme here.

Yorkshire Dales Rivers Trusts hosts groups of Riverfly monitors on the Swale, Ure and Nidd, if you are interested in getting involved in monitoring contact: marie.taylor@ydrt.co.uk