What is Riverfly Monitoring?
Riverfly are the small aquatic creatures that live amongst the sediments and plants along the river bed and its margins. Their sensitivity to water quality means that the different kinds present in a river or stream provide a valuable indicator of river pollution levels. Whilst many different aquatic organisms may be found, the most sensitive species - mayflies, stoneflies and caddisflies, are a key focus as indicators of high water quality.
Monitoring riverflies is fascinating way to record the health of our river ecosystems, discover local wildlife and enjoy time in nature. Carrying out riverfly monitoring also enables rapid identification and reporting of pollution incidents.
Serious pollution incidents in our watercourses, can spell disaster for river wildlife. Regular monitoring is the best way of identifying such incidents early and enable a rapid response. It helps rivers to be monitored more widely and at greater frequency than is possible by the Environment Agency alone.
The Riverfly Monitoring Initiative (RMI) is a national Citizen Science activity, launched by the Riverfly Partnership in 2007 to enable interested groups to actively monitor and protect their local rivers. RMI training provides knowledge and safe techniques for individuals, working in pairs to take regular monthly samples from a range of river bed and marginal habitats. Samples are sorted by the riverside and the presence and abundance of pollution-sensitive invertebrate groups can be recorded, providing insights into river health. If invertebrate numbers drop below expected levels for the site, the Environment Agency are informed and will take action to investigate suspected pollution incidents.
Riverfly data, shared via the Riverflies Cartographer platform, are uploaded by each RMI team, allow long-term changes to be identified, and the regular presence of volunteers on the river will discourage potential polluters.
RMI is used widely in the UK as a 'neighbourhood watch' for rivers, practiced by anglers, community groups and river practitioners. It has proven effective in identifying pollution incidents and ensuring action is taken. In several cases this has led to prosecution of polluters by the statutory authorities and has prevented similar future incidents.
RMI is widely recognised on all Water Framework Directive River Basin Management Plans in England and Wales.
Get involved in Riverfly Monitoring!
The Colne and Chilterns, Hertfordshire & Middlesex Riverfly Hubs provide RMI training and support to anyone wishing to monitor the health of rivers in the Colne catchment plus wider Hertfordshire, Middlesex and Chilterns areas. For any questions or if you would like to get involved in Riverfly Monitoring on the upper, main and lower River Colne networks, contact Colne Riverfly Monitoring Hub coordinator Matt at This email address is being protected from spambots. You need JavaScript enabled to view it.
The Chilterns, Hertfordshire & Middlesex Riverfly Hub* is a partnership set up in 2014 and jointly led by the Chilterns Chalk Stream Project and Herts & Middlesex Wildlife Trust. For more information, or to register your interest in becoming a Chalk Stream Riverfly monitor, please contact the CHM Riverfly Hub coordinators via This email address is being protected from spambots. You need JavaScript enabled to view it.
You can see their Annual Riverfly newsletters here: Riverfly | Chilterns Chalk Stream Project
Local Riverfly monitoring groups are active on the following rivers in the Colne catchment:
Colne - Friends of Oxhey Park / North Harrow Waltonians Angling Soc. / Bath Road Piscatorial Soc.
Ver – Ver Valley Society & Redbournbury Fishery
Gade - The Friends of Gadebridge Park / Friends of Croxley Common
Bulbourne - The Box Moor Trust
Chess – River Chess Association
Misbourne – Chiltern Society & Misbourne River Action
Pinn - River Pinn Riverfly Group
*The Chilterns Herts & Middlesex Riverfly Hub is supported by grants from Affinity Water, Natural England via the Lea Catchment Nature Improvement Area and the Chilterns Chalk Streams Project. The hub’s partners include:
