Riverfly Monitoring - Citizen Science in action

As part of the national Riverfly Partnership, ARK are the Riverfly Hub for both the Kennet and Pang catchments. 

Our trained ARK volunteers monitor 64 sites on the River Kennet and its tributaries and 6 sites on the Pang to check the health of the river and pick up otherwise undetected pollution incidents. 


If you'd like to see the latest data please email anna@riverkennet.org

Click on the map to reach our interactive Riverfly Map to find out more: 

ARK and 
Citizen Science

Riverfly monitoring assesses the water quality of Britain's rivers by identifying and counting eight key indicator invertebrate groups which live in our rivers.  The data is shared with the Environment Agency, The Riverfly Partnership, The Wildlife Trusts, Thames Valley Environmental Records Centre and any other interested parties, as well as being analysed by ARK.  

Riverfly monitoring is a proven method of picking up pollution incidents that would otherwise go undetected.  In July 2013 a major chlorpyrifos pollution event was picked up by our monitors at Elcot Mill, Marlborough and subsequently led to the prevention of any further discharge of this insecticide into the watercourse. 

The Key Indicators: 

Caddisfly (Sedge) Larvae

Cased Caddis

Caseless Caddis

caseless caddis larvae

Upwing Fly Larvae

Mayfly (Ephemeridae)

Blue-winged olive (Emphemerelidae)

blue winged olive ephemerelidae

Olives (Baetidae)

olives baetidae

Flat-bodied Heptageniidae

flat-bodied heptagenidae

Stonefly Larvae 

Stoneflies - from the order Plecoptera


Freshwater Shrimp

Gammarus pulex

Case Study

Pollution Incident 2013

In July 2013 Action for the River Kennet's riverfly monitoring volunteers were the first to discover a catastrophic pesticide pollution event in the River Kennet just downstream from Marlborough.

 The incident made the national news and caused the river to be closed to protect public heath.  The pesticide was identified as Chlorpyrifos and our volunteers established that it had killed riverfly life in the river for 15km.  

Riverfly monitoring

Since then extensive research has been carried out in to the impact of the pollution on the health of the river. A summary produced in autumn 2015 by Clare Gray from Imperial College, London can be found here.  

An article on the role of citizen science, with specific reference to the River Kennet pollution incident is here.  

If you would like to find out more about our volunteer riverfly monitors click here

ARK Riverfly on ITV Meridian

On a sunny day in May 2023 ITV Meridian came to Englefield Estate to film riverfly monitoring on the River Pang. This was a great opportunity to highlight our expansion of riverfly monitoring sites to include the Pang; and demonstrate the importantance of working in partnership with private landowners such as Englefield Estate. 
To view the coverage click on the image below: