But despite its designation as a Special Area of Conservation (SAC), the Wensum was given the lowest average rating, with the report attributing a “dramatic negative effect on flylife” to phosphate fertiliser run-off from farms, and sediment pollution.
Report author Nick Measham, the STCUK’s environmental consultant, said: “The census revealed that the river Wensum’s fly life is suffering as a result of phosphorous and sediment pollution, probably mostly as a result of run-off from agricultural activities. But whatever the source, the EA (Environment Agency) needs to take action and we are keen to help. The river ranks bottom in our census which is a truly disappointing outcome for one of the UK’s four chalk streams protected as Special Areas of Conservation under the EU habitats directive.”
The report says flies and other invertebrates such as the freshwater shrimp are excellent indicators of the underlying ecological condition of rivers,, as they play a crucial role in the aquatic food chain, supporting plants, insects, fish, mammals and bird-life.
Dr Nick Everall from ecological consultants Aquascience Consultancy, which carried out the study, said: “Breaking some of these river findings down with controlled laboratory tests has recently shown that raised levels of phosphate and sediment, akin to many of our stressed river conditions, has a detrimental impact upon the survival of early life stages of the base of the aquatic food chain for species such as the blue-winged olive.”
Picture: Stuart Crofts
Mr Measham said an action plan to reverse the degradation of river quality would be put to the Environment Agency, highlighting the need to identify and regulate polluters.An Environment Agency spokesman said: “After considerable investment, rivers in England are the healthiest for 20 years. The Environment Agency will continue to work closely with farmers, businesses and water companies to reduce pollution and improve water quality wherever, and however, possible.
“We have been working closely with the Wensum Riverfly Recording Programme and welcome the findings of the Riverfly Census. The River Wensum is a unique chalk stream and a highly protected river and we have for many years been working to maintain and improve its quality and value.
“Since 2009 we have been implementing the recommendations of the River Wensum Restoration Strategy to improve the physical form of the river and we continue to undertake proactive pollution prevention work.
“Diffuse pollution in the form of sediment is an issue associated with land use and runoff in the Wensum, as it is with many rivers in East Anglia, and we are addressing this by working with partners such as landowners, Wensum Riverfly Recording Programme, Natural England, water companies, the Rivers Trusts and others. We have been working with the water company to reduce nutrient input from sewage treatment works by stripping phosphate from treated discharges.”
Other rivers included in the census were the Avon, Dove, Camel, Ure, Axe, Eden, Coquet, Itchen, Test, Lambourn, and Welland.
Farming response
Earlier this year, the Upper Wensum Cluster Farm Group was formed in a bid to reduce the impact of agriculture on river habitats and wildlife, bringing together 15 farmers and landowners to co-ordinate their conservation efforts across 5,000 hectares of land.
Kit Papworth is chairman of the lead partner, Pensthorpe Conservation Trust, and also a director of north Norfolk-based contracting farming firm LF Papworth.
He said: “There is no doubt diffuse pollution is part of the challenge. The way to solve the phosphate problem is to stop run-off into the river and as a group we shall be making sure we protect our key resource, which is the water.
“It is always frustrating to see reports like this, but their job is to raise these issues so we can address them. We have all got to improve.
“The great thing about this group is that we have all these stakeholders working together to improve the area. But we are at an early stage of this collaborative group, so I look forward to seeing this report next year to show what progress has been made.”
