Phosphorus, Chickens and the River Wye

S&TC’s agricultural policy is simple; incentivise farmers to invest in their infrastructure and spread the word about modern soil management, but always be prepared to use the current legislation to regulate persistent offenders...

Paul Knight, S&TC Fisheries Consultant

George Monbiot writing in the Guardian recently highlighted the dreadful state of Welsh rivers.  He focussed on the Wye, where intensive chicken farming discharges phosphate (P) at far greater levels than the safe carrying capacity of the river, leading to awful water quality and subsequent impact on its wildlife.  The NFU hang on the coattails of Natural Resources Wales, who state that P has improved in the river over recent years, but rather than crow that excess nutrient is no longer a problem, it is important to understand the way P acts in a river, and why no-one should be complacent about the state of the Wye or its sister Welsh rivers.

The easiest way to explain P’s impact on a river is to think of a cliff gently sloping down until it reaches an edge, which then drops vertically into the sea – let’s give the cliff-edge a value of 30 and the top of the gentle slope as 100.  P at 40 has broadly the same impact on water quality as it does at 100 – too much nutrient leading to excess algae growth, discoloured water and the ‘dirty’ riverbed to which George Monbiot  alludes, but once it drops back to 30, the improvement is dramatic, and the symptoms fall away, you might say, over the cliff edge and into the sea.

This rather simplistic explanation has an important message, cutting P back from 100 to, say, 50, is a huge improvement, to which government agencies and the likes of the NFU will crow about the great job being done.  However, in terms of water quality improvement that actually supports more resilient and healthy life in the river, it is virtually useless.  More work needs to be done to reach 30 at the cliff edge, and then the river really starts a rapid improvement.

So why is excess P a problem to water life, apart from making the river environment murky and the bed gravels covered in algae?  S&TC’s Riverfly Census showed that P, along with sediment and toxic chemicals, are the biggest river polluters across the UK, and that agriculture is their main source. Our further research proved that high P levels, particularly in conjunction with sediment, kills water insects, the vital basis of a river’s food chain.  So, P, especially in conjunction with sediment, is actually toxic to water life unless kept down to natural values, 30 in our scenario.

S&TC is now using this evidence to press Welsh government and Natural Resources Wales, and Defra/Environment Agency (EA) in England, to take river pollution seriously and tighten agricultural regulation to ensure that the wildlife of rivers such as the Wye have a much more natural environment in which to thrive.  We can never return our watercourses to their truly natural state, there will always be human impact in such a closely managed countryside as we have in the UK, but there are issues we can do something about if we have the political commitment to address them, and cutting back agricultural impact on our rivers is definitely one of those.

Strong regulation is a must, but we do not just advocate the stick approach.  If you read the executive summary of the Axe Report, you will see that financial incentives for farmers to improve their infrastructure can produce dramatic results, albeit that they were threatened with heavy regulation if they didn’t comply.  Persuading farmers to adopt better soil management techniques is also critical, so that P is kept where it belongs, on fields, rather than being allowed to leach into rivers.

However, the most important aspect of the Axe example is that sufficient resources were made available to the EA to properly address the poor ecological state of the river, and they did that by visiting farms and advising farmers, many of whom had no idea they were polluting the river.  The result was nearly £4m of inward investment into updated infrastructure, and that is the sort of funding we need replicated across the whole of Wales and England if we are to protect our rivers into the future.

So, S&TC’s agricultural policy is simple; incentivise farmers to invest in their infrastructure and spread the word about modern soil management, but always be prepared to use the current legislation to regulate persistent offenders so that it becomes uneconomic for farmers to pollute watercourses such as the Wye.  If we can achieve that, then our wild fish and all other water wildlife will have the best possible chance to thrive, even in our micro-managed environment.