The Wye in Crisis Andrew Nixon

The Wye in Crisis

- Andrew Nixon

Concern for the condition of the River Wye remains very high profi le. What started as a problem predominantly around agricultural pollution has broadened out with growing anger both locally and nationally with water companies and their regular practice of releasing untreated sewage into our waterways. For a long time, the Wye and Lugg were in the national spotlight but this has now spread to many other rivers across the UK. It is widely reported that phosphate pollution has two main sources: waste water treatment works (WWTW) and agriculture, with each contributing approximately 25% and 65% respectively. Other fi gures have been circulated but they are usually broadly similar. Phosphate pollution is problematic because it encourages algal blooms which can shade out other aquatic plants and when it dies the algae drops to the bott om of the river and smothers gravel beds. A healthy river would have an abundance of water crowfoot growing in vast beds and the River Wye was designated a SSSI and SAC in part because of the abundance of water crowfoot habitat. These beds are now largely lost from the Wye with phosphate pollution and more extreme winter fl ood events gett ing most of the blame. These water crowfoot beds are important parts of the river ecosystem, providing a nursery for small fi sh and important sources of invertebrates, both of which are essential to the food chain.

Water crowfoot (c) Linda Pitkin/ 2020Vision

A significant proportion of this phosphate comes from sewage treatment works with outfalls from WWTWs delivering phosphate-rich water to the river. There are periods during high rainfall when combined storm overflows permit untreated sewage to enter the watercourse. This has received significant national attention this year with public outcries at the frequency of these events. Increasingly, Welsh Water are installing phosphate stripping technology on their sites which helps to reduce the amount entering rivers. Many of the issues at treatment works can be addressed and work is ongoing, albeit more slowly than is desirable and at significant cost to us the water users. However, the majority of the phosphate comes from agriculture, which is a much more difficult nut to crack. The issue stems from overapplication of manures, essentially applying more phosphate to the land than the plants can use. Some manure is washed directly into watercourses during heavy rain events and residual phosphate can build up in the soils, ultimately entering watercourses when soil is eroded. Identifying, the sources can be difficult as it is a dynamic picture and pollution sources are usually diffuse. Recent research suggests that the legacy phosphate in our soils will prevent us meeting our phosphate targets for many years, even if we were to stop applying manures today. There will not be a quick fix. Much of the manure comes from intensive poultry units (IPUs) and is particularly high in phosphate. There has been much condemnation of the ever increasing number of IPUs given planning permission across Herefordshire and Powys as they are blamed for introducing ever more phosphate to the catchment. The origin of the phosphate is the poultry feed which is often imported from overseas and in itself is not from sustainable sources. Research by Lancaster University through the RePhoKUs project has calculated an excess of 3000 tons of phosphate is added to land in the catchment every year from all sources.

To get things back into balance we have to reduce the amount of phosphate coming into the catchment and/or export phosphate out of catchment to other areas where it is needed. Actions such as moving to low phosphate poultry feed are being considered and proposals to ship manure/phosphate to the east of the country (where there is a phosphate deficit) has also been suggested. As previously stated, ongoing upgrades to Waste Water Treatment Works to strip phosphate from waste water is also underway. There are some ‘solutions’ that we need to be wary of. It is often stated that using the manure in Anaerobic Digesters is one way to get rid of phosphate. This isn’t true. The amount of phosphate that comes out of an AD plant is equal to the amount that goes in. The digestate can then be spread on the land in the same way as manure. Similarly, the creation of a pyrolysis plant to effectively burn the poultry manure also results in no net reduction but could be useful in making it more transportable to other areas. Even if we do get an overall phosphate balance in the catchment we will still need much better nutrient management on farms and landholdings. Localised over-application will no doubt still continue as well as poor land management, resulting in soils and phosphates washing into our watercourses. Working with nature is critical and natural habitats have an important part to play. Managing floodplain as species rich grassland means far fewer inputs being added to the land, reducing overland flows and providing better absorption of nutrients. They can also play a hugely important role in boosting biodiversity, capturing carbon and regulating floodwater. Similarly, good soil health is crucial. We know that heathy soils have a complex ecology with microorganisms and fungi playing an important role in unlocking nutrients

and making them available for plant growth, reducing the need to add fertilisers. Furthermore, the creation of other habitats such as wetlands, hedgerows and woodlands can interrupt the flow of water, allowing suspended silts to settle out, absorb nutrients and also provide those additional benefits to wildlife and natural flood management. Herefordshire Wildlife Trust are actively looking to acquire sites where we can undertake work to generate and demonstrate these benefits. We have also worked closely with landowners throughout the Lugg catchment to support them to undertake similar work. A good example of how nature can provide solutions is the recent creation of an integrated constructed wetland by Herefordshire Council. The wetland has been developed adjacent to the Luston Waste Water Treatment Works, intercepting water from the outfall and putting it through further treatment before it enters the River Lugg. The wetland is a series of vegetated pools which captures phosphate in growing plant material whilst also providing a wetland habitat. Developers pay the Council to offset the phosphate associated with their sites and the money is used for the creation of further wetlands. Currently the Council hopes to construct three sites. It must be remembered this only reduces phosphates in order to provide offset or ‘headroom’ for new housing to be developed. All three wetlands combined would offset approximately 350kg of phosphate per annum. Currently we have a phosphate surplus of 3,000,000 kg across the catchment. So it is not a solution for the river but a novel means by which development can continue with no net adverse effect on water quality. Work to improve the river’s water quality needs to continue in parallel to address the source problem. The water quality problems are not going away for some time and work needs to continue from all involved to find and apply the solutions. We mustn’t also forget that there are many other problems affecting our rivers and we need to make sure that we continue to tackle issues such as invasive species, damage to the banks and channel and barriers to migration.