Phosphates in Wales

This week, we have had our first taste of the Phosphate Planning Issues arising in Wales. This relates to the trickle down from the Dutch N Ruling (2018) which has been affecting various parts of the UK, since late 2020.

The Afon Teifi, Afon Tywi (River Towy), River Wye and Afon Cleddau are located in special areas of conservation, and as such affected by the ruling.

For this our first report in Wales relating to the Phosphate situation we have encountered some key differences, between Wales and England.


So Far only Carmarthenshire has release a budget calculator. Compared to the the calculators we have been using in Somerset and Cornwall, it is quite limited, although it is good that it can be used offline, so we can save a copy for later use, or reference! Take note Somerset and Cornwall (probably not though).

The Carmarthenshire calculator does not automatically calculate mitigation options. This leaves sizing of wetlands for example up to the applicant / agent / consultant. And we would consider this problematic, as even with agree methods (as indicated in Somerset / Cornwall Calculators) there is enough detail to contest, without added variability.

Treatment Works

Unlike the Sewage Treatment Works (STWs) we have seen in England, many of the welsch plants have no consent limit for Phosphates. They are also for the most part way over capacity, as some of them run in overflow mode (raw sewage in rivers) for 50% of the year.

This lack of consent limit is an advantage for developers and open the possibility of pre-treating waste water from mains connected sites, to provide a benefit.

Some Similar Problems

However, some things remain the same:

In Somerset and Cornwall we have had very little feedback on sites with wetlands, or sites which use extant uses to offset new uses, or that use off-site schemes. They are all in limbo, I wouldn’t mind some critique because at least that might seam as though things were moving along. I expect this to be the same in Wales.

There have been queries on other application in Wales that seek to discredit the accuracy of treatment efficiencies. We have seen this in England and Wales. Wetlands for example for a project in cornwall have been called in to question. With regards to banking coefficients yes they will vary. But so do treatment efficiencies of manufactured solutions, and phosphate concentrations of effluent, and as such I do not think it is meaningfully practical to adjust banking coefficients.

As with all things environmental science we are trying to take a non-numerical highly variable system (a human urinating in a toilet) and apply maths to the resultant processes. It cannot be done 100% accurately. So uncertainty has to be accounted for. If a study were undertaken of say 50 systems, monitoring for inputs and outputs after 5 years we might arrive a c. 95% certainty that certain banking coefficint would be met. But in these early stages some uncertainty will have to be accepted. 

In the majority of reported cases the 99% filtration rate is achieved, and we have agreed to monitor outfall in long term, so very little remainder risk here.

In summary we need someone in NRW (or NE in England) to start making decisions on this promptly. IF not all the benefit that could occur driven by the real need for clean rivers could be written out of existence by the stroke of a pen by Llywodraeth Cymru.

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