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David Orr's avatar

I am not sure where you get the statistic that houses are the main phosphate polluter.

Most Somerset homes are connected to a mains sewer. These lead to a Wessex Water wastewater treatment works and these have steadily got better at stripping phosphates as Environment Agency discharge limits become tougher. The last period of improvement was between 2020-25 and from 2025-30 the new even lower discharge limits for phosphates are the lowest Technically Achievable Limit (around 1/8th of 10 years ago).

Consequently, it is now the case that for the Somerset Levels and Moors, the principal phosphate pollutions is likely to be from agriculture.

You can check the facts with Dr Andrew Clegg or Cllr Hobhouse or Lancaster University - who are doing research on nutrient pollution on the Somerset Levels and Moors on behalf of the Somerset Catchment Partnership (which ironically the Competent Authority Somerset Council doesn't attend).

Dr Clegg reports much improved river quality at Langport:

I live in Martock, where the River Parrett enters its artificial channel across the Somerset Moors to the sea.

I have, with others, been measuring the phosphate flow in the Parrett catchment for three years. This has evolved into two main studies.

One is a seasonal study of the Parrett flow from South Perrott near the source, to West Sedgemoor, the largest Ramsar area on the Somerset Moors. It has included Wetmoor, the Ramsar east of Langport.

The second study is a weekly monitoring of the Parrett phosphate load at Chiselborough and Langport which uses Environment Agency flow data.

The purpose of both has been to collect real and current field data to shed light on the alarming decline in the ecological status of the Moors in recent decades.

I would like to report three relevant outcomes

1 For the first time–probably for decades–we observed a ‘good’ phosphate reading at Langport yesterday (10March). The good/moderate borderline on the Environment Agency scale is 0.94 ppm of phosphorus. This improvement follows the installation by Wessex Water, at the end of last year, of phosphate removal stages at five upstream sewage treatment plants. This programme was designed to remove over 70 tonnes from the river each year. We anticipate that the improvement we report will continue, but slowly. This is because the considerable reduction in phosphate we have noted in individual sewage works outfalls is buffered in the main river by the large quantities of legacy phosphate tied up in the river sediment.

2 The Wessex Water improvement we are now seeing will have little impact on the two Ramsar areas because the river flows past them and not through them. This was, and still is, the primary purpose of the artificial river channel begun six centuries ago. Environment Agency flow data suggests, for example, that less than 0.1% of the phosphate in the Parrett enters West Sedgemoor.

3 We are observing a significant deterioration in phosphate contamination in the West Sedgemoor Drain. It is agricultural, originating on the Stoke St Gregory side of the Moor and pollutes the Main Drain which is itself an extension in the Moor of a small stream which flows (and brings some phosphate) from the Blackdowns. The phosphate is not due to water from The Parrett. In the same area of West Sedgemoor we have initial evidence that withy plantations appear be very effective at removing phosphate from the rhynes.

It is not my intention to make any comment on the relevance of this work to the catchment mitigation scheme beyond noting that while mitigation measures will doubtless impact phosphate within the catchment land area, they cannot have more than a minimal impact on the health of the waterways within the Ramsar areas. Phosphate is very strongly bound to the clay and tends to stay there, building up over decades.

This raises the important question we should all be taking note of as we consider biodiversity policy generally - if it is not Parrett catchment nutrient pollution that is the fundamental cause of the ecological deterioration of the Levels and Moors, then what is it?

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