Duckweed on the River Brue at Plungen, September 2017

And what’s this frothy stuff floating by?


Information leaflet, August 2019

This picture of the River Brue was taken near Glastonbury in September 2017, when there was an exceptionally prolific growth of duckweed covering the river’s surface. This is caused by an excess of nutrients in the water, and if it blocks the light from the river it can seriously harm aquatic life. The river has to be cleared mechanically once a year to prevent water weed, reeds and other river plants from choking the waterway completely.

The condition of the River Brue, in terms of pollution, has since 2009 been monitored by the Environment Agency in accordance with the European Union Water Framework Directive. The Directive classifies the biological state of each river as high, good, moderate, poor or bad, and it set a target for all waterways in Europe to be in ‘good’ condition by 2027. In the UK only 27% of our rivers are classified as ‘good’, with the River Brue remaining ‘moderate’ for much of its length and ‘poor’ in its lower reaches.

This is mainly due to the effects of chemical fertiliser run-off from agricultural land, particularly phosphates. Half of all chemical fertiliser that ​is spread on the land ends up in our rivers, and the only real remedy for pollution from fertiliser run-off is a reduction in its use.

And what’s this frothy stuff floating by?The Environment Agency has responsibility for bringing about improvements, though during the first ‘cycle’ of the Directive period (up to 2015) this amounted to little more than identifying sources of pollution and offering advice, relying on voluntary compliance from private landowners. The only areas where improvements can realistically be made are those controlled by statutory bodies or local authorities, such as sewage works, where remedial measures have reduced seepage into the surrounding environment. This addresses only a minor proportion of the problem, however.

The overall results, by 2013, were not very encouraging. According to an Environment Agency report dated 2014, “Many water bodies in the Brue and Axe operational catchment have a drop in status between 2009 and 2013.” Across the country as a whole, the number of waterways in ‘good’ condition dropped during the six-year period up to 2015.

In the Environment Agency’s management plan at the beginning of the Directive’s first ‘cycle’ in 2009, it was stated that “the way in which land is managed is still having a negative impact on natural resources and further action is needed to address diffuse pollution and other key pressures in rural areas. Government will consider … restrictions on chemicals where there is evidence that voluntary actions failed to deliver.” What this might mean in practice has not been made clear, though currently there is no government commitment to introducing such controls. Once the UK has left the European Union, the Water Framework Directive will no longer apply here. If there is also economic pressure to produce cheap food, then introducing controls on chemical fertiliser is likely to be a very low priority.