All of Somerset's rivers are "polluted beyond legal limits" with unacceptable levels of mercury compounds and other chemicals.

The Environment Agency (EA) has published new data on the health and quality of England's rivers – with the findings revealing no river has been rated 'good' on the level of chemicals flowing therein.

All five rivers in Somerset have scored decently on their ecology, but have failed to meet EA standards on chemicals present in their waters – with mercury, lead, insecticides and flame-retardant compounds all making unwanted appearances.

The findings come as Somerset West and Taunton Council declared an 'ecological emergency', with one Taunton councillor warning the country was "slipping backwards" on its environmental standards.

The EA measures the quality of England's rivers in two ways – the 'ecological' measure (i.e. how diverse and healthy its wildlife is) and the 'chemical' measure (i.e. whether the rivers contains too much sewage, phosphate or other similar unpleasant substances).

Each river is divided into separate catchments, with the quality being assessed for each catchment rather than for the entire length of the river.

All five of Somerset's main rivers (the Axe, the Brue, the Parrett, the Tone and the Yeo) were examined by the EA – and all scored either 'good', 'moderate' or 'poor' on their ecology.

The River Axe – which runs from Wookey Hole to its estuary at Weston Bay – was recorded as a 'fail' for its chemical levels, with the EA raising concerns over the levels of lead and mercury compounds.

The River Brue, which runs from Brewham to Burnham-on-Sea via Bruton and Glastonbury, also fared badly, scoring 'poor' on its chemical readings.

As well as levels of mercury compounds, the EA recorded unacceptable levels of polybrominated diphenyl ethers (PBDEs), which are used to make electronics and other goods flame-retardant.

One stretch near Glastonbury also recorded high levels of perfluorooctane sulphonate (PFOS) – which is used in foam fire extinguishers and metal plating.

These same compounds were found throughout the River Parrett, which flows from Chedington in Dorset to Burnham-on-Sea via Langport and Bridgwater – with the EA rating it as a 'fail' by its chemical standards.

One stretch south of Muchelney was also found to contain unacceptable levels of cypermethrin – an insecticide and neurotoxin widely employed in commercial agriculture.

The River Tone – which runs from Huish Champflower to Burrowbridge via the Clatworthy Reservoir, Wellington and Taunton – also came up short with its levels of mercury compounds, PBDEs and PFOS.

Councillor Caroline Ellis, who represents the North Town ward in Taunton, raised the issue during a virtual full council meeting on Tuesday evening (September 29).

She said: "What really horrified me in the last week was reading the Environment Agency report the state of our rivers – which says that every single river in England is polluted beyond legal limits.

"It's absolutely terrifying. I looked up the stretch of the Tone in Taunton and that failed the EA's chemical test – so that really brings is home that we're actually slipping backwards."

The River Yeo – which flow from Henstridge Bowden to Langport via Sherborne and Yeovil – also registered a 'fail' rating for its high levels of DPBEs and mercury compounds.

Taunton Deane MP Rebecca Pow, who holds a ministerial post within Defra, addressed the issue in a written statement put before the House of Commons on Monday (September 28).

She said: "The EA's latest water body classification results showed that 16 per cent of waters overall and 14 per cent of rivers are at 'good' ecological status.

"This is the same result as the data for 2016, which means progress in improving the ecological status of England's surface water has plateaued. More needs to be done and we need to go further and faster.

"We remain committed to bringing at least three-quarters of our water to as close as possible to its natural state as soon as is practicable – and in support of this, we will be bringing forward a further legally binding target in the Environment Bill.

"We are tackling pollution from poor farming practice with regulation, financial incentives and educational schemes for farmers. Water company investment is being scaled up to £4.6bn, the highest yet, in the next five-year period.

"A new task-force comprising the government and water companies will help address the problem of sewage discharge from storm overflows, and our new chemicals strategy will build on a robust statutory regime to ensure chemicals are managed and handled safely."