A 'COCKTAIL' of human waste and bacteria is destroying Oxfordshire's beloved waterways because sewage is pouring into them unchecked, campaigners have warned.

Condom wrappers, sanitary towels and wet wipes are just a few of the items photographed by the group Windrush Against Sewage Pollution (WASP).

Of the eight major rivers which flow through the county, including the Windrush, Cherwell and Thames, the majority were recently classed as either moderate or poor.

While the fall in quality is caused by several factors, councillors and campaigners have pointed the finger at Thames Water for allegedly overusing Combined Sewer Overflows (CSOs).

CSOs are used to stop sewage backing up into homes during heavy rainfall, but WASP has found faults in the system which it says mean sewage works are overloaded.

Thames Water, which was just last year fined a record £20m for pumping untreated sewage into the Thames, does not monitor all of its 650 overflows all of the time, but said it plans to start doing so 'by 2020'.

The Environment Agency, meanwhile, which is supposed to be a watchdog for all water companies' sewage outflow, has said it is also aiming to massively increase the amount of monitoring it does by 2020.

WASP founder Ashley Smith explained he had been alarmed to discover that such widespread pollution was being allowed to happen in the 21st century.

He said: "We're talking about a massive cocktail of human waste, antibiotics and bacteria in our rivers that's become water resistant and is now a real worry.

"CSOs are often the pollution method of choice.

"It's ludicrous that in the 21st century it's been allowed to get so out-of-hand."

England’s rivers are classified in five categories against European Water Framework Directive standards: high quality, good, moderate, poor and bad.

Environment Agency statistics show that in 2016 just two sections of river were in good health across the entire county: one part of the River Ock near Abingdon and one leg of the Cherwell.

Photos taken by WASP of the Windrush at Widford, near Burford, apparently illustrate this change: where in May 2009 the river was clear with healthy green plants, pictures taken eight years later show it to be a murky grey.

Agriculture, industry and fly tipping are among the factors causing this, but WASP argues the overuse of CSOs, which discharge sewage diluted by rainwater, is accelerating the decline.

Analysis of Thames Water data obtained by the group for the CSO on the River Windrush at Bourton-on-the-Water, upstream in Gloucestershire, showed the overflow being used non-stop for seven consecutive days in April 2018.

WASP now plans to undertake similar tests at works in Burford, Witney and Standlake and has received support from county councillor Nicholas Field-Johnson.

Earlier this month, Oxfordshire County Council unanimously passed a motion proposed by Mr Field-Johnson asking the council leader Ian Hudspeth to write to Thames Water, the Environment Agency and the Environment Minister about the overuse of CSOs.

The Windrush flows through Mr Field-Johnson's division of Burford and Carterton North, and the councillor, who used to fish in the river, admitted he was concerned about its current state.

He said: "Our green and pleasant land is being compromised by grey, murky rivers full of pollutants.

"If visitors come and see a murky river with Tampax and other things floating in it, that detracts from the Cotswolds Area of Outstanding Natural Beauty somewhat.

"Rivers are the arteries of our countryside and need to remain fit and healthy."

Water companies must notify the Environment Agency about discharge from CSOs in non-storm conditions, but not during legitimate storm discharges.

Operators are required to install storm spill monitors, known as Event Duration Monitors (EDMs), but in 2015 just 10 per cent were checked by the Environment Agency, a figure it is aiming to increase to 80 per cent by 2020.

Environment Agency land and water team leader Lucy Bee told this paper: "New EDM monitoring will tell us how often, and for how long a discharge takes place.

"If there is a breach of permit condition we will take firm enforcement action in line with our published policy.

"This was the case last year when Thames Water received a record £20m fine for several pollution incidents from their works.

"The success of the case was the result of work by the local Environment Agency team."

That fine came after Thames Water pumped 1.9 billion litres of untreated sewage into the River Thames in Buckinghamshire and Oxfordshire in 2013/14.

The company pointed out that this was due to equipment failures at ‘a handful’ of treatment works and pumping stations, not the overuse of CSOs.

Thames Water also said it had made ‘significant investment and improvements’ since then, including better training for staff and millions of pounds of investment in infrastructure at its sewage works.

The company revealed it had 'reduced pollution incidents' by 69 per cent since 2013 and has pledged that all its 650 sewer overflows would be monitored by 2020.

Representatives from the Environment Agency and Thames Water will also speak at a ‘Water Day’ hosted by West Oxfordshire District Council on October 4.

Thames Water head of environmental regulation, Yvette De Garis said: "Our 2020-2025 business plan, released earlier this month, includes a commitment to further reduce pollution by 18 per cent with a long-term aspiration to have zero pollution incidents.

“We take our responsibilities to protect the environment extremely seriously along with those to protect our customers from sewer flooding."

She added: "We’re now one of nine water companies who have signed up to set of shared principles alongside 20 environmental groups to work more closely together to reduce our impact on the environment which demonstrates just how important a matter this is to us."