THE state of Oxfordshire’s rivers and the threat of a drought are causing mounting concerns with water levels described as “exceptionally low”.

Water flows in the Thames, Evenlode, Cherwell, Thame and the Ock are now believed to be around half or less the normal rate.

Thames Water said it is switching on a back-up network of underground water storage reserves for the first time since 2006, amid fears of a summer drought.

The company confirmed it still requires 80 per cent of average winter rainfall to avoid the likelihood of drought-related water-use restrictions in the region next year.

The Thames Valley has seen below average rainfall for 16 of the past 20 months, with Farmoor Reservoir 86 per cent full, at a time of year when it would be expected to be full.

Richard Aylard, Thames Water’s director of external affairs and sustainability, said: “It may come as a surprise to be talking about drought at Christmas.

“But if we don’t get close to average rainfall this winter there is a very real possibility of a drought next year.”

Thames Water spokesman Becky Johnson added: “Following below average rainfall for 16 of the past 20 months, our focus right now is getting people to use this precious resource wisely.

“To avoid the likelihood of drought-related water use restrictions in the Thames region next year we need 80 per cent of our long-term average winter rainfall this winter.

“We’re doing everything we can now to help to ensure there is enough water to go around next year.”

The company is also preparing early in the New Year to turn on the Beckton desalination plant for the first time to top up water supplies from seawater, if the weather remains dry. It would be the first time that the plant has operated since it opened last year.

The plant is capable of putting an additional 150 million litres a day into supply.

Joe Giacomelli, spokesman for the Environment Agency, said the five Oxfordshire rivers were among eight rivers viewed as being “exceptionally low”.

Riverflows in the Evenlode, Thame and some sections of the Thames were reported as being the lowest since records began for November.

He said: “We are closely monitoring the flows in our rivers.

“We are investigating reports of incidents such as occurrences of blue algae, fish in distress and pollution incidents exacerbated by lower flows, and carrying out fish rescues where appropriate.

“We are working with water companies to ensure they store as much water in reservoirs now to improve resilience of public water supplies next year.”

Mr Giacomelli added: “Low flows could also affect the ability of businesses to abstract water, and could, in turn, mean water companies may need to put in place hosepipe bans next year.”

Both the Environment Agency and Thames Water made separate appeals for people to use water more efficiently.