FEARS a reservoir built on the floodplain between Abingdon and Wantage would increase the risk of flooding have been dismissed.

Thames Water has insisted measures would be put in place because increasing the risk of flooding would not be acceptable.

The River Ock, fed by the Letcombe and Childrey brooks and swollen by rain in the wettest July since 1883, was one of the main reasons behind the floods.

More than 600 homes in Abingdon, Wantage, Grove and surrounding villages were hit. Since then, there have been fears building the reservoir would add to problems.

Tony de Vere, chairman of the Vale of White Horse District Council's Reservoir Advisory Group, said: "The prospect of such a huge reservoir being built over the floodplain of the Ock is a matter of great concern, particularly after the severe floods in July. Thames Water will have to compensate for any loss of the floodplain and the jury is still out on the reservoir."

Thames Water said the positive effect was that a reservoir would capture rain over an area of 6.4 square kilometres, rain that would otherwise add to flood flows in the Ock. But it admitted a potential negative effect was that it would displace part of the floodplain.

A Thames Water spokesman said: "Building the reservoir would result in the loss of some of the natural floodplain which provides some protection against river flooding.

"We would provide a new area of flood storage in the form of wetlands to the west of the proposed site plus 20 per cent extra as requested by the Environment Agency to take into effect climate change. We understand people's concerns in the light of the July floods and we are conscious of the effects a reservoir would have on the floodplain.

"We must comply with the guidelines laid down by the Environment Agency. Our proposals would compensate for the loss of the floodplain, in fact, the floodplain area would be even bigger."

Iain Brown, county councillor for the Hanneys and Hendreds, said: "If a reservoir is to be built, it will need to demonstrate that it does not affect the flows in the Ock and Letcombe and Childrey brooks. A flood compensation scheme should be built on about 20 acres of land between Grove and the Hanneys to prevent flooding from the increased housing development at Grove over the next 20 years."

David Bowen, chairman of Group Against Reservoir Development, said: "There is no way the floodplain could be replaced by new measures. We believe it would be impossible because there would not be enough room once the huge reservoir is built.

"The clay soil has very low permeability and drains poorly. It is hard to understand Thames Water's proposal to excavate part of the site to a greater depth in order to provide an adequate alternative floodplain, since these excavations are likely to fill from groundwater and the current capacity to retain surface water will not substantially increase."