EA asks Thames Water for cuts in untreated sewage entering the Thames

Speaking at a conference on key environmental issues facing London, Ian Adams, Thames Regional Water Quality Manager for the EA, emphasised the precarious ecology of the River Thames and the role that reductions in storm overflows could have on improving the dissolved oxygen (DO) levels within the river.

“The storm overflows operate too often and during moderate rainfall events,” Adams told an audience at the London’s Environmental Issues conference on 20 October.

Untreated sewage is released into the Thames when storm overflows are in use. In addition to creating what Adams called “aesthetically unpleasing effects”, the added oxygen demand that the sewage creates threatens the river’s DO levels. An oxygenating barge is in operation to maintain DO levels necessary for maintaining fish in the River Thames, but Adams called on Thames Water to present plans for a more long-term solution. “The use of oxygen injection relieves symptoms but it’s been criticised abroad and increasingly at home,” said Adams.

The EA requested storm overflow reduction proposals to be included in Thames Water’s Assessment Management Programme for the years 2000 to 2005 (AMP 3). The Office of Water Services is currently deliberating on AMP 3 proposal and will announce its decisions in November.

“The Environment Agency has identified five sites for us to look at during AMP 3,” a Thames Water spokesperson told edie. “We’re also involved in a joint study with the Agency on the issue.”

During his presentation of the environmental health of the River Thames, Adams confirmed that the EA is not asking Thames Water to dig up London streets and replace outmoded storm overflows. Instead, the EA is looking for “innovative” solutions, possibly involving installation of fine screen and the construction of large retention tanks that would allow Thames Water to hold more and therefore treat more water before discharging it into the Thames.