Invaders, water quality and large scale water transfers

Successive droughts and floods over the last 10 – 15 years has sharpened minds across sectors on how we address potential in balances of water supply geographically in the UK where broadly speaking there is excess water available in the North and forecasted shortfalls in the South. Various ideas have been put forward to move water around the country from a national water grid to individual schemes from Water Companies to supply neighbours who forecast drought scenarios.

There are already water transfer schemes across the country the most notable is Severn Trent Water who collect water in Wales and pipe to Birmingham for consumption and then release into the river Tame via Sewage Treatment Works to the river Tame and then into the Trent system. Other ideas that have been floated including moving water from the Severn to the Thames via pipes and the canal system.

We are concerned that such large scale infrastructure ideas pull focus away from necessary demand management options and technological advances to reduce water consumption. There are a number of issues that need to be overcome when considering water transfers. Water transfer tends to be a very energy intensive process and therefore needs serious consideration around whether it is suitable in our aims towards a low carbon economy. Another is the difference in water quality between the source water and the receiving water, for example the quality of the Severn is very different from that of the chalk streams in the upper reaches of the Thames. Transfer of sediment also needs to be minimised.

However with these new schemes where water freely flows between river basins there is one danger that so far no-one has come up with a solution and that is the accidental transfer of aquatic invasive non-native species.  Invasive non-native species currently cost the UK economy £1.7 billion per annum and many of the worst ones are found in our waterways like the Demon shrimp, the Killer shrimp & Quagga mussel all of which originate from the Black sea and spread over here through the canals and rivers of Europe predating on our native fish and invertebrates. In order to contain these species and prevent them from spreading then Water Companies will have to bring in measures to ensure that they don’t spread to areas where they are not already present but at present the only pratical options are treating the water before transferring it which would be very costly.

Practical solutions to this problem must be found before Water Companies go further with their plans for this otherwise we will have lost the chance to contain these species and further damage to our native fish and other fauna will inevitably follow.

Mark Owen, Head of Freshwater at the Angling Trust