Pipeline to revive vanishing river

THE DISAPPEARING river Darent in Kent is to have its flow restored at a cost of pounds 12m. The plan to rescue the Darent, announced yesterday, will be the most expensive and ambitious of the restoration projects now under consideration for more than 20 'low flow' English rivers.

Long stretches of the Darent have been left dry for months on end during the past three drought years. But its problems date from the early Eighties when a campaign against the environmental damage done by low flows began.

People living along its valley were distressed to see the beautiful 20-mile chalk stream, which once had brown trout, dwindling to a trickle. The prime cause was six drinking-water boreholes used by the Thames Water Authority, now the privatised Thames Water. These lower the water table in the chalk beneath the river.

The restoration costs will be split between Thames Water and the National Rivers Authority (NRA). The two sides had an angry dispute last year, with the NRA threatening to cut Thames's water abstraction licences for its Darent boreholes. Now they have reached a compromise.

The most expensive component is a 10-mile underground pipe which will carry up to 20 million litres (4.4 million gallons) of water a day from chalk pits at Northfleet to the river's middle reaches to augment the natural flow whenever necessary.

The pits go beneath the water table, and the cement company Blue Circle pumps huge quantities into the Thames estuary in order to continue operating them. The NRA realised this water could help the Darent. It will also create six springs which will recycle underground water through the Darent. Water will be pumped out of the chalk beneath directly into the river.

Thames Water will enter into a legal agreement with the NRA to cut, by 60 per cent, the amount of water it pumps out of six of its boreholes during winter. This should help underground water supplies to be fully replenished by winter rains.

In return, Thames will be allowed to take more water from a less sensitive borehole near the Darent's mouth at Dartford. But it will also have to change its water distribution system to replace the drinking water it is losing.

The restoration should be completed by 1998 and the overall aim is to ensure that a minimum of 34 million litres (7.5 million gallons) a day flow down the Darent. It is hoped brown trout will be returned to the Darent before 2000.

The project still has to be analysed to decide whether it is worth spending nearly pounds 1m a mile to rescue the Darent for wildlife, anglers and walkers.