A planned lowering of a weir in the River Derwent at the beauty spot of Kirkham, between Malton and York, will have dramatic effects, predicts an expert.
Dr Graham Smith, who formerly lived at Leavening, says the removal of the weir will affect through-navigation from Malton and Norton to the connected waterway network.
His plea for the issue to be highlighted has now been taken on board by Malton Town Council.
Dr Smith, a retired biochemist and university lecturer, said: “Lowering the weir will have two effects which will effectively prevent navigation as far as Kirkham Priory. Loss of depth for navigation is one effect, a second will be the increase in the velocity of the flow which will inhibit or prevent upstream passage.”
He said the Environment Agency is to carry out a trial lowering of the sluice at Kirkham.
“I am concerned lest we are led into a false sense of security, since the effect may not be dramatic at first. There is likely to be a long-term effect, possibly increasing over many years as the river cuts down through the silt which will have accumulated in the hundreds of years since the first impounding at Kirkham.”
Dr Smith added: “The stretch of river in the vicinity of Kirkham Priory and the bridge, is a well known and much photographed beauty spot, the attraction of which depends on the lake-like stillness of the full and quiet rover. The removal of the weir will destroy this entirely.”
He said it would have a “certain” effect on wildlife, including loss of habitat for small mammals, and fish.
“It is said that the aim is to restore a more natural flow, and that the object is to allow migratory fish to pass upstream but this can be achieved by providing salmon ladders at the weirs.”
Cllr David Lloyd-Williams, a member of both Malton and Norton Town Councils, said he was “very concerned” about the threat to the river and its potential impact on the two towns. More information is being sought from the Environment Agency on the issue, he said.
“The effect could be that the average river height in Norton and Malton could drop three to four feet which would mean there would be no ability to operate boats.“
Particularly worrying, said Cllr Lloyd-Williams, was that some of the bank sides could dry out as a result of the drop in river levels, and bring about their erosion.
Boat owner David Hopwood, of Malton, said: “I don’t want to see the river destroyed which I fear could happen. The flow will increase and as a result its wealth of wildlife will not survive. At present it is a deep river - seven metres in places - and is a slow moving river which benefits the wildlife but it would be vandalism to pull the plug on it.”
The Environment Agency said in a statement: “We are investigating the possibility of adapting the weir at Kirkham on the River Derwent to help fish migrate to important upstream spawning grounds.
“The weir and associated sluice gate act as a barrier to fish and lamprey and there is a cost to the EA in their on-going maintenance. As part of our investigation we will be carrying out a temporary lowering of the river in September to help us assess all possible impacts of the work including water levels. We will also take into account the views of local people before a decision is taken.
“The EA aims to improve or remove obstruction to fish passage and restore the Derwent to a more natural river landscape and habitat.”