After 200 years, a tributary of an important salmon river is once again flowing along its original course.

The course of the Rottal Burn, a major tributary of the River South Esk in Glen Clova, had been canalised and straightened some time around 1800 to reduce the flooding that had historically damaged agriculture in the glen.

More recently the lower part of the channel was dredged, effectively destroying the entire habitat for fish. But a pioneering project has restored the burn to more than half a mile of its original course and several thousand native trees have been planted to increase the shade.

Fiona Armstrong, Lady MacGregor of MacGregor, the well-known TV journalist, presenter and news presenter, formally reopened the restored Rottal Burn.

Dr Marshall Halliday, director of Esk Rivers & Fisheries Trust, said: "We wanted to remedy the fact that a significant section of the South Esk catchment was, because of man's historical intervention, so unsuitable for fish."

He said that by using old maps and aerial photographs to identify the original water course, they had explored several options for its restoration and reconnection to its flood plain.

"Once the final selection was made, it was subjected to additional scrutiny concerning channel stability, river bed stability, and hydrology and habitat diversity."

He said all the works were completed between May and August 2012. The final phase involved the connection of the Rottal Burn into the new channel and the closure of the old channel.

"It is heartening that salmon and sea trout almost immediately moved into the new channel where they were observed spawning in November," he said.

The possibility of transferring freshwater pearl mussels into the burn is also being explored.

Trust chairman Tom Sampson said the River South Esk had been designated as a Special Area of Conservation for Atlantic salmon and freshwater pearl mussel.

The Scottish Environment Protection Agency's Water Environment Fund provided most of the money for the project.

Alice Tree, SEPA's advice and engagement specialist, said the project had restored a significant stretch of realigned river into over one mile of natural river course and removed physical pressures affecting the burn.

Isla Martin, Scottish Natural Heritage's operations officer, added: "It is great to see that the fishery trust, in partnership with a forward thinking and visionary landowner and a wide range of interested parties, has been able to restore such a large section of river and that it is already providing a range of benefits. The Rottal Burn project is a fantastic example and we hope it will be an inspiration to others."

l RSPB Scotland has welcomed a decision by Marine Scotland not to grant consent to a 15 turbine tidal array in the River Esk Estuary at Montrose.

GlaxoSmithKline (GSK) had submitted plans for an array to provide renewable power direct to its manufacturing and supply facility, GSK Montrose, which produces pharmaceutical ingredients.

Charles Nathan, RSPB Scotland's Marine Conservation Planner, said: "Marine Scotland has made the right decision not to grant consent for a project sited in a highly environmentally sensitive area."