A South West Water project on the River Teign has recorded a wider distribution of Atlantic salmon, following more than a decade of work to restore spawning habitats.

Electric-fishing surveys show salmon are now consistently found further upstream in the South Teign where they hadn't been seen for years. Salmon have been recorded for five consecutive years at a site close to the dam wall and Salmon fry have also been found in the area, providing evidence that the fish have successfully spawned close to Fernworthy reservoir.

Around 1,000 tonnes of gravel have been added to the river over a period of 11 years to counter the impact the dam has on natural flows and sediment movement. The work is designed to recreate the loose, clean gravels that salmon and trout rely on to lay their eggs.

The findings are seen as a positive development for one of Britain’s most threatened species. Atlantic salmon numbers across the UK have fallen to record lows, but the results from Dartmoor suggest that targeted habitat restoration can deliver measurable improvements, even in some of the region’s most challenging river environments.

“We are effectively rebuilding the riverbed,” said Olivia Cresswell, Head of Fisheries and Ecology at the Westcountry Rivers Trust.

“Dams and reservoirs reduce the natural supply of gravel and stones to downstream spawning grounds. On the upper Teign, after 11 years of adding nearly 1,000 tonnes of selected gravel, we’ve brought the habitat back to something very close to pre-reservoir conditions. It’s so rewarding to see.”

Monitoring by the Trust indicates that salmon are using the newly-formed spawning beds. Brown trout numbers have also been strong, suggesting wider ecological benefits.

South West Water depends largely on surface water sources such as rivers to meet demand in Devon and Cornwall, unlike other regions that draw more heavily on groundwater. The steep, rainfall-dependent rivers of the South West can fluctuate rapidly and are not always reliable, making reservoirs critical for maintaining year-round supply.

Dartmoor rivers are particularly vulnerable to drought, with hotter and drier summers reducing flows and warming the water - two key stressors for salmon.

On some rivers in the region, fewer than 60 adult salmon return each year. Invasive species, sediment build-up, fragmented habitats and aquatic weeds reduce spawning success and add further pressure to already fragile stocks.

South West Water has brought fisheries specialists into its Water Resources division to ensure the species is considered in decisions around public water supply.

Dr Georgina Samoluk, Fisheries and Biodiversity Advisor at South West Water, said the company’s mitigation work at Fernworthy and elsewhere was “vital”.

“None of the 16 Principal Salmon Rivers in Devon and Cornwall currently support sustainable salmon populations, meaning every step we take is important,” she said. “Managing flows and protecting the fragile ecosystems that salmon rely on are at the heart of our work within the Environment Team.”

The South West’s comparatively mild winters also pose a challenge, she added, as salmon favour cooler water.

“Every salmon that makes the incredible journey upstream is a sign that our rivers can still support this species. However, now more than ever, we must work together - using engineering, science and partnership - to give these iconic fish a real fighting chance.”