Energy / Improvements at Burn of Lunklet but condition remains ‘poor’
THE BURN of Lunklet may no longer be “significantly acidified”, with “signs of improvement” noticeable.
However the burn – which was strongly affected by metals from a Viking wind farm borrow pit leaching into the water – remains in a “poor” condition.
A report from Aquaterra Ecology, which monitors the impact of Viking construction on nearby watercourses, found that mitigation efforts need to continue at the burn.
The Burn of Lunklet has been a particular cause for concern during the construction of the Viking Energy wind farm in Shetland’s Central Mainland.
An increase in trace metals had been recorded there during the construction, with a nearby borrow pit blamed for the leaching.
A January 2023 report found that conditions in the Burn of Lunklet had become “unsuited to trout”, with an “unprecedented” lack of species in the burn.
Mitigation measures were introduced by wind farm developer SSE Renewables in 2022, with the problem borrow pit capped off last year.
Aquaterra Ecology said concerns remained with the Burn of Lunklet, but that some progress appeared to be made.
“The survey suggests that streambed conditions in the Burn of Lunklet are poor and that the invertebrate fauna remains impacted by changes in water and substrate quality,” it found.
“However there are some signs of improvement, in particular the presence of Baetis rhodani [large dark olive mayfly], one of the acidity indicator species.
“Its recurrence has coincided with the improved pH in the stream.”
Metal concentrations “remain high” in some of the run-offs from the Scallafield scord, it found.
And it said that concern has been raised “on a number of occasions” that the methods used to stop leached metal reaching the Red Burn and Burn of Lunklet “may be inadequate”.
“The efficacy of the mitigation measures should be monitored and periodically reviewed, and changes made where necessary,” it said.
“It should be noted that mitigation should focus not only on increasing the pH of runoff, but ensuring that metal-rich complexes are deposited and removed before they reach sensitive stream habitats.”
SSE said it was “encouraging” to see there was evidence of its treatment systems improving water chemistry at the Burn of Lunklet.
“This treatment process work is on-going, and we are continuing to monitor water quality.
“Further evidence-based decisions on whether to continue with the treatment process or to change the treatment system will be made in spring 2025.”
The company added the findings of the report had been provided to Shetland Islands Council, SEPA and the Shetland Windfarm Environmental Advisory Group (SWEAG).
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