Plans have been submitted for safety improvement works at the Kionslieu Reservoir near Foxdale.
The scheme aims to retain the amenity lake while bringing it up to modern UK reservoir safety standards.
The reservoir, built around the end of the 18th century for lead and zinc mining, was deemed in a 2018 inspection to pose “an unacceptably high risk of failure, posing a risk to life in the downstream communities”.
A subsequent feasibility study concluded the lowest-cost option was to discontinue the reservoir, but modelling indicated this would “significantly [increase] downstream flood risk,” requiring costly mitigation.
Restore
Following further consultation, the Department of Environment, Food and Agriculture (DEFA) has opted to retain and restore the reservoir.
The approved scheme will see the water level returned to its original pre-2018 height, increasing storage capacity.
Works include replacing the overflow, constructing an auxiliary spillway, installing a new scour outlet for emergency drawdown, and re-grading the earth embankments to improve stability.
Historical assessments reveal the site was used during World War Two for live-fire amphibious assault training.
A 2022 report on unexploded ordnance (UXO) noted that “grenades are recorded to have been dropped in Kionslieu Reservoir during a training exercise and not retrieved”.
A specialist risk mitigation strategy for UXO will be followed during excavations.
The planning application notes the works are “designed to bring the reservoir up to current UK standards and are anticipated to be technically straightforward”.
It states the completed scheme “delivers a significant reduction in the risk of reservoir failure”.
You can read the full application here.