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A man-made lake near Newton Abbot in Devon, England, dating to the Georgian Period, is the site of major habitat improvement works that will help to rejuvenate the lake and its surrounding area, returning it to its former glory and benefiting a host of wildlife.
Stover Lake, a ten-acre freshwater lake within Stover Country Park, itself a Site of Special Scientific Interest, is being de-silted after it was found that the lake was in poor condition. The work is being carried out by Murlac, with Fishtek Consulting supervising the work after managing the design and consent process, including the discharge of planning conditions.
Poor water quality and accumulated sediment were having a negative effect on Stover Lake,” said Fishtek project manager Dr. Peter Brunner. “Waterlilies and other aquatic plants were lost, as were numerous invertebrate species. By removing excess sediment and phosphorous and increasing the depth of the lake, we will enable the natural regeneration of aquatic vegetation and see improvements to habitat and water quality.”
According to Brunner, 14,000 cubic meters of sediment – about 17,000 tonnes – are being removed from the lake, which will be dried out and reused within Stover Country Park on a 1.4-hectare site earmarked for future tree planting – nearly the size of two football pitches. The area will host a broadleaved woodland with some conifer and native shrub that will give a boost to the ecological diversity of Stover Country Park.
“Stover Lake is home to the endangered European eel and other important fish species, so the de-silting work is being done with minimal impact to aquatic life,” Brunner said. “Dredging operations, combined with environmental factors, can increase temperature and lower dissolved oxygen, which can lead to fish death. The works on the lake are implementing soft starts – running the machinery for five minutes to scare away fish from the area prior to dredging – and are making use of equipment to monitor dissolved oxygen levels and to mix and aerate the water, which will keep dissolved oxygen levels high.”
He said an innovative use of geotextile bags for the drying of removed sediment solved another challenge in containing the New Zealand pygmyweed (Crassula helmsii), a schedule 9 invasive species. Using the geotextile bags will ensure that any removed pygmyweed from the lake will be trapped and unable to photosynthesize and will die off during the drying of the sediment. Before spreading this sediment as topsoil, each geotextile bag will be checked by a qualified ecologist to ensure that any pygmyweed in the bags has been properly eradicated.
It is hoped that by reducing pollution and silt, white waterlilies (Nymphaea alba) – not seen at the lake since 2007 – will re-establish to provide a more diverse habitat for wildlife, such as dragonflies; 28 species of dragonfly have been recorded at Stover Lake to date, and some species have been lost, such as the scarce blue-tailed and small red damselfly, but other species have arrived over more recent years due to global warming, such as the scarce chaser and lesser emperor dragonfly, which has resulted in an overall gain.
“It is so valuable when local authorities are able to invest in these projects to maintain these sites because the health of the park, including the lake, is an important asset that needs to be nurtured and maintained for the enjoyment of all,” Brunner said. “I am sure James Templer, who built the lake back in the 1800s as part of the Georgian designed landscape of the historic Stover Park, would share this vision!”
The de-silting of the lake is part of the wider Restoring Stover Park Project implemented by Devon County Council and made possible with funding from the National Lottery Heritage Fund and National Highways. Fishtek will be further involved in the project in 2025, undertaking post-ecological monitoring of Stover Lake to determine how the lake and its ecology have responded to de-silting.
The wider scheme includes extending the current visitor center, creating a new community workshop, repairing and conserving the Grade II* listed granite gatehouse, installing new interpretation, creating two new footpaths for the public to enjoy and carrying out improvements to the car park. It will also see a 100 m portion of the Serpentine Lake restored so that it appears the same as it does in 19th century etchings of the site.
“Stover Country Park receives some 180,000 visitors a year, with Stover Lake being key to the numbers of visitors coming to the park and their enjoyment of the environment,” said Devon County Councillor Andrea Davis, cabinet member for Climate Change, Environment and Transport. “Restoring this popular ecological feature towards favorable condition will provide an ecologically rich and diverse lake for future generations to continue to enjoy.”
Fishtek Consulting (https://www.fishtek.co.uk/), part of the RSK Group, is a multidisciplinary technical consultancy with a proven track record of high-quality engineering, environmental science and fisheries expertise and advice. It was founded with the aim of developing technological solutions to fisheries issues in both marine and freshwater environments. Headquartered in Dartington, it has become an industry-leading fisheries and engineering consultancy specializing in the design of fish and eel passes, offering its services throughout the UK and further afield.
RSK (www.rskgroup.com) is a global leader in the delivery of sustainable solutions. Its family of more than 200 environmental, engineering and technical services businesses and 14,000 employees works together to provide practical solutions to some of the greatest challenges societies have ever faced. The company operates in most sectors of the economy, including many of those most critical to future global sustainability, such as water, energy, food and drink, infrastructure, urban development, mining and waste. With its integrated offerings across research and development, consultancy and on-the-ground application, RSK can deliver a complete solution that is unrivalled in the market. The company is certified to the ISO 9001, ISO 14001 and ISO 45001 international standards for quality, environmental management and health and safety management.