Watch our video to hear about our work at Wilstone Reservoir from principal project manager, Mark Stephens.
How you keep the Grand Union Canal flowing
Your support plays a crucial role in caring for our waterways, and it has recently enabled us to make essential upgrades to a vital reservoir that feeds the Grand Union Canal.
Transcript
Wilstone Reservoir is around 200 years old now. The embankments themselves need some maintenance and repair, so what we're doing here today is creating a new sheet pile wall within the earthworks. Wilstone Reservoir is incredibly important for a number of reasons. It was originally constructed to feed water to the canal so that we can use boats on the navigation, but it's also an important local resource as well for people and wildlife. What we're doing today is hopefully safeguarding its future for the next hundred years and more.
The work at Wilstone Reservoir is being undertaken completely from dry land. Our cranes are situated just outside of the reservoir and they pitch the piles, that is, lift the piles, to the piling machine. It's important that we've done the work this way. The alternatives would have involved possibly draining the reservoir completely, which aside from having an enormous impact on navigation and operation of the canal, would also be of detriment to the environment. So, we've planned the works at Wilstone Reservoir specifically so that we can take advantage of the reservoir naturally decreasing in level as the summer goes on, allowing us to do the works without causing any major disruptions or impacts to the environment.
Wilstone Reservoir feeds the canal through a pumping station which is at Tring. There are currently electric pumps situated there, and they draw the water out of Wilstone and put it into the summit pound of the Grand Union. From there, when people use a lock, water goes down through the lock and along the canal. So it's a constant process of refilling the canal from the top and allowing the water to come down the navigation.
Wilstone Reservoir has quite an interesting history. It was originally built on a much smaller scale, and since then, within about 10 to 20 years, it was extended twice, reflecting the use of the canal and ensuring that there was enough water for the boats.
The work that we're doing at Wilstone Reservoir right now is incredibly important. It’s so important that the Canal & River Trust actually funds this work and makes sure that it happens. By doing so, we're making Wilstone Reservoir resilient for the future. The works that we're doing are going to take Wilstone into the next 100 years and beyond and make sure that Wilstone Reservoir can continue to be a vital piece of navigational infrastructure, keeping the Grand Union Canal open for everyone to enjoy.
We’re responsible for 71 major reservoirs across England and Wales, and without them, our network simply wouldn’t flow. They supply the water that feeds our canals, help us manage valuable, and sometimes scarce water resources, give local people wonderful waterside spaces to enjoy, and support a plethora of water birds and wildlife.
Our canal reservoirs are among the oldest of their kind in the world, with many built over 200 years ago. As time passes and climate changes rapidly, it’s crucial to maintain them properly. That’s why, in recent years, your support has been part of a huge investment programme to prepare many of our reservoirs for the future – of which, the recent works at Wilstone Reservoir are just the latest example.
Built in 1802 to supply water to the Wendover Arm of the Grand Union Canal, Wilstone and it’s three neighbouring reservoirs near Tring in Hertfordshire, are critical pieces of infrastructure, as principal project manager Mark Stephens explains:
“Together, the four reservoirs are vital stores of water that help feed the Grand Union Canal and keep it flowing south to London or north to Birmingham. Without them there simply wouldn’t be enough supply to keep one of our longest canals in water.”
Thanks to your continued generosity, we’ve been able to make vital progress on a 15‑month project to reinforce the reservoir’s embankment.
“We identified that the earth embankments needed reinforcing to prevent possible leakage,” says Mark. “It wasn’t an emergency; nothing had broken or failed, but we have legal obligations to keep our reservoirs well-maintained and in line with modern safety standards. That’s why it was important to take this is a forward-looking preventative measure now to keep the reservoir in good working condition for the next hundred years.”
After careful planning, Mark and his team took steps to strengthen the embankment and prevent potential leaks by installing 1400 11-metre-long steel sheet piles into the reservoir’s clay embankments. It’s a big challenge as the embankments at Wilstone are among some of the longest of all the reservoirs in our care, stretching for a staggering 1,350 metres.
The project started in March last year, and the first job was to clear the site, carefully stripping back vegetation, without felling any trees, and laying down a temporary track to provide safe, easy access. Once that was done, the team began to install the steel piles.
The piling work began in June at the northeast corner of the site. To prevent draining the reservoir, which could have endangered wildlife and required a large-scale fish rescue, we embedded the steel piles into the embankments using land-based equipment. As a site designated as a Site of Special Scientific Interest (SSSI) for its diverse bird life, including Herons, Swans, and Great Crested Grebes, we used a silent press piling machine for the majority of the work to minimise disruption to wildlife.
Your generous donations helped us undertake and complete 200 linear metres of piling, that will preserve this wonderful reservoir for future generations. Although the piling work was completed last October, work has continued into this year, with upgrades to the culvert and drainage systems at the toe of the embankment, along with improvements to footpaths and walkways that attract local people to this much-loved and popular green space.
As nature and wildlife also benefit from our reservoirs, biodiversity improvements are being made, including reed bed enhancements, tree planting, and filling gaps in the reservoir’s hedgerows to keep them robust and healthy for wildlife. This planting will introduce a variety of British native plants that suit the local area, such as Crab Apple, Dog Rose, Common Dogwood, Field Maple, Guelder Rose, and Hazel.
The project is scheduled to be finished by the end May, in time for the busy summer months. With your continued support, we’re able to carry out vital preventive work like this across our network, preserving our ageing infrastructure, protecting wildlife, and safeguarding our canals and rivers against an increasingly unpredictable climate.
Why not visit Wilstone Reservoir?
See your donations in action
Last Edited: 30 March 2026
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