Our long-term plans for Crummock Water, Chapelhouse Reservoir and Overwater

We've been working with key stakeholders including the Environment Agency, Natural England, Lake District National Park Authority, National Trust, landowners, local authorities and other interest groups to develop long-term plans that would maintain access for visitors, while sensitively returning these water bodies back to a more natural state. 

There's still a long way to go before any work begins, we're still in the early stages for Ennerdale and further along with our plans for Crummock Water, Chapelhouse Reservoir and Overwater. We've held several rounds of community drop-in sessions (October 2022, February 2023 and September 2023) to share our initial proposals for the work and answer your queries.  If you've attended these sessions, thank you for taking the time to come and see us. 

Our next steps

Surveys and investigation activity: If you're visiting Crummock Water, you may notice our teams carrying out ground investigation surveys at various locations. This will involve vegetation clearance, machinery and large vehicles moving around the site, so some areas will need to be temporarily closed to keep visitors safe and allow the work to be carried out as quickly as possible.  The survey work will start on Monday 18 March 2024 and is expected to take around three weeks to complete. Thank you for your cooperation.

Our team are working to finalise the project designs and are aiming to submit the associated planning applications for Crummock Water, Chapelhouse Reservoir and Overwater by summer 2024. We'll arrange further drop-in sessions to provide updates as our Ennerdale plans progress.

If you didn't manage to make it to our most recent drop-in sessions you can view the material here and also view the Crummock Water shoreline gradient heat maps which illustrate the current and expected levels.

We've included answers to the main queries about our proposals in the drop-down panel below, but if you have any further queries, please get in touch using the feedback form

  • For more than 120 years, water for 80,000 homes and businesses in and around the towns of Egremont, Cockermouth and Whitehaven has come from local sources. But the waterbodies are also home to many rare and protected species.  The risk to wildlife, along with the growth of the population means we had to find sources other than Ennerdale Water, Crummock Water, Overwater and Chapelhouse Reservoir.

    We worked with environmental stakeholders including the Environment Agency and Natural England and stopped using these water bodies as a water source at the end of March 2023.

    Our West Cumbria abstraction licences are now permanently withdrawn as the new water network is operational and uses Thirlmere Reservoir as the water source.

  • Bringing water to the 80,000 homes and businesses via the new 62-mile long pipeline from a more strategic water source, Thirlmere reservoir, means we can better meet the demands now and for future population growth, while also protecting the very precious local environments by not taking water from these smaller sources. 

    We also have a legal agreement between ourselves, Natural England, Environment Agency and DEFRA (Department for Environment, Food and Rural Affairs) under the Habitats Directive to cease abstraction from these water bodies and carry out the work as required under this project.

    The legal agreement referred to is the compensatory measures legal agreement, which secures all the compensatory measures for the potential environmental damage caused by the Ennerdale abstraction.  Revoking the abstraction licences and removing the abstraction related infrastructure are all compensatory measures as part of the Ennerdale IROPI (imperative reasons of overriding public interest) case.

    We commissioned specialist consultants, Jacobs, to undertake an investigation into the engineering feasibility of removing the abstraction infrastructure at Crummock Water, together with a hydro-geomorphological and ecology impact assessment of infrastructure removal.  Please be mindful that the on-going design and resultant modelling has progressed and changed significantly since this report was published.  Once submitted to the Lake District National Park Authority in 2024, the full design will be available to view on their website.

  • We have undertaken significant investment over the past 15 years and continue to do so, to enable more water to be moved around our network regions more readily. 

    An example of one of these projects is the West East Link Main that connects Liverpool to Manchester, enabling Manchester to be supplied by alternative sources and is therefore less dependent on Thirlmere.

    Thirlmere is a large strategic water source and part of our integrated regional water supply system.  We will be using more of the water from Thirlmere to supply homes and businesses in Cumbria and use capacity at other sources in the south of our region to make up the difference. 

    Our Water Resources Management Plan (WRMP) sets out how much water we think our customers need, how much we have available and how we will meet that supply and demand over the next 25 years. 

    Experts assess and model what will affect the demand for water in the future and take into account factors like population growth and the impact of climate change.  Based on those assessments, which have also been subject to scrutiny by a DEFRA appointed planning inspector, Thirlmere's the right solution to meet the needs of the population now, and in the future. 

    You can view our updated draft Water Resources Management Plan which defines our strategy to meet demand from 2025 to 2085. 

  • As part of the legal obligation in operating a reservoir, we are required to conduct regular weekly inspections, as well as a 10 year inspection undertaken by an independent Qualified Civil Engineer (QCE).  In the previous inspection by the QCE at Crummock Water, repairs and upgrade work was identified which needed to be carried out by 2028 to comply with the Reservoir Safety Act 1975.

    The work would require replacement of the weir, improved overflow system and replacement of the wave wall.  In the event that Crummock Water was retained, significant construction and disruption would be required.  This would also introduce large expanses of new concrete and assets that would have a significant impact both visually, and to the environment.

    The need for additional works is reviewed every 10 years in-line with current legislation, so there is no guarantee that if the weir was kept, the site may still require significant additional investment in 10 years time.

    The weir at Crummock Water is not designed or operated as a flood risk management provision as the structure is designed to retain water for drinking water abstraction, above and beyond, the natural storage provision of the lake.  If the infrastructure was abandoned, someone would have to take ownership and responsibility under the Reservoir Safety Act to modify the infrastructure into a flood management system, combined with the liability of proactively managing flood waters.

    In order to meet the Reservoir Safety Act requirements, re-naturalising these reservoirs is the most viable solution due to a reduction in flood risk, enhancements to the environment and cost.

  • We must demonstrate to the Environment Agency and Cumberland Council that our assessment of flood risk is in accordance with National Planning Policy and that flood risk to, and from the proposed projects can be managed effectively without increasing risk to others. If we are not able to provide this, taking climate change into account, it's unlikely the project would be able to obtain planning permission.

    We've engaged with specialists to carry out extensive hydraulic modelling studies to assess how the proposed work at all three sites may alter flows. The key findings are detailed below.

    Crummock Water

    Crummock Water is full nearly all of the time and flood flows are easily transmitted through the system and out into the River Cocker. Therefore, the weir does not currently provide any flood attenuation benefit to help manage flood risk downstream.

    Removing the weir will lower the outlet level within Crummock by approximately 1.35 metres, creating greater natural storm attenuation capacity.

    The new outlet from Crummock Water would consist of two naturalised river channels, each approximately five metres wide.  The two new outlet channels, combined with a natural 'rougher' surface act as a throttle, holding back water during a storm event and slow the flow of water passing forward from the lake in comparison with the existing forty metre wide smooth outlet weir.

    Work at Park Beck would also contribute to reducing flood risk. The lower course of Park Beck is currently a straight concrete channel and provides an efficient way of transferring storm water into the reservoir. Our proposed work would remove this concrete channel and return the natural curves of the watercourse. This would reduce the rate at which the water enters into the reservoir, with multiple channels that would create several points of entry during high flows and remove the pathway for flood water to bypass Crummock Water and flow straight into the River Cocker. 

    The combined effect of lowering the water level in Crummock Water, the two re-naturalised outlet channels and the re-naturalisation of Park Beck would all contribute towards reducing the risk of flooding.

    The modelling is also assessing the impact for both flow and flood level throughout the River Cocker catchment and into the River Derwent at Cockermouth.

    Chapelhouse Reservoir and Overwater

    Chapelhouse and Overwater reservoirs, like Crummock Water, are not designed or operated as a flood management provision.

    The weir at Overwater was designed to retain a larger volume of water than would have been stored in the natural lake.  The dam at Chapelhouse was designed to create a body of water in the natural valley of the River Ellen (that is diverted around, and perched above the reservoir) to then allow water to be abstracted for drinking water purposes. 

    Chapelhouse does not route flood waters through it, this is done naturally along the River Ellen.  The reservoir is nearly full all of the time which provides little flood attenuation provision as it acts to store and retain water 'offline' for water supply and abstraction. 

    Removal of Chapelhouse does little to change the natural hydrological regime. Our modelling is also assessing the impact for both flow and flood level throughout the catchment down to Maryport.

    Click the links below to take a look at graphics which help to demonstrate the existing and proposed top water levels at Crummock Water and Overwater.

    Graphics: Crummock Water and Overwater

  • We understand that these reservoirs are valued spaces and an important landscape for visitors and the surrounding communities.  We're working closely with the Environment Agency, Natural England and our specialist ecology contractor to carry out a wide scope of surveys and assessments.

    The projects would deliver several environmental benefits including;

    • The restoration of natural salmon habitat
    • Removing barriers to fish and eel movement
    • Restoring natural flows and sediment transportation
    • Habitat enhancement such as tree planting, which form an integral part of our planning applications.

    A full suite of ecological surveys have been carried out. This started with initial habitat survey and scoping, which then led to further bat, otter, reptile and invertebrate surveys to make sure that we captured all wildlife concerns and can assess potential impacts and mitigation as part of the planning application.

    How will the project impact Arctic charr?

    The removal of the weir should have a positive impact because a physical barrier has been removed, increasing migration opportunities for the fish community and allowing them to move more freely in, and out of Crummock Water, increasing population numbers.

    An assessment of the substrate in shallow spawning activities has been carried out. Effectively, there will be a temporary reduction in the optimum spawning habitat and an increase in sub-optimal habitat for Arctic Charr.  With time, the substrates (stone sizes) will naturally start to return to their previous state and provide an ideal spawning habitat.

    The removal of the weir will have other more subtle changes relating to lake hydromorphology, changes in water level and silt deposition may have both positive and negative impacts on the spawning activities of Arctic Charr.  Other changes relating to the wider fish community may also influence Arctic Charr communities such as restoring connectivity for other species like brown trout and salmonids.

    We'll ensure that contractors appointed to carry out the work are experienced at working in sensitive locations, following practices during the construction period to protect the local landscape and habitats including sediment control to reduce impact to rivers, streams and lakes with measures in place to reuse materials in the wider scheme.

    How will the project impact aquatic plants along the lakeshore?

    Shoreweek Littorella uniflora, which a defining feature of the qualifying habitat of the River Derwent and Bassenthwaite Lake Special Area of Conservation (SAC), was recorded in significant abundance during the aquatic macrophyte survey around much of the Crummock lakes' shoreline, with most of the population recorded in the southern end of the lake.  Surveys and assessments have concluded that a drop in Crummock Water would be expected to have only minor effects on the predominant macrophyte species in Littorelletea habitats.

    Over 27 macrophyte species were recorded in Overwater and the most abundant species were widely distributed with rarer species limited to one or two discrete locations.  The survey confirmed that the aquatic macrophyte community for which Overwater was designated continues to include most of the characteristic species noted in the SSSI citation.  Two invasive species Crassula helmsii and Elodea nuttalli were found in abundance and strict biosecurity measures will be required. 

    Chapelhouse was recorded to contain 18 macrophyte species.  The most abundant and widespread being the invasive species Elodea nuttalli

    Many of the macrophyte species growing in Crummock Water, Overwater and Chapelhouse are physiologically adapted to cope with seasonal, inter-annual variations in water levels.

    Isoetid plants are reported to be 'stress tolerant' species and adaptable to periods of exposure caused by changing water levels.  Therefore, it's hypothesised that these species within Crummock are likely to adapt once the weir is removed.  However, it is possible that negative changes to the distribution of the isoetid populations might be observed as they locally compete with each other to re-colonise the new littoral zone.

    So, whilst short-term, inter-annual fluctuations in water level are unlikely to impact significantly on the overall macrophyte composition, it is hard to predict with a high degree of certainty what the long-term impact of a permanent lowering of the water level at Crummock and Overwater would be.  It is also not possible to say with a high degree of certainty that any observable impact would be small or insignificant.  This is going to have to be monitored.

    Removal of the weir and the re-naturalisation into a free flowing stream at Chapelhouse means that macrophytes characteristic of lake habitats will be lost and emergent riverine macrophytes will thrive.  A National Vegetation Classification survey (NVC) of the entire lake boundary has been carried out, along with an underwater macrophyte dive survey of both Chapelhouse and Crummock.

    A macrophyte dive survey is due to take place on Buttermere Dubs during summer 2023 due to the expected change in flow characteristics following completion of the proposed works.

  • During any construction activity we carry out, safety is always of utmost importance. Therefore, access to several areas around Crummock Water will be restricted, along with closures of some access routes during the work. 

    We're working to establish the most appropriate solution to allow safe access to be returned to users as quickly as possible.  We'll also look to provide alternative routes, where feasible, to maintain access to the areas which would not be impacted by the proposed work. 

    There would be a need to undertake some permanent Public Rights of Way diversions.  We're working closely with the Lake District National Park and National Trust to make sure that, following the work, pedestrian access is not restricted and impacts are minimised as much as possible. 

    It is likely that the use of the National Trust car park at Lanthwaite Wood will be restricted over a period of around 4-5 months while the work is carried out .  We are looking at the provision of alternative parking to provide an equivalent number of spaces during the proposed work.

    The use of Crummock Water for swimming and other water based activities (excluding powered crafts) is the responsibility of the land owner, National Trust.  We are not aware of any plans to change the current recreational activities following completion of our proposed work.  However, the lowering of the water level will widen the lake margin, which in turn could potentially change recreational access to the water from the gravel shoreline. 

    Following queries at our community drop-in sessions, we have carried out assessments to better understand the shoreline gradients and, by lowering the water level, whether this would significantly impact access to the water for recreational activities.  View these heat maps which show the shoreline lake margin gradients against both the existing and proposed water levels.  

    Further information regarding access, activities permitted in which lake and swimming in the Lake District can be found on the Lake District National Park website

    There are no plans to provide additional/improved car parking around Crummock Water following completion of the work carried out as part of this project. 

  • The bed level of Crummock Water and the outfall to the River Cocker will be reinstated to what is believed to be natural bed level.  Some information has been prepared to help explain this in more detail and a schematic diagram developed to show the history of weir modifications, the impact on water levels and the likely effects of the proposed restoration. 

    Historic information has been interpreted in the previous studies to suggest that the natural level of the bed is at the timber weir crest level, but this was holding the average winter water level from 1879, and was not the bed level.

    In addition, discussions in 2022 with the independent Qualified Civil Engineer appointed under the Reservoirs Act (1975) reiterates that to allow reservoirs to be discontinued (removed from the Act), the water level is required to be permanently lowered to be close to natural ground level and the entirety of the existing structure (including those parts below the bed) will need to be removed.  The bed will be reinstated where necessary to reflect the natural bed level and gradient. 

  • Information on the construction impacts at all of the sites was available at our September 2023 drop-in session and can be viewed here.  


  • We're also carrying out feasibility studies to explore a range of options to help evaluate and develop our long-term plans for Ennerdale Water - using the knowledge and learning from the projects at Crummock Water, Chapelhouse Reservoir and Overwater will be invaluable.

    The plans are very much in the early stages and there are lots of things to consider including:

    • Changes to lake level, river flows and flood risk
    • Protecting and enhancing habitats and biodiversity
    • Recreation, landscape and visual amenity

    We held our first community drop-in session in September 2023. As we work through the feasibility study and investigations, we'll arrange further sessions.

    We're also planning to develop similar dedicated web pages to provide further information about our plans at Ennerdale.

  • We hope you have found this information about our proposed long-term plans helpful. We've held several community drop-in sessions and really welcomed your feedback. Thank you to everyone who took the time to come along. 

    Following submission of the Planning Application for the schemes at Crummock, Chapelhouse and Overwater in summer 2024, the application documents will be available to review on the LDNPA website. We'll also provide links to the documents too.   Once the applications are made, any comments can be submitted to the LDNPA for consideration. 

    If you have any queries, please complete our feedback form

    You can view the EIA Scoping Opinion for Crummock Water and associated documents on the Lake District National Park website