More dramatic seasonal changes in the weather are increasing the probability of lower water levels in Loch Ness. With climate change these low water events are likely to increase in the future.  Low water impacts businesses, leisure users, the canal, other waterways and the loch environment.  

Whilst our Loch Kemp Storage project remains viable without any modifications to the existing weir, over the project's lifetime, water stress within the Loch Ness catchment is expected to increase, with or without more pumped storage hydro.  This will result in reduced water availability for all water users, particularly in the summer months when lower water levels typically occur. Our proposed improvements to the weir have three benefits:   

• It will reduce curtailment on pumped storage hydro in the summer months.  

• It will help provide resilience to Loch Ness for all users of its waters and those ecologically sensitive areas at its edges. There is an existing issue with low water levels, which in many cases would fall in the range below Loch Kemp Storage’s ‘Stop Pumping Level’ of 15.42m above sea level; and  

• It will help make possible the use of the canal for freight during the construction phase of pumped storage hydro projects, thus reducing the impact on the road transportation system and its users.    

Ness Weir II will help future-proof the Caledonian Canals for all users while at the same time contributing to providing vital long-duration energy storage to the National Grid. The project can help reduce the curtailment (turning off) of low-carbon energy, such as wind, and reduce the demand for high-carbon thermal power plants when it is not windy.  Reducing operational curtailment for pumped storage hydro operators, allows additional revenue to be captured, this additional revenue can help fund the necessary weir modifications.  

Ness Weir II presents an opportunity to not only build on the physical engineering legacy of Thomas Telford to dynamically manage levels in Loch Ness but also provide purpose-built modern fish pass facilities, designed to cater for the challenges that climate change presents.

Statera is aware that definitive conclusions about long-term changes in water resources cannot be made from relatively short-term data. However, gauging data published publicly by SEPA has shown a downward trend in daily mean water levels over the last 40 years. Coupled with the predictions from the Regional Climate Models (RCM) from the Met Office’s UK Climate Projections (UKCP), the Ness catchment is likely to experience wetter winters and drier summers, thus increasing the likelihood of water stress.   

In addition, through discussions with existing operators of leisure craft on the Caledonian Canal, Statera is aware that low water levels in Loch Ness have resulted in damage to vessels passing through the canal system. Increasing the average summer water levels will reduce the likelihood of lower water levels occurring and, in turn, reduce the chance of disruption to tour boats and commercial operators alike.

In 2017 Scottish Canals, as custodians of the existing weir, reinforced the structure with steel piling. This work was necessary for the weir to continue to function as it does today.  

The modifications to the weir proposed by Statera are to future-proof Ness Weir, to allow for the optimised operation of future and planned pumped storage hydro projects, as well as protect Loch Ness and the Caledonian Canal against the predicted impacts of climate change.   

The predictions for the twelve Regional Climate Models (RCM’s) analysed are shown in Figure 1.  The blue line represents RCM15 which is a median model within the distribution. It is worth noting that all the climate scenarios are showing lower flows in the summer, with some predicting around a 50% reduction in flow.

Figure 1: Ness Catchment Monthly Flow Variations based on 12 no. Regional Climate Models (RCM) based on 2051-2080 predictions.

The low water levels will have a direct impact on pumped storage hydro operations as well as canal operations during the peak summer months. As such, Ness Weir II will help reduce water stress within Loch Ness, future-proofing the Caledonian Canals for all users, while at the same time providing vital long-duration energy storage to the national grid.

Yes, the proposed weir modifications should provide more water resource for pumped storage hydro.  This means the projects can be operated more cost-effectively, helping to keep down consumer cost in the future.  

Building on the legacy of leading engineering projects within the Great Glen, we also hope to use the Caledonian Canal during the building of our Loch Kemp Storage project, should it be consented. The canal is intended to be used as a transportation route for Abnormal Indivisible Loads and bulk materials to be transported to site. This will significantly reduce the impact on the road network and local residents around Loch Ness. This intended use will result in the increased frequency of commercial boat operations on Loch Ness and the canal.   

The weir modifications have the potential to benefit all users of the loch and canal. By modifying the existing weir, it can better manage water levels to provide a sufficient buffer to account for more extreme fluctuations in the weather, providing vital resilience for all who depend on Loch Ness. This means those who use the Canal and surrounding waters for transit, tourism, leisure and business can have greater certainty in their operations.  

The proposals also include a new fish pass, which will ensure the fish environment for salmonids is protected. As with the weir structure itself, this aspect of the project is under ongoing development, and will be designed in close consultation with relevant stakeholders.

Statera is willing to play a major part in delivering the structure if consented. However, we also recognise that there has long been a desire to take a collaborative approach to water levels in the Great Glen, working alongside all stakeholders who have an interest in this. Statera see the management of this asset as best held by an independent strategic body. We are committed to working with all stakeholders involved to deliver a long-term solution on this matter.

The Ness Weir II proposal warrants its own application and consultation, given the potential impacts and benefits extend to those beyond the Loch Kemp Storage programme.   

The Ness Weir II project and Loch Kemp Storage are not dependent upon one another. Loch Kemp Storage can go ahead on its own, without the modifications to the weir, but we recognise the benefit of the weir to Statera and all other users of the loch and canal.

The proposal to modify the weir would involve raising the crest height of the existing weir, service and waste weir, which in turn allows for more effective management of the water levels. Water levels will not exceed current levels experience in the winter.  

There will be a greater fluctuation in water level with the operation of pumped storage hydro projects on Loch Ness but not necessarily as a direct consequence of the operation of the new weir structure.  

Ness Weir II would operate by raising the tilting weir structure in the summer months to, increase the summer average water level above the baseline summer average water level of 15.72 metres above sea level. This will reduce the chance of low water levels occurring around the lower end of the Loch Ness range (which is approximately ~15.3 metres above sea level), and reduce the chance of extended periods of low water levels, and in-turn, desiccation (which means extreme drying of a living organism), which can impact the ecology in and around Loch Ness. After the summer, the weir will be lowered to a lower height.  

This provides resilience to the water levels, future-proofing Loch Ness against the impacts of climate change, benefitting all those who use the waterways and providing greater certainty for all users, including pumped storage hydro developers. It is important to note that pumped storage hydro developers are subject to a ‘Stop Pumping Level’ which means when water levels drop below a certain level, they cannot operate. For our proposed Loch Kemp Storage project, this level is currently set at 15.42 m above sea level.  

Statera is undertaking an Environmental Impact Assessment (EIA), which will assess the impacts of Ness Weir II on the environment in and around Loch Ness to ensure that negative impacts may be reduced or avoided through the design and/or control of the weir to a level that is deemed environmentally acceptable. Pumped Storage Hydropower operations in Loch Ness will be included within this EIA, within the cumulative impact assessment.

The existing weir is categorised as a reservoir under the Reservoirs (Scotland) Act 2011. Any modification works to reservoir is required to demonstrate that flood risk downstream has not increased. The Ness Weir II development will be modifying the existing impoundment structure and, as such, is, going through detailed modelling, to demonstrate that flood risk is not increased downstream. A detailed Flood Risk Assessment (FRA) is currently being carried out as part of the EIA in tandem with the development of the concept design of Ness Weir II.

The operation of pumped storage hydro projects will impact the frequency and amplitude of water level variation throughout the year. Water pumped out of Loch Ness by pumped storage hydro projects will be released back into Loch Ness during the generation phase, so the operation of pumped storage hydro does not result in a net loss or net increase in water levels within the loch. 

SEPA is in charge of regulating the water levels on Loch Ness, pumped storage hydro developers are subject to a ‘Stop Pumping Level’ which means when water levels drop below a certain level, they cannot operate.

As occurs today, summer and winter spates will still be able to pass through/over the new Ness Weir structure.  

As part of the planning application, we are undertaking an Environmental Impact Assessment. It will explain how Ness Weir II could affect the environment and how impacts will either be avoided through design or controlled and reduced to a level that is environmentally acceptable.  

The assessment of the impacts on the flow regime within the River Ness is a key focus for this assessment.  The Ness Weir II structure will work to maintain a similar or improved flow regime down the River Ness, and sediment must also be transported through the structure in order to maintain or improve salmonoid habitats downstream.  

We are still at the early stage of the Environmental Impact Assessment process and design development, so we will be able to provide further updates during our second phase of consultation in Q2 2025.

Our proposals are in the early stages of consultation, and at our first consultation events in November 2024 we were encouraged by the engagement we had with canoeists and kayakers familiar with the weir. Our desire is to work with the local water sports groups to design a scheme which is safe and provides a route of passage from the loch or canal system down to the river.

Should the proposals for Ness Weir II be approved, access will be gained from the canal towpath and through neighbouring private property.  The weir alignment will be upstream (canal side) of the existing weir, adjacent the line of piling constructed in 2017. The new weir will be constructed from a temporary track that will be placed along the crest of the existing weir. In much the same fashion as the 2017 works. This track and weir will extend towards where the tilting weir will be located. 

It is proposed that a temporary cofferdam around the upstream and downstream of the existing weir to facilitate the construction of the forebay(s), which will hold the tilting weirs. A cofferdam is a watertight enclosure from which water is pumped to expose the bed of a body of water to permit the construction of the new structure. Due to their size, the tilting weirs will likely be delivered to the site via the canal and will be craned into position with a jack-up barge.  

A temporary fish passage will also be installed during construction and the main construction works will likely be carried out during two in-water working periods as set by SEPA.

We anticipate that construction will take approximately 24 months. This will not be continuous and will likely be split over two in-water working during that time. Similar methodologies to those used in 2017 will likely be used.

The work programme will be agreed with SEPA. Timing of the works will take place within an in-water working period, which will help reduce the impact of the construction works on salmonoids. We are committed to working with all management bodies with an interest in salmon to agree on the appropriate construction methodologies. As with the 2017 works this will include the provision of temporary fish pass provision.

We have now concluded our first round of public consultation following our consultation events in November, which saw approximately 130 people attend our five events over three days. We are grateful for the interest and range of feedback received during this consultation from different stakeholders.  

We are now preparing for the second round of consultation, reviewing the feedback received and undertaking further detailed technical work. We, therefore, expect to commence further public consultation and design workshops with key consultees in Q2 2025.