The issue – Why is it relevant to the work of The Rivers Trust?

The Rivers Trust movement works towards a shared vision of wild, healthy, natural rivers. However, large numbers of artificial barriers such as dams and culverts are severely impeding natural river flow. Across Europe there are thought to be over 1 million barriers fragmenting rivers and, although the data set is still developing, Ireland’s National Barriers Mitigation Programme has identified around 73,000 potential barriers in Irish rivers. There are over 23,000 barriers in the rivers of England, Scotland, and Wales, meaning that more than 99% of rivers are affected by barriers. What’s more, many of these barriers are not in use anymore; in Europe there are estimated to be 100,000 obsolete barriers while in Britain up to 20% of recorded barriers are no longer needed.

This is important because healthy rivers are free-flowing rivers. In England, 674 rivers do not achieve good ecological status because of "barriers to fish migration and impoundments”. Barriers harm river ecosystems by causing habitat loss, concentrating the effects of pollution, changing the movement of sediment and nutrients, and altering water levels. Furthermore, climate change exacerbates these harms. For example, more frequent droughts will reduce the time window for migration, meaning that fish will often fail to reach their spawning grounds in time, even in rivers not blocked by barriers.

While The Rivers Trust likes to see the public connecting with our rivers, we are aware that barriers can pose safety risks to water users. Some barriers pose a drowning risk by altering water currents. On the other hand, removing barriers can open up new opportunities for water-y recreation!

What are the contentious aspects?

There are many contentious issues around barriers in our rivers, the first of which is that people who own barriers may not want them removed. Barriers often have historical or cultural importance. For example, many of the 17,000+ weirs in the UK are attached to private property or have industrial significance as part of old mills. Whilst many are no longer used, some barriers serve important functions, like providing water for drinking, enabling navigation, or generating hydropower electricity. Some create pools where people enjoy fishing or swimming (like Warleigh Weir near Bath).

Landowners also have concerns around the cost of removals and are unaware that it is often cheaper to remove a barrier than maintain it long-term. Barriers are not designed to last forever and may not cope with increased river flows resulting from climate change. Many concrete dams built between 1930-1970 have a design life of up to 100 years, meaning we will see increasing signs of degradation, requiring expensive maintenance. When barriers collapse suddenly due to extreme flows, there is a real risk of damage to property and infrastructure. Therefore, it can be cost-effective to remove barriers in a controlled way to prevent future, costly issues such as bank destabilisation and flooding.

It is often the case that removing a barrier will decrease flood risk, rather than increase it as is the common concern. Many barriers are not in fact designed to provide flood control, and even if they were in the past, old and unmaintained barriers are not effective flood defences. Increasingly extreme weather patterns heighten the risk of barriers collapsing and causing sudden flood events. In contrast, by removing the artificial barrier using tried and tested techniques, reconnecting the river to its floodplain and rewiggling it to slow the flow of water, we can reduce the risk of flooding.

When barriers cannot be removed, they are sometimes fitted with fish passes to allow fish to travel upstream, however, these passes are not a straightforward solution. Depending on the design, fish passes may only benefit species like salmon, trout, and grayling, in the adult stages of their lifecycle, and do not help weaker swimmers like bullhead, stone loach, minnow, lamprey and eel. These passes may not restore natural sediment movement, water flow, or habitat for a wider range of plants and animals, such as invertebrates. Additionally, the success of fish passes is dependent on specific river flow conditions and whether fish can easily find them. On the other hand, modern nature-based solutions such as rock ramps and bypass channels can result in better fish passage, including for species with weaker swimming abilities. 

What is our position?

The Rivers Trust movement sees carefully managed barrier removal as a cost-effective and proven method of improving river health and restoring ecosystem function. However, we adopt a balanced approach to barrier removal that considers heritage value, social value and environmental outcomes. Member trusts work closely with local communities and stakeholders because we believe that barrier removal projects must be informed by the local context.

The legislative and policy treatment of barrier removal differs between Britain, Northern Ireland and Ireland. However, across all regions The Rivers Trust is calling for the implementation of a strategic approach to barrier removal and fish passage installation. The Rivers Trust wants wider government policy to recognise the environmental damage caused by barriers and incentivise landowners to remove them. The development of such a strategy must involve barrier removal experts, as well as planning authorities and statutory consultees. There is a wealth of best practice information and on-the-ground experience available, in coalitions such as Dam Removal Europe or World Fish Migration Foundation, as well as in local groups such as Rivers Trusts and Wildlife Trusts, and from fisheries experts. The Rivers Trust wants this expertise to shape strategic approaches to barrier removal.

In England and Wales, data about barriers, their impacts on rivers, and previous removals is relatively thorough and easily accessible. There are also existing policy drivers for removal, such as the legal obligation on public bodies to protect priority species (e.g. Atlantic salmon, European eel), which may encourage barrier removal to restore habitat. Additionally, the UK Government’s Plan for Water included funding for barrier removals in England through the new Water Restoration Fund. However, despite the data and policy drivers, there are still more questions than answers about how removals will be strategically implemented and by whom. The Rivers Trust urges the UK Government to engage with the established Catchment Based Approach network, operating in 100+ catchments in England and Wales, to drive a systematic approach to barrier removals informed by evidence and local insight.

In contrast, data is sorely lacking for rivers in Northern Ireland and the local legislative framework actively impedes barrier removal. There is a lack of incentive to remove barriers as the Water Framework Directive in Northern Ireland was never implemented for barrier removal, and planning protections for weirs erected before 1860 prevent the removal of obsolete barriers. At a legislative and planning level there remains a belief that barriers and weirs mitigate flooding despite evidence to the contrary, and this, combined with fragmented governance and the lack of local case studies, has made barrier removal in Northern Ireland highly challenging. Therefore, The Rivers Trust sees an urgent need for data gathering to understand the impact of barriers on rivers in Northern Ireland and thereby increase awareness among policymakers. Existing databases such as the River Obstacles app can log this data, reducing the public resources required. Additionally, The Rivers Trust would like to see a full legislative review in Northern Ireland to start driving the removal of barriers. We want to see Northern Ireland policy embrace a vision of a revitalised and free-flowing river system serving both environmental and community interests. This will require an integrated approach, demanding enhanced collaboration across departments and stakeholder engagement.

Ireland will need to play its part in the EU’s target to restore at least 25,000km of river by 2030. The EU intends to reach this goal primarily through barrier removal and floodplain restoration, so Ireland must up its game in terms of monitoring and managing its in-river barriers to match EU ambition. The National Barriers Mitigation Programme by Inland Fisheries Ireland is working to develop assessment tools, a national barriers database and guidance for planning and construction. Recently, a new role in the form of Head of the Barrier Mitigation Division has been filled and The Rivers Trust hopes that this appointment will see action on the ground accelerated. Data already gathered in the database must be put to use and drive much-needed restoration of flow across the Irish river network.

The Rivers Trust also calls for greater site-specific monitoring of the impact of barriers and their removal. Monitoring of removals using consistent methods, tracking river health indicators before and after removal, should feed into accessible databases that can inform future removals.

What are we doing about the issue?

Many of the 60+ member trusts in The Rivers Trust movement are involved in barrier removal. In 2022-2023, the movement eased, passed, or removed 105 fish barriers and opened up 1,329km of river for fish passage. The Rivers Trust movement takes a strategic approach to barrier removal and aims to carry out removals that maximise positive environmental results. However, we balance the benefits to the environment and to society, taking account of the function and value some barriers provide. The Rivers Trust movement is also opportunistic; we are open to removing barriers when an opportunity presents itself through public funding, landowner proposal, or local demand.

Alongside practical removal work, member trusts are deeply involved in educating the public and stakeholder groups about barriers, removals, and their environmental effects. Member trusts engage with local communities and stakeholders, including landowners, anglers, and heritage groups, to raise public awareness and ensure they are involved in removal projects. River Trusts also liaise with statutory groups to ensure our removals work is strategic, effective, and transparent.

The Rivers Trust movement supports existing monitoring efforts, while calling for more thorough and standardised data-collection. We work with the Environment Agency to track all the barriers in England, including ones that have been removed. Working with others, like the Zoological Society of London, Thames Estuary Partnership, River Restoration Centre, and Natural Apptitude, we created the River Obstacles app to help citizen scientists and professionals map barriers across the UK and Ireland.

Within the Rivers Trust movement and through the Catchment Based Approach we share data and best practice and facilitate access to barrier removal funding. In England and Wales, we also work with water companies to remove barriers that are linked to their property. The Rivers Trust supports barrier removal work and advocacy internationally; we are part of the Dam Removal Europe consortium, a pan-European barrier removal campaign, and we also support World Fish Migration Foundation.

This statement was co-authored by Josh Jones (Senior Technical Analyst, The Rivers Trust), Kezia Saunders (Advocacy Officer, The Rivers Trust), and Barry Bendall (Operations Director, The Rivers Trust) and informed by steering group discussions with Peter King of Ouse & Adur Rivers Trust, Jack Spees and Mark Taylor of Ribble Rivers Trust and Olivia Creswell of Westcountry Rivers Trust. With additional material from Gary Houston of Lagan Rivers Trust and Jason Nash of Bandon Rivers Trust.