Dear Editor,

I would like to respond to the article called ‘Powering up the river Thames’ by Osman Goring, published in the November issue of IWP&DC (pp34-5). Goring says there is great potential for small hydro power on the river Thames in the UK but adds that environmental regulators are hindering its development.

The Environment Agency strongly supports the government’s targets for the use of renewable energy. It recognises the cumulative contribution which hydro power schemes can make to the reduction in the emissions of greenhouse gases. We also recognise the potential benefits of small scale hydro power to rural communities and in meeting local needs for power.

The Agency’s duties are derived from a breadth of complex legislation. The Thames is a heavily managed river where a wide range of issues have to be considered carefully within this statutory remit. The Environment Agency constantly strives to maintain the right balance between the needs of flood control, public water supply, navigation, water quality, fisheries, conservation and amenity use. It is not a straightforward process to integrate a hydro power scheme with these existing uses — there is the potential to affect them all. It is for this reason that we would always want to sit down with a potential developer to discuss how the proposed scheme might affect the other existing interests on the river; interests which, by law, we must not prejudice.

From these discussions would stem the scope of an environmental assessment, tailored carefully to the location, scale and potential impact of the proposal. What we ask for would be no more than is needed to ensure that we are dealing with a hydro power scheme which takes into account its impact on other interests. Almost every other country in Europe requires an impact assessment to be made in respect of hydro power schemes. We are not seeking to impose ‘environmental barriers’, as Goring suggests, but instead to understand whether a scheme is truly sustainable or whether modifications are needed.

Salmon are returning to the Thames and we are working to restore a salmon population to the river Kennet. If a developer were to construct or substantially rebuild an existing weir, then we might require a fish pass to be incorporated. Where the changes to a weir are minimal then a pass may not be a requirement: at weirs which already have a fish pass there may be concern that the hydro power scheme may modify the flow regime to such an extent that the existing fish pass becomes inoperative. This is an example of a concern which the environmental assessment would address.

When a turbine is installed within an existing weir then it may not require an abstraction licence (the law is complex and each case would be treated on a site-specific basis) but an impounding licence and land drainage consent are likely to be needed. In such cases, as Goring states, the water is flowing through the turbine rather than over the weir: a measurement of the flow is likely to be required in these circumstances. The issue is more likely to be one of ensuring careful control of levels so that all the various interests (flood defence, navigation, fish passage etc) were protected.

So, is there hydro power potential on the Thames? The answer is probably. For hydro power schemes to come to fruition on the Thames (and anywhere else in England and Wales) however, they must be designed to be sympathetic to their location and fail-safe in their operation.

The Environment Agency will take a positive view of reasonable and well-designed proposals for hydro power schemes and will work with developers and others in attempting to agree a viable, sustainable project. In working towards this goal developers need to recognise that the Agency cannot compromise its statutory duties. A scheme may require measures to mitigate impact, even where this may be at the expense of generating capacity, in order to be acceptable.