The Scottish Environment Protection Agency (SEPA) is in the process of determining an application by Scottish and Southern Energy’s (SSE) to modify flows within areas of the Tay and Spey catchments in order to improve the quality of some rivers as required by the European Water Framework Directive.

SSE has applied for variations to its authorisation under the Water Environment (Controlled Activities)(Scotland) Regulations 2011 for some of the controlled activities it operates as part of its Tummel Valley hydroelectricity scheme. The Tummel scheme is one of Scottish and Southern Energy’s oldest and most extensive assets, with nine power stations and a total installed capacity of approximately 245 megawatts.

The Tummel catchment area extends over 1,800km2 and utilises water from both the River Tay and River Spey catchments. All water bodies within the scope of SSE’s application have been designated as heavily modified due to changes to the physical shape and characteristics of the bed and banks of rivers, such as river straightening, culverting and building dams for the purpose of electricity generation.

The rivers cannot be returned to a completely natural condition as this would affect the generation of power.

SSE's proposals are aimed at improving the ecological potential of several of the rivers it abstracts water from, to contribute to them achieving good ecological potential by 2015, an objective established in the Scotland River Basin District Management Plan. Other abstracted water bodies within the catchments are identified for improvements in future cycles up to 2027.

Commenting on the application, Colin Anderson, SEPA’s Area Manager said:

“We have determined the appropriate flows for all of the water bodies in accordance with the guidance set down by UKTAG (www.wfduk.org/). Revised flow figures were given to SSE in mid March and SSE has now confirmed how these changes would affect generation from the hydroscheme, and confirmation of what flows they consider are technically infeasible to provide.”

Once SEPA has assessed the information submitted by SSE a draft determination of the application will be produced.

SEPA is currently working with SSE and the Tay District Salmon Fisheries Board on a flow trial in the River Garry to compare low flow options to ensure that the most ecologically suitable flow is licensed as a result of the application. Discussions with SSE have suggested that there is a significant issue regarding the proposed volume of water to provide adequate flows within the River Garry and how this will affect generating capability.