Case Study Project on Heavily Modified Waters in Scotland
SR(02)11 A,B,C and D

November 2002


This study arises in the context of the Water Framework Directive (2000/60/EC), brought into force on 22 December 2000. Its focus is the identification and designation of Heavily Modified Water Bodies (HMWB), a mechanism by which the normal requirements of the Directive may be altered on account of environmental, practical or economic considerations in relation to the present uses of water bodies. In a Heavily Modified Water Body, the normal standard of Good Ecological Status is replaced by a locally adapted standard of Good Ecological Potential.

The research comprises three case studies – for the Forth Estuary, the River Tummel (Perthshire) and the River Dee (Galloway). The purpose of the studies has been to trial the process of identifying water bodies which may require designation under the terms of the Directive, and to trial the designation process.

The study areas for Scotland were chosen to focus on the hydro power industry and “transitional” (estuary) waters, as part of a co-ordinated United Kingdom effort. More widely, the studies contribute to a total of 32 studies undertaken across Europe, covering a broad range of water body types and major water body uses, and across the diversity of social, economic and cultural conditions encompassed within the European Union. At the time of writing this Executive Summary, the Scottish studies had already made a substantial contribution to the formulation of pan-European guidance, which will ultimately be issues to all Member States and used to help deliver effective and appropriate implementation of the Directive.

Each of the three Scottish reports follows a common format. After a brief Preface and summary of key statistics (Chapters 1 + 2), an Introduction (Chapter 3) provides local background specific to the study. A Description of the Case Study Area (Chapter 4) provides a broadly-based context covering physical characteristics of the water bodies, land and water use of the study area, and relevant socio-economic descriptions. Chapter 5 deals with the Physical Alterations to water bodies in the study area, including hydrological and morphological changes. Such information is vital since designation applies only to physically altered water bodies. Chapter 6 addresses equally important assessments of Ecological Status. The Identification and Designation of HMWBs is reported in Chapter 7, along with the appropriate justifications, following the rubric of the Directive. For those bodies designated, Chapters 8 and 9 respectively outline the Definitions of Maximum and Good Ecological Potential and their justifications. These are key to the establishment of management objectives which will form an important part of the implementation of the Directive. Finally, Chapter 10 provides Conclusions, Options and Recommendations.

The reports each provide insight and recommendations for the future application of the Directive – both in the study areas and more widely. They consider the basis on which water bodies may be identified. They indicate the results of ecological status assessments – water bodies classified as less than “Good” on account of physical alterations must be considered for designation. Alternative means of achieving the ends presently supported by the water bodies are considered, along with their likely costs, benefits and viability in order to identify optimum environmental solutions. The results of designation testing are presented, and in most cases involve HMWB status being awarded.


Heavily Modified Water Body, Water Framework Directive, ecological status, physical alteration, pressures and uses, identification, environmental options, designation, Maximum Ecological Potential, Good Ecological Potential Copies of these reports are available from the Foundation:

N.B. These reports are available for download from the SNIFFER Website