Large Nature Restoration Project for the Gudenå River and Tange Lake 

When the power plant at Tange was constructed in 1921, Tange Lake was established and the Gudenå River was thus separated into an upper and a lower part. Simultaneously, the power plant formed a barrier preventing the natural flora and fauna from moving in the longest river in Denmark. Species such as the Gudenå salmon became extinct and others have been drastically reduced.

A permanent solution

The Tange power plant's license to utilise the water from the Gudenå River expired at the beginning of 2001. The Danish Parliament has extended the license for another two years in order to find a solution to the barrier problem at Tange. This means that the Parliament must decide on a permanent solution to ensure the passage of the Gudenå River at Tange power plant before 2003. Alternatively, the license will have to be extended once more.

In order to improve conditions for flora and fauna along the Gudenå River the Ministry of the Environ-ment and the Ministry of Food, Agriculture and Fisheries have prepared a conceptual design in coopera-tion with COWI. This design includes eight bypass-models with alternative water courses and a proposal to restore the Gudenå River downstream the power plant at Tange. The models vary from a short bypass of 1.5 km to a long bypass of 13 km. All models ensure the preservation of Tange Lake and the recreational areas around it.

"The recommended solution comprises a restoration of the upper part of the Gudenå River to its old course and diverts the lower part into an artificial course which bypasses Tange Lake. This way the water quality is improved, a free passage for all species is created, breeding grounds are restored and the best conditions for a good water course system are provided. At the same time, Tange Lake is preserved without forming the present barrier between the upper and the lower part of the Gudenå River. This solution will amount to approximately DKK 120 million, but when advantages and improvements are taken into consideration, this is in fact inexpensive," says COWI project manager Henrik Lynghus.

A complex task with many contributors

COWI has provided consultancy services which include a wide variety of disciplines such as hydraulics, 3D-modelling, construction techniques, socio-economic analyses, biological assessments, geotechniques, estimates on sustainable use of excavated gravel, 3D visualisations, graphic layout, contract management of consultants and procurement.

The client is a workgroup consisting of the Danish Forest and Nature Agency which belongs under the Ministry of the Environment, the Ministry of Food, Agriculture and Fisheries, the National Environ-mental Research Institute, the Danish Institute for Fisheries Research, the Danish Directorate for Fisheries, Viborg County, Århus County and Vejle County. The workgroup, COWI and a series of technical consultants have contributed to the conceptual design.

The project is described in a summary printed in 2000 copies. The summary together with the complete project material can be found by clicking on the 'Summary' link to the right. 

Published 04.03.2002