Case study:Restoration of Ilabekken brook

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Location: 63° 25' 50", 10° 21' 52"
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Project overview

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Status Complete
Project web site
Themes Fisheries, Flood risk management, Habitat and biodiversity, Monitoring
Country Norway
Main contact forename Morten
Main contact surname Bergan
Main contact user ID User:Arolam
Contact organisation Niva
Contact organisation web site http://
Partner organisations Municipality of Trondheim and The Norwegian Public Roads Administration
Parent multi-site project
This is a parent project
encompassing the following
Ilabekken after restoration 2012 (photo by Morten Bergan)

Project summary

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The Ilabekken brook is a small watercourse in the City of Trondheim. Since the early 20th century the area of the brook has urbanized. Because of the urbanization and loading from the sewage waters there has been loss of habitats and natural biodiversity in the brook. The sea trout (Salmo trutta L.) population had disappeared, in addition to other aquatic organisms and birds.

Local actions were taken during 2005-2008 to restore the area. Dedicated plan for the whole Ila valley was done integrating the needs of many different stakeholders. Large construction projects, especially the construction of a new ring road system around the town centre required relocation and upgrading of sewage and water works. The idea of opening the old water course of Ilabekken brook was assessed early in the planning process

The aim of the restoration was to improve the whole Ila valley area for recreation and well-being. The object was to reopen the Ilabekken brook and to stop the loading from sewage waters. Also habitat adaptations were made to recover the biodiversity in the brook for example creating more spawning and living places for sea trout and aquatic organisms by adding stones and gravel in the stream.

After the restoration the area of the Ilabekken brook has been a popular respite site in the city. The content of phosphorous and other pollutants have decreased in to the natural levels and populations of pollution sensitive species has recovered. Salmonid fish has rehabitated the brook and right after the restoration spawning and reproduction of trout has been also successful. Also macroinvertebrate communities have been re-established after the restorations. Monitoring studies performed by NIVA from the last 5 years have showned rapid recolonization from upstream during the first year. And maintaining this biodiversity will reflect to more pristine streches upstream. This is in accordance with the enhanced water quality, more steady water level (during winter) and habitat improvement measures that have been taken during the restoration project. The restoration of Ilabekken brook has been a good example of good co-operation between different stakeholders. There were open and broad channels of communication with the local population and other actors throughout the planning process.

Monitoring surveys and results

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Lessons learnt

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Image gallery

Ilabekken year 1896 (photo from Morten Bergan)
Ilabekken year 1956 (photo from Morten Bergan)

Catchment and subcatchment


Name Ilabekken Brook in the city of Trondheim
WFD water body codes
WFD (national) typology
WFD water body name
Pre-project morphology
Reference morphology
Desired post project morphology
Heavily modified water body Yes
National/international site designation
Local/regional site designations
Protected species present Yes
Invasive species present No
Species of interest Trout, Salmon
Dominant hydrology
Dominant substrate
River corridor land use Urban
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Project background

Reach length directly affected (m) 7000
7,000 m
7 km
700,000 cm
Project started 2005
Works started
Works completed
Project completed 2008/09/01
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Cost for project phases

Phase cost category cost exact (k€) Lead organisation Contact forename Contact surname
Investigation and design
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Reasons for river restoration

Mitigation of a pressure Loss of biodiversity
Hydromorphology Continuity for organisms
Biology Fish, Invertebrates
Other reasons for the project


Structural measures
Bank/bed modifications
Floodplain / River corridor
Planform / Channel pattern
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Management interventions
Social measures (incl. engagement)


Hydromorphological quality elements

Element When monitored Type of monitoring Control site used Result
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Any other monitoring, e.g. social, economic

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Monitoring documents

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Supplementary Information

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