Case study:Dam removal at Grönkullen, River Rolfsån

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Location: 57° 40' 21.34" N, 12° 35' 56.72" E

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Project overview

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Status	Complete
Project web site
Themes	Fisheries, Habitat and biodiversity, Hydropower
Country	Sweden
Main contact forename	Andreas
Main contact surname	Bäckstrand
Main contact user ID	User:Arolam
Contact organisation	Länsstyrelsen västra Götalands län
Contact organisation web site	http://projektwebbar.lansstyrelsen.se/rolfsan/Sv/folj-atgardsarbetet/Pages/soran.aspx?keyword=gr%C3%B6nkullen
Partner organisations	Municipality of Bollebygds
Parent multi-site project	Case_study:Biologisk återställning i Rolfsåns vattensystem
This is a parent project encompassing the following projects	No

Grönkullen stream (photo. Maria Arola)

Project summary

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Grönkullen hydro power station is located in one of the upstream tributaries of River Rolfså, River Sörån. Restorations took place after the county administrative board wanted to make migration possible for lake dwelling brown trout in lake Lygnern. Because a chemical plant and a railway are situated next to the river and there is a possible concentration of chemicals in the river, investigations were accomplished to find out whether the dam removal has any effect to the stability conditions. Conclusion was that there would not be any significant effect of the dam removal to the stability or water levels of the river. Investigations were made in 2002-2004 and the municipality of Bollebygds bought the plant 2005 to be able to remove the dam.

Restoration was done in 2005. A new river was rebuilt upstream and downstream of the old dam, altogether along a 200 m stretch. A small part of the old dam was saved as a reminder of how it once was. Stones and gravel were added to the river bank. Total cost of the restoration was about 5 million Swedish crones (ca. 500 000 euros).

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Image gallery

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Downstreams from the dam(photo. Maria Arola)

Part of the old dam (photo. Maria Arola)

Removed dam (photo. Maria Arola)

Catchment and subcatchment Select a catchment/subcatchment Edit the catchment and subcatchment details (affects all case studies in this subcatchment) Catchment River basin district Skagerrak and Kattegat River basin River basin Rolfsån River Basin Subcatchment River name River Rolfsån Area category Area (km2) Maximum altitude category Maximum altitude (m) Dominant geology Organic (i.e. Peat) Ecoregion Fenno-Scandian Shield Dominant land cover Woodland, Intensive agriculture (arable) Waterbody ID Other case studies in this subcatchment: Apelnäs fishway at River Rolfså, Biologisk återställning i Rolfsåns vattensystem, Bosgården nature-like fishway at River Rolfså, Restorations of River Nolån-Hulta dam removal, ´Restorations of River Nolån-Bypass channel in Hulta Hydro power plant, ´Restorations of River Nolån-Fishway in Forsa hydro power plant, Ålgårda nature-like bypass channel at River Rolfsån Site Edit site Name Grönkullen hydro power station WFD water body codes WFD (national) typology WFD water body name River Sörån Pre-project morphology Artificial bed, Artificial channel, Embanked, Over deepened, Over-widened Reference morphology Desired post project morphology Heavily modified water body Yes National/international site designation Local/regional site designations Protected species present No Invasive species present No Species of interest Lake dwelling brown trout Dominant hydrology Dominant substrate River corridor land use Woodland Average bankfull channel width category Average bankfull channel width (m) Average bankfull channel depth category Average bankfull channel depth (m) Mean discharge category Mean annual discharge (m3/s) Average channel gradient category Average channel gradient Average unit stream power (W/m2) Project background Edit project background Reach length directly affected (m) 200200 m <br />0.2 km <br />20,000 cm <br /> Project started 2002 Works started 2005/08/01 Works completed 2005/10/31 Project completed 2005/10/31 Total cost category 500 - 1000 k€ Total cost (k€) 500500 k€ <br />500,000 € <br /> Benefit to cost ratio Funding sources Cost for project phases Phase cost category cost exact (k€) Lead organisation Contact forename Contact surname Investigation and design Stakeholder engagement and communication Works and works supervision Post-project management and maintenance Monitoring Supplementary funding information The total costs were about 5 million Swedish crones including investigations, purchase of appropriate rights and their implementation, demolition of the dam and river restoration measures. Reasons for river restoration Edit reasons for restoration Mitigation of a pressure Barriers to fish migration, Hydropower Hydromorphology Continuity for organisms, Quantity & dynamics of flow Biology Fish Physico-chemical Other reasons for the project Measures Edit Measures Structural measures Bank/bed modifications Barrier removal, Bed raising Floodplain / River corridor Planform / Channel pattern Other Non-structural measures Management interventions Social measures (incl. engagement) Other Monitoring Hydromorphological quality elements Edit Hydromorphological quality elements Element When monitored Type of monitoring Control site used Result Before measures After measures Qualitative Quantitative Biological quality elements Edit biological quality elements Element When monitored Type of monitoring Control site used Result Before measures After measures Qualitative Quantitative Physico-chemical quality elements Edit Physico-chemical quality elements Element When monitored Type of monitoring Control site used Result Before measures After measures Qualitative Quantitative Any other monitoring, e.g. social, economic Edit Other responses Element When monitored Type of monitoring Control site used Result Before measures After measures Qualitative Quantitative Monitoring documents Upload monitoring documents Additional documents and videos Upload additional documents Additional links and references Edit links and references Link Description Supplementary Information Edit Supplementary Information