Case study:Bosgården nature-like fishway at River Rolfså

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Location: 57° 36' 29", 12° 28' 9"
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Project overview

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Status Complete
Project web site http://projektwebbar.lansstyrelsen.se/rolfsan/Sv/folj-atgardsarbetet/Pages/storan_bosgarden.aspx
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/storan bosgarden.aspx
Partner organisations
Parent multi-site project

Case_study:Biologisk återställning i Rolfsåns vattensystem

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encompassing the following
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Project summary

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Building and rebuilding of Bosgården hydroelectric plant during 1940-1960 decreased lake migrating brown trout populations, as 90 % of the spawning grounds were lost. In 1995 three pool-type fishways were constructed and minimum disharge was objected for natural riverbed which was often dry before. Still migrating fish population was suffered from the inconstant and low flows and complete dryness of riverbed for 100 metres at times.

the solution was to replace one pool-type fishway with a nature-like fish channel and tear down a weir in the main river near the outlet of the power plant. In addition, the minimum flow was increased from 300 to 600 L/s and an attraction flow was developed as the power plant shuts down in September and October annually for altogether 90 hours.Increasement of flow has returned spawning habitats to the river.

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Catchment and 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, Dam removal at Grönkullen, River Rolfsån, 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

Name Bosgården hydropower plant
WFD water body codes
WFD (national) typology
WFD water body name
Pre-project morphology Artificial bed, Artificial channel
Reference morphology Step-pool
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 Sea migrating brown trout, The freshwater pearl mussel, European eel (Anguilla anguilla)
Dominant hydrology Artificially regulated
Dominant substrate
River corridor land use Intensive agriculture (arable)
Average bankfull channel width category
Average bankfull channel width (m)
Average bankfull channel depth category
Average bankfull channel depth (m)
Mean discharge category 1 - 10 m³/s
Mean annual discharge (m3/s) 6
6 m³/s
6,000 l/s
Average channel gradient category
Average channel gradient
Average unit stream power (W/m2)


Project background

Reach length directly affected (m)
Project started
Works started
Works completed 2009/06/04
Project completed
Total cost category 100 - 500 k€
Total cost (k€) 290
290 k€
290,000 €
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



Reasons for river restoration

Mitigation of a pressure
Hydromorphology
Biology
Physico-chemical
Other reasons for the project


Measures

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


Monitoring

Hydromorphological quality elements

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative

Biological quality elements

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative

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

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative


Monitoring documents



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Supplementary Information

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