Evaluating the feasibility of implementing ecological flows at Fridafors Hydropower plant

Abstract: Sweden’s almost 2200 hydropower plants and their attached dams are going to be re-licensed with regards to the new environmental legislations made by the government and EU’s water framework directive. As a solution to restore and improve the health of the Swedish riverine systems, a number of different mitigation measures are suggested. One of those being implementation of ecological flows. Ecological flows contribute to larger habitats and improves the connectivity in the water systems that has been disrupted by human factors such as the expansion of hydropower plants for favoring the electricity production. Variability of flow is important for habitats, including fish migration.  To be able to identify if ecological flows contribute to larger habitat areas and specifically improved habitats for juvenile salmons, the study was focused to a specific location, Fridafors located along Mörrumsån. To be able to investigate the status of the habitat in the natural river reach at the site a hydraulic model of the reach was set up. By combining the model with a method used for identification and classification of habitat for juvenile salmon, it could be predicted if the flowrate caused larger habitat area or not at the site. The simulation showed that larger habitat areas was created with higher flowrate spilled into the river reach, but a higher classification of habitat was achieved at lower flowrates.  Implementations of these kinds of measures causes production losses at the hydro power plant, which in turn causes costs for the hydropower plant owner. This cost can be reduced by applying for financial help from Vattenkraftens Miljöfond AB which works as a financial support when environmentally implementations are being made at hydropower plants. The results from implementation of ecological flows into the natural river reach, showed that at a total 11,7% production loss at the power plant, ecological flows were approximately 12 times more expensive than implementation of biotope conservation measurements at the site.  To conclude the study, it was possible to observe a larger habitat area with an increased flow rate into the natural river reach, but the implementation of these ecological flows led to large production loss cost for Vattenkraftens Miljöfond to replace and therefore biotope conservation together with a more dynamic flow regime is seen as more suitable at the site.