Hydro-power production and fish habitat suitability: Assessing impact and effectiveness of ecological flows at regional scale

•The assessment of e-flows should be defined at a regional scale and quantitatively.•Slight increases in e-flows may have a tremendous impact on hydro-power production.•Increasing e-flows does not necessarily imply improvements in fish habitat conditions.•Habitat Suitability Duration Curve (HSDC) can rapidly assess habitat suitability.