Currently, Statkraft knows that they have oil spills from their hydraulic system, but the problem is that the amount of the oil spilled is not clear. Furthermore, Statkraft is missing a tool that can be used when decisions need to be made on what power plants that should be prioritized to be renovated next or which oil system that they should be switched to. In order to answer these points a look has been taken onto the environmental effects and the amount of oil spilled from hydropower plants, the general oil system inside a power plant, and in Kaplan turbines. Furthermore, two maps were developed: one presenting areas of interest for humans and environment around the hydropower plants and a second map about the river shorelines sensitivity to oil spills represented in form of an ESI ranked river shoreline. The maps give a general overview and can be used as a starting point to include environmental aspects into the planning and decision making process. The outcomes of the study are that more detailed information about the amount of oil spills released in small amounts from the turbines is needed. The catchment areas, where Statkraft Sverige AB has hydropower plants, which are most sensitive to oil spills, are Moälven and Nätraån. The hydropower plant with the most sensitive river shoreline is the Stennäs power plant due to a large wetland close by. Those areas should therefore be prioritized in projects about reducing the amount of oil inside Statkraft`s hydropower plants.