Abstract
Downstream migrating fish face injury and mortality risks from turbines and hydraulic structures due to cavitation, pressure drops, blade strikes, and hydraulic shear. Waterproof autonomous sensors measured these risks by tracking pressure changes and strike events. The study, conducted at the Funnefoss and Kongsvinger power plants in the Glomma River, evaluated Nadir pressure, pressure rate of change, and strike events, comparing results to known mortality thresholds, particularly for grayling. The study found low risk of fish mortality at the two power plants. Future research should focus on varying turbine flows, different river conditions, and better understanding fish migration patterns in the Glomma River.