Storvatn Dam is a well instrumented, 90m high rockfill structure with an asphaltic concrete core, located in Western Norway. A series of linear and non-linear finite element analyses of its behaviour was carried out on three cross sections under plane strain conditions, simulating its true construction sequence and simultaneous filling of the reservoir. Material parameters were derived from large scale laboratory triaxial and oedometer tests and from field plate bearing tests. The mathematical model was calibrated by back analysing the early construction stages of the dam and comparing the calculated movements against field measurements. Subsequently the model was used to make predictions of the behaviour of the dam during filling of the reservoir up to full reservoir level. The analyses showed that the simple linear model may be used effectively to simulate the complex behaviour of the dam and to calculate the strains and movements within the dam.