The paper evaluates the performance of a non-parametric scheme, the nearest neighbour (NN) method, to predict the daily mean discharge in a mountain basin supplying a hydroelectric reservoir in northeastern Italy. The results are compared with those of an autoregressive model with exogenous input (ARX), coupled with a previously developed snow cover evolution model. Both methods give good performances, but the NN prediction requires a much simpler simulation structure. In the case investigated, for example, the snowpack accumulation-melting model can be completely eliminated. This greater simplification assumes considerable importance in the Electric Load Distribution Institutes of the Italian National Electricity Board (ENEL), where many hydroelectric basins are managed every day.