Lake Ledro (Trentino – Italy) is located at 652 with a surface of 2.1 km2, a volume of 68∙106 m3 and a maximum depth of 48 m. It is used as a reservoir for hydropower produces and is one of the main touristic resource for the surrounding areas. In the recent years it was affected by intense blooms of the harmful cyanobacterium Planktotrix rubescens. The algal vertical distribution depends on several factors like thermal stratification, light penetration, nutrients availability and the withdrawal of water. As a first step in the analysis of the influence of physical processes on the algal dynamics, we present a study of the driven-wind circulation in lake Ledro by the means of LES-COAST model, taking in account the effect of density stratification and the non-homogeneity of wind distribution on the surface of lake.