Water from the forests flows through streams in reservoirs, which provide security of supply for times of drought. One of these reservoirs is formed by the Thomson Dam on the Thomson River located about 130 km east of Melbourne in Gippsland, from where water flows through a 19 km long tunnel through the Great Dividing Range into the Upper Yarra Reservoir and then onto Silvan Reservoir for distribution as drinking water in Melbourne. In recent years, drought has resulted in depletion of much of the water in the reservoir of the Thomson Dam.