The Lake Zug (Deutsch. Zugersee) is one of the minor Swiss lakes, on the outskirts of the Alps and north of Lake Lucerne. Probably at some former date it was connected by means of the Lake Lauerz and the plain of Brunnen with Lake Lucerne. At present it is formed by the Aa, which descends from the Rigi and enters the southern extremity of the lake. The Lorze pours its waters into the lake at its northern extremity, but 1¾ mi further west issues from the lake to pursue its course towards the Reuss.
For the most part the lake is in the Canton of Zug, but the southern end is, to the extent of about ten square kilometres, in that of Schwyz, while the Canton of Lucerne claims about two square kilometres to the north of Immensee. Toward the south-west extremity of the lake the Rigi descends rather steeply to the water's edge, while part of its east shore forms a narrow level band at the foot of the 1,583 metres (5,194 ft) high Rossberg, and the Zugerberg.
At its northern end the shores are nearly level, while on the west shore the wooded promontory of Buonas (with its castles, old and new) projects picturesquely into the waters. The principal place on the lake is the town of Zug. Three railways follow the shore of the lake, one from Zürich via Zug and Arth-Goldau to the St Gotthard, one from Lucerne via Arth-Goldau to the St Gotthard and one from Zürich via Zug to Lucerne.
Many fish (including pike and carp of considerable weights) are taken in the lake, which is especially famous for an endemic kind of trout (Salmo salvelinus, locally called Rolheli). Due to the impact of agricultural run-off, the Lake of Zug is considered one of Switzerland's less clean lakes.
In 1911 a railway (formerly part of the St Gotthard main route) ran along its eastern shore past Walchwil to Arth at its south end, which was connected by a steam tramway with the Arth-Goldau station of the St Gotthard line. This line ran from Arth along the western shore to Immensee, where it bears south-west to Lucerne, while from Immensee another railway led (at first some way from the shore) to Cham, Шаблон:Convert west of Zug.
The first steamer was placed on the lake in 1852.
