Most of the principal rivers of Germany have their source or their outlet in non-German territory. The Rhine, rising in Switzerland, is now a frontier river for a part of its course, and finds the sea in Holland; the Danube rises in Germany but flows over its greater length elsewhere; the Elbe rises in the mountains of Bohemia, now called Czecho-Slovakia; the Oder traverses Lower Silesia; and the Niemen now bounds the frontier of East Prussia and has its source in Russia. Of these, the Rhine and the Niemen are frontier rivers, the Elbe is primarily German but in its upper reaches has much importance for Bohemia, the Danube in its German parts appears to have little concern for any country but Germany, and the Oder is an almost purely German river unless the result of the plebiscite is to detach all Upper Silesia.
Rivers which, in the words of the Treaty, "naturally provide more than one State with access to the sea," properly require some measure of international regulation and adequate guarantees against discrimination. This