The German for reservoir is Talsperre (valley obstruction).
See: List of reservoirs and dams
North Rhine-Westphalia
... Upravlenie[?] (GRU) Sluzhba Vneshney Razvedki[?] (SVR) Union of Soviet Socialist Republics (USSR) Cheka (1917-1922) Gosudarstvennoye Politicseskoy ...