The secret police (Stasi) collected photographic evidence of environmental damage, confirming the dramatic extent of the problem in internal dossiers. East German environmental activists had previously published similar pictures in the West German media. The GDR dictatorship was very touchy on the subject, reacting with persecution of the activists.
Quelle: Bundesbeauftragte für die Unterlagen des Staatssicherheitsdienstes der ehemaligen DDR