The first arms of Gronau were granted in 1898 and showed a golden bend, with silver lining in a green field. On the bend were three black bars. The green field is canting (Gronau comes from Grüne Aue, or green field). The bend symbolises the Dinkel river that runs through the city.
Own work using: http://www.ngw.nl/int/dld/g/gronau2.htm
UnknownUnknown  - constructed and added by Jürgen Krause