Dornbirner Ach is a river in Vorarlberg

Vorarlberg

Vorarlberg is the westernmost federal-state of Austria. Although it is the second smallest in terms of area and population , it borders three countries: Germany , Switzerland and Liechtenstein...

, Austria

Austria

Austria , officially the Republic of Austria , is a landlocked country of roughly 8.4 million people in Central Europe. It is bordered by the Czech Republic and Germany to the north, Slovakia and Hungary to the east, Slovenia and Italy to the south, and Switzerland and Liechtenstein to the...

, with its source up in the valley near the alpine village Ebnit. It flows through the famous "Rappenlochschlucht" gorge straight to Dornbirn

Dornbirn

Dornbirn is a city in Vorarlberg, Austria. It is the administrative center of the district Dornbirn, which also includes the city of Hohenems, and the market town Lustenau....

, cuts through the town and the meanders off over a broad meadow landscape, the Lauterach Ried, finally flowing into Lake Constance

Lake Constance

Lake Constance is a lake on the Rhine at the northern foot of the Alps, and consists of three bodies of water: the Obersee , the Untersee , and a connecting stretch of the Rhine, called the Seerhein.The lake is situated in Germany, Switzerland and Austria near the Alps...

 parallel and quite close to the mouth of the Rhine.