“Staudamm” is commonly used for “dam,” plain and simple. For instance, the official web site of the Hoover dam introduces the history of the famous dam as follows:

http://www.hooverdam.usbr.gov/german/germanmain.html

1937 begann das Landgewinnungsamt mit den Führungen durch den Hoover Staudamm und das Kraftwerk.

“Staumauer” is sometimes used for “dam” as well, as in the following bilingual page:

http://www.ibk.baum.ethz.ch/emeriti/Bachmann/publ/FWB93.html

Deutsch: Das Verhalten von Gewichtstaumauern unter starkem Erdbeben ist nicht allein von den Eigenschaften der Staumauer selbst bestimmt, sondern in beträchtlichem Maße auch von der Interaktion mit dem angrenzenden Stausee und dem Untergrund.

English: The behaviour of concrete gravity dams subjected to a strong earthquake is not fully determined by the properties of the dam alone but to a large extent also by the interaction of the dam with the adjacent reservoir and the foundation.


But even when “dam” as an acceptable translation of “Staumauer,” the general reference seems to be mostly to the dam wall, rather than the dam reservoir. Look at the following bilingual example:

http://www.high-in-africa.de/

Wußten Sie schon ... daß die Staumauer des Katse Damms mit 183 mtr. die höchste in Afrika ist?

Did you know ... that the wall of the Katse Dam, 183 m, is the highest one in Africa?


I have also spotted some instances where “Staumauer” is used in a much narrower sense. Take a look at the following bilingual example:

http://www.colenco.ch/de/cpe/aktuelles/2000-09.html

Höchste Staumauer in Lateinamerika


http://www.colenco.ch/en/cpe/news/2000-09.html

Highest Arch Dam in Latin America


I acknowledge the inherent confusion, but I hope this sheds some light.

Fuad