Lembach is a commune in the Bas-Rhin department and Grand Est region of north-eastern France. The toponym Lembach is of Germanic origin…Lembach is a commune in the Bas-Rhin department and Grand Est region of north-eastern France. The toponym Lembach is of Germanic origin, cognate to modern German Lehm, denoting clay. The Germanic hydronym *-bak entered the French language via High German, and took on two forms: the Germanic form -bach and Romantic -bais.