The Guérande basin, where Trad y Sel's Guérande salt is produced, extends over 1,620 hectares. The solar technique used has a two-thousand year history. Some salt works from Carolingian times are still in their original state; the most recent date from the 18th century. They are the northernmost salt works in Europe.
Salt production in the Loire Atlantique département is spread over two distinct basins :
TRAD Y SEL has chosen to work exclusively with salt from the Guérande marshes. The quality of the salt depends on the quality of water run-off from watersheds through the channels. A large part of the Guérande basin is not in contact with water run-off from the land.
The Mès watershed, on the other hand, is much larger, and the risk of water contamination from human activity is much more important.