Tide mills are buildings used to grind cereals that work by taking advantage of the tidal cycle. They are located on the sea coast, always linked to a weir or pond that fills up naturally when the sea rises. They are two-storey rectangular constructions. The lower storey houses the mill's rolling mill, a rotating mechanism driven by the force of the water flowing out of the pond. The upper floor houses the milling machinery (the adella, the moa and the pe, the tremiñado, etc.).
In the southeast sector of the Banca de Casó or wall that separates the pond from the estuary, a tide mill was built to grind grain twice a day, taking advantage of the rising sea. The remains of this mill are still preserved at Punta do Carregal. The mill was built by the French engineer Felipe Auguste Cazaux (pronounced casó).
The researcher Begoña Bas, who documented the remains of this mill at the end of the 1980s, wrote about it:"Various informants indicated that this dam had different purposes, such as a sawmill for wood, and that some mills were installed - or an attempt was made to install them - that had been milled with sea water. Next to this wall today there are some millstones and feet, slave quarters, which did not necessarily belong to this complex. In this respect, while some informants say that they are there for no other purpose than ornamentation, others say that they were taken there to be installed but that it was never done, and there are also those who say that they remember when their elders told them that they had gone to grind on these benches (...).
Both because of the location in this large dry area, and because of the characteristics of the wall and the presence of the millstones, we think that it would have been possible to install a tide mill in these old salt pans, but the lack of data does not allow us to reach a concrete conclusion".