The lake was called Porta Beltrame after a gate on the fringes of Pietrasanta, and is fed by the streams that begin at the foot of the Porta cliffs. At the source, which is found near the Torretta Medicea, the water maintains a temperature of around 17 degrees centigrade. The wet areas, contained by embankments, is mostly covered by reeds, with little open water.
A wood, similar to the damp surroundings of historical Versilia, has recently developed among the reeds and the wetlands, made up of trees typical of marshy areas: black alder, different kinds ofwillows and poplars. In certain areas there are some wet meadows, characterised by the presence of larch and rushes. A highly rare butterfly, the Large Copper, lives in this environment, in danger of extinction.