
Crossing Ploemeur, Lorient and Larmor-Plage, the river Ter, consisting of 25 kilometers of water and 35 km2 of watershed, flows into the sea in the harbor of Lorient.
Its estuary, under marine influence, once housed in its brackish waters trout, mules, plaice, bass and wild oysters. It now feeds the two ponds of Saint-Mathurin and Kermélo.
The first, was constituted in 1756 during the construction of the dike of the Moulin Neuf which takes its name from a chapel. It was built near the bridge crossing the Ter, it was destroyed by the Germans during the construction of the railway line. The Kermélo pond was formed in 1967 when a dyke bridge was built.