The island of Bois Gérard stands in the center of Madine Lake. Each year in spring, around 80 sheep are transported on its grounds by boat. They will stay there until the fall and maintain the island's 98 acres (40 ha) in an environment-friendly way. Green Island is north of the lake and is almost three times smaller, with its 37 acres (15 ha). Each year, the students of the agricultural high school of Pixérécourt clean its area. Both islands are forbidden to access for the public.