Opened in April of 2011, this area has 229 acres adjacent to the 27 acre Lake in the Hills Fen State Nature Preserve. Within LITH Fen there are several places where the clay layer is exposed and the water is able to “seep” out. Unlike single-source springs, seep water exits the ground all along the line of the exposed clay. When the exposed clay layer lies along a hillside or near the top of a hill, the emerging water from the seep runs downhill. These geological features are called “hanging fens,” designating a wetland on a slope. Lake in the Hills Fen has nine seep locations and eight of them include hanging fens. There are only 26 acres of hanging fens in the nation and the Lake in the Hills Fen has approximately four of them.