Bluff Spring Fen (the Fen) is a 100 acre Illinois Nature Preserve in Elgin, Illinois named for it’s rich, calcareous fens. These rare wetlands are fed by springs coming up through the ground bringing mineral-rich water. This alkaline water comes out of the ground at about 50 degrees, keeping the springs and streams flowing year round, and supporting animals and specialized plants that are adapted to these conditions.

The Fen is not just the wetlands. It is a myriad of habitats including prairies, savannas, wetlands, and woodlands. Each one of these groups can be broken down further into subcategories. The prairies contain dry hill prairie, gravel prairie (similar to dry hill prairie), mesic prairie, and wet prairie (similar to sedge meadow). The wetlands consist of sedge meadow and fen intermixed, stream floodplain, and marsh. There are two types of savanna - oak-hickory and red oak. Then lastly, there are the woodlands. These are degraded woods currently consisting mostly of non-native, weedy trees. All of these habitats come together in a mosaic of plant diversity which supports birds, mammals, reptiles, amphibians, and thousands of different insects including butterflies and dragonflies. Rare and endangered species can be found here, such as the Small White Lady’s Slipper Orchids, the Baltimore Checkerspot Butterflies, and the Elfin Skimmer Dragonflies. To date, over 450 plant species, 57 butterfly species, more than 20 dragonfly species, and almost 100 bird species, including 33 nesting, have been recorded at the Fen.

The Fen forms the middle portion of a larger green space of almost 225 acres. All of the green space has the potential to be restored to native habitats in the future. The green space, consisting of lands owned by the City of Elgin (Elgin), the Forest Preserve District of Cook County (FPDCook) and the Forest Preserve District of Kane County (FPDKane). This green space straddles the Cook County/Kane County line in southeast Elgin. The nature preserve portion is managed by the volunteer group Friends of the Bluff Spring Fen (FBSF) under the auspices of the Illinois Nature Preserves Commission (INPC), FPDCook, and Elgin. All of these agencies work together to manage and protect the Fen.