In postglacial times, Lake Huron and Saginaw Bay extended much farther inland than they do now. When the water receded, it left behind a flat, sandy wetland surrounded by low hills. It served as the drainage zone for an area of lower Michigan that covers approximately ten counties. The region was a treasure-house of the wetland timber industry in the late 19th century. After the old-growth trees had almost all been removed, starting in 1903 farmers tried to ditch and tile-drain the land for arable crops. The "Ferguson Bayou" region of this drained land did not prove to be well-suited for this purpose, although the wildlife refuge continues to use, maintain, and rebuild many of the ditches, drains, and dikes dug during this period. The Shiawassee National Wildlife Refuge was established in 1953.