Park Visitor: Comments, Memories and Reviews
September 25 trails are open during daylight hours by Friend of Shiawassee NWR
The trails are open during daylight hours (even when the office is closed).
http://www.fws.gov/refuge/shiawassee/
July 16
My family and I made a 1+ hour trek mid-day on a summer Saturday to the preserve only to find it closed. My advice is to email ahead (there is no phone number apparent) to be sure entrance to the preserve is allowed.