Ice Slough/Ice Springs Station - Pony Express
Located 12 miles from Three Crossings Station and 12 miles from Warm Springs Station just north of the Old Emigrant Road and South of Ice Springs Creek.
Bishop and Henderson, as well as the mail contract of 1861, identify Ice Slough or Ice Springs as a C.O.C. & P.P. Express Co. station between Three Crossings and Warm Springs.  Other sources do not list the slough as a station, but they mention its nearly year-round ice as a well-known landmark.  Franzwa locates Ice Spring and Ice Slough separately in his Oregon Trail maps, but he does not list either site as a Pony Express station. 
This is possibly the station Twain mentions as passing through in the night. He tells of buried ice there that can be carved out for easy use.