About 2.7 miles west of South Pass in Fremont County, Wyoming, on the Oregon Trail is what is known as Pacific Springs. Pacific Springs is 300 feet lower than South Pass, and is the first good water west of South Pass that the emigrants would encounter, but it was a difficult crossing. It was recorded that once across, there was an abundance of grass, good water and plenty of Wild Sage for fuel, but after leaving the Springs, there was good water, but very little water. Several graves are known to exist in the area.
However, also in Fremont County, Wyoming, was located The Ice Slough, an amazing natural wonder. It has been an oasis of sorts for centuries, but to the westward emigrants who had just trudged through deep sand and had been confronted with three crossings of the Sweetwater River, it became a welcome landmark along the Oregon Trail. There they found a marshy tributary which drains into the Sweetwater River. And just below the surface of the grassy swamp they would find a bed of solid clear ice.
The ice slough is actually a small tributary which drains into the Sweetwater. A variety of marsh grasses and plans form a patchwork of surface plant life. Water flowing under this peat like vegetation freezes solid in the winter, and then remains frozen during the spring and early summer.
Finding the ice slough for the early pioneers was to them a minor miracle. The slough became a perfect place to stop and replenish, and a great source for refrigerating meat. The emigrants found the ice an exceptional treat, and the area became a popular camping site. While at the slough, many emigrants dug up large blocks of ice and stored it in their water barrels to provide cold water for the long difficult stretch ahead.
One emigrant wrote in 1849 that, "The surface is dug up all around by travelers, as much from curiosity as to obtain so desirable a luxury in a trip so dry and thirsty."
Today's irrigation diversions have left the slough almost dry, and very little ice now forms. The ice slough is found on now private lands in Fremont County, Wyoming.