The Prouty Glacier, located on the northeast side of the South Sister, is the mountain’s largest glacier. The Prouty occupies an elevation between 8,500 to 9,500 feet, and heads forks of both Squaw Creek and Park Creek. Meltwater from the glacier also fills Carver lake. The below picture, courtesy of John Scurlock, was taken on August 28, 2007.
Like most of the cascade glaciers, the Prouty is in retreat. Historical photos from the turn of the century show a glacier with much more volume and mass than the glacier that exists today. The below photos offer a bit of a comparison, although not taken from exactly the same spot. The first photo, taken by I.C. Russell and courtesy of the US Geological Survey, was taken in 1903 from the Diller Glacier on the Middle Sister. The second photo, taken on July 31, 2017 from the Hayden Glacier on Middle Sister, shows much less glacial mass and much more exposed bedrock.
Touring on the Prouty affords access to some nice terrain for turns, but does require a bit of effort to get to the glacier. Like any glacial travel, touring requires caution, as objective hazards such as a crevasses and bergschrunds still exist. Rockfall is also a concern.
Spring and early summer turns on the Prouty glacier can be excellent. If you’re feeling up for a spicy descent, you can combine turns on the glacier with turns off the summit via a steep chute through the glacier’s headwall. Bottom line — a trip to the Prouty is committing, but worth the effort.