John Kelly Hartt was a principal owner of three of the largest sheep companies in U.S. history—Pioneer, Cow Creek and Yellowstone.

The Cow Creek and Pioneer sheep summered near Hahn's Peak, Colorado in the place that is now Pearl Lake.

John Kelly Hartt died in the early 1950s, eventually resulting in the sale of the land by his wife, Pearl, to the U.S. Forest Service.

[2] Recreational opportunities in Pearl State Park include camping, boating, fishing and picnicking.

The 167-acre (0.68 km2) lake permits boating, including gasoline and electric motors (though boaters are restricted to wakeless speeds).