Boulder Glacier is located on the southeast slope of Mount Baker, a stratovolcano near the Pacific coast of North America in the Cascade Range of Washington. Boulder Glacier is the sixth largest on Mount Baker with an area of 1.3 square miles. It flows from the summit crater between Grant Peak and Sherman Peak to about 5,000 ft. It is noteworthy for retreating 1,610 ft between 1987 and 2008, leaving newly exposed rock and soil behind.
Between 1850 and 1950, the glacier retreated 8,700 ft. William Long of the United States Forest Service observed the glacier beginning to advance due to cooler and wetter weather in 1953. This was followed by a 2,438-foot advance by 1979. The 1979 terminus position is where the small stream enters Boulder Creek from the southwest. Observations in 2005 suggest that the lowest thousand feet or several hundred meters of the glacier is stagnant and will likely disappear. In the pictures, this section of the glacier is gray with rock debris and has few crevasses. On the west side of Boulder Creek is a small waterfall revealed by the recent recession of the glacier.
Boulder Glacier may be approached via the Boulder Ridge Trail number 605.