17.8 mile-long (28.6 km) Mill Creek originates in the San Bernardino Mountains and is a major tributary of the Santa Ana River. Part of the upper creek flows through the San Bernardino National Forest and entrance requires a Wilderness Adventure Pass. The streambed is completely dry in places, though it widens in some areas during the spring.
These boulders were in the dry bed on June 21st when I visited the area. This photo was made with the Yashica Mat 124 on Fuji Neopan 100 Acros.