The outlet works intake structure and tunnel are on the right side. Foundation rock conditions for the spillway and outlet works are similar to rock described above. An inferred east-west trending fault has been mapped a short distance north on the left abutment. The abutments upstream and downstream are natural bedrock slopes, which are stable. The excavated slope of rock adjacent to the spillway and outlet works is stable.
None appear to be subject to landslides or rock falls.
Basement igneous rocks enclose the basin, which makes the water holding capability of the reservoir satisfactory. Recreation and Land Use Cascade Reservoir is a prime land use and recreation resource, receiving year-round recreation use. The Water and Power Resources Service in Boise, Idaho is responsible for administering a total of 35,928 acres of project lands and surface waters. The Forest Service administers 1,198 acres of non-flooded land on the west side of the reservoir. The Central Snake Projects Office is responsible to manage the land use interests and recreation facilities at Cascade Reservoir.