Cascade Dam, near Cascade, Idaho, on the North Fork on the
Payette River, is a zoned earthfill structure 785 feet across
the crest. The initial total storage capacity was 703,200 acre-
feet (active 653,200 acre-feet). The spillway is located on the
right abutment of the dam. The invert is 45 feet wide at the
crest under the radial gates and about 330 feet long excluding
the open cut channel to the reservoir. The design capacity is
12,500 cubic feet per second with the water surface at elevation
4828.0 feet. Two 21-foot wide by 20-foot high radial gates are
installed on the crest of the spillway to provide means for
regulating the discharge of water over the spillway and to
provide protection for the dam in the event of a sudden rise in
reservoir water level. A sedimentation survey completed in 1995
at Lake Cascade estimated the total capacity at 693,200 acre-
feet (active 646,500 acre-feet). Cascade Dam is sited on igneous
rock of granitic type, which generally is of fair quality, but
there are numerous localiz