In the project area, the main canal separates into two supply lines which serve 27,186 acres by gravity flow. About 20 miles below Black Canyon Dam, a pumping plant lifts water from the main canal into a lateral system serving 26,014 acres. The 6,881-acre Notus Unit of the Payette Division obtains water from two Arrowrock Division drains south of the Boise River near Caldwell. The three acreages are in the Black Canyon Irrigation District. Both canals divert water from the Payette River at Black Canyon Dam.
Power is produced at Black Canyon Dam.
The total storage capacity is 703,200 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 cfs with the water surface at elevation 4828.0 feet. The radial gates consist of a curved leaf which is a true sector of a circle and two arms connected to pivots at the center of curvature.