Joes Valley Dam is an earthfill dam 1,290,000 cubic yards in volume, 187 feet above streambed, and 750 feet long at the crest. The project provides for regulation of Seely Creek, a major tributary of Cottonwood Creek. The reservoir has a total capacity of 62,460 acre-feet and a surface area of 1,170 acres.
Water is released from storage flows on Seely Creek to Cottonwood Creek and the Cottonwood Creek-Huntington Canal, which heads at Swasey Diversion Dam.
The dam and its abutments are founded on the flat lying Blackhawk Formation that contains numerous lignite (coal) beds interlaced among the sandstones.