It impounds the North Fork Kings River to form Wishon Reservoir.

The earthen and rockfill gravity dam was constructed in 1958 (67 years ago) (1958) by Pacific Gas and Electric Company (PG&E) with a height of 260 feet (79 m) and a length of 3,330 feet (1,010 m) at its crest.

Helms Power Plant is 1,000 feet (300 m) underground in a chamber carved out of solid granite at the north end of Wishon Lake.

It is similar to Southern California Edison's Eastwood Powerhouse near Shaver Lake, which is also a pumped-storage plant.

[4] PG&E maintains Lily Pad Campground with 15 campsites on the southern shore, and recreation includes fishing (for German brown, rainbow or Eastern Brook trout), boating, camping and hiking.