[2] When full, the reservoir covers 1,296 acres (524 ha), with a shoreline of roughly 15 mi (24 km) and a maximum depth of 195 ft (59 m).

Early proposals included the diversion of streams from west of the Continental Divide to augment the arid region's water supply, but eventually the project was pared down to comprise two storage dams on the Sun River and a tributary, Willow Creek; two off-stream reservoirs and a diversion dam; and seven main canals.

This method allowed the USBR to save an estimated 41,000 cu yd (31,000 m3) of concrete, lowering costs significantly, since otherwise a considerable safety margin would have had to be built into the dam.

Preliminary excavations and site clearing were followed by the placement of a wooden flume to divert the river before concrete pouring in the foundation work could begin.

[6] At least three people were killed on the project, including Paddock and an unknown workman; the latter fell from a 60 ft (18 m) height and struck the former on April 20, 1929.

[9] By halting the Sun River's spring freshet, Gibson Dam has prevented an estimated $3,044,000 in flooding damage between 1950 and 1999.

Tollhouse Energy of Bellingham, WA a small-business hydropower developer and Greenfields Irrigation District of Fairfield, MT a farmer-managed water utility, are proposing the addition of a 15 megawatt (MW) powerhouse at the base of the dam.

The powerhouse would generate electricity from irrigation water releases with an estimated annual production of 42.9 million kilowatt hours.