Overview

Jackson Lake Dam, a temporary rockfilled crib dam was completed in 1907 by the Bureau of Reclamation at Jackson Lake to store 200,000 acre-feet for the Minidoka Project until the storage requirements could be determined. A portion of this dam failed in 1910, and in 1911 a concrete gravity structure with earth embankment wings was built at the site. The new dam increased storage capacity to 380,000 acre-feet. In 1916, further construction raised the dam 17 feet to a structural height of 65.5 feet, with a total storage capacity of 847,000 acre-feet (active 847,000 acre-feet).

Safety concerns were identified at the dam in the mid-1970s, and from 1977 to 1989 the level of Jackson Lake was maintained at a lower than normal level because of concerns for possible dam failure during an earthquake. The dam foundation was completely replaced using a technique called dynamic compaction, and a grout curtain was installed below the foundation. The combination water release structure/bridge was also replaced. This work was completed in 1989 under authority of Reclamation's Safety of Dams Act making the full capacity available again.

Geology

Foundation: Rock ledge about 30 feet thick underlain by a 10 foot layer of stiff, blue clay overlying second rock formation.

General

Dimensions

Hydraulics & Hydrology