Gem State Left Dike
Gem State Left Dike is an earth dam located in Bonneville County, Idaho, built in 1988. It carries a High hazard potential classification and has a satisfactory condition assessment.
About Gem State Left Dike
The primary purpose of Gem State Left Dike is hydroelectric. The dam generates hydroelectric power by channeling water through turbines, converting the energy of flowing water into electricity. The dam is owned by City Of Idaho Falls (local government). It impounds the Snake River near Shelley, Id.
The dam stands 30 feet tall and stretches 7,920 feet across, creates a reservoir covering 305 acres, has a maximum storage capacity of 6,700 acre-feet, and collects water from a drainage area of 4,650 square miles. Completed in 1988, the structure is 38 years old.
This dam carries a high hazard potential classification, which means that a failure or uncontrolled release of water would likely cause loss of human life. This classification reflects the consequences of failure, not the likelihood — it indicates that people live or work in the area downstream. Its condition is rated satisfactory, indicating no existing or potential dam safety deficiencies are recognized. An emergency action plan is in place for this dam. The most recent inspection on record was 10/18/2022.
Living Downstream
If you live or work downstream of this dam, consider taking these steps: learn your local evacuation routes, check whether your county emergency management office has a dam failure inundation map, and sign up for local emergency alerts. The Idaho dam safety program can provide more specific information about emergency planning for this structure.
Search for dams near your address to see all dams in your area with hazard classifications and safety data.
Location
| State | Idaho |
| County | Bonneville |
| Nearest City | Shelley, Id |
| River/Stream | Snake River |
| Coordinates | 43.42950, -112.09510 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 30 ft |
| Dam Height | 30 ft |
| Dam Length | 7,920 ft |
| Year Completed | 1988 (38 years old) |
Storage & Hydraulics
| NID Storage | 6,700 acre-ft |
| Max Storage | 6,700 acre-ft |
| Normal Storage | 5,000 acre-ft |
| Surface Area | 305 acres |
| Drainage Area | 4,650 sq mi |
| Spillway Type | None |
Ownership & Safety
| Purpose | Hydroelectric |
| Owner | City of Idaho Falls |
| Owner Type | Local Government |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 10/18/2022 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | ID83077 |
| Federal ID | ID83006S002 |
| More Info | State Dam Safety Program |