Gem State dam
Gem State
Gem State is a hydroelectric dam located in Shelley, Idaho, along the Snake River. Constructed in 1988, it stands at a height of 40 feet and has a maximum storage capacity of 6,700 acre-feet. The dam serves multiple purposes including hydroelectric power generation and irrigation for the surrounding area, with a spillway width of 230 feet to manage controlled releases of water.
Managed by the Federal Energy Regulatory Commission, Gem State is regulated by the Idaho Department of Water Resources and undergoes regular state inspections and enforcement measures. The dam has a high hazard potential and is considered to have a very high risk level. Despite its age, the condition assessment of Gem State is currently listed as "Not Available" with emergency action plans last revised in December 2020. With its strategic location along the Snake River, Gem State plays a crucial role in water resource management and climate resilience efforts in the region.
Dam data reference
Condition Assessment
- Satisfactory
- No existing or potential dam safety deficiencies are recognized. Acceptable performance is expected under all loading conditions (static, hydrologic, seismic) in accordance with the minimum applicable state or federal regulatory criteria or tolerable risk guidelines.
- Fair
- No existing dam safety deficiencies are recognized for normal operating conditions. Rare or extreme hydrologic and/or seismic events may result in a dam safety deficiency. Risk may be in the range to take further action.
- Poor
- A dam safety deficiency is recognized for normal operating conditions which may realistically occur. Remedial action is necessary. POOR may also be used when uncertainties exist as to critical analysis parameters which identify a potential dam safety deficiency.
- Unsatisfactory
- A dam safety deficiency is recognized that requires immediate or emergency remedial action for problem resolution.
- Not Rated
- The dam has not been inspected, is not under state or federal jurisdiction, or has been inspected but, for whatever reason, has not been rated.
Hazard Potential Classification
- High
- Dams assigned the high hazard potential classification are those where failure or mis-operation will probably cause loss of human life.
- Significant
- Dams assigned the significant hazard potential classification are those dams where failure or mis-operation results in no probable loss of human life but can cause economic loss, environmental damage, disruption of lifeline facilities, or impact other concerns. Significant hazard potential classification dams are often located in predominantly rural or agricultural areas but could be in areas with population and significant infrastructure.
- Low
- Dams assigned the low hazard potential classification are those where failure or mis-operation results in no probable loss of human life and low economic and/or environmental losses. Losses are principally limited to the owner's property.
- Undetermined
- Dams for which a downstream hazard potential has not been designated or is not provided.
Plan around the weather
Same NOAA / yr.no feed Snoflo's iOS app uses. Watch the precipitation column on the meteogram -- rain on the basin upstream typically lifts inflow 24-72 hours later.
Next 5 days, hour by hour
Temperature line with weather symbols on top, snow + rain accumulation as columns, humidity as a dotted line.
5-day forecast table
Every 3 hours, broken out across temperature, snow, rain, humidity, and wind. Each cell is colour-coded relative to the column min/max.
| Time | Condition | Temp (°F) | Snow (in) | Rain (in) | Humidity (%) | Wind (mps) | Wind dir |
|---|---|---|---|---|---|---|---|
| Loading detailed forecast… | |||||||
15-day temperature & precipitation
Daily temperatures, snow, and rain projected over the next two weeks.
Nearby streamflow gauges
USGS streamgauges around Gem State -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Snake River Nr Shelley Id | 4,970 cfs | → |
| Willow Cr Floodway Channel At Mouth Nr Id Falls Id | 4 cfs | → |
| Blackfoot River Nr Shelley Id | 489 cfs | → |
| Great Western Spillback Nr Idaho Falls Id | 63 cfs | → |
| Snake River Ab Eagle Rock Nr Idaho Falls Id | 5,250 cfs | → |
| Willow Creek Bl Floodway Channel Nr Ucon Id | 98 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Gem State.
Boat launches
- East 1250 North Bingham County
- River Parkway Downtown
- Bonneville County
- East Lincoln Road Bonneville County
- East Airport Road Blackfoot
Campgrounds
- Idaho Falls North Tourist Park
- Kepp's Crossing Dispersed Camping Area
- Rose Park
- Juniper Park - Ririe Reservoir
- Juniper Co Park
- Jefferson County Lake
Track Gem State in the Snoflo app
Save this dam as a favorite and get the local NOAA / yr.no forecast plus regional flow context wherever you are.
About Gem State
Where does the data for Gem State come from?
Structural and regulatory data come from the U.S. Army Corps of Engineers' National Inventory of Dams (NID). Weather forecast comes from NOAA / yr.no -- the same feed Snoflo's iOS app uses.
How often is the report updated?
NID structural data refreshes annually as the Corps publishes updated assessments. The weather forecast refreshes throughout the day.
What does the High hazard rating mean?
The Corps of Engineers' hazard potential classification grades probable consequences if the dam fails: High = probable loss of human life; Significant = no probable loss of human life but possible economic loss / environmental damage; Low = no probable loss of human life, only minor economic / environmental losses. See the Dam Data Reference card above for the full definitions.
What's "% of normal"?
The current storage value compared to the historical average storage on this calendar day. 100% = right on average; values above 100% mean above-normal storage (wet year); values below mean below-normal (dry year or drought).
Can I get alerts when storage crosses a threshold?
Yes -- alerts are managed in the Snoflo iOS app. Favorite this dam, set a threshold, and you'll get a push the moment conditions cross.
Other water bodies near here
Snoflo-tracked reservoirs and dams within driving distance of Gem State.