Island Park dam
Island Park
Island Park, located in Idaho along the Henrys Fork River, is a federal-owned irrigation dam managed by the Bureau of Reclamation. Built in 1937, this earth dam stands at a height of 93.4 feet and has a storage capacity of 169,646 acre-feet, making it crucial for agricultural irrigation in the region. The dam, with a spillway width of 257 feet, also serves as a high-hazard potential structure due to its significant hydraulic height of 73 feet.
Over the years, Island Park has undergone multiple modifications to enhance its structural integrity and seismic resilience. The dam has been inspected regularly by the Bureau of Reclamation, with the last inspection conducted in July 2020. Despite its high hazard potential, the dam is rated to have a moderate risk level (3), indicating the need for ongoing risk management measures to ensure the safety of surrounding communities in Saint Anthony, Idaho. With its strategic location and critical role in water resource management, Island Park remains a vital infrastructure for sustaining agricultural activities and safeguarding against potential flood risks 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 Island Park -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Henrys Fork Nr Island Park Id | 276 cfs | → |
| Henrys Fork Blw Coffee Pot Rapids Nr Macks Inn Id | 372 cfs | → |
| Big Springs At Big Springs Id | 128 cfs | → |
| Henrys Fork Nr Lake Id | 7 cfs | → |
| Red Rock Cr Ab Lakes Nr Lakeview Mt | 69 cfs | → |
| Madison River Near West Yellowstone Mt | 495 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Island Park.
Boat launches
- Island Park Boating Site
- Fremont County
- Forest Road 413 Fremont County
- Mccrea Road Fremont County
- Old Highway Island Park
- Big Springs Boating Launch
Campgrounds
Fishing spots
Paddle runs
- Box Canyon
- Elk Creek To Slackwater Of Ponds Power Dam
- Island Park Dam To Box Canyon Summer Homes
- Coffee Pot Campground To Mccrea's Bridge
- Buffalo River Springs To Confluence With Elk Creek
- Box Canyon Summer Homes To Northern Boundary Of Harriman Park
More reservoirs
Track Island Park 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 Island Park
Where does the data for Island Park 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 Island Park.