Arrowrock dam
Arrowrock
Arrowrock Dam, located in Boise, Idaho, is a federally owned structure built in 1915 by the Bureau of Reclamation to primarily reduce flood risks in the area. This concrete dam stands at a height of 350 feet and has a hydraulic height of 257 feet, with a storage capacity of 283,700 acre-feet and a maximum discharge rate of 16,080 cubic feet per second. The dam also serves purposes such as irrigation, recreation, and water supply, making it a vital resource for the region.
Managed by the Bureau of Reclamation, Arrowrock Dam is regulated by the Idaho Department of Water Resources and undergoes regular inspections to ensure its structural integrity. With a high hazard potential, the dam's emergency action plan is in place, and risk assessments have determined it to have a very high risk ranking. The dam's controlled spillway, drum outlet gates, and associated structures contribute to its efficient operation and management, while its location on the Boise River and Snake River provides essential water resources for the surrounding communities.
Arrowrock Dam's historical significance, architectural design, and impact on water management in the region make it a fascinating structure for water resource and climate enthusiasts. Its role in flood risk reduction, irrigation, and recreational activities highlights the importance of sustainable water infrastructure in supporting the needs of both human populations and natural ecosystems. As a key component of the Bureau of Reclamation's operations, Arrowrock Dam exemplifies the agency's commitment to managing water resources effectively and ensuring the safety and well-being of the local communities it serves.
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 Arrowrock -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Mores Creek Ab Robie Creek Nr Arrowrock Dam Id | 65 cfs | → |
| Cottonwood Creek Bel Fivemile Cr Nr Boise Id | 1 cfs | → |
| Sf Boise River At Neal Bridge Nr Arrowrock Dam Id | 360 cfs | → |
| Boise River Nr Twin Springs Id | 782 cfs | → |
| Boise River At Glenwood Bridge Nr Boise Id | 634 cfs | → |
| Dry Creek Nr Eagle Id | 0 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Arrowrock.
Boat launches
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Campgrounds
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Fishing spots
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River runs
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More reservoirs
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About Arrowrock
Where does the data for Arrowrock 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 below 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.
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.