Grand Coulee dam
Grand Coulee
Grand Coulee, located in Okanogan, Washington, is a concrete gravity dam on the Columbia River that was completed in 1941 by the Bureau of Reclamation. Standing at a height of 550 feet with a hydraulic height of 380 feet, this dam serves the primary purpose of flood risk reduction along with irrigation. With a normal storage capacity of 9,562,000 acre-feet and a maximum discharge of 265,000 cubic feet per second, Grand Coulee plays a crucial role in managing water resources in the region.
Owned and operated by the Bureau of Reclamation, Grand Coulee is a significant structure with a high hazard potential and very high risk assessment. The dam spans a length of 5,673 feet and has a spillway width of 1,485 feet, showcasing its impressive scale and engineering design. While the condition assessment of the dam is not available, regular inspections and emergency action plans are in place to ensure its safety and reliability in the face of potential hazards.
As a key component of the water infrastructure in the area, Grand Coulee contributes to the management of the Columbia River and plays a vital role in water supply, flood control, and irrigation for the region. With its strategic location and impressive specifications, this dam stands as a testament to human ingenuity in harnessing and managing water resources amidst changing climatic conditions.
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 Grand Coulee -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Wilson Creek Below Corbett Draw Near Almira | 0 cfs | → |
| Omak Creek Near Omak | 3 cfs | → |
| Okanogan River At Malott | 4,980 cfs | → |
| Crab Creek At Irby | 9 cfs | → |
| Methow River Near Pateros | 3,980 cfs | → |
| Chelan River At Chelan | 268 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Grand Coulee.
Track Grand Coulee 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 Grand Coulee
Where does the data for Grand Coulee 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 Grand Coulee.