Grasmere Middle Dam dam
Grasmere Middle Dam
Grasmere Middle Dam, also known as Grasmere Reservoir North Middle Dam, is a privately owned structure located in Owyhee, Idaho. Completed in 1936, this earth dam stands at a height of 15.5 feet and has a hydraulic height of 12.2 feet. It plays a crucial role in water resource management, with a storage capacity of 420.2 acre-feet and a surface area of 152.9 acres.
Situated on Rattlesnake Creek and Marys Creek, Grasmere Middle Dam serves various purposes beyond water storage. Despite its poor condition assessment and low hazard potential, the dam is deemed to have a moderate risk level. With a drainage area of 1.3 square miles and a maximum discharge rate of 18 cubic feet per second, this structure is subject to state regulation, inspection, and enforcement by the Idaho Department of Water Resources.
While Grasmere Middle Dam does not have a federal owner or funding, its presence is essential for maintaining water resources in the region. The dam's uncontrolled spillway, lack of outlet gates, and poor condition warrant attention for potential risk management measures. For water resource and climate enthusiasts, understanding the role and condition of Grasmere Middle Dam is vital for ensuring the safety and sustainability of the surrounding communities and ecosystems.
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 Grasmere Middle Dam -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Bruneau River Nr Hot Spring Id | 144 cfs | → |
| Bruneau River At Rowland Nv | 24 cfs | → |
| Owyhee R Nr Mountain City | 120 cfs | → |
| Jarbidge River Below Jarbidge | 21 cfs | → |
| Owyhee R Nr Gold Creek | 109 cfs | → |
| Ef Owyhee River At Crutcher Crossing | 25 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Grasmere Middle Dam.
Track Grasmere Middle Dam 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 Grasmere Middle Dam
Where does the data for Grasmere Middle Dam 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 Low 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 Grasmere Middle Dam.