Big Rock Detention Dam dam
Big Rock Detention Dam
Big Rock Detention Dam, located in Valley County, Montana, serves as a crucial flood risk reduction structure along Willow Creek and the Milk River. Built in 1961 by the Bureau of Land Management, this gravity-type dam stands at a structural height of 13 feet and has a hydraulic height of 9 feet, with a length of 1793 feet and a storage capacity of 265 acre-feet. Despite its low hazard potential, the dam's condition assessment is currently marked as unsatisfactory, highlighting the need for ongoing maintenance and inspection.
The dam's primary purpose is flood risk reduction, with an emphasis on protecting the surrounding area from potential inundation during periods of heavy rainfall or snowmelt. While there are no associated locks or outlet gates, the dam features an uncontrolled spillway with a width of 3 feet. The risk assessment for Big Rock Detention Dam indicates a moderate level of risk, emphasizing the importance of continued risk management measures to ensure the safety and functionality of the structure.
As a federally-owned and operated dam under the jurisdiction of the Bureau of Land Management, Big Rock Detention Dam plays a crucial role in water resource management and climate resilience in the region. With its strategic location and design, the dam serves as a vital asset in protecting the local community and environment from the impacts of flooding, underscoring the importance of ongoing monitoring and maintenance to safeguard its effectiveness in mitigating flood risks.
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 Big Rock Detention Dam -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Milk River At Tampico Mt | 39 cfs | → |
| Beaver Creek Near Hinsdale Mt | 36 cfs | → |
| Milk River At Nashua Mt | 135 cfs | → |
| Milk River At Juneberg Bridge Nr Saco Mt | 182 cfs | → |
| Beaver Cr Bl Guston Coulee Nr Saco Mt | 67 cfs | → |
| Milk River At Malta Mt | 43 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Big Rock Detention Dam.
Track Big Rock Detention 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 Big Rock Detention Dam
Where does the data for Big Rock Detention 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 Big Rock Detention Dam.