Dry Hollow dam
Dry Hollow
Dry Hollow is a privately owned irrigation dam located in Madison County, Montana, along Dry Hollow Creek. Completed in 1999, this earth dam stands at 25 feet high and spans 550 feet in length, with a storage capacity of 41.7 acre-feet. The dam serves the primary purpose of irrigation, providing water for agricultural use in the surrounding area.
Managed by the Montana Department of Natural Resources and Conservation (DNRC), Dry Hollow Dam is regulated, inspected, and enforced by the state agency to ensure its safety and compliance with regulations. With a low hazard potential and a moderate risk assessment rating, the dam poses minimal risk to downstream areas. Despite not being rated for its condition, the dam is regularly monitored for any necessary maintenance or repairs.
Located in a picturesque setting near the city of Harrison, Dry Hollow Dam offers a unique opportunity for water resource and climate enthusiasts to study the intersection of human-made structures and natural water systems. Its presence along Dry Hollow Creek serves as a vital resource for sustaining agricultural activities in the region, highlighting the importance of responsible water management practices for a sustainable future.
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 Dry Hollow -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Willow Creek Near Harrison Mt | 39 cfs | → |
| Madison River Bl Ennis Lake Nr Mcallister Mt | 1,720 cfs | → |
| Madison River Ab Powerplant Nr Mcallister Mt | 239 cfs | → |
| Jefferson River Near Three Forks Mt | 2,800 cfs | → |
| Gallatin River At Logan Mt | 940 cfs | → |
| Gallatin River Near Gallatin Gateway Mt | 1,040 cfs | → |
About Dry Hollow
Where does the data for Dry Hollow 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 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.