Thelma #1 dam
Thelma #1
Thelma #1 is a privately owned Earth dam located in Emigrant, Montana, along the TR-Yellowstone River. Designed by the USDA NRCS and completed in 1962, this dam primarily serves the purpose of irrigation and has a storage capacity of 106 acre-feet. With a low hazard potential and a height of 19 feet, Thelma #1 plays a crucial role in water resource management in the area.
Managed by the DNRC and regulated by the state of Montana, Thelma #1 is subject to regular inspections and enforcement to ensure its safety and functionality. Although its condition is currently not rated, the dam has not undergone any modifications and continues to operate within its design parameters. With a maximum discharge of 120 cubic feet per second, Thelma #1 remains a vital piece of infrastructure for the surrounding agricultural community.
As a key component of the irrigation system in Park County, Thelma #1 provides essential water resources for local farmers and ranchers. Its location along the Yellowstone River and its storage capacity make it a valuable asset for mitigating drought and ensuring a reliable water supply for the region. Climate and water resource enthusiasts can appreciate the role that Thelma #1 plays in sustainable water management practices in Montana.
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 Thelma #1 -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Yellowstone River At Corwin Springs Mt | 6,680 cfs | → |
| Gardner River Near Mammoth Ynp | 410 cfs | → |
| Boiling River At Mammoth | 25 cfs | → |
| Hyalite C At Hyalite R S Nr Bozeman Mt | 46 cfs | → |
| Gallatin River Near Gallatin Gateway Mt | 1,630 cfs | → |
| Yellowstone River Near Livingston Mt | 8,020 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Thelma #1.
Boat launches
- Old Yellowstone Trail Park County
- Carbella Boat Ramp
- Daily Lake Road Park County
- Murphy Lane Park County
- Us 89 Park County
Campgrounds
Fishing spots
Paddle runs
- Gallatin Forest Boundary, Sec. 32, T7s, R7e To Yellowstone National Park, Sec. 23, T9s, R8e
- Yankee Jim Canyon (Joe Brown To Miner)
- Gardiner Town Run
- Moose To Storm Castle
- Gallatin Canyon, Sec. 19, T4s, R4e To Yellowstone National Park, Sec. 27, T9s, R5e
- The Headwaters, In The Gallatin Range To Ends Downstream Of Osprey Falls
More reservoirs
Track Thelma #1 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 Thelma #1
Where does the data for Thelma #1 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 Thelma #1.