Flathead dam
Flathead
Flathead, located in Washakie, Wyoming, is an irrigation dam constructed in 1979 on the Gomer Gulch river. The dam stands at a height of 40 feet with a hydraulic height of 36 feet and a structural height of 45 feet. Its primary purpose is irrigation, serving the area with a normal storage capacity of 417 acre-feet and a surface area of 29 acres. However, the dam is currently assessed to be in poor condition with a significant hazard potential, pointing to the need for maintenance and upgrades to ensure its safety and functionality.
Managed by private owners, Flathead is subject to state regulations, permitting, inspections, and enforcement. It features an uncontrolled spillway with a width of 90 feet and three valve outlet gates. The dam's risk assessment categorizes it as moderate, highlighting the importance of implementing risk management measures to mitigate potential hazards. The last inspection in November 2017 indicated a need for improvements to bring the dam up to standard, emphasizing the necessity of ongoing monitoring and maintenance to safeguard the surrounding community and water resources.
In addition to its structural details, Flathead's location in Manderson, Wyoming, and its association with the Gomer Gulch river make it a significant water resource for the region. With its historical and hydrological importance, Flathead underscores the intersection of water management, climate resilience, and infrastructure maintenance in sustaining agricultural activities and ecological balance in the area.
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 Flathead -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Bighorn R At Worland Wyo | 4,350 cfs | → |
| Shell Creek Above Shell Creek Reservoir | 12 cfs | → |
| North Fork Powder River Near Hazelton | 3 cfs | → |
| Bighorn River At Basin | 1,010 cfs | → |
| Shell Creek Near Shell | 74 cfs | → |
| South Piney Creek At Willow Park | 0 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Flathead.
Campgrounds
- Medicine Lodge Archaeological Site
- Leigh Creek Campground
- Leigh Creek
- Tensleep Creek
- Castle Gardens Scenic Area Campground
- Castle Gardens Scenic Area Campsite 1
Track Flathead 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 Flathead
Where does the data for Flathead 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 Significant 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.