Thomsen Dam dam
Thomsen Dam
Thomsen Dam, located in Anthon, Iowa, along the TR-Little Sioux River, was completed in 1959 by the USDA NRCS and serves multiple purposes including fire protection, stock, and small fish pond. With a dam height of 38 feet and a length of 550 feet, the earth dam holds a normal storage capacity of 49 acre-feet and a maximum storage capacity of 91 acre-feet. The dam's low hazard potential and moderate risk assessment make it a crucial asset for water resource management in Woodbury County.
Managed by a private owner, Thomsen Dam is regulated by the Iowa DNR and undergoes state inspection and enforcement to ensure its structural integrity. The dam's primary source agency is the state of Iowa, and it falls under the jurisdiction of the Rock Island District. Despite its uncontrolled spillway type and lack of outlet gates, the dam's risk management measures and moderate risk assessment highlight its importance in mitigating potential flood risks and ensuring water resource sustainability in the region.
Water resource and climate enthusiasts will be captivated by Thomsen Dam's role in providing essential services such as fire protection and stock pond maintenance while also serving as a habitat for small fish species. Its location along the TR-Little Sioux River and its significant storage capacity make it a key infrastructure for water management in Woodbury County. With a focus on safety and risk management, the dam stands as a vital asset in safeguarding the surrounding communities and ecosystems from potential water-related hazards.
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 Thomsen Dam -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Little Sioux River At Correctionville | 1,400 cfs | → |
| West Fork Ditch At Hornick | 80 cfs | → |
| Maple River At Mapleton | 264 cfs | → |
| Floyd River At James | 323 cfs | → |
| Missouri River At Sioux City | 26,000 cfs | → |
| Perry Creek Near Milnerville | 25 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Thomsen Dam.
Track Thomsen 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 Thomsen Dam
Where does the data for Thomsen 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 Thomsen Dam.