Thomson Dam No 11 dam
Thomson Dam No 11
Thomson Dam No 11, also known as Nos 11, 11-1/2, and Upper Gate House, is a key structure located in Thomson, Minnesota, along the St. Louis River. Built in 1907 for hydroelectric purposes, this gravity dam stands at 17 feet tall and stretches 365 feet in length, with a storage capacity of 4352 acre-feet. Owned and regulated by the Minnesota Department of Natural Resources, this dam is inspected regularly to ensure its safety and functionality, with the Federal Energy Regulatory Commission overseeing its operation.
With a high hazard potential due to its location and design, Thomson Dam No 11 plays a crucial role in managing water resources and generating hydroelectric power in the region. Its controlled spillway and associated structures support its function for flood control, recreation, and water storage. The dam's risk assessment indicates a very high level of risk, highlighting the importance of ongoing monitoring, maintenance, and emergency preparedness to safeguard the surrounding community and environment.
Thomson Dam No 11 serves as a historic and vital infrastructure for water resource management and climate resilience in Carlton County, Minnesota. As part of the larger St. Paul District of the US Army Corps of Engineers, this dam exemplifies the collaboration between state and federal agencies to ensure the safety, sustainability, and efficiency of water infrastructure for the benefit of both people and the environment.
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 Thomson Dam No 11 -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| St. Louis River At Scanlon | 2,770 cfs | → |
| Nemadji River Near South Superior | 508 cfs | → |
| Knife River Near Two Harbors | 121 cfs | → |
| Bois Brule River At Brule | 167 cfs | → |
| St. Croix River Near Danbury | 1,320 cfs | → |
| Kettle River Below Sandstone | 476 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Thomson Dam No 11 .
Boat launches
- Saint Louis River -- Oliver - Sajac Memorial Park Access
- Woodstock Bay
- Pokegama River -- Access
- Saint Louis River -- Arrowhead Fishing Pier Access
- Billings Park Boat Launch
- Midway Road Saint Louis County
Campgrounds
- Jay Cooke State Park
- Silver Creek Backpack Campsite
- High Landing Backpack Campsite
- Ash Ridge Backpack Campsite
- Lost Lake Backpack Campsite
- Spafford City Park Campground
Paddle runs
- Upper Saint Louis
- Carlton County State Aid Highway #12 Bridge To The Site Of Old Sandstone Hydroelectric Dam
- The Site Of Old Sandstone Hydroelectric Dam To The Confluence With St. Croix River
- The Boundary Between Logan And Workman Townships In Aitkin County To The Dam Entrance Of The Flood Diversion Channel
Track Thomson Dam No 11 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 Thomson Dam No 11
Where does the data for Thomson Dam No 11 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 High 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 Thomson Dam No 11 .