Little Thompson dam
Little Thompson
Little Thompson, also known as Hillsboro, is a private earth dam located in Weld County, Colorado, specifically in the city of Milliken. Completed in 1896, this irrigation dam stands at 29 feet tall and stretches 1000 feet in length, with a storage capacity of 767 acre-feet. It is regulated by the Colorado Department of Water Resources and undergoes regular inspections to ensure its structural integrity.
The dam's primary purpose is irrigation, serving the local community by providing water for agricultural use. It is situated on the Little Thompson River-OS and is managed by private owners. Despite its significant hazard potential, the dam is currently in satisfactory condition and meets regulatory guidelines. With a moderate risk assessment rating, the dam is equipped with an uncontrolled spillway and has a maximum discharge capacity of 618 cubic feet per second.
Water resource and climate enthusiasts will find Little Thompson to be a historic and essential infrastructure in Colorado's water management system. Its presence contributes to the region's agricultural sustainability and highlights the importance of proper dam maintenance and regulation in the face of changing climate conditions. As a key player in local water resource management, Little Thompson stands as a testament to the ongoing efforts to balance water usage, safety, and environmental stewardship in the region.
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 Little Thompson -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| St. Vrain Creek At Mouth | 181 cfs | → |
| Big Thompson River At Mouth | 74 cfs | → |
| Big Thompson River At Loveland | 120 cfs | → |
| St Vrain Cr Blw Boulder Cr At Hwy 119 Nr Longmont | 181 cfs | → |
| St. Vrain Creek Below Longmont | -999,999 cfs | → |
| Boulder Creek At Mouth | 44 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Little Thompson.
Boat launches
- Boat Ramp Larimer County
- Lagerman Trail Boulder County
- Brighton
- Adams County
- Filter Plant River Access Point (Put-In)
Campgrounds
- Missile Site Park
- Boyd Lake State Park
- St. Vrain State Park
- Union Reservoir
- Carter Lake - South Side Campgrounds
- Boulder County Fairground
Fishing spots
- Ehrlich Lake
- Johnstown Reservoir
- Promontory Point Park Ponds
- Big Thompson Ponds
- Simpson Ponds Swa
- Mead Ponds
Paddle runs
- October Hole
- Black Bear Hole & A-Hole
- Main Section
- Gnar Section
- Ssv - Confluence To Picnic Grounds
- Lower Boulder Canyon
More reservoirs
Track Little Thompson 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 Little Thompson
Where does the data for Little Thompson 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.
Other water bodies near here
Snoflo-tracked reservoirs and dams within driving distance of Little Thompson.