Pierce Mills dam
Pierce Mills
Pierce Mills is a historic hydroelectric dam located on the Passumpsic River in St. Johnsbury, Vermont. Built in 1928, this concrete gravity dam stands at a height of 19 feet and has a length of 140 feet. With a storage capacity of 300 acre-feet, it serves as a key source of hydroelectric power in the area. The dam is owned by a public utility and is not state-regulated, making it an important asset for the local community.
The dam has a low hazard potential and is currently rated as "Not Rated" in terms of its condition assessment. Despite not being regularly inspected or permitted by state agencies, Pierce Mills continues to operate efficiently, providing clean and renewable energy to the region. The last inspection of the dam was conducted in May 2000, and it meets all necessary safety guidelines. The surrounding area is at low risk for inundation, and emergency preparedness plans are in place to ensure the safety of nearby residents in the event of a dam failure.
With its picturesque location on the Passumpsic River and its important role in supplying hydroelectric power, Pierce Mills remains a significant landmark in Caledonia County, Vermont. As a multi-arch dam with a solid foundation on rock and soil, it represents a sustainable and reliable source of renewable energy. Climate and water resource enthusiasts will appreciate the historical significance and environmental impact of this well-maintained dam.
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 Pierce Mills -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Sleepers River (Site W-5) Near St. Johnsbury | 98 cfs | → |
| Pope Brook (Site W-3) Nr. N. Danville | 9 cfs | → |
| Passumpsic River At Passumpsic | 1,110 cfs | → |
| Moose River At Victory | 204 cfs | → |
| East Branch Passumpsic River Near East Haven | 144 cfs | → |
| Connecticut River Near Dalton | 3,750 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Pierce Mills.
Boat launches
- Shadow Lake Road Concord
- Harveys Hollow Road Peacham
- Taylor Road Peacham
- North Pond Road Walden
- Perkins Landing Road Littleton
- Old Waterford Road Littleton
Campgrounds
- Sugar Ridge Rv Resort
- Burke Mountain Campground
- Crazy Horse Family Campground
- Boy Scout's Of America
- New Discovery State Park
- Big Deer State Park
Track Pierce Mills 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 Pierce Mills
Where does the data for Pierce Mills 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 Pierce Mills.