Gilman dam
Gilman
Gilman, also known as Centennial Mill Dam, is a privately owned concrete gravity dam located in Dalton, New Hampshire. Built in 1898, this historic structure stands at a height of 38.3 feet with a length of 319 feet, serving primarily for hydroelectric purposes on the Connecticut River. The dam has a storage capacity of 705 acre-feet and a maximum discharge rate of 3538 cubic feet per second.
Managed by the Federal Energy Regulatory Commission (FERC), Gilman is subject to regular state inspections and enforcement to ensure its safety and compliance. Despite a low hazard potential, the dam poses a very high risk due to its age and structural condition assessment being unavailable. Emergency action plans are in place, with a last revision date in January 2018, although detailed risk management measures are not specified in the data. In the event of an emergency, contact information and inundation maps are crucial for effective response and mitigation efforts. Water resource and climate enthusiasts will find Gilman to be a fascinating piece of infrastructure with a rich history and complex risk profile in the realm of dam safety and management.
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 Gilman -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Connecticut River Near Dalton | 3,330 cfs | → |
| Moose River At Victory | 164 cfs | → |
| Ammonoosuc River At Bethlehem Junction | 267 cfs | → |
| Sleepers River (Site W-5) Near St. Johnsbury | 87 cfs | → |
| Passumpsic River At Passumpsic | 942 cfs | → |
| East Branch Passumpsic River Near East Haven | 128 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Gilman .
Boat launches
- Connecticut River Boat Launch
- Forest Lake Boat Launch
- Vermont Fish And Game Boat Lau Lunenburg
- Perkins Landing Road Littleton
- Burns Pond Boat Launch
- Martin Meadow Pond Boat Launch
Campgrounds
- Boy Scout's Of America
- Crazy Horse Family Campground
- Twin Mountain Koa
- Living Water Campground
- Fransted Campground
- Haystack Road
Paddle runs
- Headwaters At Profile Lake To Southern Boundary Of Franconia Notch State Park
- Woodstock/Thornton Town Line To Thornton Railroad Bridge
- Thornton Railroad Bridge To Bridgewater/Bristol Town Line
More reservoirs
Track Gilman 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 Gilman
Where does the data for Gilman 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 Gilman .