Hopkinton dam
Hopkinton
Hopkinton, also known as Contoocook Dam, is a hydroelectric structure located in Merrimack, New Hampshire. Owned by the local government, this concrete dam was completed in 1890 and serves as a key component in harnessing the power of the Contoocook River for energy generation. With a height of 10 feet and a length of 325 feet, the dam boasts a storage capacity of 380 acre-feet and a maximum discharge of 7000 cubic feet per second.
Managed by the Federal Energy Regulatory Commission, Hopkinton Dam has a low hazard potential and is regularly inspected to ensure its structural integrity. The dam's spillway type is uncontrolled, with a width of 270 feet, allowing for the safe release of excess water during periods of high flow. Despite its moderate risk assessment rating, the dam's emergency action plan was last revised in 2006, highlighting the need for updated preparedness measures in the event of a potential hazard.
Water resource and climate enthusiasts will appreciate the role that Hopkinton Dam plays in the local hydroelectric infrastructure, providing renewable energy while also managing water flow along the Contoocook River. With its historical significance dating back over a century, this structure serves as a testament to the innovative engineering techniques of the time and continues to contribute to the sustainable development of the region's water resources.
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 Hopkinton -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Warner River At Davisville | 405 cfs | → |
| Contoocook R Bl Hopkinton Dam At W Hopkinton | 1,080 cfs | → |
| Blackwater River Near Webster | 19 cfs | → |
| Contoocook River Near Henniker | 782 cfs | → |
| Piscataquog River Bl Everett Dam | 8 cfs | → |
| Soucook River | 22 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Hopkinton .
Boat launches
- Depot Lane Hopkinton
- Maple Street Hopkinton
- Clement Pond Boat Launch
- Hopkinton-Everett Reservoir Boat Launch
- French Pond Boat Launch
Campgrounds
- Mile-Away Campground
- Camp Spaulding
- Camp Wilmot
- Fox Brook Tent Site
- Northstar Campground
- Saddleback Campground
Paddle runs
- Sewall's Island To Manchester Street Bridge
- Begins In Franklin To Sewall's Island
- Thornton Railroad Bridge To Bridgewater/Bristol Town Line
- Woodstock/Thornton Town Line To Thornton Railroad Bridge
- First Bridge Upstream On Route 100 To Confluence With West River
- Headwaters To First Bridge Upstream On Route 100
Track Hopkinton 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 Hopkinton
Where does the data for Hopkinton 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 Hopkinton .