Alton Power Dam dam
Alton Power Dam
The Alton Power Dam, also known as the Wentworth Dam, is a concrete buttress dam located in Alton, New Hampshire on the Merrymeeting River. Completed in 1923, the dam primarily serves a recreational purpose, offering activities such as boating and fishing for visitors. With a height of 16 feet and a length of 190 feet, the dam has a storage capacity of 3392 acre-feet and a maximum discharge of 3900 cubic feet per second.
Despite its recreational value, the Alton Power Dam has a high hazard potential and is currently in poor condition according to a 2016 assessment. The dam is regulated by the NHDES Dam Bureau, with state permitting, inspection, and enforcement in place to ensure its safety. With a risk assessment rating of moderate, efforts to manage and mitigate potential risks associated with the dam are ongoing, though further improvements may be necessary to enhance its safety and stability for the surrounding community and environment.
In light of its historical significance and potential risks, the Alton Power Dam stands as a focal point for water resource and climate enthusiasts, highlighting the importance of maintaining and managing aging infrastructure to ensure the safety and sustainability of our water resources. As discussions continue regarding the dam's future and potential upgrades, it remains a critical structure in the region, balancing both recreational and safety considerations in the face of evolving climate challenges.
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 Alton Power Dam -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Suncook River At North Chichester | 221 cfs | → |
| Winnipesaukee River At Tilton | 1,610 cfs | → |
| Cocheco River Near Rochester | 97 cfs | → |
| Isinglass R At Rochester Neck Rd | 53 cfs | → |
| Soucook River | 22 cfs | → |
| Merrimack River At Franklin Junction | 4,850 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Alton Power Dam.
Boat launches
- Lake Winnipesaukee Boat Launch
- Merrymeeting Lake Boat Launch
- Crystal Lake Boat Launch
- Halfmoon Lake Boat Launch
- Upper Suncook Lake Boat Launch
- Brindle Pond Boat Launch
Campgrounds
Paddle runs
- Begins In Franklin To Sewall's Island
- Sewall's Island To Manchester Street Bridge
- Thornton Railroad Bridge To Bridgewater/Bristol Town Line
- Woodstock/Thornton Town Line To Thornton Railroad Bridge
- Headwaters At Profile Lake To Southern Boundary Of Franconia Notch State Park
Track Alton Power Dam 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 Alton Power Dam
Where does the data for Alton Power Dam 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 Alton Power Dam.