Ayers Island dam
Ayers Island
Ayers Island in Bristol, New Hampshire is a captivating site for water resource and climate enthusiasts. This private dam, constructed in 1924 by the Ambursen Dam Company, stands at a height of 80 feet and spans 699 feet along the Pemigewasset River. With a storage capacity of 10,000 acre-feet and a maximum discharge of 92,100 cubic feet per second, Ayers Island serves a primary purpose of hydroelectric power generation.
Managed by the Federal Energy Regulatory Commission, Ayers Island is a significant structure with a hazard potential classified as "Significant" and a moderate risk assessment rating of 3. The dam's spillway width of 267 feet and uncontrolled spillway type add to its unique features, making it an essential part of the water infrastructure in the area. With state regulation, inspection, and enforcement in place, Ayers Island is a well-maintained and regulated dam that showcases the intersection of human engineering with natural 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 Ayers Island -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Smith River Near Bristol | 460 cfs | → |
| Pemigewasset River At Plymouth | 3,350 cfs | → |
| Merrimack River At Franklin Junction | 9,360 cfs | → |
| Winnipesaukee River At Tilton | 1,380 cfs | → |
| Baker River Near Rumney | 740 cfs | → |
| Blackwater River Near Webster | 19 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Ayers Island .
Boat launches
- Mooney Clark Landing Road Bristol
- Wickwas Lake Boat Launch
- School Pond Boat Launch
- Giles Pond Boat Launch
- Winona Lake Boat Launch
- Highland Lake Boat Launch
Campgrounds
Paddle runs
- Begins In Franklin To Sewall's Island
- Thornton Railroad Bridge To Bridgewater/Bristol Town Line
- Sewall's Island To Manchester Street Bridge
- Woodstock/Thornton Town Line To Thornton Railroad Bridge
- Headwaters At Profile Lake To Southern Boundary Of Franconia Notch State Park
- Source Above Fr 55 To Proclamation Boundary (Stony Brook)
Track Ayers Island 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 Ayers Island
Where does the data for Ayers Island 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 Ayers Island .