Surry Mountain Dam dam
Surry Mountain Dam
Surry Mountain Dam, also known as Surry Mountain Lake, is a rockfill dam located in Cheshire County, New Hampshire. Built in 1941 by the US Army Corps of Engineers, the dam stands at a height of 83 feet and has a maximum storage capacity of 44,000 acre-feet. Its primary purpose is flood risk reduction, protecting downstream communities along the Ashuelot River, such as Keene, Swanzey, Winchester, and Hinsdale, from potential flooding events.
Although Surry Mountain Dam significantly reduces the risk of flooding to surrounding areas, there are still moderate risks associated with the dam. The most likely scenario for downstream flooding would be an uncontrolled high volume release of water through the spillway during significant storm events. However, the dam's failure in extreme scenarios, such as the capacity being exceeded or damage to the spillway structure, could result in devastating flooding downstream, impacting towns and cities further along the river, including Hartford, Connecticut. To manage these risks, the US Army Corps of Engineers continually monitors and maintains the dam, works with emergency managers to raise awareness and preparedness, and regularly updates the emergency action plan.
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 Surry Mountain Dam -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Ashuelot River Below Surry Mt Dam | 259 cfs | → |
| Ashuelot River Near Gilsum | 126 cfs | → |
| Otter Brook Below Otter Brook Dam | 12 cfs | → |
| Ashuelot River Above The Branch | 21 cfs | → |
| Ashuelot River At West Swanzey | 598 cfs | → |
| S Br Ashuelot River At Webb | 25 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Surry Mountain Dam.
Boat launches
- Surry Mountain Lake
- Chapman Pond Boat Launch
- Bolster Pond Boat Launch
- Wilson Pond Boat Launch
- Granite Lake Boat Launch
- Lake Warren Boat Launch
Campgrounds
- Wheelock Park Campground
- Pilgrim Pines Camping Area
- Swanzey Lake Camping Area
- Fox Brook Tent Site
- Mt Monadnock State Park Campground
- Camp Wanocksett
Paddle runs
- First Bridge Upstream On Route 100 To Confluence With West River
- Headwaters To First Bridge Upstream On Route 100
- Headwaters To Confluence With West River (End Of Sherman Road)
- Headwaters To Crossing Of Route 100 Near Route 155
- Headwaters To North Of Searsburg Reservoir
- End Of Kendall Farm Road To Confluence With West River
Track Surry Mountain 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 Surry Mountain Dam
Where does the data for Surry Mountain 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 Surry Mountain Dam.