Site 19 Souhegan dam
Site 19 Souhegan
Located in High Bridge, Hillsborough, New Hampshire, Site 19 Souhegan, also known as Site 19 Floodwater Dam, is a state-owned earth dam designed by the USDA NRCS in 1963 for the primary purpose of flood risk reduction along the Souhegan River. With a dam height of 35 feet and a length of 725 feet, this structure provides a maximum storage capacity of 2,238 acre-feet and serves a drainage area of 11.37 square miles. Despite being regulated by the NHDES WD, this dam is not subject to state permitting, inspection, or enforcement.
The dam's spillway, with an uncontrolled design and a width of 460 feet, can accommodate a maximum discharge of 18,577 cubic feet per second. However, its hazard potential is rated as high, indicating potential risks in the event of a significant flood event. The condition assessment of Site 19 Souhegan is currently listed as "Not Rated," with the last inspection conducted in August 2014. While the risk assessment is moderate, with a rating of 3, there is no detailed risk management plan or inundation maps prepared for this dam.
Despite its critical role in flood risk reduction, Site 19 Souhegan presents challenges in terms of its maintenance and emergency preparedness. With a high hazard potential and limited regulatory oversight, there is a need for increased monitoring and risk management measures to ensure the safety and effectiveness of this earth dam in protecting the surrounding community and environment from potential flooding events along the Souhegan River.
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 Site 19 Souhegan -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| North Nashua River At Fitchburg | 101 cfs | → |
| Souhegan River (Site Wlr-1) Near Milford | 216 cfs | → |
| Contoocook River At Peterborough | 118 cfs | → |
| Squannacook River Near West Groton | 95 cfs | → |
| Millers River Near Winchendon | 121 cfs | → |
| Otter River At Otter River | 105 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Site 19 Souhegan.
Boat launches
- Grassy Pond Boat Launch
- Cunningham Pond Boat Launch
- Contoocook Lake Boat Launch
- Pool Pond Boat Launch
- Melendy Pond Boat Launch
- Whalom Lake Public Boat Ramp
Campgrounds
- Damon Pond Campground
- Pearl Hill Campground
- Lake Dennison State Park
- East Dennison Camping Area
- North Dennison Camping Area
- Otter River State Forest
Track Site 19 Souhegan 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 Site 19 Souhegan
Where does the data for Site 19 Souhegan 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 Site 19 Souhegan.