Minnewawa dam
Minnewawa
Minnewawa, a privately owned hydroelectric dam located in Marlborough, New Hampshire, stands as a testament to early 20th-century engineering excellence. Completed in 1923, this concrete arch dam boasts a height of 63 feet and a length of 265 feet, harnessing the power of Minnewawa Brook to generate electricity. With a storage capacity of 155 acre-feet, the dam serves as a vital resource for the surrounding area, providing a maximum discharge of 1700 cubic feet per second.
Managed by the New Hampshire Department of Environmental Services Dam Bureau and regulated by the Federal Energy Regulatory Commission, Minnewawa Dam has a high hazard potential due to its size and location. Despite its age, the dam remains in moderate condition, with a risk assessment rating of 3 out of 5. Emergency action plans are in place, although the last inspection in September 2020 highlighted the need for further assessment of the dam's structural integrity.
Enthusiasts of water resources and climate will find Minnewawa Dam a fascinating example of early hydraulic engineering in New Hampshire. Its historical significance, combined with its continued operation as a hydroelectric facility, makes it a key player in the region's energy infrastructure. As climate change impacts water resources, understanding and monitoring dams like Minnewawa become increasingly important to ensure their safety and functionality for future generations.
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 Minnewawa -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Otter Brook Below Otter Brook Dam | 12 cfs | → |
| S Br Ashuelot River At Webb | 25 cfs | → |
| Ashuelot River Above The Branch | 21 cfs | → |
| Ashuelot River At West Swanzey | 598 cfs | → |
| Ashuelot River Below Surry Mt Dam | 259 cfs | → |
| Ashuelot River Near Gilsum | 126 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Minnewawa .
Boat launches
- Stone Pond Boat Launch
- Meetinghouse Pond Boat Launch
- Silver Lake Boat Launch
- Wilson Pond Boat Launch
- Dublin Pond Boat Launch
- Harrisville Pond Boat Launch
Campgrounds
- Wheelock Park Campground
- Mt Monadnock State Park Campground
- Camp Wanocksett
- Pilgrim Pines Camping Area
- Swanzey Lake Camping Area
- Fox Brook Tent Site
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)
- Sewall's Island To Manchester Street Bridge
- Headwaters To North Of Searsburg Reservoir
- Headwaters To Crossing Of Route 100 Near Route 155
Track Minnewawa 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 Minnewawa
Where does the data for Minnewawa 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 Minnewawa .