Cabot Spillway dam
Cabot Spillway
Located in Greenfield, Massachusetts, the Cabot Spillway is a concrete gravity dam completed in 1915 for hydroelectric and recreational purposes. With a height of 35 feet and a length of 168 feet, the dam has a maximum storage capacity of 21,500 acre-feet and serves a drainage area of 7,163 square miles. The spillway, with a controlled type and a width of 120 feet, can discharge up to 16,000 cubic feet per second.
Managed by the Federal Energy Regulatory Commission, the Cabot Spillway has a low hazard potential and a very high risk assessment rating. Despite not being state-regulated, inspected, or permitted, the dam features eight slide gates for outlet control and is associated with six other structures in the area. While its condition assessment is not currently available, the dam's emergency action plan was last revised in 2011, highlighting the importance of preparedness in the face of potential climate-related challenges.
For water resource and climate enthusiasts, the Cabot Spillway presents an intriguing case study of a historic dam in New England with significant hydroelectric capacity. As debates around dam safety and climate resilience continue, the risk management measures and emergency protocols for the Cabot Spillway serve as a reminder of the importance of proactive planning and monitoring in safeguarding critical infrastructure against potential hazards and impacts of a changing climate.
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 Cabot Spillway -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Connecticut River At Montague City | 36,200 cfs | → |
| Deerfield River Near West Deerfield | 601 cfs | → |
| South River Near Conway | 27 cfs | → |
| Millers River At Erving | 1,210 cfs | → |
| North River At Shattuckville | 116 cfs | → |
| Green River Near Colrain | 71 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Cabot Spillway .
Boat launches
- Kellogg Hill Road, Hatfield
- Connecticut River Boat Launch
- Regulating Dam Road, New Salem
- North Orange Road 52-534, Athol
- Main Street 2010, Athol
- Doane Hill Road Royalston
Campgrounds
- Barton Cove
- Erving State Forest
- Richardson-Zlogar Cabin
- Dar State Forest
- Fort Dummer State Park
- Federated Womens' Club State Forest Primitive Campsite
Paddle runs
- Headwaters To North Of Searsburg Reservoir
- Headwaters To Confluence With West River (End Of Sherman Road)
- Stamford Town Line To Confluence With City Stream
- Headwaters To First Bridge Upstream On Route 100
- First Bridge Upstream On Route 100 To Confluence With West River
- First Bridge To Walloomsac Brook
Track Cabot Spillway 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 Cabot Spillway
Where does the data for Cabot Spillway 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 Low 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 Cabot Spillway .