Holyoke - Overflow No. 1 dam
Holyoke - Overflow No. 1
Holyoke - Overflow No. 1 is a historic masonry dam located in Holyoke, Massachusetts, along the Connecticut River. Built in 1850, this structure serves primarily for hydroelectric power generation and also provides recreational opportunities. With a height of 30 feet and a length of 1400 feet, it has a storage capacity of 26,000 acre-feet and covers a surface area of 2290 acres.
Managed by the Federal Energy Regulatory Commission, Holyoke - Overflow No. 1 has a controlled spillway with a width of 300 feet and four slide (sluice) gates for water release. The dam's high hazard potential and very high risk assessment highlight the importance of ongoing monitoring and emergency preparedness. Despite its age, the condition assessment for this dam is currently not available, underscoring the need for further evaluation to ensure its continued safety and functionality for both water resource management and climate adaptation efforts.
This iconic structure, associated with three other structures in the area, stands as a testament to the intersection of history, engineering, and environmental stewardship. As water resource and climate enthusiasts explore the intricacies of Holyoke - Overflow No. 1, its significance as a key component of the region's infrastructure and landscape becomes apparent, sparking interest in its preservation and sustainable management 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 Holyoke - Overflow No. 1 -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Connecticut R At Interstate 391 Bridge At Holyoke | 24,800 cfs | → |
| Chicopee River At Indian Orchard | 1,030 cfs | → |
| Westfield River Near Westfield | 388 cfs | → |
| Mill River At Northampton | 41 cfs | → |
| Middle B Westfield River At Goss Heights | 8 cfs | → |
| Westfield River At Knightville | 159 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Holyoke - Overflow No. 1 .
Boat launches
- Mount Tom Road 900-978, Easthampton
- Old Apremont Way, Westfield
- Water Street 266-334, Springfield
- West Street 121, Springfield
- South End Bridge Agawam
- Red Bridge Road 16, Wilbraham
Campgrounds
- Westover Arb Military
- Koa Weathampton
- Chester - Blanford State Forest
- Primitve Camping Area
- Dar State Forest
- Granville State Forest
Fishing spots
- Lake Washington Fishing Area
- Trout Hatchery
- Great Brook Reservoir
- Lower Fulton Park Pond
- Lake Quassapaug
Paddle runs
- The Massachusetts-Connecticut State Line In Hartland To The Confluence With The Salmon Brook Main Stem
- The Confluence Of The East And West Branches To The Confluence With The Farmington River In East Granby
- Begins Below The Tailrace Of The Rainbow Dam To The Confluence With The Connecticut River
- The Hartland Headwaters To The Confluence With The Salmon Brook Main Stem
- New Hartford/Canton Town Line To The Confluence With The Nepaug River
- The Confluence With The Nepaug River To A Point 0.2 Miles Below The Lower Collinsville Dam Tailrace
Track Holyoke - Overflow No. 1 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 Holyoke - Overflow No. 1
Where does the data for Holyoke - Overflow No. 1 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 Holyoke - Overflow No. 1 .