Great Hill Pond Dam Dam
Great Hill Pond Dam
Great Hill Pond Dam, located in Portland, Connecticut, stands as a historic structure with a primary purpose of recreation. Constructed in 1870, this masonry dam spans 193 feet in length and reaches a height of 14 feet, providing a storage capacity of 358 acre-feet in the Great Hill Pond Brook watershed. The dam's surface area covers 71.6 acres, with a drainage area of 1.22 square miles, showcasing its importance in water resource management.
Despite its rich history and recreational significance, the dam is currently rated as having poor condition, with a significant hazard potential. Regular inspections conducted by the Connecticut Department of Energy and Environmental Protection (DEEP) ensure the safety and integrity of the structure, with the last assessment taking place in September 2020. The dam's emergency action plan (EAP) was last revised in December 2017, highlighting the importance of preparedness and risk management in safeguarding the surrounding community and environment from potential hazards.
As water resource and climate enthusiasts explore the intricate details of Great Hill Pond Dam, its role in water storage, recreation, and environmental protection becomes increasingly apparent. With its unique design and historical significance, the dam serves as a focal point for both local residents and conservation efforts, emphasizing the importance of maintaining and managing our water resources effectively in the face of changing climate conditions.
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 Great Hill Pond Dam -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Connecticut R At Middle Haddam | 5,720 cfs | → |
| Salmon River Near East Hampton | 16 cfs | → |
| Coginchaug River At Middlefield | 9 cfs | → |
| Hockanum River Near East Hartford | 46 cfs | → |
| Eightmile R At North Plain | 3 cfs | → |
| East Branch Eightmile River Near North Lyme | 4 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Great Hill Pond Dam.
Boat launches
See all →
Campgrounds
See all →
Fishing spots
See all →
River runs
See all →
About Great Hill Pond Dam
Where does the data for Great Hill Pond 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 Significant 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 below 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.
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.