Lake Mahopac Dam dam
Lake Mahopac Dam
Lake Mahopac Dam, located in Mahopac Falls, New York, is a vital structure managed by the local government for recreational purposes. Completed in 1940, this earth-type dam stands at a height of 9 feet and spans 190 feet in length, with a maximum storage capacity of 17,850 acre-feet and a normal storage capacity of 16,684 acre-feet. The dam overlooks the Muscoot River and covers a surface area of 583 acres, serving as a popular spot for outdoor activities and water recreation.
The dam's spillway type is uncontrolled, with a width of 8 feet, and a maximum discharge capacity of 109 cubic feet per second. Despite a high hazard potential, the dam's condition assessment remains unrated, indicating room for improvement in safety measures. Regular inspections are conducted every 2 years to ensure the dam's integrity, with the last inspection taking place in April 2019. While the risk assessment is moderate, with a score of 3 out of 5, the dam's emergency action plan was last revised in July 2020 to meet updated guidelines for risk management.
Lake Mahopac Dam stands as a significant structure in the region, providing not only recreational opportunities but also essential water resource management for the surrounding area. With its picturesque location and historical significance, the dam represents a balance between human enjoyment and environmental stewardship in the face of changing climate conditions. By adhering to state regulations and implementing necessary safety measures, the dam continues to serve as a valuable asset for the local community and visitors alike.
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 Lake Mahopac Dam -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Muscoot River At Baldwin Place Ny | 4 cfs | → |
| West Branch Croton River Near Carmel Ny | 10 cfs | → |
| West Branch Croton River Near Croton Falls Ny | 26 cfs | → |
| W Br Croton River Below Dam Near Kent Cliffs Ny | 10 cfs | → |
| Muscoot River Below Dam At Amawalk Ny | 12 cfs | → |
| East Branch Croton River Near Croton Falls Ny | 46 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Lake Mahopac Dam.
Boat launches
- Bear Mountain Bridge Road Cortlandt
- Hudson Avenue Peekskill
- Broadway Buchanan
- Lake Kenosia
- Cortlandt Street Cortlandt
- Croton Riverwalk Croton-On-Hudson
Campgrounds
- Clarence Fahnestock State Park
- Camping For Hikers On Ballfield Graymoor Center
- Mountain Lakes Park
- Blue Mountain Reservation
- Ward Pound Ridge Reservation
- Round Pond Military
Fishing spots
Paddle runs
- Kent Bridge To Boardman Bridge
- Pond Downstream Of Shepaug Reservoir Dam, Marked By Service Road Bridge To Ends In Backwaters Of Lake Lillinonah, Near Roxbury Falls
- Begins Downstream Of The Borough Of Bantam, At Stoddard Road Bridge To The Confluence With The Shepaug River
- Falls Mountain Road In Canaan, Connecticut To Kent Bridge
- The Massachusetts-Connecticut Border To Falls Mountain Road In Canaan, Connecticut
- Begins Below The Tailrace Of The Lower Collinsville Dam To The Route 187 Bridge
Track Lake Mahopac Dam 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 Lake Mahopac Dam
Where does the data for Lake Mahopac 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 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 Lake Mahopac Dam.