Lake Tappan Dam dam
Lake Tappan Dam
Lake Tappan Dam, located in Old Tappan, New Jersey, is a significant earth dam that was completed in 1966 for the primary purpose of water supply. With a height of 34 feet and a length of 590 feet, the dam has a storage capacity of 13,600 acre-feet and a surface area of 560 acres. It is situated on the Hackensack River in Bergen County and is owned and regulated by private entities, with oversight from the New Jersey Department of Environmental Protection.
Despite being classified as having a high hazard potential, the dam's condition has been assessed as satisfactory during its last inspection in June 2021. The emergency action plan for the dam was last revised in February 2022, indicating preparedness for potential risks associated with its operation. The dam's drainage area covers 49.2 square miles, with a maximum discharge capacity of 27,000 cubic feet per second, highlighting its critical role in flood control and water resource management in the region.
Lake Tappan Dam serves as a vital infrastructure for water supply and flood control in the area, demonstrating the intersection of water resource management and climate resilience. Its strategic location on the Hackensack River, coupled with its storage capacity and regulatory oversight, underscores its importance in ensuring water security and mitigating potential risks associated with its operation. As climate change impacts continue to pose challenges to water resources, the maintenance and monitoring of dams like Lake Tappan Dam become increasingly crucial for sustainable water management in the region.
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 Tappan Dam -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Hackensack River At Rivervale Nj | 32 cfs | → |
| Pascack Brook At Westwood Nj | 31 cfs | → |
| Pascack Brook At Park Ridge Nj | 7 cfs | → |
| Hackensack River At New Milford Nj | 12 cfs | → |
| Saddle River At Ridgewood Nj | 11 cfs | → |
| Saddle River At Upper Saddle River Nj | 3 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Lake Tappan Dam.
Boat launches
- Warburton Avenue 565, Hastings-On-Hudson
- Riverside Avenue Little Ferry
- Veterans Court Passaic
- Croton Riverwalk Croton-On-Hudson
- Lakeside Avenue Pompton Lakes
- Ringwood-Ramapo Trail Ringwood
Campgrounds
- Croton Point Park
- Beaver Pond - Harriman State Park
- Beaver Pond Campsite
- Blue Mountain Reservation
- Camping For Hikers On Ballfield Graymoor Center
- Camp Lewis
Fishing spots
Track Lake Tappan 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 Tappan Dam
Where does the data for Lake Tappan 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 Tappan Dam.