Shadow Lake Dam dam
Shadow Lake Dam
Shadow Lake Dam, located in Mahwah, New Jersey, is a privately owned structure on Hohokus Creek with a primary purpose of recreation. Built in 1928, this earth dam stands at a height of 16 feet and has a length of 565 feet, providing a storage capacity of 72 acre-feet. With a significant hazard potential but a satisfactory condition assessment as of December 2021, the dam is regulated by the New Jersey Department of Environmental Protection and undergoes regular inspections.
The dam's maximum discharge capacity is 1600 cubic feet per second, serving a drainage area of 1.6 square miles and covering a surface area of 18 acres. Even though there are no associated structures, Shadow Lake Dam plays a crucial role in providing recreational opportunities while managing the water resources in the region. With Congressman Josh S. Gottheimer representing the area, the dam's emergency action plan was last revised in February 2018, ensuring preparedness in case of any unforeseen events.
Overall, Shadow Lake Dam is a vital infrastructure on Hohokus Creek, contributing to the conservation and recreational aspects of the area. Its historical significance, coupled with the ongoing regulatory oversight and satisfactory condition, highlights the importance of this earth dam in water resource management and climate resilience efforts in Bergen County, New Jersey.
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 Shadow Lake Dam -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Hohokus Brook At Ho-Ho-Kus Nj | 20 cfs | → |
| Ramapo River Near Mahwah Nj | 73 cfs | → |
| Ramapo River At Pompton Lakes Nj | 122 cfs | → |
| Saddle River At Upper Saddle River Nj | 12 cfs | → |
| Wanaque R At Wanaque Nj | 14 cfs | → |
| Pequannock River At Riverdale Nj | 29 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Shadow Lake Dam.
Boat launches
- Lakeside Avenue Pompton Lakes
- North Corporate Drive 2, Riverdale
- Ringwood-Ramapo Trail Ringwood
- Greenwood Lake Turnpike Ringwood
- Blue Lake Road Town Of Warwick
- Island Avenue Little Falls
Campgrounds
- Camp Lewis
- Beaver Pond - Harriman State Park
- Beaver Pond Campsite
- Rock Lodge Club
- Croton Point Park
- Blue Mountain Reservation
Fishing spots
Track Shadow Lake 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 Shadow Lake Dam
Where does the data for Shadow Lake 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 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 Shadow Lake Dam.