Mcmillan Reservoir Dam dam
Mcmillan Reservoir Dam
Mcmillan Reservoir Dam, located in Mahwah Township, Bergen County, New Jersey, serves as a vital recreational resource along the Ramapo River-TR. This earth dam stands at a height of 21 feet and spans a length of 265 feet, with a storage capacity of 141 acre-feet. While its primary purpose is for recreation, the dam also plays a role in flood control and water management within the region.
Managed by the local government, the Mcmillan Reservoir Dam is regulated by the New Jersey Department of Environmental Protection (NJDEP) and undergoes regular inspections to ensure its structural integrity. With a low hazard potential and fair condition assessment, the dam poses minimal risk to surrounding communities. In the event of an emergency, the dam's Emergency Action Plan (EAP) is expected to provide guidance and ensure public safety.
As a significant component of the region's water infrastructure, the Mcmillan Reservoir Dam offers both recreational opportunities and essential water management functions. With its strategic location and adherence to state regulations, this dam serves as a testament to responsible stewardship and proactive risk management in safeguarding water resources and supporting community well-being in New Jersey's diverse landscape.
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 Mcmillan Reservoir Dam -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Ramapo River Near Mahwah Nj | 73 cfs | → |
| Ramapo River At Suffern Ny | 35 cfs | → |
| Ramapo River At Ramapo Ny | 55 cfs | → |
| Ringwood Creek Near Wanaque Nj | 8 cfs | → |
| Wanaque R At Wanaque Nj | 14 cfs | → |
| West Brook Near Wanaque Nj | 7 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Mcmillan Reservoir Dam.
Boat launches
- Ringwood-Ramapo Trail Ringwood
- Greenwood Lake Turnpike Ringwood
- Lakeside Avenue Pompton Lakes
- Blue Lake Road Town Of Warwick
- North Corporate Drive 2, Riverdale
- Laurel Meadow Drive Town Of Warwick
Campgrounds
- Beaver Pond - Harriman State Park
- Beaver Pond Campsite
- Camp Lewis
- Rock Lodge Club
- Croton Point Park
- Blue Mountain Reservation
Fishing spots
Track Mcmillan Reservoir 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 Mcmillan Reservoir Dam
Where does the data for Mcmillan Reservoir 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 Low 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 Mcmillan Reservoir Dam.