Grassy Sprain Reservoir Dam dam
Grassy Sprain Reservoir Dam
Grassy Sprain Reservoir Dam, located in Yonkers, New York, is a significant structure designed for recreational purposes. Constructed in 1876, this earth dam stands at a height of 40 feet and spans a length of 600 feet, with a storage capacity of 3550 acre-feet. The dam overlooks the picturesque Grassy Sprain Brook and serves as a popular spot for water resource and climate enthusiasts to engage in various outdoor activities.
This high-hazard dam is regulated and inspected by the New York State Department of Environmental Conservation to ensure its structural integrity and safety. With a satisfactory condition assessment and a moderate risk rating, the dam is equipped with an uncontrolled spillway and has a maximum discharge capacity of 1025 cubic feet per second. The area surrounding the reservoir spans 150 acres, providing ample space for recreational activities and wildlife habitat preservation.
Water resource and climate enthusiasts can appreciate the historical significance and environmental impact of Grassy Sprain Reservoir Dam. From its construction in the 19th century to its current maintenance and regulation, this dam continues to play a vital role in water storage, flood control, and recreational opportunities in Westchester County. Its presence highlights the importance of sustainable water management practices and the interconnectedness of human activities with the natural environment.
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 Grassy Sprain Reservoir 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 | → |
| Hackensack River At New Milford Nj | 12 cfs | → |
| Hackensack River At West Nyack Ny | 7 cfs | → |
| Pascack Brook At Park Ridge Nj | 7 cfs | → |
| Saddle River At Ridgewood Nj | 11 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Grassy Sprain Reservoir Dam.
Boat launches
- Warburton Avenue 565, Hastings-On-Hudson
- Park Crescent 345, Queens
- Riverside Avenue Little Ferry
- Seagate Road 3, Greenwich
- Secaucus Greenway Secaucus
- River Barge Park
Campgrounds
- Croton Point Park
- Blue Mountain Reservation
- Beaver Pond - Harriman State Park
- Beaver Pond Campsite
- Ward Pound Ridge Reservation
- Battle Row
Fishing spots
Track Grassy Sprain 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 Grassy Sprain Reservoir Dam
Where does the data for Grassy Sprain 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 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 Grassy Sprain Reservoir Dam.