Grassy Sprain Reservoir Dam
Grassy Sprain Reservoir Dam is an earth dam located in Westchester County, New York, built in 1876. It carries a High hazard potential classification and has a satisfactory condition assessment.
About Grassy Sprain Reservoir Dam
The primary purpose of Grassy Sprain Reservoir Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by City Of Yonkers (local government). It impounds the Grassy Sprain Brook near Yonkers.
The dam stands 40 feet tall and stretches 600 feet across, creates a reservoir covering 150 acres, has a maximum storage capacity of 3,550 acre-feet, and collects water from a drainage area of 1 square miles. Completed in 1876, the structure is over a century old.
This dam carries a high hazard potential classification, which means that a failure or uncontrolled release of water would likely cause loss of human life. This classification reflects the consequences of failure, not the likelihood — it indicates that people live or work in the area downstream. Its condition is rated satisfactory, indicating no existing or potential dam safety deficiencies are recognized. An emergency action plan is in place for this dam. The most recent inspection on record was 01/12/2024.
At 40 feet, this dam is taller than 87% of dams nationwide.
Living Downstream
If you live or work downstream of this dam, consider taking these steps: learn your local evacuation routes, check whether your county emergency management office has a dam failure inundation map, and sign up for local emergency alerts. The New York dam safety program can provide more specific information about emergency planning for this structure.
Search for dams near your address to see all dams in your area with hazard classifications and safety data.
Location
| State | New York |
| County | Westchester |
| Nearest City | Yonkers |
| River/Stream | Grassy Sprain Brook |
| Coordinates | 40.96056, -73.85139 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 40 ft |
| Dam Height | 40 ft |
| Dam Length | 600 ft |
| Year Completed | 1876 (150 years old) |
Storage & Hydraulics
| NID Storage | 3,550 acre-ft |
| Max Storage | 3,550 acre-ft |
| Normal Storage | 2,960 acre-ft |
| Surface Area | 150 acres |
| Drainage Area | 1 sq mi |
| Max Discharge | 1,025 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Recreation |
| Owner | CITY OF YONKERS |
| Owner Type | Local Government |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 01/12/2024 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | NY00022 |
| Federal ID | NY00022 |
| More Info | State Dam Safety Program |