First Reservoir Dam
High HazardPoor ConditionEmergency Action Plan: Yes
Location
| County | Rockland |
| Nearest City | Thiells |
| River/Stream | HORSE CHOCK BROOK |
| Coordinates | 41.21623, -74.05820 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 46 ft |
| Dam Height | 46 ft |
| Dam Length | 650 ft |
| Year Completed | 1917 (109 years old) |
Storage & Hydraulics
| NID Storage | 116 acre-ft |
| Max Storage | 116 acre-ft |
| Normal Storage | 68 acre-ft |
| Surface Area | 6 acres |
| Drainage Area | 1 sq mi |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Water Supply |
| Owner | NYSOPRHP - PALISADES INTERSTATE PARK COMMISSION |
| Owner Type | State |
| Hazard Classification | High |
| Condition Assessment | Poor |
| Last Inspection | 05/07/2025 |
| Emergency Action Plan | Yes |