Monhagen Lake Dam
Monhagen Lake Dam is an earth dam located in Orange County, New York, built in 1867. It carries a Significant hazard potential classification and has a fair condition assessment.
About Monhagen Lake Dam
The primary purpose of Monhagen Lake Dam is water supply. The dam stores water for municipal, industrial, or agricultural use, helping ensure a reliable supply for the surrounding area. The dam is owned by City Of Middletown (local government). It impounds the Monhagen Brook near Middletown.
The dam stands 12 feet tall and stretches 300 feet across, creates a reservoir covering 65 acres, has a maximum storage capacity of 858 acre-feet, and collects water from a drainage area of 0 square miles. Completed in 1867, the structure is one of the older dams in the region, with over a century and a half of service.
This dam has a significant hazard potential classification, meaning that a failure could cause significant economic damage — flooding roads, bridges, or property downstream — but is not expected to result in loss of life. Its condition is rated fair — the dam has minor deficiencies that are being addressed or do not pose an immediate safety threat. An emergency action plan is in place for this dam. The most recent inspection on record was 04/03/2025.
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Location
| State | New York |
| County | Orange |
| Nearest City | Middletown |
| River/Stream | Monhagen Brook |
| Coordinates | 41.46083, -74.45306 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 12 ft |
| Dam Height | 12 ft |
| Dam Length | 300 ft |
| Year Completed | 1867 (159 years old) |
Storage & Hydraulics
| NID Storage | 858 acre-ft |
| Max Storage | 858 acre-ft |
| Normal Storage | 635 acre-ft |
| Surface Area | 65 acres |
| Drainage Area | 0 sq mi |
| Max Discharge | 42 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Water Supply |
| Owner | CITY OF MIDDLETOWN |
| Owner Type | Local Government |
| Hazard Classification | Significant |
| Condition Assessment | Fair |
| Last Inspection | 04/03/2025 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | NY16220 |
| Federal ID | NY16220 |
| More Info | State Dam Safety Program |