Otisco Lake Dam
Otisco Lake Dam is a concrete dam located in Onondaga County, New York, built in 1956. It carries a High hazard potential classification and has a satisfactory condition assessment.
About Otisco Lake Dam
The primary purpose of Otisco Lake Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Onondaga County Water Authority (ocwa) (public utility). It impounds the Ninemile Creek near Marietta.
The dam stands 18 feet tall and stretches 310 feet across, creates a reservoir covering 2,291 acres, has a maximum storage capacity of 47,890 acre-feet, and collects water from a drainage area of 39 square miles. Completed in 1956, the structure is well into its service life at over 50 years 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 10/23/2023.
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 | Onondaga |
| Nearest City | Marietta |
| River/Stream | Ninemile Creek |
| Coordinates | 42.90444, -76.31250 |
Physical Characteristics
| Dam Type | Concrete |
| NID Height | 18 ft |
| Dam Height | 18 ft |
| Dam Length | 310 ft |
| Year Completed | 1956 (70 years old) |
Storage & Hydraulics
| NID Storage | 47,890 acre-ft |
| Max Storage | 47,890 acre-ft |
| Normal Storage | 26,067 acre-ft |
| Surface Area | 2,291 acres |
| Drainage Area | 39 sq mi |
| Max Discharge | 31,345 cfs |
| Spillway Type | Controlled |
Ownership & Safety
| Purpose | Recreation |
| Owner | ONONDAGA COUNTY WATER AUTHORITY (OCWA) |
| Owner Type | Public Utility |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 10/23/2023 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | NY00753 |
| Federal ID | NY00753 |
| More Info | State Dam Safety Program |