Saint John is a dam located in Oneida County, Idaho, built in 1918. It carries a High hazard potential classification and has a unsatisfactory condition assessment.
Dam profile
NID height · 43 ft43 ft tall and 680 ft long, taller than 89% of U.S. dams with a recorded height. Height is drawn to scale against a two-story house, about 25 ft; the profile is a generic embankment section and the water level is illustrative.
About Saint John
The primary purpose of Saint John is irrigation. The dam stores and diverts water for agricultural irrigation, supporting farming operations in the surrounding area. The dam is private-owned. It impounds the Birch Creek Malad River near St Johns.
The dam stands 43 feet tall and stretches 680 feet across, creates a reservoir covering 41 acres, has a storage capacity of 630 acre-feet, and collects water from a drainage area of 10 square miles. Completed in 1918, 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 unsatisfactory, indicating serious safety deficiencies exist that require immediate attention or remedial action. Notably, no emergency action plan is currently on file for this high-hazard dam. The most recent inspection on record was 04/23/2019. That was 7 years ago, which is on the longer end for a high-hazard structure.
At 43 feet, this dam is taller than 89% 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 Idaho 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 | Idaho |
| County | Oneida |
| Nearest City | St Johns |
| River/Stream | Birch Creek Malad River |
| Coordinates | 42.22750, -112.28870 |
Physical Characteristics
| NID Height | 43 ft |
| Dam Height | 43 ft |
| Dam Length | 680 ft |
| Year Completed | 1918 (108 years old) |
Storage & Hydraulics
| NID Storage | 630 acre-ft |
| Normal Storage | 630 acre-ft |
| Surface Area | 41 acres |
| Drainage Area | 10 sq mi |
| Max Discharge | 76 cfs |
| Spillway Type | Controlled |
Ownership & Safety
| Purpose | Irrigation |
| Owner Type | Private |
| Hazard Classification | High |
| Condition Assessment | Unsatisfactory |
| Last Inspection | 04/23/2019 |
| Emergency Action Plan | No |
Identifiers
| NID ID | ID00001 |
| Federal ID | ID00001 |
| More Info | State Dam Safety Program |