Grasmere East Dam is a dam located in Owyhee County, Idaho. It carries a Significant hazard potential classification and has a poor condition assessment.
Dam profile
NID height · 11 ft11 ft tall and 4,000 ft long. 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 Grasmere East Dam
The primary purpose of Grasmere East Dam 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 Rattlesnake Creek Marys Creek near Highway 51.
The dam stands 11 feet tall and stretches 4,000 feet across, creates a reservoir covering 152 acres, has a storage capacity of 452 acre-feet, and collects water from a drainage area of 1 square miles.
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 poor, meaning the dam has recognized safety deficiencies that require remediation to address risks. The most recent inspection on record was 08/27/2020.
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Location
| State | Idaho |
| County | Owyhee |
| Nearest City | Highway 51 |
| River/Stream | Rattlesnake Creek Marys Creek |
| Coordinates | 42.34850, -115.89610 |
Physical Characteristics
| NID Height | 11 ft |
| Dam Height | 11 ft |
| Dam Length | 4,000 ft |
Storage & Hydraulics
| NID Storage | 452 acre-ft |
| Normal Storage | 452 acre-ft |
| Surface Area | 152 acres |
| Drainage Area | 1 sq mi |
| Max Discharge | 58 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Irrigation |
| Owner Type | Private |
| Hazard Classification | Significant |
| Condition Assessment | Poor |
| Last Inspection | 08/27/2020 |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | ID00516 |
| Federal ID | ID00516 |
| More Info | State Dam Safety Program |