Twin Granite is a dam located in Adams County, Idaho, built in 1920. It carries a Low hazard potential classification and has a fair condition assessment.
Dam profile
NID height · 25 ft25 ft tall and 620 ft long, taller than 50% 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 Twin Granite
The primary purpose of Twin Granite 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 Twin Lakes Goose Creek.
The dam stands 25 feet tall and stretches 620 feet across, creates a reservoir covering 40 acres, has a storage capacity of 600 acre-feet, and collects water from a drainage area of 0 square miles. Completed in 1920, the structure is over a century old.
This dam has a low hazard potential classification, meaning that failure would cause minimal damage, limited primarily to the dam owner's property, with no expected 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. The most recent inspection on record was 07/25/2019.
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Location
| State | Idaho |
| County | Adams |
| River/Stream | Twin Lakes Goose Creek |
| Coordinates | 45.10330, -116.18250 |
Physical Characteristics
| NID Height | 25 ft |
| Dam Height | 25 ft |
| Dam Length | 620 ft |
| Year Completed | 1920 (106 years old) |
Storage & Hydraulics
| NID Storage | 600 acre-ft |
| Normal Storage | 600 acre-ft |
| Surface Area | 40 acres |
| Drainage Area | 0 sq mi |
| Max Discharge | 64 cfs |
| Spillway Type | Controlled |
Ownership & Safety
| Purpose | Irrigation |
| Owner Type | Private |
| Hazard Classification | Low |
| Condition Assessment | Fair |
| Last Inspection | 07/25/2019 |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | ID00260 |
| Federal ID | ID00260 |
| More Info | State Dam Safety Program |