Mcmullen is a dam located in Twin Falls County, Idaho, built in 1948. It carries a Significant hazard potential classification and has a fair condition assessment.
Dam profile
NID height · 25 ft25 ft tall and 1,850 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 Mcmullen
The primary purpose of Mcmullen 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 Cottonwood Creek Rock Creek near Hollister.
The dam stands 25 feet tall and stretches 1,850 feet across, creates a reservoir covering 45 acres, has a storage capacity of 350 acre-feet, and collects water from a drainage area of 31 square miles. Completed in 1948, the structure is well-established, with more than 75 years 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. The most recent inspection on record was 05/24/2018.
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Location
| State | Idaho |
| County | Twin Falls |
| Nearest City | Hollister |
| River/Stream | Cottonwood Creek Rock Creek |
| Coordinates | 42.41280, -114.42490 |
Physical Characteristics
| NID Height | 25 ft |
| Dam Height | 25 ft |
| Dam Length | 1,850 ft |
| Year Completed | 1948 (78 years old) |
Storage & Hydraulics
| NID Storage | 350 acre-ft |
| Normal Storage | 350 acre-ft |
| Surface Area | 45 acres |
| Drainage Area | 31 sq mi |
| Max Discharge | 370 cfs |
| Spillway Type | Controlled |
Ownership & Safety
| Purpose | Irrigation |
| Owner Type | Private |
| Hazard Classification | Significant |
| Condition Assessment | Fair |
| Last Inspection | 05/24/2018 |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | ID00046 |
| Federal ID | ID00046 |
| More Info | State Dam Safety Program |