Herrick is an earth dam located in Converse County, Wyoming, built in 1946. It carries a Low hazard potential classification and has a fair condition assessment.
Dam profile
NID height · 30 ft30 ft tall and 550 ft long, taller than 68% 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 Herrick
The primary purpose of Herrick is irrigation. The dam stores and diverts water for agricultural irrigation, supporting farming operations in the surrounding area. The dam is owned by Mill Iron Diamond Ranch (private). It impounds the Twenty Mile Creek near Edgemont Sd.
The dam stands 30 feet tall and stretches 550 feet across, creates a reservoir covering 10 acres, and has a maximum storage capacity of 146 acre-feet. Completed in 1946, the structure is well-established, with more than 75 years of service.
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 06/12/2024.
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Location
| State | Wyoming |
| County | Converse |
| Nearest City | Edgemont Sd |
| River/Stream | Twenty Mile Creek |
| Coordinates | 42.93556, -105.07583 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 30 ft |
| Dam Height | 30 ft |
| Dam Length | 550 ft |
| Year Completed | 1946 (80 years old) |
Storage & Hydraulics
| NID Storage | 146 acre-ft |
| Max Storage | 146 acre-ft |
| Normal Storage | 87 acre-ft |
| Surface Area | 10 acres |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Irrigation |
| Owner | Mill Iron Diamond Ranch |
| Owner Type | Private |
| Hazard Classification | Low |
| Condition Assessment | Fair |
| Last Inspection | 06/12/2024 |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | WY00724 |
| Federal ID | WY00724 |
| More Info | State Dam Safety Program |