Porcupine
Porcupine is an earth dam located in Converse County, Wyoming, built in 1979. It carries a Low hazard potential classification and has a poor condition assessment.
About Porcupine
The primary purpose of Porcupine is irrigation. The dam stores and diverts water for agricultural irrigation, supporting farming operations in the surrounding area. The dam is owned by Powder River Coal Co. (private). It impounds the Porcupine Creek near Edgemont, Sd.
The dam stands 35 feet tall and stretches 1,450 feet across, creates a reservoir covering 70 acres, and has a maximum storage capacity of 865 acre-feet. Completed in 1979, the structure is 47 years 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 poor, meaning the dam has recognized safety deficiencies that require remediation to address risks. The most recent inspection on record was 09/27/2023.
At 35 feet, this dam is taller than 82% of dams nationwide.
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Location
| State | Wyoming |
| County | Converse |
| Nearest City | Edgemont, Sd |
| River/Stream | Porcupine Creek |
| Coordinates | 43.49444, -105.24972 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 35 ft |
| Dam Height | 35 ft |
| Dam Length | 1,450 ft |
| Year Completed | 1979 (47 years old) |
Storage & Hydraulics
| NID Storage | 865 acre-ft |
| Max Storage | 865 acre-ft |
| Normal Storage | 590 acre-ft |
| Surface Area | 70 acres |
| Max Discharge | 390 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Irrigation |
| Owner | POWDER RIVER COAL CO. |
| Owner Type | Private |
| Hazard Classification | Low |
| Condition Assessment | Poor |
| Last Inspection | 09/27/2023 |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | WY00733 |
| Federal ID | WY00733 |
| More Info | State Dam Safety Program |