Pond 4 (dam 2a) is an earth dam located in Sweetwater County, Wyoming, built in 1992. It carries a Significant hazard potential classification and has a fair condition assessment.
Dam profile
NID height · 39 ft39 ft tall and 750 ft long, taller than 85% 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 Pond 4 (dam 2a)
The primary purpose of Pond 4 (dam 2a) is tailings. Tailings dams contain waste material from mining operations — typically a slurry of finely ground rock left over after valuable minerals have been extracted. These structures require ongoing monitoring because tailings can contain heavy metals and other contaminants. The dam is owned by Ciner Wyoming LLC (private). It impounds the Stevens Draw near Green River.
The dam stands 39 feet tall and stretches 750 feet across, creates a reservoir covering 239 acres, has a maximum storage capacity of 4,612 acre-feet, and collects water from a drainage area of 4 square miles. Completed in 1992, the structure is 34 years old.
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 06/05/2025.
At 39 feet, this dam is taller than 85% of dams nationwide.
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Location
| State | Wyoming |
| County | Sweetwater |
| Nearest City | Green River |
| River/Stream | Stevens Draw |
| Coordinates | 41.73240, -109.66720 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 39 ft |
| Dam Height | 27 ft |
| Dam Length | 750 ft |
| Year Completed | 1992 (34 years old) |
Storage & Hydraulics
| NID Storage | 4,612 acre-ft |
| Max Storage | 4,612 acre-ft |
| Normal Storage | 4,612 acre-ft |
| Surface Area | 239 acres |
| Drainage Area | 4 sq mi |
| Max Discharge | 1,850 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Tailings |
| Owner | Ciner Wyoming LLC |
| Owner Type | Private |
| Hazard Classification | Significant |
| Condition Assessment | Fair |
| Last Inspection | 06/05/2025 |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | WY02046 |
| Federal ID | WY02046 |
| More Info | State Dam Safety Program |