Ethyl No. 2 is an earth dam located in Johnson County, Wyoming, built in 1969. It carries a Low hazard potential classification and has a fair condition assessment.
Dam profile
NID height · 25 ft25 ft tall and 460 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 Ethyl No. 2
The primary purpose of Ethyl No. 2 is irrigation. The dam stores and diverts water for agricultural irrigation, supporting farming operations in the surrounding area. The dam is owned by Hesse Ranch LLC (private). It impounds the Ethyl Draw near Arvada.
The dam stands 25 feet tall and stretches 460 feet across, creates a reservoir covering 9 acres, and has a maximum storage capacity of 104 acre-feet. Completed in 1969, the structure is well into its service life at over 50 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 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 07/03/2025.
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Location
| State | Wyoming |
| County | Johnson |
| Nearest City | Arvada |
| River/Stream | Ethyl Draw |
| Coordinates | 43.92050, -106.26810 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 25 ft |
| Dam Height | 25 ft |
| Dam Length | 460 ft |
| Year Completed | 1969 (57 years old) |
Storage & Hydraulics
| NID Storage | 104 acre-ft |
| Max Storage | 104 acre-ft |
| Normal Storage | 44 acre-ft |
| Surface Area | 9 acres |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Irrigation |
| Owner | Hesse Ranch LLC |
| Owner Type | Private |
| Hazard Classification | Low |
| Condition Assessment | Fair |
| Last Inspection | 07/03/2025 |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | WY00555 |
| Federal ID | WY00555 |
| More Info | State Dam Safety Program |