Johnson No. 1
Johnson No. 1 is an earth dam located in Natrona County, Wyoming, built in 1914. It carries a Low hazard potential classification and has a fair condition assessment.
About Johnson No. 1
The primary purpose of Johnson No. 1 is irrigation. The dam stores and diverts water for agricultural irrigation, supporting farming operations in the surrounding area. The dam is owned by Casper Creek Ranch Inc (private). It impounds the Middle Casper Creek Offstream near Casper.
The dam stands 20 feet tall and stretches 6,654 feet across, creates a reservoir covering 700 acres, and has a maximum storage capacity of 12,351 acre-feet. Completed in 1914, the structure is over a century 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 04/18/2023.
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Location
| State | Wyoming |
| County | Natrona |
| Nearest City | Casper |
| River/Stream | Middle Casper Creek Offstream |
| Coordinates | 43.01500, -106.70000 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 20 ft |
| Dam Height | 20 ft |
| Dam Length | 6,654 ft |
| Year Completed | 1914 (112 years old) |
Storage & Hydraulics
| NID Storage | 12,351 acre-ft |
| Max Storage | 12,351 acre-ft |
| Normal Storage | 11,865 acre-ft |
| Surface Area | 700 acres |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Irrigation |
| Owner | CASPER CREEK RANCH INC |
| Owner Type | Private |
| Hazard Classification | Low |
| Condition Assessment | Fair |
| Last Inspection | 04/18/2023 |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | WY00235 |
| Federal ID | WY00235 |
| More Info | State Dam Safety Program |