Grayrocks
Grayrocks is an earth dam located in Platte County, Wyoming, built in 1980. It carries a High hazard potential classification and has a fair condition assessment.
About Grayrocks
Grayrocks is a dam in Platte, Wyoming. The dam is owned by Basin Electric Power Cooperative (public utility). It impounds the Laramie River near Fort Laramie.
The dam stands 95 feet tall and stretches 2,625 feet across, creates a reservoir covering 3,547 acres, has a maximum storage capacity of 194,000 acre-feet, and collects water from a drainage area of 4,484 square miles. Completed in 1980, the structure is 46 years old.
This dam carries a high hazard potential classification, which means that a failure or uncontrolled release of water would likely cause loss of human life. This classification reflects the consequences of failure, not the likelihood — it indicates that people live or work in the area downstream. Its condition is rated fair — the dam has minor deficiencies that are being addressed or do not pose an immediate safety threat. An emergency action plan is in place for this dam. The most recent inspection on record was 10/06/2023.
At 95 feet, this dam is taller than 98% of all dams in the United States.
Living Downstream
If you live or work downstream of this dam, consider taking these steps: learn your local evacuation routes, check whether your county emergency management office has a dam failure inundation map, and sign up for local emergency alerts. The Wyoming dam safety program can provide more specific information about emergency planning for this structure.
Search for dams near your address to see all dams in your area with hazard classifications and safety data.
Location
| State | Wyoming |
| County | Platte |
| Nearest City | Fort Laramie |
| River/Stream | Laramie River |
| Coordinates | 42.16681, -104.69250 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 95 ft |
| Dam Height | 95 ft |
| Dam Length | 2,625 ft |
| Year Completed | 1980 (46 years old) |
Storage & Hydraulics
| NID Storage | 194,000 acre-ft |
| Max Storage | 194,000 acre-ft |
| Normal Storage | 104,110 acre-ft |
| Surface Area | 3,547 acres |
| Drainage Area | 4,484 sq mi |
| Max Discharge | 112,300 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Other |
| Owner | BASIN ELECTRIC POWER COOPERATIVE |
| Owner Type | Public Utility |
| Hazard Classification | High |
| Condition Assessment | Fair |
| Last Inspection | 10/06/2023 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | WY01496 |
| Federal ID | WY01496 |
| More Info | State Dam Safety Program |