Opal Dam is an earth dam located in Meade County, South Dakota, built in 1937. It carries a High hazard potential classification and has a fair condition assessment.
Dam profile
NID height · 22 ft22 ft tall and 515 ft long. 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 Opal Dam
The primary purpose of Opal Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Gf&p (state). It impounds the Middle Beaver Dam Creek.
The dam stands 22 feet tall and stretches 515 feet across, creates a reservoir covering 38 acres, has a maximum storage capacity of 558 acre-feet, and collects water from a drainage area of 7 square miles. Completed in 1937, the structure is well-established, with more than 75 years of service.
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 11/09/2021.
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 South Dakota 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 | South Dakota |
| County | Meade |
| Nearest City | None |
| River/Stream | Middle Beaver Dam Creek |
| Coordinates | 44.91002, -102.42179 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 22 ft |
| Dam Height | 22 ft |
| Dam Length | 515 ft |
| Year Completed | 1937 (89 years old) |
Storage & Hydraulics
| NID Storage | 558 acre-ft |
| Max Storage | 558 acre-ft |
| Normal Storage | 260 acre-ft |
| Surface Area | 38 acres |
| Drainage Area | 7 sq mi |
| Max Discharge | 2,935 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Recreation |
| Owner | Gf&p |
| Owner Type | State |
| Hazard Classification | High |
| Condition Assessment | Fair |
| Last Inspection | 11/09/2021 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | SD00308 |
| Federal ID | SD00308 |
| More Info | State Dam Safety Program |