| Dam Name | Wanapum |
| Incident Date | 7/12/2005 |
| Country | United States |
| State/Province | Washington |
| Dam Height (m) | 28.3 |
| Uncontrolled Release of the Reservoir | No |
| Dam Type | Concrete; Rockfill; Gravity |
| Detailed Dam Type | |
| Incident Type | |
| Incident Description | On Tuesday July 12, 2005, GCP notified the D2SI-PRO that while Gate 12 was being opened to pass flows for downstream fish migration, a malfunction in the left lifting chain mechanism occurred which left the gate inoperable and in the closed position. At approximately 18:00 hours on July 11, 2005, the control room began raising Gate 12 so that releases could be made through the bulkhead notch. It takes about 80 to 90 minutes to raise the gate to full height. After approximately 80 minutes the operator checked the gate status and noted that the gate controls showed erratic readings. GCP staff were sent to the spillway to investigate the erratic readings and found the Gate 12 left hoist chain was off the drive sprocket and bunched up in the guide housing. The gate upper left guide roller and lower right guide roller had been sheared off and concrete on the top of the left pier had minor damage. The left hoist chain came off the sprocket so staff returned the gate to the fully closed position at approximately 1:00 AM Tuesday morning using only one hoist chain. The gates were redesigned in the early 1990’s to be lifted by only one hoist chain. The loss of the guide roller resulted in damage to the gate right side seal and edge of the skin plate. With the gate closed, leakage past the damaged area was estimated to be 100 to 200 cfs. Appropriate resource agencies were notified of the loss of the fish spill facility and contingency plans are being developed. |
| High Level Failure Mode | |
| Lessons Learned | |
| Initiating Event | Equipment Failure |
| Initiating Event Description | |
| Structures/Components | |
| Failure Mode Description | |
| Emergency Action Plan Implemented | Unknown |
| Consequences | Consequence Data Unavailable |
| Geographic Coordinates - Decimal Degrees | 46.8731, -119.9703 |
| Normal Reservoir Storage (m3): | |
| Crest Elevation (m) |