 | 09/29/1982 | | | Penstock rupture | A 22 foot diameter conduit ruptured. | 73 acres eroded. Damage to power line. Small concrete bridge destroyed. Construction equipment lost. |
| 02/24/1984 | Landslide | | | Penstock failure caused by landslide. | Powerhouse inoperative. |
| 12/05/1984 | | Steel | Penstock structural failure | Penstock failure caused by poor weld. | Four employees killed. Extensive powerhouse damage. |
| 03/01/1985 | | Steel | Penstock buckling | Localized buckling of one steel penstock liner during pump-filling of upper reservoir. | Delay commercial operation dates of first units. |
| 12/18/1986 | | | Penstock collapse | Penstock rupture and collapse.
| 7000 ft. of pipe collapsed.
|
| 12/31/1986 | | | Penstock collapse | Pipeline failure from vacuum collapse
| None |
| 04/24/1988 | Fabrication Error | | | Failure of low pressure conduit due to fabrication error. | Some property damage. Loss of generation. |
| 02/08/1989 | Frozen Vent | | Penstock collapse | Penstock failure from frozen air vent | None |
| 03/23/1989 | Settlement | | | Failure of low pressure conduit due to settlement. | Loss of generation. |
| 05/01/1989 | Rockfall | Wood | Penstock rupture due to rock slide | Rupture of wood stave pipeline by rock slide. | Temporary loss of generation. |
