A review found the central rotor had “split along its diameter,” according to the lawsuit. The split took shape along “certain imperfections in the metal suggesting that the specific rotor had unique flaws.”

Tests, however, proved inconclusive, EWEB contends.

Two days before Christmas last year, roll gate #1 crashed down in a similar matter while it was being lowered. Two-thirds of the "18 lobes around the central rotor's circumference" have been sheared off," claims EWEB.

The utility, in its lawsuit, said that after the second incident it was able to conclude that the failure of the hydraulic motors was due to "systematic design error."

Federal regulaors earlier this year ordered the hydraulic hoists on two of the dam's gates to be replaced with electric motors as a "safety measure," the EWEB lawsuit states. The hydraulic hoist on the third gate was already in the process of being replaced at the time.

The lawsuit mentions the motor manufacturer but says the utility's contract with Advanced American makes it responsible for any subcontractors' work.