Monterey, Calif.-based Century Aluminum (CENX) may be forced to cease operations at its Hawesville, Ky., aluminum smelter, the company warned Tuesday.

Citing the high price of power to keep the plant running, Century issued a federal Worker Adjustment and Retraining Notification Act (WARN) notification to the effect that the company may have to "curtail 100%" (i.e., shut down) plant operations on Aug. 20, 2013, if it is unable to find a power supplier offering better rates.

Century's Hawesville plant currently receives power from the Big Rivers Electric Corporation, but its contract expires on Aug. 20.

According to S&P Capital IQ, more than half of Century's 1,300 employees work at the Hawesville plant. In the event of a plant shutdown, all 750 jobs would be at risk.

Century shares rose 1.4% in Tuesday trading to close at $6.70 before news of the WARN notification was released.