Idaho Power Company residential customers will see a 12.5 percent rate increase beginning Saturday. The Idaho Public Utilities Commission said it will be the fourth-highest power cost adjustment in Idaho history.
For an average residential customer who uses 1,050 kilowatt-hours per month, the average monthly increase will be about $11.38.
The adjustment is the result of declining water supply, which reduced revenue from surplus energy sales at Idaho Power hydroelectric facilities. Ongoing wind power expenses also contributed to a $140 million adjustment.
The IPUC said the surcharge will be in effect for one year. For all customer classes combined, it will average 15.3 percent.
The commission rejected a suggestion to spread the increase out over more than one year, worried another short water year could follow. Commissioners argued that could expose customers to an even larger rate hike next year.
The PUC emphasized that none of the money collected in the surcharge can be used to increase Idaho Power earnings or salaries and is kept in a deferred account for paying extraordinary power supply expenses.
According to the commission, about a part of the adjustment is related to Hoku. The Pocatello polysilicon plant failed last year, and $23 million in anticipated revenue to Idaho Power never materialized.