MidAmerican Energy plans to raise electric rates by 3 to 4 percent in 2012 to cover rising costs.
Spokeswoman Tina Porto says letters to customers will be sent in February, with the increase by March. She says it's necessary to recover rising environmental requirements and energy production costs.
Iowa law allows utilities to impose rate increases on a temporary basis until the Iowa Utilities Board can make a final decision.
MidAmerican Energy, the state's Iowa's largest utility, has 770,000 customers in Iowa. It has been operating under a rate freeze that preserves rates until 2013. But the agreement with state regulators allows MidAmerican to impose special adjustment charges.
MidAmerican, a subsidiary of Berkshire Hathaway of Omaha, Neb., has not raised base electric rates in 16 years.