Customers of Interstate Power Company are getting good news today. Alliant’s Karmen Wilhelm says beginning June 1st, customer bills will be lower.Wilhelm says a temporary rate hike has ended, lowering the bills. The cost-recovery increase had been granted for the company’s energy-efficiency program expenses from 1993 to 1995.Wilhelm admits many people may not notice the reduction in their bills. People who’ll benefit from the changes live in parts of Iowa served by Interstate Power Company, a subsidiary of Alliant Energy.