SEATTLE — The Bonneville Power Administration has adopted a 9 percent average wholesale power rate increase, as well as an 11 percent spike to transmission rates. BPA says the new rates will affect local utilities differently, depending on the amount of power and type of service they purchase. Those utilities will ultimately decide how the rate will impact individual customers and businesses. The new rates take effect Oct. 1. BPA says the transmission rate increases are necessary for improvements to infrastructure and for mandatory compliance and security requirements. The power rates increase stems from higher costs to operate and maintain the federal hydroelectric system, higher costs to fund existing long-term agreements for the fish and wildlife mitigation program and because revenue from selling surplus power has shrunk.