Soda Springs, Idaho-Rocky Mountain Power – formerly Utah Power & Light – is seeking a 14.5 percent electricity rate increase for Agrium’s phosphate fertilizer plant and a 24.1 percent increase for Monsanto Corp.’s elemental phosphorus plant, both of which operate in Caribou County. Monsanto is the largest customer of PacifiCorp in its six-state territory. Rocky Mountain Power, a division of PacifiCorp, wants the Idaho Public Utilities Commission to grant it an average 10.3 percent increase in rates for its 67,000 customers in Eastern Idaho. Rocky Mountain wants the new rates to take effect on Jan. 1, 2008. The IPUC has the authority to accept, deny, or modify the company’s proposal. Rocky Mountain claims it must collect $18.5 million more in annual revenue to meet cost increases for fuel, wholesale market power, new generation, transmission, and distribution plant investment, and for labor-related cost increases.