Puget Sound Energy ratepayers should expect a 13. 2 percent increase in their monthly electricity bills triggered by a federal court ruling...

Puget Sound Energy ratepayers should expect a 13.2 percent increase in their monthly electricity bills triggered by a federal court ruling earlier this month.

That ruling by the 9th U.S. Circuit Court of Appeals questioned the legality of Bonneville Power Administration payments to Puget Sound Energy (PSE) and other investor-owned Northwest utilities that collectively serve some 60 percent of the region.

The BPA regrets suspending payments and “we understand that this may rapidly result in large, and for some, severe rate consequences,” said Steve Wright, a BPA administrator.

The BPA payments have averaged about $28 million a month to six utilities, according to the BPA. Those payments are passed through to residential and small-farm ratepayers in the form of a credit on bills.

Puget Sound Energy is the region’s largest energy utility, with more than 1 million electricity customers in 11 counties. On average, residential ratepayers face a $10.28 increase in their monthly bills, while some other electricity users — such as irrigators — face much greater dollar increases, according to Martha Monfried, a Puget Sound Energy spokeswoman. The credit would disappear once the utility gains approval for this action from the Washington Public Utilities Commission, according to Monfried.

The BPA is a federal agency that markets about 40 percent of the electricity consumed in the Northwest. That power is produced from 31 federal dams and one nuclear plant.

The payments have helped investor-owned utilities gain some benefits of low-cost federal hydropower, which BPA sells to publicly owned utilities such as Seattle City Light.