(Pierre, SD) — Tens of thousands of South Dakotans are going to have to pay more on their natural gas bills. NorthWestern Energy plans to hike rates for its nearly 50-thousand customers across the state. Yesterday, the South Dakota Public Utilities Commission agreed to a settlement that allows NorthWestern Energy to raise all of its rates and to increase monthly fees. The company originally asked to charge about six-million dollars more a year, but the settlement reduced that to four-point-six million. The last time NorthWestern Energy was allowed to raise its natural gas rates was in 2011. Customers can expect to see those increases to take effect tomorrow.