NorthWestern Energy has filed an application with the South Dakota Public Utility Commission to adjust its rates for natural gas services in the US state of South Dakota.
The company seeks an increase of $4.1m annually due to increased operations and maintenance costs and to complete its remediation of manufactured gas plant (MGP) sites in the state.
If approved by the commission in its entirety, the average residential bill for natural gas service will increase $8.31 per month.
About $1.4m of the requested increase relates to the annual estimated MGP remediation costs.
In the event MGP costs are lower than estimated during the time period, the difference will be subject to a refund to customers, the company said.
The rate filing covers operations and maintenance costs associated with the natural gas delivery service and do not affect the cost of the commodity.