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NorthWestern Energy Settles Natural Gas Rate Case with South Dakota Public Utility Commission

HURON, S.D., Nov. 22, 2011 /PRNewswire/ -- NorthWestern Energy (NYSE: NWE) announced today that the South Dakota Public Utility Commission has approved a stipulated agreement to settle the company's natural gas rate case.

As a result of the settlement, NorthWestern Energy will increase rates by approximately $1.8 million annually beginning December 1. Customers using 100 therms of natural gas per month will see their bills increase by $4.37 or about 4.9%. Customers are encouraged to read the insert in their December bill about the rate increase which includes a breakdown of potential impact depending on usage ranging from 10 to 500 therms per month.

The $1.8 million annual increase is comprised of about $1.5 million annually for an increase due to higher operating and maintenance costs related to the natural gas system in South Dakota and about $.3 million annually for the company's ongoing remediation of manufactured gas plant ("MGP") sites in the state. The original request included a $1.4 million increase related to MGP remediation costs. While the settlement for MGP remediation costs is lower than the original request, it also includes a provision to track these costs. If MGP remediation costs are higher than our annual collections from customers, NorthWestern Energy will track these costs and recover them in future years.

Commodity costs are adjusted monthly based on the price of natural gas.

NorthWestern Energy has been working over the years to remediate several MGP plants that date back to the early 1900s and pre-dated the introduction of natural gas systems. The plants converted coal and oil to gas for heating, lighting and cooking. Byproducts of this process include coal tar and purifier wastes which must now be remediated. There are several old MGP sites in NorthWestern Energy's system including Aberdeen, Huron and Milbank.

Customers with questions about our natural gas services, the proposed rate increases, or how to sign up for bill payment programs may call Customer Service at 800 245-6977, or stop by one of our local offices for assistance or visit www.northwesternenergy.com.

About NorthWestern Energy

NorthWestern Energy provides electricity and natural gas in the Upper Midwest and Northwest, serving approximately 665,000 customers in Montana, South Dakota and Nebraska. More information on NorthWestern Energy is available on the Company's Web site at www.northwesternenergy.com.

SOURCE NorthWestern Corporation