NEWS

WIRES

OTHER

Williston Basin Interstate Pipeline to Expand Bakken Natural Gas Delivery Volumes

The proposed expansion would add up to 30 million cubic feet per day (MMcf/d) to existing volumes from the Bakken production area for delivery to Northern Border Pipeline. The expansion project will be accomplished by adding facilities to an existing compressor station in northwestern North Dakota. The targeted in-service date of this expansion project is November 2011.

"Williston Basin owns and operates the most extensive transmission pipeline system in the Bakken production area and currently transports natural gas for most of the producers and processors active in the area," said Steven L. Bietz, president and CEO of Williston Basin. "We are very excited about the level of current activity in Bakken region and remain committed to expanding our transportation capacity from the area to ensure natural gas producers continue to have access to attractive markets. This latest project increases our delivery volumes out of the Bakken by one-third and further demonstrates our commitment to the region."

Williston Basin's existing natural gas pipeline system runs throughout the Bakken production area in western North Dakota and eastern Montana. Williston Basin completed a major expansion of its pipeline system in 2008 and currently transports approximately 90 MMcf/d per day of natural gas from 11 Bakken production area receipt points. Along with the currently proposed pipeline expansion project, Williston Basin is also working with numerous natural gas producers and processors to add additional natural gas receipt points to its system throughout the Bakken production area.

An open season for the Bakken Expansion Project will begin on May 19, 2010, and will run through June 2, 2010. Open season documents will be available on Williston Basin's website at www.wbip.com.

The information in this release includes forward-looking statements, including statements by the president and chief executive officer of Williston Basin Interstate Pipeline Company regarding plans to develop and potential benefits of expanding natural gas transportation volumes from the Bakken production area, within the meaning of Section 21E of the Securities Exchange Act of 1934. Although the company believes that its expectations are based on reasonable assumptions, actual results may differ materially. Important factors that could cause actual results to differ materially from those in the forward-looking statements include fluctuations in natural gas prices; the timely receipt of necessary permits and approvals; market demand for, and/or available supplies of, energy-related products and services; and unanticipated project delays. For a discussion of other important factors that could cause actual results to differ, refer to Item 1A - Risk Factors in MDU Resources' most recent Form 10-K and Form 10-Q.

Williston Basin Interstate Pipeline Company provides natural gas transportation and underground storage through a pipeline system spanning sections of North Dakota, South Dakota, Montana and Wyoming. Williston Basin is an indirect subsidiary of MDU Resources Group, Inc., a multidimensional natural resource enterprise traded on the New York Stock Exchange as "MDU." For more information about Williston Basin, visit the company's website at www.wbip.com.

Media Advisory - Map artwork available:

A print-ready map showing the location of the expansion project is available for download at: http://www.wbip.com/Documents/Bakken_Expansion%20Map%202010.jpg

MDU Resources Group, Inc.
Investor Relations:
Phyllis A. Rittenbach, 701-530-1057
director of investor relations
or
Media:
Tim Rasmussen, 701-530-1069
operating company public relations manager
or
Industry:
Rob Johnson, 701-530-1622
director of market services & system planning
or
Mark Anderson, 701-530-1623
market services manager