MDU Resources Group, Inc. and Calumet Specialty Products Partners, L.P. Announce Receipt of Air Permit to Construct for Dakota

  MDU Resources Group, Inc. and Calumet Specialty Products Partners, L.P.
  Announce Receipt of Air Permit to Construct for Dakota Prairie Refining

Business Wire

BISMARCK, N.D. -- February 25, 2013

MDU Resources Group, Inc. (NYSE: MDU) and Calumet Specialty Products Partners,
L.P. (NASDAQ: CLMT) announced that the North Dakota Department of Health has
issued an Air Quality Permit to Construct for Dakota Prairie Refining, a
diesel refinery the two companies are developing in southwestern North Dakota.

“Approval of the air quality permit means that we can begin construction
within the next month, and the facility can be operational and helping supply
North Dakota’s diesel fuel market by late 2014,” said David L. Goodin,
president and CEO of MDU Resources. “We are committed to operating this
state-of-the-art facility responsibly and safely, and we appreciate the
rigorous permitting process conducted by the health department.”

“This facility will be an important contributor to the local and state
economy,” said Jennifer G. Straumins, president and chief operating officer of
Calumet’s general partner. “We appreciate the help of the state’s agencies and
officials to identify issues and help solve problems in a manner that has
brought this project from concept to reality.”

The facility will process 20,000 barrels per day of Bakken crude oil. The
plant will be located on a 318-acre site located west of Dickinson in Stark
County, N.D. It will employ approximately 100 people. Hiring and training of
operating personnel is expected to begin in 2013. The plant will employ its
own plant manager and management team, who will report to a governing board
composed of representatives of WBI Energy and Calumet.

MDU Resources Group, Inc., a member of the S&P MidCap 400 index, provides
value-added natural resource products and related services that are essential
to energy and transportation infrastructure, including regulated utilities and
pipelines, exploration and production, and construction materials and services
companies. For more information about MDU Resources, see the company's website
at www.mdu.com or contact the Investor Relations Department at
investor@mduresources.com.

Calumet Specialty Products Partners, L.P. is a master limited partnership and
is a leading independent producer of high-quality, specialty hydrocarbon
products in North America. Calumet Specialty Products Partners, L.P. processes
crude oil and other feedstocks into customized lubricating oils, solvents and
waxes used in consumer, industrial and automotive products. Calumet also
produces fuel products including gasoline, diesel and jet fuel. Calumet
Specialty Products Partners, L.P. is based in Indianapolis, Indiana and has
eleven facilities located in northwest Louisiana, northwest Wisconsin, western
Pennsylvania, Texas and eastern Missouri.

Forward-Looking Statements

Except for the historical information contained herein, the matters discussed
in this release are forward-looking statements that involve certain risks and
uncertainties that could cause actual results to differ materially from
results anticipated in the forward-looking statements. These risks and
uncertainties include, among other things, the ability of the parties to
complete financing of the project, the ability of the parties to obtain
required regulatory permits, the cost and time to complete the project, and
the availability of crude petroleum product and markets for processed
products. These and any other statements about future expectations, beliefs,
goals, plans or prospects constitute forward-looking statements within the
meaning of the Private Securities Litigation Reform Act of 1995. Any
statements that are not statements of historical fact (including statements
containing the words “believes,” “plans,” “anticipates,” “expects,”
“estimates” and similar expressions) should also be considered to be
forward-looking statements.

Contact:

MDU Resources Group Contacts:
Financial:
Phyllis A. Rittenbach, director - investor relations, 701-530-1057
or
Media:
Rick Matteson, director of communications and public affairs, 701-530-1700
or
Tim Rasmussen, operating company public relations manager, 701-530-1069
or
Calumet Specialty Products Partners Contact:
Jennifer Straumins, president and chief operating officer, 317-328-5660
jennifer.straumins@calumetspecialty.com