MDU Resources Group, Inc. and Calumet Specialty Products Partners, L.P. announced that the Dickinson, North Dakota-based Dakota Prairie refinery, the first greenfield fuels refinery built in the U.S. in nearly 40 years, has commenced operations. The facility has begun producing diesel fuel and is expected to begin sales of diesel as the plant ramps up during May.

The refinery is designed to process 20,000 barrels per day (bpd) of locally sourced Bakken crude oil, resulting in a production slate that includes up to 7,000 bpd of diesel fuel that will be sold from the plant to regional, North Dakota-based customers.

MDU Resources and Calumet are joint owners and operators of the refinery.

“With more than two-thirds of North Dakota’s diesel fuel currently imported into the state, the Dakota Prairie refinery is well positioned to meet strong regional demand with additional, locally produced supplies of diesel fuel,” said David L. Goodin, president and CEO of MDU Resources. “Over time, we expect that this refinery has the potential to be an important contributor to the economic growth of the local and state economy.

“We are thankful for the support of local and state officials and agencies, and for the economic development climate that they have created in North Dakota,” Goodin said. “Together with our committed partner, Calumet, we are proud to have built the first refinery in this country since 1976.”

The Dakota Prairie refinery also will produce up to 6,500 barrels per day of naphtha, which is used as a diluent to transport heavy oil by pipeline or as a feedstock in gasoline production; up to 6,000 barrels per day of atmospheric tower bottoms, which can be used as a feedstock for lubricating oils; and other refined products.

Construction of the facility began on March 26, 2013 on a 318-acre site that is located about four miles west of Dickinson in southwest North Dakota. More than 800 workers were on site at peak construction. Total cost of the plant is estimated to be approximately $425 million to $435 million, and the facility employs about 80 people.

About MDU Resources Group, Inc.

MDU Resources Group, Inc., (NYSE:MDU) 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, construction materials and services, and exploration and production. 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.

About Calumet

Calumet Specialty Products Partners, L.P. (NASDAQ:CLMT) is a master limited partnership and a leading independent producer of high-quality, specialty hydrocarbon products in North America. Calumet 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 is based in Indianapolis, Indiana and has fourteen manufacturing facilities located in northwest Louisiana, northwest Wisconsin, northern Montana, western Pennsylvania, Texas, New Jersey, Oklahoma, eastern Missouri and North Dakota.

See the site of the Dakota Prairie refinery