EX-21 6 exhibit21.htm SUBSIDIARIES OF MDU RESOURCES GROUP, INC.
MDU RESOURCES GROUP, INC.
List of Subsidiaries
(effective December 31, 2012)

Subsidiaries | Jurisdiction of Formation
Alaska Basic Industries, Inc. | Alaska
Ames Sand & Gravel, Inc. | North Dakota
Anchorage Sand and Gravel Company, Inc. | Alaska
Baldwin Contracting Company, Inc. | California
BEH Electric Holdings, LLC | Nevada
Bell Electrical Contractors, Inc. | Missouri
BMH Mechanical Holdings, LLC | Nevada
Bombard Electric, LLC | Nevada
Bombard Mechanical, LLC | Nevada
Capital Electric Construction Company, Inc. | Kansas
Capital Electric Line Builders, Inc. | Kansas
Cascade Natural Gas Corporation | Washington
Centennial Energy Holdings, Inc. | Delaware
Centennial Energy Resources International, Inc. | Delaware
Centennial Energy Resources LLC | Delaware
Centennial Holdings Capital LLC | Delaware
Central Oregon Redi-Mix, LLC | Oregon
CGC Resources, Inc. | Washington
Concrete, Inc. | California
Connolly-Pacific Co. | California
Continental Line Builders, Inc. | Delaware
Coordinating and Planning Services, Inc. | Delaware
D S S Company | California
Desert Fire Holdings, Inc. | Nevada
Desert Fire Protection, a Nevada Limited Partnership | Nevada
Desert Fire Protection, Inc. | Nevada
Desert Fire Protection, LLC | Nevada
E.S.I., Inc. | Ohio
Fairbanks Materials, Inc. | Alaska
Fidelity Exploration & Production Company | Delaware
Fidelity Oil Co. | Delaware
Frebco, Inc. | Ohio
FutureSource Capital Corp. | Delaware
Granite City Ready Mix, Inc. | Minnesota
Hamlin Electric Company | Colorado
Harp Engineering, Inc. | Montana
Hawaiian Cement, a partnership | Hawaii
ILB Hawaii, Inc. | Hawaii
Independent Fire Fabricators, LLC | Nevada
Intermountain Gas Company | Idaho
International Line Builders, Inc. | Delaware
InterSource Insurance Company | Vermont

Jebro Incorporated | Iowa
JTL Group, Inc. (Montana corporation) | Montana
JTL Group, Inc. (Wyoming corporation) | Wyoming
Kent’s Oil Service | California
Knife River Corporation | Delaware
Knife River Corporation – North Central | Minnesota
Knife River Corporation – Northwest | Oregon
Knife River Corporation – South | Texas
Knife River Dakota, Inc. | Delaware
Knife River Equipment, Inc. | Delaware
Knife River Hawaii, Inc. | Delaware
Knife River Marine, Inc. | Delaware
Knife River Midwest, LLC | Delaware
KRC Holdings, Inc. | Delaware
LME&U Holdings, LLC | Nevada
Lone Mountain Excavation & Utilities, LLC | Nevada
Loy Clark Pipeline Co. | Oregon
LTM, Incorporated | Oregon
MDU Brasil Ltda. | Brazil
MDU Construction Services Group, Inc. | Delaware
MDU Energy Capital, LLC | Delaware
MDU Industrial Services, Inc. | Delaware
MDU Resources International LLC | Delaware
MDU Resources Luxembourg I LLC S.a.r.l. | Luxembourg
MDU Resources Luxembourg II LLC S.a.r.l. | Luxembourg
Midland Technical Crafts, Inc. | Delaware
Netricity LLC | Alaska
Nevada Solar Solutions, LLC | Delaware
Northstar Materials, Inc. | Minnesota
Oregon Electric Construction, Inc. | Oregon
Pouk & Steinle, Inc. | California
Prairie Cascade Energy Holdings, LLC | Delaware
Prairie Intermountain Energy Holdings, LLC | Delaware
Prairielands Energy Marketing, Inc. | Delaware
Prairielands Magnetics Limited | Scotland
Rocky Mountain Contractors, Inc. | Montana
USI Industrial Services, Inc. | Delaware
Wagner Group, Inc., The | Delaware
Wagner Industrial Electric, Inc. | Delaware
Wagner-Smith Company, The | Ohio
Wagner-Smith Equipment Co. | Delaware
Wagner-Smith Pumps & Systems, Inc. | Ohio
Warner Enterprises, Inc. | Nevada
WBI Canadian Pipeline, Ltd. | Canada
WBI Energy Midstream, LLC | Colorado
WBI Energy Services, Inc. | Delaware
WBI Energy Transmission, Inc. | Delaware
WBI Energy, Inc. | Delaware
WBI Holdings, Inc. | Delaware
WHC, Ltd. | Hawaii