INSTRUMENT OF AMENDMENT TO THE
MDU RESOURCES GROUP, INC.
401(k) RETIREMENT PLAN

The MDU Resources Group, Inc. 401(k) Retirement Plan as restated June 1, 2009
(the “Plan”), is hereby further amended, effective January 1, 2010, as follows:

1.  
By removing the definition of “Retirement” in Article I of the Plan and
replacing it with a definition for “Normal Retirement Age” as follows:

Normal Retirement Age – The time a Participant attains age 60.

Explanation:  This amendment removes the reference to termination of employment
after age 55, since it does not have any relevance.  This clarifies eligibility
to share in Retirement Contributions and Profit Sharing Contributions, and for
vesting purposes.

2.  
By replacing Section D-4-2 Eligibility to Share in the Retirement Contribution,
Special Transition Contribution, and Profit Sharing Feature of Supplement D-4
Provisions Relating to the Cascade Natural Gas Corporation Retirement
Contribution, Special Transition Contribution, and Profit Sharing Contribution,
in its entirety, with the following:

 
D-4-2
Eligibility to Share in the Retirement Contribution, Special Transition
Contribution, and Profit Sharing Feature. In order to share in the allocation of
any Retirement Contribution, Special Transition Contribution, or Profit Sharing
Contribution made by Cascade pursuant to Paragraph 3 or 4 for a given Plan Year,
a Participant must be an Eligible Employee of Cascade, complete 1,000 Hours of
Service in that Plan Year, and be (a) a non-bargaining unit employee, (b) a part
of the CSR Bargaining Unit (“CBU”), or (c) a part of the Field Operations
Bargaining Unit (“FOBU”).  Effective as of January 1, 2008, a Participant must
also be employed by Cascade on the last day of the Plan Year in order to be
eligible to share in the allocation of a Profit Sharing Contribution for such
Plan Year. However, any Participant who died or became disabled during the Plan
Year, or terminated employment on or after attaining age 60 is eligible to share
in the Retirement Contribution or Profit Sharing Contribution, if any, for such
Plan Year.  Participants who meet the preceding requirements are referred to
herein as “Supplement D-4 Participants.”

Notwithstanding the foregoing, certain identified Cascade employees who transfer
to Montana-Dakota Utilities Co. effective December 21, 2009 and remain employed
on December 31, 2009 shall be entitled to an allocation of the Profit Sharing
Contribution for the 2009 Plan Year.

 
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Explanation:  This amendment clarifies that employees who die, become disabled,
or terminate employment on or after age 60 (reduced from age 65) are not
required to complete 1,000 hours of service in the Plan Year to receive the
Retirement Contribution or Profit Sharing Contribution.  This amendment also
allows employees who transfer from Cascade to Montana-Dakota Utilities on
December 21, 2009 as a result of  reorganization, to receive a Profit Sharing
Contribution from Cascade as long as they complete 1,000 hours of service and
they are employed by Montana-Dakota Utilities on December 31, 2009.

3.  
By replacing “age 65” with “age 60” throughout the Plan.

Explanation:  This amendment reduces the age at which Participants who terminate
employment are eligible to share in Retirement and Profit Sharing Contributions
for that Plan Year without completing the 1,000 hours of service or end of year
employment requirements. It also reduces the age at which Participants become
fully vested regardless of the number of years of service.

IN WITNESS WHEREOF, MDU Resources Group, Inc., as Sponsoring Employer of the
Plan, has caused this Supplement to be duly executed by a member of the MDU
Resources Group, Inc. Employee Benefits Committee (“EBC”) on this 30th day of
December, 2009.

 
MDU RESOURCES GROUP, INC.
 
   EMPLOYEE BENEFITS COMMITTEE
             
By:
/s/ Vernon A. Raile                           
   
Vernon A. Raile, Chairman

 
 

 
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