Exhibit 10.1

MUTUAL NOTICE OF EXTENSION

This Mutual Notice of Extension (the “Notice”) is provided as of January 31,
2008, by and among Black Hills Corporation, a South Dakota corporation (“Black
Hills”), Aquila, Inc., a Delaware corporation (“Aquila”), and Great Plains
Energy Incorporated, a Missouri corporation (“Great Plains”).

Background

The parties have entered into an Agreement and Plan of Merger (“Merger
Agreement), an Asset Purchase Agreement (“APA”) and a Partnership Interests
Purchase Agreement (“PIPA”), each dated February 6, 2007. These agreements
provide that each of them may be terminated at any time prior to the Effective
Time (as defined in the agreements) if, among other things, the transactions
contemplated by the agreements have not been consummated by the first
anniversary of the agreements (the “Termination Date”). The agreements further
provide that either Aquila or Great Plains may extend the Termination Date of
the Merger Agreement, and either Aquila or Black Hills may extend the
Termination Date of the APA and PIPA, from time to time up to a date not beyond
18 months after the dates of the agreements, if any of them determines that
additional time is necessary to obtain any of the Material Company Regulatory
Consents or the Material Parent Regulatory Consents (as defined in the Merger
Agreement), or the Required Regulatory Approvals (as defined in the APA and
PIPA).

Each of the parties has determined that additional time is necessary to obtain
the Material Company Regulatory Consents, the Material Parent Regulatory
Consents and the Required Regulatory Approvals, and each desires to initially
extend the Termination Dates of the Merger Agreement, APA and PIPA.

Mutual Notice of Extension

Each of Aquila and Great Plains hereby provides written notice to the other,
pursuant to Section 9.2 of the Merger Agreement, that the Termination Date, as
defined in that agreement, is hereby initially extended to May 1, 2008.

Each of Black Hills and Aquila hereby provides written notice to the other and
to Great Plains, pursuant to Sections 10.1(b) of the APA and the PIPA, that the
Termination Date, as defined in those agreements, is hereby initially extended
to May 1, 2008.

[signature page follows]

IN WITNESS WHEREOF, this Mutual Notice of Extension has been duly executed and
delivered by the duly authorized officers of the parties as of the date first
written above.

 

BLACK HILLS CORPORATION

 

By: /s/ Steven J. Helmers

 

Name:

Steven J. Helmers

 

Title:

Senior Vice President and General Counsel

 

GREAT PLAINS ENERGY INCORPORATED

 

By: /s/ Terry Bassham

 

Name:

Terry Bassham

 

Title:

Executive Vice President – Finance and Strategic

 

Development and Chief Financial Officer

 

AQUILA, INC.

 

By: /s/ Christopher M. Reitz

 

Name:

Christopher M. Reitz

 

Title:

Senior Vice President, General Counsel and Secretary