April 28, 2008

Exhibit 10.1.5

April 28, 2008

Xxxxxx Xxxxxxx, Esq.	Xxxxxxxxxxx Xxxxx, Esq.
Black Hills Corporation	Aquila, Inc.
000 Xxxxx Xxxxxx	00 Xxxx Xxxxx Xxxxxx
Xxxxx Xxxx, XX 00000	Xxxxxx Xxxx, XX 00000

Re: Partnership Interests Purchase Agreement and Asset Purchase Agreement (collectively, the "Agreements") by and among Aquila, Inc. ("Aquila"), Black Hills Corporation ("Black Hills"), Great Plains Energy Incorporated ("Great Plains") and Xxxxxxx Acquisition Corp. ("Xxxxxxx")

Dear Xxxxx and Xxxxx:

Under the terms of the Agreements, as modified by those certain letters dated as of June 29, 2007, August 31, 2007, September 28, 2007, November 30, 2007, January 30, 2008, February 28, 2008, and March 28, 2008, Black Hills, Aquila and Great Plains are to attach schedules setting forth Retained Agreements and Shared Agreements prior to April 30, 2008.  We recognize that this deadline may be implausible and therefore propose extending the date set forth under section 2.2(1) and 8.5(d) of the Agreements to May 30, 2008.

If you are in agreement, please sign below on the attached signature page where indicated and return a copy of this letter to me by fax or e-mail.

Very truly yours,

Great Plains Energy Incorporated

By: /s/ Xxxx X. English

Name: Xxxx X. English

Title: General Counsel

ACKNOWLEDGED, CONSENTED TO, AND ACCEPTED BY:

BLACK HILLS CORPORATION

By:  /s/ Xxxxxx X. Xxxxxxx

Name:	Xxxxxx X. Xxxxxxx
Title:	Sr. Vice President and General Counsel

AQUILA, INC.

By:  /s/ Xxxxx Xxxxx

Name:	Xxxxx Xxxxx
Title:	General Counsel

XXXXXXX ACQUISITION CORP.

By:  /s/ Xxxx X. English

Name:	Xxxx X. English
Title:	Secretary and Treasurer