Exhibit 10.28

TENTH AMENDMENT TO LOAN AGREEMENT AND
AMENDMENT TO INTERCREDITOR AGREEMENT

THIS TENTH AMENDMENT TO LOAN AGREEMENT AND AMENDMENT TO INTERCREDITOR AGREEMENT (herein called this "Amendment") is made as of the 3rd day of January, 2003, by
and among Western Gas Resources, Inc. ("Borrower"), Bank of America, N.A. ("Agent"), and the Lenders under the Loan Agreement referred to below.

W I T N E S S E T H:

WHEREAS, Borrower, Agent, and Lenders have entered into that certain Loan Agreement dated as of April 29, 1999 (as amended, restated, or supplemented to
the date hereof, the "Original Agreement"), for the purposes and consideration therein expressed, pursuant to which Lenders made and became obligated to make loans to Borrower as therein provided;

WHEREAS,
Borrower, Agent, and Lenders desire to amend the Original Agreement for the purposes described herein;

WHEREAS,
Borrower previously issued to The Prudential Insurance Company of America ("PICA") and Pruco Life Insurance Company ("PRUCO") those certain Senior Notes dated October 27,
1992, September 22, 1993, December 27, 1993, October 27, 1994, and July 28, 1995, pursuant to a Master Shelf Agreement dated as of December 19, 1991 by and between
Borrower and PICA (as heretofore amended, supplemented or modified, the "Original Prudential Agreement");

WHEREAS,
Borrower is entering into a Third Amended and Restated Master Shelf Agreement dated as of December 19, 1991 (effective as of January 13, 2003) (the "Restated
Prudential Agreement"), with PICA, PRUCO and Prudential Investment Management, Inc. ("Prudential"), amending and restating the Original Prudential Agreement, pursuant to which, among other
things, the period during which senior notes may be issued thereunder is being extended and the facility size is being increased by $65,000,000 (allowing Borrower to issue an additional $65,000,000 in
Debt Securities);

WHEREAS,
Agent, Lenders, and Prudential (as successor in interest to PICA) entered into that certain Intercreditor Agreement dated as of April 26, 2001 (the "Original
Intercreditor Agreement"), to evidence their agreement with respect to certain payments that may be received by the Lenders and PICA under or in connection with the various guaranties executed by
Related Persons in favor of the Lenders and Prudential;

WHEREAS,
Prudential is succeeding to all of PICA's rights and obligations under the Original Intercreditor Agreement;

WHEREAS,
Borrower desires that Majority Lenders consent to the Restated Master Shelf Agreement and the terms set forth therein; and

WHEREAS,
Agent, Lenders and Prudential desire to amend the Original Intercreditor Agreement on the terms set forth herein.

NOW,
THEREFORE, in consideration of the premises and the mutual covenants and agreements contained herein and in the Original Agreement, in consideration of the loans which may hereafter
be made by Lenders to Borrower, and for other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the parties hereto do hereby agree as follows:

ARTICLE I.
Definitions and References

§
1.1.Defined Terms.Unless the context otherwise requires or unless otherwise expressly defined
herein, the terms defined in the Original Agreement shall have the same meanings whenever used in this Amendment. As used herein, the following terms shall have the following meanings:

"Amendment"means this Tenth Amendment to Loan Agreement and Amendment to Intercreditor Agreement.

"Intercreditor Agreement"means the Original Intercreditor Agreement as amended by this Amendment.

"Loan Agreement"means the Original Agreement as amended by this Amendment.

ARTICLE II.
Amendment

§
2.1.Definitions.

(a)  The
definition of "Debt Securities" in Section 1.1 of the Original Agreement is hereby amended in its entirety to read as follows:



(b)  The
following definitions are hereby added to Section 1.1 of the Original Agreement, in alphabetical order, to read as follows:



§
2.2.Committed Loans.Section 2.1 of the Original Agreement is hereby amended in its
entirety to read as follows:

"Section 2.1Committed Loans.



§
2.3.Mandatory Prepayments.Sections 2.7(a) and 2.7(b) of the Original
Agreement are hereby amended in their entirety to read as follows:



§
2.4.Facility Fees.Section 2.9 of the Original Agreement is hereby amended in its entirety
to read as follows:



§
2.5.LCs.Article III of the Original Agreement is hereby amended in its entirety to read
as follows:

"ARTICLE
III



§ 2.6.Reliance by Agent.The third sentence of Section 9.2 of the Original Agreement is
hereby amended in its entirety to read as follows:



§
2.7.Waivers and Amendments.Section 10.1(b) of the Original Agreement is hereby
amended in its entirety to read as follows:



§
2.8.Limitation on Sales of Property.The following clause (C) is hereby added to
subsection (iii) of Section 6.2(d) of the Original Agreement:



§
2.9.Assignments and Participations.Section 10.5 of the Original Agreement is hereby
amended in its entirety to read as follows:



§
2.10.Foreign Lenders.Section 10.14 is hereby added to the Original Agreement to read as
follows:



§
2.11.Lenders Schedule and Assignment and Acceptance.Schedule 3 attached to the Original
Agreement is deleted and Schedule 3 hereto is substituted therefor. Exhibit G attached to the Original Agreement is deleted and Exhibit G hereto is substituted therefor.

ARTICLE IIA.
Amendment to Intercreditor Agreement

§
2.1A.Amendment to Intercreditor Agreement.Each of Agent, Prudential, as successor in interest to
PICA and each Lender hereby agrees that the term "Prudential Affiliate" in the Original Intercreditor Agreement is hereby amended in its entirety to mean the following:



Agent,
Prudential and Lenders hereby further agree that, for purposes of the definition of "Prudential Affiliate" the terms "control", "controlling" and "controlled" shall mean the ownership, directly
or through subsidiaries, of a majority of a corporation's or other entity's voting stock or equivalent voting securities or interests.

ARTICLE IIB.
Consent to Restated Master Shelf Agreement

§
2.1B.Consent of Majority Lenders.Majority Lenders hereby consent to Borrower's execution of the
Restated Prudential Agreement and the provisions contained therein, including without limitation, the extension of the period during which senior notes may be issued thereunder and the increase of the
facility size by $65,000,000 (allowing Borrower to issue an additional $65,000,000 in Debt Securities).

ARTICLE III.
Conditions of Effectiveness

§
3.1.Effective Date.

(a)  Article II
of this Amendment shall become effective as of July 30, 2002 when, and only when:



(b)  Article IIA
of this Amendment shall become effective as of the date first written above when and only when Agent shall have received this Amendment, duly
authorized, executed and delivered by Agent, each Lender and Prudential.

(c)  The
remainder of this Amendment shall become effective as of the date first written above when and only when:



ARTICLE IV.
Representations and Warranties

§
4.1.Representations and Warranties of Borrower.In order to induce each Lender to enter into this
Amendment, Borrower represents and warrants on the date hereof and as of the Effective Date to each Lender that:



ARTICLE V.
Miscellaneous

§
5.1.Ratification of Agreements.The Original Agreement as hereby amended is hereby ratified and
confirmed in all respects. Any reference to the Loan Agreement in any Loan Document shall be deemed to be a reference to the Original Agreement as hereby amended. The Loan Documents, as they may be amended or affected by this Amendment, are hereby ratified and confirmed in all respects. The execution, delivery and effectiveness of this Amendment shall not, except as expressly
provided herein, operate as a waiver of any right, power or remedy of Lenders under the Loan Agreement, the Notes, or any other Loan Document nor constitute a waiver of any provision of the Loan
Agreement, the Notes, or any other Loan Document.

§
5.2.Survival of Agreements.All representations, warranties, covenants and agreements of Borrower
herein shall survive the execution and delivery of this Amendment and the performance hereof, including without limitation the making or granting of the Loans, and shall further survive until all of
the Obligations are paid in full. All statements and agreements contained in any certificate or instrument delivered by Borrower hereunder or under the Loan Agreement to any Lender shall be deemed to
constitute representations and warranties by, and/or agreements and covenants of, Borrower under this Amendment and under the Loan Agreement.

§
5.3.Loan Documents.This Amendment is a Loan Document, and all provisions in the Loan Agreement
pertaining to Loan Documents apply hereto.

§
5.4.Governing Law.This Amendment shall be governed by and construed in accordance the laws of
the State of Texas and any applicable laws of the United States of America in all respects, including construction, validity and performance.

§
5.5.Counterparts.This Amendment may be separately executed in counterparts and by the different
parties hereto in separate counterparts, each of which when so executed shall be deemed to constitute one and the same Amendment. This Amendment may be duly executed by facsimile or other electronic
transmission.

THIS AMENDMENT AND THE OTHER LOAN DOCUMENTS REPRESENT THE FINAL AGREEMENT BETWEEN THE PARTIES AND MAY NOT BE CONTRADICTED BY EVIDENCE OF
PRIOR, CONTEMPORANEOUS, OR SUBSEQUENT ORAL AGREEMENTS OF THE PARTIES. THERE ARE NO UNWRITTEN ORAL AGREEMENTS OF THE PARTIES.

[THE
REMAINDER OF THIS PAGE IS INTENTIONALLY LEFT BLANK.]



IN WITNESS WHEREOF, this Amendment is executed as of the date first above written.

| |  | WESTERN GAS RESOURCES, INC.                 
| |  | --------------------------------------------
| |  | By:                                         
| |  | BANK OF AMERICA, N.A., as Agent and Lender  
| |  | By:                                         
| |  | ABN AMRO BANK N.V., a Lender                
| |  | By:                                         
| |  | By:                                         
| |  | BANK ONE, NA (MAIN OFFICECHICAGO), a Lender
| |  | By:                                         
| |  | COMERICA BANKTEXAS, a Lender               
| |  | By:                                         
| |  | CREDIT LYONNAIS NEW YORK BRANCH, a Lender   
| |  | By:                                         

| |  | FLEET NATIONAL BANK, a Lender              
| |  | -------------------------------------------
| |  | By:                                        
| |  | SOCIÉTÉ GÉNÉRALE SOUTHWEST AGENCY, a Lender
| |  | By:                                        
| |  | UNION BANK OF CALIFORNIA, N.A., a Lender   
| |  | By:                                        
| |  | U.S. BANK NATIONAL ASSOCIATION, a Lender   
| |  | By:                                        
| |  | WELLS FARGO BANK, N.A., a Lender           
| |  | By:                                        



The
undersigned is executing this Tenth Amendment to Loan Agreement and Amendment to Intercreditor Agreement for the sole purpose of agreeing to Section 2.1A, Amendment to
Intercreditor Agreement, and for no other purpose.

| |  | PRUDENTIAL INVESTMENT MANAGEMENT, INC., for itself and on behalf of the holders of the Notes
| |  | --------------------------------------------------------------------------------------------
| |  | By:                                                                                         

CONSENT AND AGREEMENT

Each of the undersigned hereby (i) consents to the provisions of this Amendment and the transactions contemplated herein, and (ii) ratifies and
confirms its respective Guaranty dated as of April 29, 1999 made by it in favor of Agent for the benefit of each Lender, and agrees that its obligations and covenants thereunder are unimpaired
hereby and shall remain in full force and effect. This Consent and Agreement is effective as of July 30, 2002.

Date:                        ,
2003

| |  | MIGC, INC.                       
| |  | ---------------------------------
| |  | WESTERN GAS RESOURCES TEXAS, INC.
| |  | MOUNTAIN GAS RESOURCES, INC.     
| |  | LANCE OIL & GAS COMPANY, INC.    
| |  | WESTERN GAS WYOMING, L.L.C.      
| |  | By:                              

CONSENT AND AGREEMENT

The undersigned hereby (i) consents to the provisions of this Amendment and the transactions contemplated herein, and (ii) ratifies and confirms its
Guaranty dated as of October 14, 1999 made by it in favor of Agent for the benefit of each Lender, and agrees that its obligations and covenants thereunder are unimpaired hereby and shall
remain in full force and effect. This Consent and Agreement is effective as of July 30, 2002.

Date:                        ,
2003

| |  | MGTC, INC.
| |  | ----------
| |  | By:       



EXHIBIT G

FORM OF ASSIGNMENT AND ACCEPTANCE

Reference is made to that certain Loan Agreement, dated as of April 29, 1999 (as amended, restated, extended, supplemented or otherwise modified in writing
from time to time, the "Agreement;" the terms defined therein being used herein as therein defined), among Western Gas Resources, Inc., a
Delaware corporation (the ''Borrower"), the Lenders from time to time party thereto, and Bank of America, N.A., as Agent and Issuing Bank.

The
assignor identified on the signature page hereto (the "Assignor") and the assignee identified on the signature
page hereto (the "Assignee") agree as follows:

1.    (a) Subject
to paragraph 11, effective as of the date specified on Schedule 1 hereto (the "Effective
Date"), the Assignor hereby irrevocably sells and assigns to the Assignee without recourse to the Assignor, and the Assignee hereby irrevocably purchases and assumes from the
Assignor without recourse to the Assignor, the interest described on Schedule 1 hereto (the "Assigned Interest") in and to the Assignor's rights
and obligations under the Agreement.

(b)  From
and after the Effective Date, (i) the Assignee shall be a party under the Agreement and will have all the rights and obligations of a Lender for all purposes
under the Loan Documents to the extent of the Assigned Interest and be bound by the provisions thereof, and (ii) the Assignor shall relinquish its rights and be released from its obligations
under the Agreement to the extent of the Assigned Interest. The Assignor and/or the Assignee, as agreed by the Assignor and the Assignee, shall deliver, in immediately available funds, any applicable
assignment fee required underSection 10.5of the Agreement.

2.    On
the Effective Date, the Assignee shall pay to the Assignor, in immediately available funds, an amount equal to the purchase price of the Assigned Interest as agreed
upon by the Assignor and the Assignee.

3.    From
and after the Effective Date, the Agent shall make all payments under the Agreement and the Notes, if any, in respect of the Assigned Interest (including all
payments of principal, interest and fees with respect thereto) to the Assignee. The Assignor and the Assignee shall make all appropriate adjustments in payments under the Agreement and such Notes, if
any, for periods prior to the Effective Date directly between themselves.

4.    The
Assignor represents and warrants to the Assignee that:



The
Assignor makes no representation or warranty and assumes no responsibility with respect to the financial condition of the Borrower or any of its Affiliates or the performance by the
Borrower or any of its Affiliates of their respective obligations under the Loan Documents, and assumes no responsibility with respect to any statements, warranties or representations made under or in
connection with any Loan Document or the execution, legality, validity, enforceability, genuineness, sufficiency or value of any Loan Document other than as expressly set forth above.

5.    The
Assignee represents and warrants to the Assignor and the Agent that:



6.    The
Assignee appoints and authorizes the Agent to take such action as agent on its behalf and to exercise such powers and discretion under the Agreement, the other Loan
Documents or any other instrument or document furnished pursuant hereto or thereto as are delegated to the Agent by the terms thereof, together with such powers as are incidental thereto.

7.    If
either the Assignee or the Assignor desires a Note to evidence its Loans, it shall request the Agent to procure a Note from the Borrower.

8.    The
Assignor and the Assignee agree to execute and deliver such other instruments, and take such other action, as either party may reasonably request in connection with
the transactions contemplated by this Assignment and Acceptance.

9.    This
Assignment and Acceptance shall be binding upon and inure to the benefit of the parties and their respective successors and assigns; provided, however, that the Assignee shall not assign its rights or
obligations hereunder without the prior written consent of the Assignor and any
purported assignment, absent such consent, shall be void.

10.  This
Assignment and Acceptance may be executed by facsimile signatures with the same force and effect as if manually signed and may be executed in one or more
counterparts, each of which shall be deemed an original, but all of which together shall constitute one and the same instrument. This Assignment and Acceptance shall be governed by and construed in
accordance with the laws of the state specified in the Section of the Agreement entitled "Governing Law."

11.  The
effectiveness of the assignment described herein is subject to:



By
signing below, the Agent agrees to register the Assignee as a Lender under the Agreement, effective as of the Effective Date with respect to the Assigned Interest, and will adjust the
registered Percentage Share of the Assignor under the Agreement to reflect the assignment of the Assigned Interest.

12.  Attached
hereto as Schedule 2 is all contact, address, account and other administrative information relating to the Assignee.



IN WITNESS WHEREOF,the parties hereto have caused this Assignment and Acceptance to be executed as of the date first above written by
their respective duly authorized officers.

|                                                              |  | Assignor:                  
|------------------------------------------------------------- |  | ---------------------------
|                                                              |  | [Name of Assignor]         
|                                                              |  | By:                        
|                                                              |  | Name:                      
|                                                              |  | Title:                     
|Tax forms required bySection 2.14(d)of the Agreement included |  | Assignee:[Name of Assignee]
|                                                              |  | By:                        
|                                                              |  | Name:                      
|                                                              |  | Title:                     
|(Signatures continue)                                         |  |                            

In accordance with and subject to Section 10.05 of the Loan Agreement, the undersigned consent to the foregoing assignment as of the Effective Date:

|WESTERN GAS RESOURCES, INC.                   |  | 
|--------------------------------------------- |  | 
|By:                                           |  | 
|Name:                                         |  | 
|Title:                                        |  | 
|BANK OF AMERICA, N.A., as Agent and LC Issuer |  | 
|By:                                           |  | 
|Name:                                         |  | 
|Title:                                        |  | 



SCHEDULE 1
TO
ASSIGNMENT AND ACCEPTANCE

THE ASSIGNED INTEREST

Effective Date:

Assigned Commitment

Type and amount of outstanding Obligations assigned

Assigned Tranche A Percentage Share/Tranche B Percentage Share$


[type]$

%




SCHEDULE 2
TO
ASSIGNMENT AND ACCEPTANCE

ADMINISTRATIVE DETAILS

(Assignee to list names of credit contacts, addresses, phone and facsimile numbers, electronic mail addresses and account and payment
information)

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