CONTRIBUTION, CONVEYANCE AND ASSUMPTION AGREEMENT

Execution Version

CONTRIBUTION, CONVEYANCE AND ASSUMPTION
AGREEMENT

WESTERN GAS PARTNERS, LP

WESTERN GAS HOLDINGS, LLC

ANADARKO PETROLEUM CORPORATION

WESTERN GAS RESOURCES, INC.

WESTERN GAS OPERATING, LLC

And

Dated as of May 14, 2008

CONTRIBUTION, CONVEYANCE AND ASSUMPTION
AGREEMENT

     This Contribution, Conveyance and Assumption Agreement, dated as of May 14, 2008 (this “ Agreement ”), is by and among Western Gas Partners, LP, a Delaware limited partnership (the “ Partnership ”), Western Gas Holdings, LLC, a Delaware limited liability company and the general partner of the Partnership (the “ General Partner ”), Anadarko Petroleum Corporation, a Delaware corporation (“ Anadarko ”), WGR Holdings, LLC, a Delaware limited liability company (“ WGR Holdings ”), Western Gas Resources, Inc., a Delaware corporation (“ WGR ”), WGR Asset Holding Company LLC, a Delaware limited liability company (“ Asset HoldCo ”), Western Gas Operating, LLC, a Delaware limited liability company (“ Operating GP ”), and WGR Operating, LP, a Delaware limited partnership (“ OLP ”). The above-named entities are sometimes referred to in this Agreement each as a “ Party” and collectively as the “ Parties .” Capitalized terms used herein shall have the meanings assigned to such terms in Article I.

RECITALS

      WHEREAS , the General Partner and Asset HoldCo have formed the Partnership, pursuant to the Delaware Revised Uniform Limited Partnership Act (the “ Delaware LP Act ”), for the purpose of engaging in any business activity that is approved by the General Partner and that lawfully may be conducted by a limited partnership organized pursuant to the Delaware LP Act.

      WHEREAS , in order to accomplish the objectives and purposes in the preceding recital, each of the following actions has been taken prior to the date hereof:

	1.		Asset HoldCo formed WGR Holdings under the terms of the Delaware Limited Liability Company Act (the “ Delaware LLC Act ”) and contributed $4,000 in exchange for all of the member interests in WGR Holdings.
	2.		Asset HoldCo formed the General Partner under the terms of the Delaware LLC Act and contributed $1,000 in exchange for all of the membership interests in the General Partner.
	3.		The General Partner and Asset HoldCo formed the Partnership under the terms of the Delaware LP Act and contributed $60 and $2,940, respectively, in exchange for a 2% general partner interest and a 98% limited partner interest, respectively, in the Partnership.
	4.		Asset HoldCo contributed all of the membership interests in the General Partner and the 98% limited partner interest in the Partnership to WGR Holdings.
	5.		The Partnership formed Operating GP under the terms of the Delaware LLC Act and contributed $1,000 in exchange for all of the membership interests in Operating GP.
	6.		Operating GP and the Partnership formed OLP under the terms of the Delaware LP Act and contributed $0.10 and $999.90, respectively, in exchange for a 0.01%

			general partner interest and a 99.99% limited partner interest, respectively, in OLP.
	7.		Asset HoldCo distributed all of the membership interests in WGR Holdings to WGR.

      WHEREAS , concurrently with the consummation of the transactions contemplated hereby, each of the following transactions shall occur:

	1.		Asset HoldCo will distribute all of its membership interests in Anadarko Gathering Company LLC, a Delaware limited liability company (“ AGC ”), Pinnacle Gas Treating LLC, a Texas limited liability company (“ PGT ”) and MIGC LLC, a Delaware limited liability company (“ MIGC ”), to WGR.
	2.		WGR will contribute (on behalf of WGR Holdings) a portion of its membership interest in AGC with a value equal to 2% of the equity value of the Partnership based on upon the pricing of its initial public offering (the “ GP Contribution Interest ”) to the General Partner.
	3.		WGR will convey its remaining membership interest in AGC as well as all of the membership interest in Pinnacle and MIGC (collectively, the “ Partnership Contribution Interests ”) to WGR Holdings.
	4.		The General Partner will contribute the GP Contribution Interest to the Partnership in exchange for (i) 1,083,115 general partner units in the Partnership representing a continuation of its 2% general partner interest in the Partnership and (ii) the Incentive Distribution Rights.
	5.		WGR Holdings will contribute the Partnership Contribution Interests to the Partnership in exchange for (i) 4,973,806 Common Units representing a 9.1843% limited partner interest in the Partnership, (ii) 26,536,306 Subordinated Units representing a 49.0% limited partner interest in the Partnership, (iii) the right to receive a distribution of $14,265,625 as a reimbursement for certain capital expenditures and (iv) the right to receive, upon the earlier to occur of the expiration of the Over-Allotment Option period or the exercise in full of the Over-Allotment Option, (A) a number of additional Common Units that is equal to the excess, if any, of (x) 2,812,500 over (y) the aggregate number of Common Units, if any, actually purchased by and issued to the Underwriters pursuant to the exercise of the Over-Allotment Option on the Option Closing Date(s), and (B) a reimbursement of pre-formation capital expenditures in an amount equal to the aggregate amount of cash, if any, contributed by the Underwriters to the Partnership on the Option Closing Date(s) with respect to Common Units purchased by and issued to the Underwriters pursuant to each exercise of the Over-Allotment Option, if any.
	6.		The Partnership will contribute all of the membership interests in AGC, Pinnacle and MIGC to OLP, of which 0.01% of such membership interest contributed to OLP shall be contributed on behalf of Operating GP.

	7.		The Partnership will (i) pay transaction expenses estimated to be approximately $5.0 million and (ii) loan $260.0 million to Anadarko pursuant to a 30-year note bearing interest at a fixed annual rate of 6.50%.
	8.		The 98% limited partner interest in the Partnership held by WGR Holdings and the 2% general partner interest in the Partnership held by the General Partner will be redeemed and the respective initial capital contributions of Asset HoldCo and the General Partner will thereupon be refunded, and any interest or other profit that may have resulted from the investment or other use of such capital contributions will be distributed to WGR Holdings and the General Partner in proportion to such capital contributions.
	9.		The agreements of limited partnership and the limited liability company agreements of the aforementioned entities will be amended and restated to the extent necessary to reflect the applicable matters set forth above and contained in this Agreement.

      WHEREAS , at the Effective Time, the public, through the Underwriters, will purchase from the Partnership for $309,375,000 million in cash, less the amount of $20,109,375 payable to the Underwriters after taking into account the Underwriters’ discount of 6.0% and the structuring fee of $1,546,875 payable to UBS Securities LLC, 18,750,000 Common Units owned by the Partnership on such date (representing a 34.6224% limited partner interest in the Partnership).

      NOW , THEREFORE , in consideration of the mutual covenants, representations, warranties and agreements herein contained, the parties hereto agree as follows:

ARTICLE I
DEFINITIONS

     The terms set forth below in this Article I shall have the meanings ascribed to them below or in the part of this Agreement referred to below:

     “ Common Units ” means the common units representing limited partner interests in the Partnership.

     “ Commission ” means the U.S. Securities and Exchange Commission.

     “ Effective Time ” means immediately prior to the closing of the initial public offering pursuant to the Underwriting Agreement.

     “ Incentive Distribution Rights ” has the meaning assigned to such term in the Partnership Agreement.

     “ Option Closing Date ” has the meaning assigned to such term in the Partnership Agreement.

     “ Over-Allotment Option ” has the meaning assigned to such term in the Partnership Agreement.

     “ Partnership Agreement ” means the First Amended and Restated Agreement of Limited Partnership of the Partnership dated as of May 14, 2008.

     “ Registration Statement ” means the Registration Statement on Form S-1 filed with the Commission (Registration No. 333-146700), as amended and effective at the Effective Time.

     “ Subordinated Units ” has the meaning assigned to such term in the Partnership Agreement.

     “ Securities Act ” means the Securities Act of 1933, as amended.

     “ Underwriters ” means those underwriters listed in the Underwriting Agreement.

     “ Underwriting Agreement ” means that certain Underwriting Agreement between UBS Securities LLC, Citigroup Global Markets Inc., Credit Suisse Securities (USA) LLC and Morgan Stanley & Co. Incorporated, as representatives of the Underwriters, the General Partner, the Partnership, Anadarko, WGR and WGR Holdings, dated as of May 8, 2008.

ARTICLE II
CONTRIBUTION, ACKNOWLEDGEMENTS AND DISTRIBUTIONS

      Section 2.1 Distribution of the AGC, Pinnacle and MIGC Interests by Asset HoldCo to WGR . Asset HoldCo hereby grants, distributes, bargains, conveys, assigns, transfers, sets over and delivers to WGR, its successors and assigns, for its and their own use forever, all right, title and interest in and to its entire membership interests in AGC, Pinnacle and MIGC, and WGR hereby accepts such membership interests.

      Section 2.2 Contribution of the GP Contribution Interest by WGR to the General Partner . On behalf of WGR Holdings, WGR hereby grants, contributes, bargains, conveys, assigns, transfers, sets over and delivers to the General Partn