** **

**UNITEDSTATES**

**SECURITIESAND EXCHANGE COMMISSION**

**Washington, D.C. 20549**

** **

----

 

**FORM 10-K/A**

**(Amendment No. 1)**

 
| x                                                                                                                                                                                                                                             | **ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF  THE SECURITIES EXCHANGE ACT OF 1934**     |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------|
| **For the fiscal year ended December 31, 2007.**                                                                                                                                                                                         |
| **or**                                                                                                                                                                                                                                        |
| o                                                                                                                                                                                                                                             | **TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF  THE SECURITIES EXCHANGE ACT OF 1934** |
| ** **                                                                                                                                                                                                                                    |
| **for the transition period from                  to                 .** |
| ** **                                                                                                                                                                                                                                    |
| **Commission File Number 001-31239**                                                                                                                                                                                                     |

 

----

 

**MARKWESTENERGY PARTNERS, L.P.**

(Exact name of registrant asspecified in its charter)

 

| **Delaware**                                                     | ** ** | **27-0005456**                        |
|------------------------------------------------------------------|------------|---------------------------------------|
| (State or other  jurisdiction of  incorporation or organization) |       | (I.R.S. Employer  Identification No.) |

 

**1515 Arapahoe Street, Tower 2, Suite 700, Denver, CO80202-2126**

(Address of principalexecutive offices)

 

Registrant’s telephonenumber, including area code: **303-925-9200**

 

Securities registeredpursuant to Section 12(b) of the Act: **Common units representing limitedpartner interests, New York Stock Exchange**

 

Securities registeredpursuant to Section 12(g) of the Act: **None**

 

Indicate by check markwhether the registrant is a well-known seasoned issuer, as defined in Rule 405of the Securities Act. Yes x No o

 

Indicate by check mark ifthe registrant is not required file reports pursuant to Section 13 or Section 15(d) ofthe Act. Yes o No x

 

Indicate by check markwhether the registrant (1) has filed all reports required to be filed by Section 13or 15(d) of the Securities Exchange Act of 1934 during the preceding12 months (or for such shorter period that the registrant was required tofile such reports), and (2) has been subject to such filing requirementsfor the past 90 days. Yes x No o

 

Indicate by check mark ifdisclosure of delinquent filers pursuant to Item 405 of Regulation S-Kis not contained herein, and will not be contained, to the best of registrant’sknowledge, in definitive proxy or information statements incorporated byreference in Part III of this Form 10-K or any amendment to this Form 10-K. x

 

Indicate by check markwhether the registrant is a large accelerated filer, an accelerated filer, anon-accelerated filer, or a smaller reporting company. See definitions of“large accelerated filer,” “accelerated filer,” and “smaller reporting company”in Rule 12b-2 of the Exchange Act. (Check one):

 

| Large accelerated filer  x |   | Accelerated filer o |   | Non-accelerated filer o                        |   | Smaller reporting  company o |
|----------------------------|--------|---------------------|--------|------------------------------------------------|--------|------------------------------|
|                       |   |                |   | (Do not check if a  smaller reporting company) |   |                         |

 

Indicate by check markwhether the registrant is a shell company (as defined in Rule 12b-2 of theAct). Yes o No x

 

The aggregate market valueof common units held by non-affiliates of the registrant on June 29, 2007was approximately $1.1 billion.

 

As of February 28,2008, the number of the registrant’s common units were 50,876,295.

 

**DOCUMENTS INCORPORATED BY REFERENCE:**

 

The information required by Part IIIof this Report, to the extent not set forth herein, is incorporated herein byreference from the registrant’s definitive proxy statement relating to theAnnual Meeting of Shareholders to be held in 2008, which definitive proxystatement shall be filed with the Securities and Exchange Commission within120 days after the end of the fiscal year to which this Report relates.

 

 

----

 

**Explanatory Note**

 

This Amendment No. 1on Form 10-K/A (the “Amendment”) to MarkWest Energy Partners, L.P.’s (the “Partnership,”“we” or “us”) Annual Report on Form 10-K for the year ended December 31,2007, originally filed on February 29, 2008 (Commission File No. 001-31239or the “Original Filing”), is being filed to address comments made by the SECin connection with the commission’s review of the Original Filing.  The Amendment includes in Part IV, Item15(b), revised Exhibits 10.29 and 10.33, both of which we filed in the OriginalFiling with a request for confidential treatment.  In response to the commission’s review, we areincluding certain portions of those agreements that were omitted from theOriginal Filing.

 

This Amendmentdoes not update any other disclosure to reflect events occurring after thefiling of the original Form 10-K.  Pursuant to Rule 12b-15 underthe Securities Exchange Act of 1934, as amended, we have restated in itsentirety each item of the original Form 10-K affected by this Amendment.

 

2

----

 

**PART IV**

 

**ITEM 15. Exhibits and Financial Statement Schedules**

 

(b)                                 Exhibits

 
| **Exhibit Number** | ** ** | **Description**                                                                                                                                                                                                                                                                                                                                       |
|-------------------------|------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| ** **              | ** ** | ** **                                                                                                                                                                                                                                                                                                                                            |
| 2.1(2)                  |       | Purchase Agreement dated  as of March 24, 2003, among PNG Corporation, Energy Spectrum  Partners LP, MarkWest Texas GP, L.L.C., MW Texas Limited, L.L.C.  and MarkWest Energy Partners, L.P.                                                                                                                                      |
|                    |       |                                                                                                                                                                                                                                                                                                                                                  |
| 2.2(2)                  |       | Plan of Merger entered  into as of March 28, 2003, by and among MarkWest Blackhawk L.P.,  MarkWest Pinnacle L.P., MarkWest PNG Utility L.P., MarkWest Texas  PNG Utility L.P., Pinnacle Natural Gas Company, Pinnacle Pipeline  Company, PNG Transmission Company, PNG Utility Company and Bright Star  Gathering, Inc. |
|                    |       |                                                                                                                                                                                                                                                                                                                                                  |
| 2.3(3)                  |       | Asset Purchase-and-Sale  Agreement dated as of November 18, 2003, by and between American Central  Western Oklahoma Gas Company, L.L.C., MarkWest Western Oklahoma Gas Company,  L.L.C. and American Central Gas Technologies, Inc.                                                                                                         |
|                    |       |                                                                                                                                                                                                                                                                                                                                                  |
| 2.4(4)                  |       | Purchase and Sale  Agreement, dated as of November 7, 2003, by and between Shell Pipeline  Company, LP and Equilon Enterprises L.L.C., dba Shell Oil Products US,  and MarkWest Michigan Pipeline Company, L.L.C.                                                                                                                           |
|                    |       |                                                                                                                                                                                                                                                                                                                                                  |
| 2.5(8)                  |       | Asset Purchase and Sale  Agreement and addendum, thereto, dated as of July 1, 2004, by and  between American Central Eastern Texas Gas Company Limited Partnership, ACGC  Gathering Company, L.L.C. and MarkWest Energy East Texas Gas  Company’s L.P.                                                                                 |
|                    |       |                                                                                                                                                                                                                                                                                                                                                  |
| 2.6(15)                 |       | Purchase and Sale  Agreement effective as of January 1, 2005 between MarkWest Energy  Partners L.P. and Enterprise Products Operating L.P.                                                                                                                                                                                             |
|                    |       |                                                                                                                                                                                                                                                                                                                                                  |
| 2.7(16)                 |       | Purchase and Sale  Agreement, dated as of September 16, 2005, by and between El Paso  Corporation, as seller, and MarkWest Energy Partners, L.P. as buyer.                                                                                                                                                                                  |
|                    |       |                                                                                                                                                                                                                                                                                                                                                  |
| 2.8(16)                 |       | Purchase and Sale  Agreement, dated as of September 16, 2005, by and between Kerr McGee  Corp., KM Investment Corp., and Javelina Holdings Corp., as joint sellers,  and MarkWest Energy Partners, L.P. as buyer.                                                                                                                           |
|                    |       |                                                                                                                                                                                                                                                                                                                                                  |
| 2.9(16)                 |       | Purchase and Sale  Agreement, dated as of September 16, 2005, by and between Valero Energy  Corp., and Valero Javelina, L.P., as sellers, and MarkWest Energy  Partners, L.P. as buyer.                                                                                                                                                |
|                    |       |                                                                                                                                                                                                                                                                                                                                                  |
| 2.10(31)                |       | Agreement and Plan of  Redemption and Merger dated September 5, 2007 by and among MarkWest  Hydrocarbon, Inc. MarkWest Energy Partners, L.P. and MWEP, L.L.C.                                                                                                                                                                          |
|                    |       |                                                                                                                                                                                                                                                                                                                                                  |
| 3.1(1)                  |       | Certificate of Limited  Partnership of MarkWest Energy Partners, L.P.                                                                                                                                                                                                                                                                            |
|                    |       |                                                                                                                                                                                                                                                                                                                                                  |
| 3.2(5)                  |       | Amended and Restated  Agreement of Limited Partnership of MarkWest Energy Partners, L.P.,  dated as of May 24, 2002.                                                                                                                                                                                                                        |
|                    |       |                                                                                                                                                                                                                                                                                                                                                  |
| 3.3(1)                  |       | Certificate of Formation  of MarkWest Energy Operating Company, L.L.C.                                                                                                                                                                                                                                                                                |
|                    |       |                                                                                                                                                                                                                                                                                                                                                  |
| 3.4(5)                  |       | Amended and Restated  Limited Liability Company Agreement of MarkWest Energy Operating Company,  L.L.C., dated as of May 24, 2002.                                                                                                                                                                                                               |
|                    |       |                                                                                                                                                                                                                                                                                                                                                  |
| 3.5(1)                  |       | Certificate of Formation  of MarkWest Energy GP, L.L.C.                                                                                                                                                                                                                                                                                          |
|                    |       |                                                                                                                                                                                                                                                                                                                                                  |
| 3.6(5)                  |       | Amended and Restated  Limited Liability Company Agreement of MarkWest Energy GP, L.L.C., dated  as of May 24, 2002.                                                                                                                                                                                                                         |
|                    |       |                                                                                                                                                                                                                                                                                                                                                  |
| 3.7(12)                 |       | Amendment No. 1 to  Amended and Restated Limited Partnership Agreement MarkWest Energy  Partners, L.P.                                                                                                                                                                                                                                      |
|                    |       |                                                                                                                                                                                                                                                                                                                                                  |
| 3.8(23)                 |       | Amendment No. 2 to  Amended and Restated Limited Partnership Agreement MarkWest Energy Partners, L.P.                                                                                                                                                                                                                                       |
|                    |       |                                                                                                                                                                                                                                                                                                                                                  |
| 3.9(28)                 |       | Amendment No. 3 to  Amended and Restated Limited Partnership Agreement MarkWest Energy  Partners, L.P.                                                                                                                                                                                                                                      |

 

3

----

 
| **Exhibit Number** | ** ** | **Description**                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
|-------------------------|------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| 4.1(6)                  |       | Purchase Agreement dated  as of June 13, 2003, by and among MarkWest Energy Partners, L.P.  and Tortoise Capital Advisors, LLC as attorney-in-fact for the  Purchasers.                                                                                                                                                                                                                                                                                                                                                                                                                                |
|                    |       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
| 4.2(6)                  |       | Registration Rights  Agreement dated as of June 13, 2003, by and among MarkWest Energy  Partners, L.P. and Tortoise Capital Advisors, LLC as  attorney-in-fact for the Purchasers.                                                                                                                                                                                                                                                                                                                                                                                                                     |
|                    |       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
| 4.3(8)                  |       | Unit Purchase Agreement  dated as of July 29, 2004 among MarkWest Energy Partners, L.P., and  MarkWest Energy GP, L.L.C. and each of Kayne Anderson Energy  Fund II, L.P., and MarkWest Energy GP, L.L.C. and each of  Kayne Anderson Energy Fund II, L.P., Kayne Anderson Capital Income  Partners, L.P., Kayne Anderson MLP Fund, L.P., Kayne Anderson  Capital Income Fund, LTD., Kayne Anderson Income Partners, L.P.,  HFR RV Performance Master Trust, Tortoise Energy Infrastructure Corporation  and Energy Income and Growth Fund as Purchasers. |
|                    |       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
| 4.4(8)                  |       | Registration Rights  Agreement dated as of July 29, 2004, among MarkWest Energy  Partners, L.P., and each of Kayne Anderson Energy  Fund II, L.P., Kayne Anderson Capital Income Fund, LTD., Kayne  Anderson Income Partners, L.P., HFR RV Performance Master Trust,  Tortoise Energy Infrastructure Corporation and Energy Income and Growth Fund.                                                                                                                                                                                                                                     |
|                    |       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
| 4.5(10)                 |       | Purchase Agreement dated  October 19, 2004, among MarkWest Energy Partners, L.P., MarkWest  Energy Finance Corporation, the Guarantors named therein and the Initial  Purchasers named therein.                                                                                                                                                                                                                                                                                                                                                                                                             |
|                    |       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
| 4.6(10)                 |       | Registration Rights  Agreement dated October 25, 2004, among MarkWest Energy  Partners, L.P., MarkWest Energy Finance Corporation, the Guarantors  named therein and the Initial Purchasers named therein.                                                                                                                                                                                                                                                                                                                                                                                                  |
|                    |       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
| 4.7(10)                 |       | Indenture dated as of  October 25, 2004, among MarkWest Energy Partners, L.P., MarkWest  Energy Finance Corporation, the Guarantors named therein and Wells Fargo  Bank, National Association, as Trustee.                                                                                                                                                                                                                                                                                                                                                                                                  |
|                    |       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
| 4.8(10)                 |       | Form of 6.875%  Series A Senior Notes due 2014 with attached notation of Guarantees  (incorporated by Reference to Exhibits A and D of Exhibit 4.7  hereto)                                                                                                                                                                                                                                                                                                                                                                                                                                       |
|                    |       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
| 4.9(17)                 |       | Registration Rights  Agreement, dated as of November 9, 2005                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |
|                    |       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
| 4.10(17)                |       | Unit Purchase Agreement,  dated as of November 9, 2005                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |
|                    |       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
| 4.11(18)                |       | Registration Rights  Agreement, dated as of December 23, 2005                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
|                    |       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
| 4.12(18)                |       | Unit Purchase Agreement,  dated as of December 23, 2005                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
|                    |       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
| 4.13(24)                |       | Registration Rights  Agreement dated as of July 6, 2006 among MarkWest Energy  Partners, L.P., with MarkWest Energy Finance Corporation as the Issuers,  the Guarantors named therein, and each of RBC Capital Markets Corporation,  J.P. Morgan Securities Inc., Wachovia Capital Markets, LLC, A.G.  Edwards & Sons, Inc., Credit Suisse Securities (USA) LLC,  Fortis Securities LLC, Mizuho International plc, Piper  Jaffray & Co. and SG Americas Securities, LLC collectively  as Initial Purchasers.                                      |
|                    |       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
| 4.14(24)                |       | Indenture dated as of  July 6, 2006, among MarkWest Energy Partners, L.P., MarkWest Energy  Finance Corporation, as Issuers, the Guarantors named therein, and Wells  Fargo Bank, National Association, as Trustee.                                                                                                                                                                                                                                                                                                                                                                                         |
|                    |       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
| 4.15(24)                |       | Form of 8.5%  Series A and Series B Senior Notes due 2016 with attached notation  of Guarantees (incorporated by Reference to Exhibits A and D of  Exhibit 4.11 hereto.                                                                                                                                                                                                                                                                                                                                                                                                                      |
|                    |       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
| 4.16(25)                |       | Registration Rights  Agreement dated as of October 20, 2006 among MarkWest Energy  Partners, L.P., with MarkWest Energy Finance Corporation as the Issuers,  the Guarantors named therein, and RBC Capital Markets as the Initial  Purchaser.                                                                                                                                                                                                                                                                                                                                                               |
|                    |       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
| 4.17(30)                |       | Unit Purchase Agreement  dated April 9, 2007 by and among MarkWest Energy Partners, L.P.,  MarkWest Energy G.P., L.L.C., and each of Kayne Anderson MLP Investment  Company, GPS Income Fund, L.P., GPS High Yield Equities  Fund, L.P., GPS New Equity Fund, L.P., Agile Performance Fund,  L.L.C., Tortoise Energy Infrastructure Corporation, Tortoise Energy Capital  Corporation, Royal Bank of Canada, Structured Finance Americas, L.L.C., The  Cushing MLP Opportunity Fund I, L.P., and ZLP Fund, L.P. as  purchasers.                           |
|                    |       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
| 4.18(30)                |       | Registration Rights  Agreement dated April 9, 2007 by and between MarkWest Energy  Partners, L.P., and each of Kayne Anderson MLP Investment  Company, GPS Income Fund, L.P., GPS High Yield Equities  Fund, L.P., GPS New Equity Fund, L.P., Agile Performance Fund,  L.L.C., Tortoise Energy Infrastructure Corporation, Tortoise Energy Capital  Corporation, Royal Bank of Canada, Structured Finance Americas, L.L.C., The  Cushing MLP Opportunity Fund I, L.P., and ZLP Fund, L.P. as  purchasers.                                                      |

 

4

----

 
| **Exhibit Number** | ** ** | **Description**                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
|-------------------------|------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
|  4.19(36)          |       | Unit Purchase Agreement,  dated as of December 18, 2007                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
|                    |       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
|  4.20(36)          |       | Registration Rights  Agreement, dated as of December 18, 2007                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |
|                    |       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
| 10.1(5)                 |       | Credit Agreement dated as  of May 20, 2002, among MarkWest Energy Operating Company, L.L.C (as the  Borrower), MarkWest Energy Partners, L.P. (as a Guarantor), Bank of  America (as Administrative Agent), and Lenders Party Hereto $60,000,000  Senior Credit Facility, and Banc of America Securities, L.L.C. as sole lead  arranger and book manager.                                                                                                                                                                                                                                                                                          |
|                    |       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
| 10.2(3)                 |       | Amended and Restated  Credit Agreement dated as of December 1, 2003, among MarkWest Energy  Operating Company, L.L.C., as Borrower, MarkWest Energy Partners, L.P.,  as Guarantor, Royal Bank of Canada, as Administrative Agent, Bank One, NA, as  Syndication Agent, Fortis Capital Corp., as Documentation Agent, to the $140,000,000  Senior Credit Facility.                                                                                                                                                                                                                                                                                  |
|                    |       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
| 10.3(5)                 |       | Contribution, Conveyance  and Assumption Agreement dated as of May 24, 2002, by and among MarkWest  Energy Partners, L.P.; MarkWest Energy Operating Company, L.L.C.;  MarkWest Energy GP, L.L.C.; MarkWest Michigan, Inc.; MarkWest  Energy Appalachia, L.L.C.; West Shore Processing Company, L.L.C.; Basin  Pipeline, L.L.C.; and MarkWest Hydrocarbon, Inc.                                                                                                                                                                                                                                                                     |
|                    |       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
| 10.4(5)                 |       | MarkWest Energy  Partners, L.P. Long-Term Incentive Plan.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |
|                    |       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
| 10.5(5)                 |       | First Amendment to  MarkWest Energy Partners, L.P. Long-Term Incentive Plan.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
|                    |       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
| 10.6(5)                 |       | Omnibus Agreement dated of  May 24, 2002, among MarkWest Hydrocarbon, Inc.; MarkWest  Energy GP, L.L.C.; MarkWest Energy Partners, L.P.; and MarkWest  Energy Operating Company, L.L.C.                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
|                    |       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
| 10.7(5)+                |       | Fractionation, Storage and  Loading Agreement dated as of May 24, 2002, between MarkWest Energy  Appalachia, L.L.C. and MarkWest Hydrocarbon, Inc.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
|                    |       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
| 10.8(5)+                |       | Gas Processing Agreement  dated as of May 24, 2002, by and between MarkWest Energy Appalachia,  L.L.C. and MarkWest Hydrocarbon, Inc.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
|                    |       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
| 10.9(5)+                |       | Pipeline Liquids  Transportation Agreement dated as of May 24, 2002, by and between  MarkWest Energy Appalachia, L.L.C. and MarkWest Hydrocarbon, Inc.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
|                    |       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
| 10.10(5)                |       | Natural Gas Liquids  Purchase Agreement dated as of May 24, 2002, by and between MarkWest  Energy Appalachia, L.L.C. and MarkWest Hydrocarbon, Inc.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |
|                    |       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
| 10.11+                  |       | Gas Processing Agreement  (Maytown) dated as of May 28, 2002, between Equitable Production Company  and MarkWest Hydrocarbon, Inc.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
|                    |       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
| 10.12+                  |       | Amendment to Gas  Processing Agreement (Maytown) dated as of March 26, 2002, between  Equitable Production Company and MarkWest Hydrocarbon, Inc.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
|                    |       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
| 10.13(7)                |       | Services Agreement dated  January 1, 2004 between MarkWest Energy GP, L.L.C. and MarkWest  Hydrocarbon, Inc.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
|                    |       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
| 10.14(8)                |       | Second Amended and  Restated Credit Agreement dated as of July 30, 2004 among MarkWest  Energy Operating Company, L.L.C., as Borrower, MarkWest Energy  Partners, L.P., as Guarantor, Royal Bank of Canada, as Administrative  Agent, Fortis Capital Corp., as Syndication Agent, Bank One, NA, as  Documentation Agent and Societe Generale, as Documentation Agent to the  $315,000,000 Senior Credit Facility.                                                                                                                                                                                                                                  |
|                    |       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
| 10.15(8)                |       | First Amendment to the  Second Amended and Restated Credit Agreement dated as of August 20,  2004, among MarkWest Energy Operating Company, L.L.C., as Borrower, MarkWest  Energy Partners, L.P., as Guarantor, Royal Bank of Canada, as  Administrative Agent, Fortis Capital Corp., as Syndication Agent, Bank One,  NA, as Documentation Agent and Societe Generale, as Documentation Agent.                                                                                                                                                                                                                                                    |
|                    |       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
| 10.16(11)               |       | Third Amended and Restated  Credit Agreement dated as of October 25, 2004 among MarkWest Energy  Operating Company, L.L.C., as Borrower, MarkWest Energy Partners, L.P.,  as Guarantor, Royal Bank of Canada, as Administrative Agent, Bank One, N.A.,  as Syndication Agent, Fortis Capital Corp., as Documentation Agent, U.S. Bank  National Association, as Documentation Agent, Societe Generale, as  Documentation Agent, and Wachovia Bank, National Association, as  Documentation Agent, RBC Capital Markets and J.P. Morgan  Securities Inc., as Lead Arrangers and Joint Bookrunners, to the  $200,000,000 Senior Credit Facility. |
|                    |       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
| 10.18(14)r              |       | Executive Employment  Agreement effective September 5, 2007 between MarkWest  Hydrocarbon, Inc. and Frank Semple.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |

 

5

----

 
| **Exhibit Number** | ** ** | **Description**                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |
|-------------------------|------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| 10.19(19)               |       | Fourth Amended and  Restated Credit Agreement, dated as of November 1, 2005, among MarkWest  Energy Operating Company, L.L.C., as borrower, MarkWest Energy  Partners, L.P., as Guarantor, Royal Bank of Canada, as Administrative  Agent, JP Morgan Chase Bank, N.A., as Co-Syndication Agent, Fortis Capital  Corp., as Co-Syndication Agent, Societe Generale, as Co-Documentation Agent,  Wachovia Bank, National Association, as Co-Documentation Agent and RBC  Capital Markets, as Sole Lead Arranger and Bookrunner to the $100,000,000  Revolver Facility and $400,000 Term Loan.                                                                                                                 |
|                    |       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
| 10.20(20)               |       | Fifth amended and restated  credit agreement dated as of December 29, 2005, among MarkWest Energy  Operating Company, L.L.C., as Borrower, MarkWest Energy Partners, L.P.,  as Guarantor, Royal Bank of Canada, as Administrative Agent, Bank One, N.A.,  as Syndication Agent, Forties Capital Corp., as Documentation Agent, U.S.  Bank National Association, as Documentation Agent, Society General, as  Documentation Agent, and Wachovia Bank, National Association, as  Documentation Agent, RBC Capital Markets and J.P. Morgan  Securities Inc., as Lead Arrangers and Joint Bookrunners, to the  $615,000,000 Senior Credit Facility.                                                       |
|                    |       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
| 10.21(26)               |       | Office Lease Agreement,  dated April 19, 2006, by and between Park Central Property LLC, the  landlord, and MarkWest Energy Partners, L.P., the tenant.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |
|                    |       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
| 10.22(14)r              |       | Form of Executive  Employment Agreement effective September 5, 2007 between MarkWest  Hydrocarbon, Inc. and Nancy K. Buese, C. Corwin Bromley,  John C. Mollenkopf and Randy S. Nickerson.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |
|                    |       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
| 10.23(29)               |       | Form of  Indemnification Agreement between MarkWest Energy Partners, LLP and each  Non-employee Director and the following Officers of the Company: Frank  Semple, President and Chief Executive Officer; Nancy Buese, Senior Vice  President and Chief Financial Officer; Randy Nickerson, Senior Vice President  and Chief Commercial Officer; John Mollenkopf, Senior Vice President and  Chief Operations Officer; C. Corwin Bromley, Senior Vice President, General  Counsel and Secretary; David Young, Senior Vice President of Corporate  Services; Richard Ostberg, Vice President of Risk and Compliance, and Andrew  Schroeder, Vice President and Treasurer dated as of January 26, 2007. |
|                    |       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
| 10.24(31)               |       | Exchange Agreement dated  September 5, 2007 by and among MarkWest Energy Partners, L.P.,  MarkWest Hydrocarbon, Inc., and MarkWest Energy, GP L.L.C.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
|                    |       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
| 10.25(31)               |       | Voting Agreement dated  September 5, 2007 by and among MarkWest Energy Partners, L.P. and  the Fox Family Holders.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
|                    |       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
| 10.26(34)+              |       | Hydrogen Supply Agreement  dated September 28, 2007, by and between MarkWest Blackhawk, L.P.  and CITGO Refining and Chemicals Company L.P.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |
|                    |       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
| 10.27(32)               |       | Amended and Restated  Class B Membership Interest Contribution Agreement dated  October 26, 2007 by and among MarkWest Energy Partners, L.P. and  John M. Fox, Donald C. Heppermann, Frank M. Semple,  Nancy K. Buese, Randy S. Nickerson, John C. Mollenkopf,  C. Corwin Bromley, Andrew L. Schroeder, Jan Kindrick, Cindy  Kindrick, Kevin Kubat and Art Denney as the Sellers.                                                                                                                                                                                                                                                                             |
|                    |       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
| 10.28(33)               |       | Amended and Restated  Form of Indemnification Agreement dated October 26, 2007 by and  between MarkWest Energy Partners, L.P. and each non-employee director  and executive officer of the General Partner, including the following named  executive officers: Frank Semple, President and Chief Executive Officer;  Nancy Buese, Senior Vice President and Chief Financial Officer; Randy  Nickerson, Senior Vice President and Chief Commercial Officer; John  Mollenkopf, Senior Vice President and Chief Operations Officer; C. Corwin  Bromley, Senior Vice President, General Counsel and Secretary and Andrew  Schroeder, Vice President and Treasurer.                                        |
|                    |       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
| 10.29*+                 |       | Gas Processing Agreement  dated as of November 1, 2007, by and between MarkWest Javelina Company  and CITGO Refining and Chemicals Company, L.P.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |
|                    |       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
| 10.30(37)+              |       | Amendment to Gas  Processing Agreement dated as of December 11, 2007, by and between  MarkWest Javelina Company and CITGO Refining and Chemicals Company, L.P.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
|                    |       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
| 10.31(35)               |       | Amended Class B  Membership Interest Contribution Agreement dated as of October 26, 2007,  to Agreement and Plan of Redemption and Merger by and among the Partnership,  MarkWest Hydrocarbon, Inc. and MWEP, L.L.C.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
|                    |       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
| 10.32(37)               |       | Omnibus Termination  Agreement dated as of November 16, 2007, by and between MarkWest Energy  Appalachia, L.L.C. and Equitable Production Company and Equitable  Gathering LLC                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |

 

6

----

 
| **Exhibit Number** | ** ** | **Description**                                                                                                                                                                                                                                                                                  |
|-------------------------|------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| 10.33*+                 |       | Natural Gas Liquids  Transportation, Fractionation, and Marketing Agreement dated as of  November 16, 2007, by and between MarkWest Energy Appalachia, L.L.C. and  Equitable Gathering LLC                                                                                             |
|                    |       |                                                                                                                                                                                                                                                                                             |
| 10.34(37)               |       | Assignment and Bill of  Sale and Assumption Agreement dated as of November 16, 2007, by and  between MarkWest Energy Appalachia, L.L.C. and Equitable Production Company  and Equitable Gathering LLC                                                                                  |
|                    |       |                                                                                                                                                                                                                                                                                             |
| 10.35(37)+              |       | Second Amendment to the  Gas Processing Agreement dated as of December 26, 2007, by and between  MarkWest Energy Appalachia, L.L.C. and MarkWest Hydrocarbon, Inc.                                                                                                                     |
|                    |       |                                                                                                                                                                                                                                                                                             |
| 16.1(22)                |       | Changes in registrants  certifying accountants. MarkWest Energy Partners, L.P. dismissed  KPMG LLP as the Partnership’s independent registered public accounting  firm and engaged Deloitte & Touche LLP as its new independent  registered public accounting firm. |
|                    |       |                                                                                                                                                                                                                                                                                             |
| 21.1(37)                |       | List of subsidiaries                                                                                                                                                                                                                                                                             |
|                    |       |                                                                                                                                                                                                                                                                                             |
| 23.1(37)                |       | Consent of  Deloitte & Touche LLP                                                                                                                                                                                                                                                  |
|                    |       |                                                                                                                                                                                                                                                                                             |
| 23.2(37)                |       | Consent of  PricewaterhouseCoopers LLP                                                                                                                                                                                                                                                      |
|                    |       |                                                                                                                                                                                                                                                                                             |
| 31.1*                   |       | Chief Executive Officer  Certification Pursuant to Section 13a-14 of the Securities Exchange Act                                                                                                                                                                                            |
|                    |       |                                                                                                                                                                                                                                                                                             |
| 31.2*                   |       | Chief Financial Officer  Certification Pursuant to Section 13a-14 of the Securities Exchange Act                                                                                                                                                                                            |
|                    |       |                                                                                                                                                                                                                                                                                             |
| 32.1*                   |       | Certification of Chief  Executive Officer of the General Partner pursuant to 18 U.S.C.  Section 1350, as adopted pursuant to Section 906 of the  Sarbanes-Oxley Act of 2002.                                                                                                           |
|                    |       |                                                                                                                                                                                                                                                                                             |
| 32.2*                   |       | Certification of Chief  Financial Officer of the General Partner pursuant to 18 U.S.C.  Section 1350, as adopted pursuant to Section 906 of the  Sarbanes-Oxley Act of 2002.                                                                                                           |

 

----

(1)                                  Incorporated byreference to the Registration Statement (No. 33-81780) on Form S-1filed January 31, 2002.

 

(2)                                  Incorporated byreference to the Current Report on Form 8-K filed April 14, 2003.

 

(3)                                  Incorporated byreference to the Current Report on Form 8-K filed December 16, 2003.

 

(4)                                  Incorporated byreference to the Current Report on Form 8-K filed December 31, 2003.

 

(5)                                  Incorporated byreference to the Current Report on Form 8-K filed June 7, 2002.

 

(6)                                  Incorporated byreference to the Current Report on Form 8-K filed June 19, 2003.

 

(7)                                  Incorporated byreference to the Annual Report on Form 10-K filed March 15, 2004.

 

(8)                                  Incorporated byreference to the Current Report on form 8-K/A filed September 13,2004.

 

(9)                                  Incorporated byreference to the Current Report on Form 8-K filed September 20, 2004.

 

(10)                            Incorporated byreference to the Current Report on Form 8-K filed October 25, 2004.

 

(11)                            Incorporated byreference to the Current Report on Form 8-K filed October 29, 2004.

 

(12)                            Incorporated byreference to the Current Report on Form 8-K filed January 6, 2005.

 

(13)                            Incorporated byreference to the Quarterly Report of MarkWest Hydrocarbon, Inc. on Form 10-Qfiled November 13, 1997.

 

(14)                            Incorporated byreference to the Current Report on Form 8-K filed September 11, 2007.

 

(15)                            Incorporated byreference to the Current Report on Form 8-K filed April 6, 2005.

 

(16)                            Incorporated byreference to the Current Report on Form 8-K filed September 21, 2005.

 

7

----

 

(17)                            Incorporated byreference to the Current Report on Form 8-K filed November 16, 2005.

 

(18)                            Incorporated byreference to the Current Report on Form 8-K/A filed December 29,2005.

 

(19)                            Incorporated byreference to the Current Report on Form 8-K filed November 7, 2005.

 

(20)                            Incorporated byreference to the Current Report on Form 8-K filed January 5, 2006.

 

(21)                            Incorporated byreference to the Current Report on Form 8-K filed March 1, 2004.

 

(22)                            Incorporated byreference to the Current Report on Form 8-K filed September 23, 2005.

 

(23)                            Incorporated byreference to the Current Report on Form 8-K filed June 15, 2005.

 

(24)                            Incorporated byreference to the Current Report on Form 8-K filed July 7, 2006.

 

(25)                            Incorporated byreference to the Current Report on Form 8-K filed October 24, 2006.

 

(26)                            Incorporated byreference to the Current Report on Form 8-K filed April 25, 2006.

 

(27)                            Incorporated byreference to the Current Report on Form 8-K filed November 1, 2006.

 

(28)                            Incorporated byreference to the Current Report on Form 8-K filed January 31, 2007.

 

(29)                            Incorporated byreference to the Annual Report on Form 10-K filed March 7, 2007.

 

(30)                            Incorporated byreference to the Current Report on Form 8-K filed April 11, 2007.

 

(31)                            Incorporated byreference to the Current Report on Form 8-K filed September 6, 2007.

 

(32)                            Incorporated byreference to the Current Report on Form 8-K filed November 13, 2007.

 

(33)                            Incorporated byreference to the Current Report on Form 8-K filed November 1, 2007.

 

(34)                            Incorporated byreference to the Quarterly Report on Form 10-Q filed November 8,2007.

 

(35)                            Incorporated byreference to the Current Report on Form 8-K filed November 13, 2007.

 

(36)                            Incorporated byreference to the Current Report on Form 8-K filed December 19, 2007.

 

(37)                            Incorporated byreference to the Annual Report on Form 10-K filed February 29, 2008.

 

+                                         Application hasbeen made to the Securities and Exchange Commission for confidential treatmentof certain provisions of these exhibits. Omitted material for whichconfidential treatment has been requested and has been filed separately withthe Securities and Exchange Commission.

 

*                                         Filed herewith.

 

r                                   Identifies eachmanagement contract or compensatory plan or arrangement.

 

8

----

 

**SIGNATURES**

 

Pursuant to the requirementsof section 13 or 15(d) of the Securities Exchange Act of 1934, theRegistrant has duly caused this Report to be signed on its behalf by theundersigned, thereunto duly authorized.

 
|                   |   | MarkWest Energy Partners, L.P. |
|------------------------|--------|-------------------------------------|
|                   |   |                                | (Registrant) |
|                   |   | By:                                 | MarkWest Energy GP, L.L.C., |
|                   |   | Its                                 | General Partner |
|                   |   |                                |
| Date: May 7, 2008 |   | By:                                 | /s/ FRANK M. SEMPLE |
|                   |   |                                | Frank M. Semple |
|                   |   |                                | *President  and Chief Executive Officer* |
|                   |   |                                | *(Principal  Executive Officer)* |

 

Pursuant to the requirementsof the Securities Exchange Act of 1934, this report has been signed below bythe following persons on behalf of the Registrant and in the capacities withMarkWest Energy GP, L.L.C., the General Partner of MarkWest EnergyPartners, L.P., the Registrant, and on the dates indicated.

 
| Date: May 7, 2008 |   | By:    | /s/ FRANK M. SEMPLE                      |
|------------------------|--------|--------|------------------------------------------|
|                   |   |   | Frank M. Semple                          |
|                   |   |   | *President  and Chief Executive Officer* |
|                   |   |   | *(Principal  Executive Officer)*         |

 
| Date: May 7, 2008 |   | By:    | /s/ NANCY K. BUESE                                     |
|------------------------|--------|--------|--------------------------------------------------------|
|                   |   |   | Nancy K. Buese                                         |
|                   |   |   | *Senior  Vice President & Chief Financial Officer* |
|                   |   |   | *(Principal  Financial Officer and*                    |
|                   |   |   | *Principal  Accounting Officer)*                       |

 
| Date:  |   | By:    |                                  |
|--------|--------|--------|---------------------------------------|
|   |   |   | John M. Fox                           |
|   |   |   | *Chairman  of the Board and Director* |

 
| Date: May 7, 2008 |   | By:    | /s/ Keith E. Bailey |
|------------------------|--------|--------|---------------------|
|                   |   |   | Keith E. Bailey     |
|                   |   |   | *Director*          |

 
| Date: May 7, 2008 |   |   | /s/ MICHAEL L. BEATTY |
|------------------------|--------|--------|-----------------------|
|                   |   |   | Michael L. Beatty     |
|                   |   |   | *Director*            |

 
| Date: May 7, 2008 |   | By:    | /s/ CHARLES K. DEMPSTER |
|------------------------|--------|--------|-------------------------|
|                   |   |   | Charles K. Dempster     |
|                   |   |   | *Director*              |

 
| Date: May 7, 2008 |   | By:    | /s/ DONALD C. HEPPERMANN |
|------------------------|--------|--------|--------------------------|
|                   |   |   | Donald C. Heppermann     |
|                   |   |   | *Director*               |

 
| Date: May 7, 2008 |   | By:    | /s/ WILLIAM A. KELLSTROM |
|------------------------|--------|--------|--------------------------|
|                   |   |   | William A. Kellstrom     |
|                   |   |   | *Director*               |

 

9

----

 
| Date:  |   |   |            |
|--------|--------|--------|-----------------|
|   |   |   | Anne E. Mounsey |
|   |   |   | *Director*      |

 
| Date: May 7, 2008 |   | By:    | /s/ WILLIAM P. NICOLETTI |
|------------------------|--------|--------|--------------------------|
|                   |   |   | William P. Nicoletti     |
|                   |   |   | *Director*               |

 
| Date: May 7, 2008 |   |   | /s/ DONALD D. WOLF |
|------------------------|--------|--------|--------------------|
|                   |   |   | Donald D. Wolf     |
|                   |   |   | *Director*         |

 

10

----