MarkWest Energy Partners Announces Open Season for Arkoma Connector Pipeline

Business Wire, March 20, 2008

DENVER -- MarkWest Pioneer, L.L.C., a wholly owned subsidiary of MarkWest Energy Partners, L.P. (MarkWest) (NYSE:MWE), today announced that it is holding a binding open season through April 21, 2008, to solicit shipper commitments for firm year-round transportation service on its proposed Arkoma Connector Pipeline (the "Pipeline").

The transportation service would originate northeast of Coalgate, Oklahoma, and extend south to near Bennington, Oklahoma, where the Pipeline will interconnect with the proposed Midcontinent Express and Gulf Crossing pipelines. The targeted in-service date for the transportation service is the second quarter of 2009, subject to approval of the Federal Energy Regulatory Commission (FERC). MarkWest has undertaken review of the Pipeline project through the pre-filing process with the FERC (Docket No. PF08-2-000).

MarkWest will determine the capacity, scope, and cost of the Pipeline based on the results of this open season. The estimated throughput capacity of the Pipeline is approximately 625,000 dekatherms per day (Dth/d). To meet the diverse needs of the region's gas producers, MarkWest anticipates offering firm and volumetric-based transportation service.

Additional information, including the binding service request form, is available at www.markwest.com under "Operations / FERC Pipelines / Arkoma Connector Pipeline." All transportation service requests must be executed and returned to MarkWest by close of business on April 21, 2008.

Questions regarding the open season should be directed to MarkWest business development representative Bob Powell at 713-666-6747 or via email at bpowell@markwest.com.

MarkWest Energy Partners, L.P. (NYSE:MWE) is a publicly traded master limited partnership with a solid core of midstream assets and a growing core of gas transmission assets. It is one of the largest processors of natural gas in the Northeast and is the largest gas gatherer of natural gas in the prolific Carthage field in east Texas. It also has a growing number of other gas gathering and intrastate gas transmission assets in the Southwest, primarily in Texas and Oklahoma.

This press release includes "forward-looking statements." All statements other than statements of historical facts included or incorporated herein may constitute forward-looking statements. Actual results could vary significantly from those expressed or implied in such statements and are subject to a number of risks and uncertainties. Although we believe that the expectations reflected in the forward-looking statements are reasonable, we can give no assurance that such expectations will prove to be correct. The forward-looking statements involve risks and uncertainties that affect our operations, financial performance and other factors as discussed in our filings with the Securities and Exchange Commission. Among the factors that could cause results to differ materially are those risks discussed in our Form 10-K for the year ended December 31, 2007, as filed with the SEC. You are urged to carefully review and consider the cautionary statements and other disclosures made in those filings, specifically those under the heading "Risk Factors." We do not undertake any duty to update any forward-looking statement.