<Page> EXHIBIT 99.1 CONSENT OF INDEPENDENT CHARTERED ACCOUNTANTS We consent to the inclusion of our report dated October 19, 2001, with respect to the combined financial statements of Leland/Watford Group included in the current report of MarkWest Hydrocarbon, Inc., on Form 8-K/A dated May 24, 2002, filed with the Securities and Exchange Commission. /s/ KPMG LLP Chartered Accountants Calgary, Canada May 24, 2002 43