Duke Energy Transport & Trading Company

MarkWest Energy Partners is engaged in the gathering, transmission and processing of natural gas and the transportation, fractionation and storage of natural gas liquids. The company processes gas from the Appalachian Basin and Michigan. Through several acquisitions completed during 2003 and 2004, the company has also expanded the geographic coverage of its natural gas gathering, processing and transmission to the southwest United States. In addition, one of its acquisitions in Michigan has allowed the company to enter into the crude oil transportation business. MarkWest Energy Partners is a publicly owned company. Its shares are listed on the American Stock Exchange under the ticker symbol MWE. The company is headquartered in Englewood, Colo.

The Tri-State Generation and Transmission Association, founded in 1952, is an electric power supplier to more than 40 electric utilities and distribution systems. It generates and transports electricity to its member systems in a more than 200,000 square-mile service territory in Colorado, Nebraska, New Mexico and Wyoming. The association owns and operates coal and natural gas plants, as well as generates energy through federal hydroelectricity allocations and renewable resource technologies. The Tri-State Generation and Transmission Association serves more than 1 million consumers and has a work force of over 1,000 employees. The company works in partnership with the Colorado River Energy Distributors Association, National Rural Electric Cooperative Association, Rocky Mountain Electrical League and Western Electricity Coordinating Council.