Cornerstone Propane Partners, L.P. Reports New Acquisitions.

WATSONVILLE, Calif.--(BUSINESS WIRE)--Dec. 6, 1999--

Cornerstone Propane Partners, L.P. (NYSE:CNO), ("Cornerstone" or the "Partnership"), today reported that during the month of October it joined with Tri County Bottle Gas (Schenectady, NY), Streat Fuel Company (Flint, MI), Pegasus Propane Company (Port Huron, MI), and Temecula Valley Propane (Temecula, CA).

These additions to the Cornerstone family will add approximately 2.7 million annualized retail gallons and approximately 5,700 customers. Since its inception in December 1996, Cornerstone has added approximately 105 million retail gallons and 135,000 customers through its acquisition efforts.

Keith G. Baxter, president and chief executive officer for Cornerstone, stated "Cornerstone continues its external as well as internal growth programs at a record pace. I am proud of our team as they continue to execute on our accretive cash flow additions to the Cornerstone family".

"Cornerstone, like all other propane master limited partnerships, is experiencing a period of warm weather and rising interest rates," said Mr. Baxter. "Despite these external factors, management believes that the base business is strong and poised for continued growth. Because of this, management and the Board of Directors remain committed to the company's unit distribution policy," he added.

Since the formation of Cornerstone in December 1996, the master limited partnership has paid unit distributions of $.54 per unit to common unitholders for each quarter. Merle D. Lewis, chairman and chief executive officer of Northwestern Corporation (NYSE:NOR) and chairman of Northwestern Growth Corporation, the controlling shareholder of Cornerstone's General Partner, stated "Northwestern is committed to the long-term viability of the retail propane industry and our investment in Cornerstone. We fully support the growth and market leadership of Cornerstone and its management team which we believe is one of the industry's best."

Cornerstone Propane Partners, L.P. is a master limited partnership. The Partnership is the nation's fourth largest retail propane marketer serving over 460,000 customers with annual sales of approximately 335 million retail gallons, doing business in 34 states through more than 300 customer service centers. Through its North American energy solutions service team, Coast Energy Group, the Partnership also supplies, purchases, processes and markets over 43,000 barrels per day of natural gas liquids to resellers and major end users, an average of approximately .8 Bcf per day in natural gas sales and 95,000 barrels per day in crude oil sales in the United States and Canada. For more information, please visit our websites at www.cornerstonepropane.com and www.coastenergy.com.

The information presented herein may contain certain "forward-looking statements" within the meaning of the federal securities laws. The Partnership's actual future performance will be affected by a number of factors, risks and uncertainties, including without limitation, weather conditions, regulatory changes, competitive factors, the Partnership's success in dealing with the Year 2000 issues and the operations of vendors, suppliers and customers, many of which are beyond the Partnership's control. Future events and results may vary substantially from what the Partnership currently foresees, and there can be no assurance that the Partnership's actual results will not differ materially from its expectations. The Partnership undertakes no obligation to publicly release any revision to these forward-looking statements to reflect events or circumstances after the date of such statements or reflect the occurrence of anticipated or unanticipated events.