Palomar Open Season to Gauge Interest from Rocky Mountain Shippers

PORTLAND, OREGON--(Marketwire - May 26, 2008) - Palomar Gas Transmission LLC (Palomar) announced today a non-binding open season to gauge interest in capacity from shippers seeking to move Rocky Mountain natural gas into markets in the Willamette Valley and I-5 Corridor.

The results of Palomar's initial open season last year provided sufficient commercial support to proceed with the proposed pipeline's environmental pre-filing with the Federal Energy Regulatory Commission (FERC). Several months into that process, proposals for new pipelines to move Rockies natural gas into western markets have emerged.

Palomar wants to provide those shippers the opportunity to express interest in capacity before Palomar makes its certificate application with FERC later this year.

"Palomar represents the shortest, most cost-effective route to move incremental supplies of natural gas into Pacific Northwest markets," said Hal Kvisle, TransCanada president and chief executive officer. "Palomar represents a low cost alternative, diversifying delivery options and enhancing reliability for customers. Shippers on recently proposed pipelines heading west out of the Rockies have expressed interest in seeing how Palomar might help them better access prime markets such as Portland and Seattle."

The Palomar pipeline will consist of approximately 220 miles of up to 36-inch-diameter pipeline. It will connect TransCanada's existing GTN System in central Oregon with Northwest Pipeline's Grants Pass Lateral and NW Natural's distribution system near Molalla, Oregon (the eastern segment), approximately 30 miles southeast of Portland, and a western segment to allow deliveries along NW Natural's distribution system west and north of Molalla. The system will provide transportation capacity of up to 1.3 billion cubic feet per day. If approved, Palomar would begin service in late 2011.

The open season runs through June 20, 2008. Potential customers interested in participating in the open season can find more information on Palomar by visiting www.palomargas.com or by contacting David White at 503.833.4321.

Palomar is a joint venture of TransCanada Corporation (TransCanada) (TSX:TRP) (NYSE:TRP) and Northwest Natural Gas Company (NW Natural) (NYSE:NWN).

TransCanada is a leader in the responsible development and reliable operation of North American energy infrastructure. TransCanada's network of more than 36,500 miles of pipeline taps into virtually all major gas supply basins in North America. TransCanada is one of the continent's largest providers of gas storage and related services with approximately 360 billion cubic feet of storage capacity. A growing independent power producer, TransCanada owns, controls or is developing approximately 8,300 megawatts of power generation. TransCanada's Gas Transmission Northwest system, headquartered in Portland, has been operating in Oregon since 1963.

NW Natural, also headquartered in Portland, is the largest independent natural gas utility in the Pacific Northwest, serving approximately 657,000 home, business, and industrial customers in Oregon and southwest Washington.

FORWARD-LOOKING INFORMATION

This news release may contain certain information that is forward looking and is subject to important risks and uncertainties. The words "anticipate", "expect", "may", "should", "estimate", "project", "outlook", "forecast" or other similar words are used to identify such forward looking information. All forward-looking statements reflect TransCanada's beliefs and assumptions based on information available at the time the statements were made. Actual results or events may differ from those predicted in these forward-looking statements. Factors which could cause actual results or events to differ materially from current expectations include, among other things, the ability of TransCanada to successfully implement its strategic initiatives and whether such strategic initiatives will yield the expected benefits, the operating performance of the Company's pipeline and energy assets, the availability and price of energy commodities, regulatory processes and decisions, changes in environmental and other laws and regulations, competitive factors in the pipeline and energy industry sectors, construction and completion of capital projects, labour, equipment and material costs, access to capital markets, interest and currency exchange rates, technological developments and the current economic conditions in North America. By its nature, such forward-looking information is subject to various risks and uncertainties, which could cause TransCanada's actual results and experience to differ materially from the anticipated results or expectations expressed. Additional information on these and other factors is available in the reports filed by TransCanada with Canadian securities regulators and with the U.S. Securities and Exchange Commission. Readers are cautioned not to place undue reliance on this forward-looking information, which is given as of the date it is expressed in this news release or otherwise, and to not use future-oriented information or financial outlooks for anything other than their intended purpose. TransCanada undertakes no obligation to update publicly or revise any forward-looking information, whether as a result of new information, future events or otherwise, except as required by law.

The results or events predicted in this information may differ from actual results or events. Factors which could cause actual results or events to differ materially from current expectations include, among other things, the ability of Palomar Gas Transmission to obtain the needed permits, gather landowner approvals, complete any needed financing , and the typical construction risks inherent in pipeline projects for materials and labor availability.

This release and other information made by NW Natural from time to time may contain forward-looking statements within the meaning of Section 21E of the Securities Exchange Act of 1934, as amended. Forward-looking statements include statements concerning plans, objectives, goals, strategies, future events or performance, and other statements that are other than statements of historical facts. NW Natural's expectations, beliefs and projections are expressed in good faith and are believed to have a reasonable basis. However, each such forward-looking statement involves uncertainties and is qualified in its entirety by reference to the factors described in Part I, Item 1A, "Risk Factors," and "Forward-Looking Statements" following Part II, Item 7A, in NW Natural's 2006 Annual Report on Form 10-K, and in "Forward-Looking Statements" following Part I, Item 2, of NW Natural's Quarterly Report on Form 10-Q for the quarter ended March 31, 2007, that could cause the actual results of NW Natural to differ materially from those projected in such forward-looking statements.

All subsequent forward-looking statements, whether written or oral and whether made by or on behalf of TransCanada or NW Natural, also are expressly qualified by these cautionary statements. Any forward-looking statement speaks only as of the date on which such statement is made, and the companies undertake no obligation to update any forward-looking statement to reflect events or circumstances after the date on which such statement is made or to reflect the occurrence of unanticipated events. New factors emerge from time to time and it is not possible for the companies to predict all such factors, nor can they assess the impact of each such factor or the extent to which any factor, or combination of factors, may cause results to differ materially from those contained in any forward-looking statement.

Shipper Inquiries:
Palomar Gas Transmission LLC
David White
(503) 833-4321
or
Media Inquiries:
Northwest Natural Gas Company
Steve Sechrist
(503) 220-2594
or
Media Inquiries:
TransCanada
Shela Shapiro/Cecily Dobson
(403) 920-7859 or (800) 608-7859
or
Investor Inquiries:
Northwest Natural Gas Company
Bob Hess
(503) 220-2388
or
Investor Inquiries:
TransCanada
David Moneta/Myles Dougan/Terry Hook
(403) 920-7911 or (800) 361-6522, ext. 7911