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Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company. See the definitions of “large accelerated filer,” “accelerated filer”filer,” and “smaller reporting company” in Rule 12b-2 of the Exchange Act. (Check one):

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act).

 

     Certain matters contained in this report include “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended. These forward-looking statements relate to anticipated financial performance, management’s plans and objectives for future operations, business prospects, outcome of regulatory proceedings, market conditions and other matters. We make these forward-looking statements in reliance on the safe harbor protections provided under the Private Securities Litigation Reform Act of 1995.

     All statements, other than statements of historical facts, included in this report that address activities, events or developments that we expect, believe or anticipate will exist or may occur in the future, are forward-looking statements. Forward-looking statements can be identified by various forms of words such as “anticipates,” “believes,” “could,” “may,” “should,” “continues,” “estimates,” “expects,” “forecasts,” “intends,” “might,” “objectives,” “planned,” “potential,” “projects,” “scheduled”“scheduled,” “will” or other similar expressions. These forward-looking statements are based on management’s beliefs and assumptions and on information currently available to management and include, among others, statements regarding:

     Forward-looking statements are based on numerous assumptions, uncertainties and risks that could cause future events or results to be materially different from those stated or implied in this report. Many of the factors that will determine these results are beyond our ability to control or predict. Specific factors that could cause actual results to differ from results contemplated by the forward-looking statements include, among others, the following:

     Given the uncertainties and risk factors that could cause our actual results to differ materially from those contained in any forward-looking statement, we caution investors not to unduly rely on our forward-looking statements. We disclaim any obligations to and do not intend to update the above list or to announce publicly the result of any revisions to any of the forward-looking statements to reflect future events or developments.

     In addition to causing our actual results to differ, the factors listed above and referred to below may cause our intentions to change from those statements of intention set forth in this report. Such changes in our

     Because forward-looking statements involve risks and uncertainties, we caution that there are important factors, in addition to those listed above, that may cause actual results to differ materially from those contained in the forward-looking statements. For a detailed discussion of those factors, see Part I, Item 1A. Risk Factors in our Annual Report on Form 10-K for the year ended December 31, 2008, and Part II, Item 1A. Risk Factors in this Quarterly Report on Form 10-Q.

     The accompanying interim consolidated financial statements do not include all the notes in our annual financial statements, and therefore, should be read in conjunction with the consolidated financial statements and notes thereto in our 2008 Annual Report on Form 10-K. The accompanying unaudited financial statements include all adjustments both normal recurring and others which, in the opinion of our management, are necessary to present fairly our financial position at JuneSeptember 30, 2009, and results of operations for the three and sixnine months ended JuneSeptember 30, 2009 and 2008, and cash flows for the sixnine months ended JuneSeptember 30, 2009 and 2008.

     The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Actual results could differ from those estimates.

     Estimates and assumptions which, in the opinion of management, are significant to the underlying amounts included in the financial statements and for which it would be reasonably possible that future events or information could change those estimates include: 1) litigation-related contingencies; 2) environmental remediation obligations; 3) impairment assessments of long-lived assets; 4) depreciation; 5) pension and other post-employment benefits; and 6) asset retirement obligations.

     Northwest Pipeline GP (Northwest) is owned 35 percent by Williams Pipeline Partners Holdings LLC, a wholly-owned subsidiary of Williams Pipeline Partners L.P. (WMZ) and 65 percent by WGPC Holdings LLC, a wholly-owned subsidiary of The Williams Companies, Inc. (Williams). Through its ownership interests in each of our partners, Williams directly and indirectly owns 81.7 percent of Northwest as of JuneSeptember 30, 2009.

     In this report, Northwest is at times referred to in the first person as “we”, “us” or “our.”

     The accompanying consolidated financial statements include the accounts of Northwest and Northwest Pipeline Services LLC, a variable interest entity (VIE) for which Northwest is the primary beneficiary.

     We have evaluated our disclosure of subsequent events through the time of filing this Form 10-Q with the SEC on August 6,October 29, 2009.

     In June 2009, the Financial Accounting Standards Board (FASB) issued Statement of Financial Accounting Standards (SFAS) No. 167, “Amendments to FASB Interpretation No. 46(R)” (SFAS No. 167). This Statement amends Interpretation 46(R) to require an entity to perform a qualitative analysis to determine whether the entity’s variable interest or interests give it a controlling financial interest in a VIE. This analysis identifies the primary beneficiary of a VIE as the entity that has both the power to direct the activities that most significantly impact the VIE’s economic performance and the obligation to absorb losses or the right to receive benefits of the VIE. SFAS No. 167 amends Interpretation 46(R) to replace the quantitative-based risks and rewards approach previously required for determining the primary beneficiary of a VIE. SFAS No. 167 is effective as of the beginning of an entity’s first annual reporting period that begins after November 15, 2009 and for interim periods within that first annual reporting period. Earlier application is prohibited. We will assess the application of this Statement on our Consolidated Financial Statements.

     In March 2008, the EPA promulgated a new, lower National Ambient Air Quality Standard (NAAQS) for ground-level ozone. Within two years, the EPA iswas expected to designate new eight-hour ozone non-attainment areas. Designation of new eight-hour ozone non-attainment areas will result in additional federal and state regulatory actions that willwould likely impact our operations. Theoperations and increase the cost of additions to property, plant and equipment. In September 2009, the EPA announced it would reconsider the 2008 NAAQS for ground level ozone to ensure that the standards are clearly grounded in science, and are protective of both public health and the environment. As a result, the EPA has delayed designation of new eight-hour ozone non-attainment areas under the 2008 standards until the reconsideration is complete. Additionally, the EPA is expected to promulgate additional hazardous air pollutant regulations in 2010 that will likely impact our operations. As a result, we expect the cost of additions to

     Our debt agreements contain restrictions on our ability to incur secured debt beyond certain levels.

     We areWilliams has a borrower under Williams’ $1.5 billion unsecured revolving credit facility (Credit Facility) andwith a maturity date of May 1, 2012. We have access to $400 million ofunder the facilityCredit Facility to the extent not utilized by Williams. Letters of credit totaling $45.4 million, none of which are associated with us, have been issued by the participating institutions. There were no revolving credit loans outstanding as of June 30, 2009. Our ratio of debt to capitalization must be no greater than 55 percent under the Credit Facility. We are in compliance with this covenant at June 30, 2009.

     During the periods presented, our revenues include transportation transactions and rental of communication facilities with subsidiaries of Williams. Combined revenues for these activities totaled $3.6$1.2 million and $7.2$9.0 million for the three and sixnine months ended JuneSeptember 30, 2009, respectively, and $3.5$3.6 million and $7.5$11.1 million for the three and sixnine months ended JuneSeptember 30, 2008, respectively.

     We leaseThrough July 2009, we leased the Parachute Lateral facilities from an affiliate. Under the terms of the operating lease, we paypaid monthly rent equal to the revenues collected from transportation services on the lateral less 3 percent to cover costs related to the operation of the lateral. This lease expense, totaling $2.5$0.9 million and $5.0$5.9 million for the three and sixnine months ended JuneSeptember 30, 2009, respectively, and $2.5$2.6 million and $5.0$7.6 million for the three and sixnine months ended JuneSeptember 30, 2008, respectively, is included in “Operation and maintenance expense” on the

     Our strategy to create value focuses on maximizing the contracted capacity on our pipeline by providing high quality, low cost natural gas transportation and storage services to our markets. We grow our business primarily through expansion projects that are designed to increase our access to natural gas supplies and to serve the demand growth in our markets.

     The pipeline projects listed below are significant future pipeline projects for which we have significant customer commitments.

     On June 1, 2009, we commenced construction of a new 27-mile, 24-inch diameter lateral to connect the Meeker/White River Hub near Meeker, Colorado to our mainline south of Rangely, Colorado. This project is referred to as the Colorado Hub Connection (CHC Project). It is estimated that the construction of the CHC Project will cost up to $60 million with service targeted to commence in November 2009. We will combine the lateral capacity with existing mainline capacity to provide approximately 363 thousand dekatherms (MDth) per day of firm transportation from various receipt points to delivery points on the mainline as far south as Ignacio, Colorado. Approximately 243 MDth per day of this capacity was originally held by Pan-Alberta Gas under a contract that would have terminated on October 31, 2012 and approximately 98 MDth per day was sold on a short-term basis.

     In addition to providing greater opportunity for contract extensions for the short-term firm and Pan-Alberta capacity, the CHC Project provides direct access to additional natural gas supplies at the Meeker/White River Hub for our on-system and off-system markets. We have entered into transportation agreements for approximately 363 MDth per day of capacity with terms ranging between eight and fifteen years at maximum rates for all of the short-term firm and Pan-Alberta capacity resulting in the successful re-contracting of the capacity out to 2018 and beyond. In April 2009, the FERC issued a certificate approving the CHC Project, including the presumption of rolling in the costs of the project in any future rate case filed with the FERC.

     The Jackson Prairie Storage Project, connected to our transmission system near Chehalis, Washington, is operated by Puget Sound Energy and is jointly owned by Puget Sound Energy, Avista Corporation and us. A phased capacity expansion is currently underway and a deliverability expansion was placed in service on November 1, 2008.

     As a one-third owner of Jackson Prairie, in early 2006, we held an open season for a new firm storage service based on our 100 million cubic feet per day share of the planned 2008 deliverability expansion and approximately 1.2 billion cubic feet of our share of the working natural gas storage capacity expansion being developed over approximately a six-year period from 2007 through 2012.

     As a result of the open season, four shippers have executed long-term service agreements for the full amount of incremental storage service offered at contract terms averaging 33 years. The firm service relating to storage capacity rights will be phased-in as the expanded working natural gas capacity is developed. Our one-third share of the deliverability expansion was placed in service on November 1, 2008 at a cost of approximately $16.0 million. Our estimated capital cost for the capacity expansion component of the new storage service is $6.1 million, primarily for base natural gas.

     In May 2009, we filed an application with the FERC for the proposed Sundance Trail Expansion to construct approximately 16 miles of 30-inch loop between our existing Green River and Muddy Creek compressor stations in Wyoming as well as an upgrade to our existing Vernal compressor station, with service targeted to commence in November 2010. The total project is estimated to cost up to $65 million, including the cost of replacing the existing compression at Vernal, which will enhance the efficiency of our system. We

executed a precedent agreement to provide 150 MDth per day of firm transportation service from the

attributed to reductions in accrued property taxes totaling $2.6 million resulting primarily from lower than anticipated tax settlements partially offset by higher property tax accruals related to property additions.and $1.7 million lower expense from the termination of the Parachute Lateral lease agreement.

     Interest charges increased $2.0$1.7 million, or 95 percent, due primarily to the May 2008 refinancing of the $250.0 million revolver debt with the issuance of $250.0 million of 6.05 percent senior unsecured notes.

     We fund our working capital and capital requirements with cash flows from operating activities, and, if required, borrowings under the Williams Credit Facility (described below) and return of advances made to Williams.

     We invest cash through participation in Williams’ cash management program. At JuneSeptember 30, 2009, the

     With respect to Fitch, a rating of “BBB” or above indicates an investment grade rating. A rating below “BBB” is considered speculative grade. A “BB” rating from Fitch indicates that there is a possibility of credit risk developing, particularly as the result of adverse economic change over time; however, business or financial alternatives may be available to allow financial commitments to be met. Fitch may add a “+” or a “-” sign to show the obligor’s relative standing within a major rating category.

     For quantitative and qualitative disclosures about market risk, see “Item 7A. Quantitative and Qualitative Disclosures about Market Risk,” of our Annual Report on Form 10-K for the year ended December 31, 2008. Our exposures to market risk have not changed materially since December 31, 2008.

     Our management, including our Senior Vice President and our Vice President and Treasurer, does not expect that our disclosure controls and procedures (as defined in Rules 13a-15(e) and 15d-15(e) of the Securities Exchange Act) (Disclosure Controls) or our internal controls over financial reporting (Internal Controls) will prevent all errors and all fraud. A control system, no matter how well conceived and operated, can provide only reasonable, not absolute, assurance that the objectives of the control system are met. Further, the design of a control system must reflect the fact that there are resource constraints, and the benefits of controls must be considered relative to their costs. Because of the inherent limitations in all control systems, no evaluation of controls can provide absolute assurance that all control issues and instances of fraud, if any, within Northwest have been detected. These inherent limitations include the realities that judgments in decision-making can be faulty, and that breakdowns can occur because of simple error or mistake. Additionally, controls can be circumvented by the individual acts of some persons, by collusion of two or more people, or by management override of the control. The design of any system of controls also is based in part upon certain assumptions about the likelihood of future events, and there can be no assurance that any design will succeed in achieving its stated goals under all potential future conditions. Because of the inherent limitations in a cost-effective control system, misstatements due to error or fraud may occur and not be detected. We monitor our Disclosure Controls and Internal Controls and make modifications as necessary; our intent in this regard is that the Disclosure Controls and the Internal Controls will be modified as systems change and conditions warrant.

     An evaluation of the effectiveness of the design and operation of our Disclosure Controls was performed as of the end of the period covered by this report. This evaluation was performed under the supervision and with the participation of our management, including our Senior Vice President and our Vice President and Treasurer. Based upon that evaluation, our Senior Vice President and our Vice President and Treasurer concluded that these Disclosure Controls are effective at a reasonable assurance level.

     There have been no changes during the secondthird quarter of 2009 that have materially affected, or are reasonably likely to materially affect, our Internal Controls.

     Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

Date: August 6,October 29, 2009