UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-K/A

(Amendment No. 1)

(Mark One)

ý ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the fiscal year ended December 31, 2018

or

¨ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the transition period from to

Commission file number 1-7414

NORTHWEST PIPELINE LLC

(Exact name of registrant as specified in its charter)

DELAWARE	26-1157701
(State or other jurisdiction of incorporation or organization)	(I.R.S. Employer Identification No.)
295 Chipeta Way Salt Lake City, Utah	84108
(Address of principal executive offices)	(Zip Code)

Registrant’s telephone number, including area code: (801) 583-8800

Securities registered pursuant to Section 12(b) of the Act: None

Securities registered pursuant to Section 12(g) of the Act: None

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act.     Yes  ¨    No  þ

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act.     Yes  ¨    No  þ

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.     Yes  þ    No  ¨

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files).     Yes  þ    No  ¨

Indicate by check mark if disclosure of delinquent filers pursuant to Item 405 of Regulation S-K (§229.405 of this chapter) is not contained herein, and will not be contained, to the best of registrant’s knowledge, in definitive proxy or information statements incorporated by reference in Part III of this Form 10-K or any amendment to this Form 10-K. þ

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

Large accelerated filer ¨ Accelerated filer ¨ Non-accelerated filer þ Smaller reporting company ¨ Emerging growth company ¨

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ¨

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act).     Yes  ¨    No  þ

DOCUMENTS INCORPORATED BY REFERENCE:

None

THE REGISTRANT MEETS THE CONDITIONS SET FORTH IN GENERAL INSTRUCTION (I)(1)(a) AND (b) OF FORM 10-K AND IS THEREFORE FILING THIS FORM 10-K WITH THE REDUCED DISCLOSURE FORMAT.

EXPLANATORY NOTE

Northwest Pipeline LLC is filing this Amendment No. 1 (the “Form 10‑K/A”) to its Annual Report on Form 10‑K for the fiscal year ended December 31, 2018 that was filed with the Securities and Exchange Commission (“SEC”) on February 21, 2019 (the “Form 10‑K”) for the sole purpose of amending Part IV, Item 15 of the Form 10-K to omit Exhibit 23.1 thereto, which was inadvertently filed as an exhibit to the Form 10-K.

No other revisions or amendments have been made to the Form 10-K. This Form 10-K/A does not otherwise purport to modify or update the disclosures in, or exhibits to, the Form 10‑K, or to update the original 10‑K to reflect events occurring after the date of such filing.

PART IV

Item 15. EXHIBITS AND FINANCIAL STATEMENT SCHEDULES

	Page Reference to 2018 Form 10-K
(a) 1. and 2. Northwest Pipeline LLC financials
Index
Covered by reports of independent auditors:
Statement of Comprehensive Income (Loss) for the Years Ended December 31, 2018, 2017, and 2016	24
Balance Sheet at December 31, 2018 and 2017	25
Statement of Member’s Equity for the Years Ended December 31, 2018, 2017, and 2016	27
Statement of Cash Flows for the Years Ended December 31, 2018, 2017, and 2016	28
Notes to Financial Statements	29
Not covered by reports of independent auditors:
Quarterly Financial Data (Unaudited)	44

All other schedules have been omitted since the required information is not present or is not present in amounts sufficient to require submission of the schedule, or because the information required is included in the financial statements and notes thereto.

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(a) 3 and b. Exhibits:

Exhibit	Description
2	Certificate of Conversion of Northwest Pipeline GP (filed on July 3, 2013 as Exhibit 2.1 to our current report on Form 8-K (File No. 001-07414) and incorporated herein by reference).
3.1	Certificate of Formation of Northwest Pipeline LLC (filed on July 3, 2013 as Exhibit 2.2 to our current report on Form 8-K (File No. 001-07414) and incorporated herein by reference).
3.2	Operating Agreement of Northwest Pipeline LLC (filed on July 3, 2013 as Exhibit 3.1 to our current report on Form 8-K (File No. 001-07414) and incorporated herein by reference).
4.1	Senior Indenture, dated as of November 30, 1995 between Northwest Pipeline Corporation and Chemical Bank, relating to Northwest Pipeline’s 7.125% Debentures due 2025 (filed on September 14, 1995 as Exhibit 4.1 to our registration statement on Form S-3 (File No. 033-62639) and incorporated herein by reference).
4.2	Indenture, dated as of April 3, 2017, between Northwest Pipeline LLC and The Bank of New York Mellon Trust Company, N.A., as trustee (filed on April 3, 2017 as Exhibit 4.1 to our current report on Form 8-K (File No. 001-07414) and incorporated herein by reference).
10.1	Administrative Services Agreement, dated January 24, 2008, between Northwest Pipeline GP and Northwest Pipeline Services LLC (filed on January 30, 2008 as Exhibit 10.1 to our current report on Form 8-K (File No. 001-07414) and incorporated herein by reference).
10.2	Assignment Agreement dated February 13, 2013, by and between Northwest Pipeline Services LLC and Williams WPC-I, LLC, effective January 1, 2013 (filed on February 3, 2015 as Exhibit 10(b) to our annual report on Form 10-K (File No. 001-07414) and incorporated herein by reference).
10.3	Credit Agreement dated as of July 13, 2018, between The Williams Companies, Inc., Northwest Pipeline LLC, and Transcontinental Gas Pipeline Company, LLC, as co-borrowers, the lenders named therein, and Citibank, N.A. as Administrative Agent (filed on July 17, 2018 as Exhibit 10.1 to The Williams Companies, Inc.’s Current Report on Form 8-K (File No. 001-04174) and incorporated herein by reference).
10.4	Registration Rights Agreement, dated August 24, 2018 between Northwest Pipeline LLC and the initial purchasers listed therein (filed on August 24, 2018 as Exhibit 10.1 to our current report on Form 8-K (File No. 001-07414) and incorporated herein by reference).
31.1*	Certification of Principal Executive Officer pursuant to Rules 13a-14(a) and 15d-14(a) promulgated under the Securities Exchange Act of 1934, as amended and Item 601(b)(31) of Regulation S-K, as adopted pursuant to Section 302 of The Sarbanes-Oxley Act of 2002.
31.2*	Certification of Principal Financial Officer pursuant to Rules 13a-14(a) and 15d-14(a) promulgated under the Securities Exchange Act of 1934, as amended, and Item 601(b)(31) of Regulation S-K, as adopted pursuant to Section 302 of The Sarbanes-Oxley Act of 2002.
32**	Certification of Principal Executive Officer and Principal Financial Officer pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002.
101.INS	XBRL Instance Document (incorporated by reference to our Annual Report on Form 10-K (File No. 001-07414) filed on February 21, 2019).
101.SCH	XBRL Taxonomy Extension Schema (incorporated by reference to our Annual Report on Form 10-K (File No. 001-07414) filed on February 21, 2019).
101.CAL	XBRL Taxonomy Extension Calculation Linkbase (incorporated by reference to our Annual Report on Form 10-K (File No. 001-07414) filed on February 21, 2019).
101.DEF	XBRL Taxonomy Definition Linkbase (incorporated by reference to our Annual Report on Form 10-K (File No. 001-07414) filed on February 21, 2019).
101.LAB	XBRL Taxonomy Extension Label Linkbase (incorporated by reference to our Annual Report on Form 10-K (File No. 001-07414) filed on February 21, 2019).
101.PRE	XBRL Taxonomy Extension Presentation Linkbase (incorporated by reference to our Annual Report on Form 10-K (File No. 001-07414) filed on February 21, 2019).

* Filed herewith

** Furnished herewith

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SIGNATURES

Pursuant to the requirements of Section 13 or 15(d) 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.

NORTHWEST PIPELINE LLC
(Registrant)
By	/s/ Kathleen R. Hambleton
	Kathleen R. Hambleton
	Controller

Date: February 21, 2019

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