UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Form 10-K ☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2017 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: 001-35666 Summit Midstream Partners, LP (Exact name of registrant as specified in its charter) Delaware 45-5200503 (State or other jurisdiction of (I.R.S. Employer incorporation or organization) Identification No.) 1790 Hughes Landing Blvd, Suite 500 The Woodlands, TX 77380 (Address of principal executive offices) (Zip Code) Registrant’s telephone number, including area code: (832) 413-4770 Securities registered pursuant to Section 12(b) of the Act: Title of each class Name of exchange on which registered Common Units New York Stock Exchange 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 Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or 15(d) of the Securities Act.  Yes  No 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  No Indicate by check mark whether the registrant has submitted electronically and posted on its corporate Web site, if any, every Interactive Data File required to be submitted and posted 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  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.  Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or 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 ☐ (Do not check if a smaller reporting company) 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 Act).  Yes  No The aggregate market value of the common units held by non-affiliates of the registrant as of June 30, 2017, was $928,653,216. Indicate the number of shares outstanding of each of the issuer’s classes of common stock, as of the latest practicable date: The registrant had 73,085,996 common units and 1,490,999 general partner units outstanding at February 16, 2018. DOCUMENTS INCORPORATED BY REFERENCE None Table of Contents TABLE OF CONTENTS Organizational Chart 3 Commonly Used or Defined Terms 4 PART I 7 Item 1. Business. 7 Item 1A. Risk Factors. 24 Item 1B. Unresolved Staff Comments. 57 Item 2. Properties. 57 Item 3. Legal Proceedings. 58 Item 4. Mine Safety Disclosures. 59 PART II 60 Item 5. Market for Registrant’s Common Equity, Related Stockholder Matters and Issuer 60 Purchases of Equity Securities. Item 6. Selected Financial Data. 62 Item 7. Management’s Discussion and Analysis of Financial Condition and Results of 65 Operations. Item 7A. Quantitative and Qualitative Disclosures about Market Risk. 98 Item 8. Financial Statements and Supplementary Data. 99 Item 9. Changes in and Disagreements With Accountants on Accounting and Financial 152 Disclosure. Item 9A. Controls and Procedures. 152 Item 9B. Other Information. 156 Part III 156 Item 10. Directors, Executive Officers and Corporate Governance. 156 Item 11. Executive Compensation. 162 Item 12. Security Ownership of Certain Beneficial Owners and Management and Related 177 Stockholder Matters. Item 13. Certain Relationships and Related Transactions, and Director Independence. 180 Item 14. Principal Accounting Fees and Services. 182 Part IV 183 Item 15. Exhibits, Financial Statement Schedules. 183 Item 16. Form 10-K Summary. 187 Signature Page 188 2 Table of Contents ORGANIZATIONAL CHART 3 Table of Contents COMMONLY USED OR DEFINED TERMS 2014 SRS the Partnership's shelf registration statement initially filed with the SEC in July 2014 and amended in February 2017 which registered an indeterminate amount of common units, debt securities and guarantees (superseded by the 2017 SRS) 2016 Drop Down the Partnership's March 3, 2016 acquisition of substantially all of (i) the issued and outstanding membership interests in Summit Utica, Meadowlark Midstream and Tioga Midstream and (ii) SMP Holdings’ 40% ownership interest in Ohio Gathering from SMP Holdings 2016 SRS the Partnership's shelf registration statement declared effective in November 2016 which registered up to $1.5 billion of equity and debt securities in primary offerings and 36,701,230 common units beneficially owned by Summit Investments and affiliates of the Sponsor 2017 SRS the Partnership's automatic shelf registration statement of well-known seasoned issuers filed with the SEC in July 2017 which registered an indeterminate amount of common units, preferred units, debt securities and guarantees and subsequently amended in November 2017 5.5% Senior Notes Summit Holdings' and Finance Corp.’s 5.5% senior unsecured notes due August 2022 7.5% Senior Notes Summit Holdings' and Finance Corp.’s 7.5% senior unsecured notes redeemed in March 2017 5.75% Senior Notes Summit Holdings' and Finance Corp.’s 5.75% senior unsecured notes due April 2025 AMI area of mutual interest; AMIs require that any production from wells drilled by our customers within the AMI be shipped on and/or processed by our gathering systems associated natural gas a form of natural gas which is found with deposits of petroleum, either dissolved in the oil or as a free gas cap above the oil in the reservoir ASU Accounting Standards Update Audit Committee the audit committee of the board of directors of our General Partner Bbl one barrel; used for crude oil and produced water and equivalent to 42 U.S. gallons Bcf one billion cubic feet Bcfe/d the equivalent of one billion cubic feet per day; generally calculated when liquids are converted into gas; determined using a ratio of six thousand cubic feet of natural gas to one barrel of liquids Bison Midstream Bison Midstream, LLC Board of Directors the board of directors of our General Partner CAA Clean Air Act CEA Commodity Exchange Act CERCLA Comprehensive Environmental Response, Compensation and Liability Act CFTC Commodity Futures Trading Commission Compensation the compensation committee of the board of directors of our General Partner Committee Compensation BDO USA, L.L.P. Consultant condensate a natural gas liquid with a low vapor pressure, mainly composed of propane, butane, pentane and heavier hydrocarbon fractions Conflicts Committee the conflicts committee of the board of directors of our General Partner CWA Clean Water Act Deferred Purchase Price the deferred payment liability recognized in connection with the 2016 Drop Down Obligation DFW Midstream DFW Midstream Services LLC DJ Basin Denver-Julesburg Basin Dodd-Frank Act Dodd-Frank Wall Street Reform and Consumer Protection Act of 2010 DOT U.S. Department of Transportation dry gas natural gas primarily composed of methane where heavy hydrocarbons and water either do not exist or have been removed through processing or treating Energy Capital Partners Energy Capital Partners II, LLC and its parallel and co-investment funds; also known as the Sponsor EPA Environmental Protection Agency 4 Table of Contents Epping Epping Transmission Company, LLC EPU earnings or loss per unit Exchange Act Securities Exchange Act of 1934, as amended FASB Financial Accounting Standards Board FERC Federal Energy Regulatory Commission Finance Corp. Summit Midstream Finance Corp. FTC Federal Trade Commission GAAP accounting principles generally accepted in the United States of America General Partner Summit Midstream GP, LLC GHG greenhouse gas(es) Grand River Grand River Gathering, LLC hub geographic location of a storage facility and multiple pipeline interconnections ICA Interstate Commerce Act IDR incentive distribution rights IPO initial public offering IRS Internal Revenue Service LIBOR London Interbank Offered Rate Mbbl/d one thousand barrels per day MD&A Management's Discussion and Analysis of Financial Condition and Results of Operations Meadowlark Midstream Meadowlark Midstream Company, LLC MMcf/d one million cubic feet per day Mountaineer Midstream Mountaineer Midstream gathering system MQD minimum quarterly distribution MVC minimum volume commitment NAAQS national ambient air quality standard NEPA National Environmental Policy Act NGA Natural Gas Act NGL natural gas liquids; the combination of ethane, propane, normal butane, iso-butane and natural gasolines that when removed from unprocessed natural gas streams become liquid under various levels of higher pressure and lower temperature NGPA Natural Gas Policy Act of 1978 Niobrara G&P Niobrara Gathering and Processing system NYSE New York Stock Exchange OCC Ohio Condensate Company, L.L.C. OGC Ohio Gathering Company, L.L.C. Ohio Gathering Ohio Gathering Company, L.L.C. and Ohio Condensate Company, L.L.C. OPA Oil Pollution Control Act OpCo Summit Midstream OpCo, LP PHMSA Pipeline and Hazardous Materials Safety Administration play a proven geological formation that contains commercial amounts of hydrocarbons Permian Finance Summit Midstream Permian Finance, LLC Polar and Divide the Polar and Divide system; collectively Polar Midstream and Epping Polar and Divide Drop the Partnership's May 18, 2015 acquisition of all of the issued and outstanding Down membership interests in Polar Midstream and Epping from SMP Holdings Polar Midstream Polar Midstream, LLC produced water water from underground geologic formations that is a by-product of natural gas and crude oil production PSD Prevention of Significant Deterioration RCRA Resource Conservation and Recovery Act Red Rock Drop Down the Partnership's March 18, 2014 acquisition of all of the issued and outstanding membership interests in Red Rock Gathering from SMP Holdings Red Rock Gathering Red Rock Gathering Company, LLC Remaining Consideration management's estimate of the consideration to be paid to SMP Holdings in 2020 in connection with the 2016 Drop Down, the present value of which is reflected on our balance sheets as the Deferred Purchase Price Obligation Revolving Credit Facility the Third Amended and Restated Credit Agreement dated as of May 26, 2017 SEC Securities and Exchange Commission 5 Table of Contents Securities Act Securities Act of 1933, as amended segment adjusted total revenues less total costs and expenses; plus (i) other income excluding interest EBITDA income, (ii) our proportional adjusted EBITDA for equity method investees, (iii) depreciation and amortization, (iv) adjustments related to MVC shortfall payments, (v) unit-based and noncash compensation, (vi) the change in the Deferred Purchase Price Obligation fair value, (vii) early extinguishment of debt expense, (viii) impairments and (ix) other noncash expenses or losses, less other noncash income or gains shortfall payment the payment received from a counterparty when its volume throughput does not meet its MVC for the applicable period SMLP Summit Midstream Partners, LP SMLP LTIP SMLP Long-Term Incentive Plan SMP Holdings Summit Midstream Partners Holdings, LLC SPCC Spill Prevention Control and Countermeasure Sponsor Energy Capital Partners II, LLC and its parallel and co-investment funds; also known as Energy Capital Partners Summit Holdings Summit Midstream Holdings, LLC Summit Investments Summit Midstream Partners, LLC Summit Niobrara Summit Midstream Niobrara, LLC Summit Marketing Summit Midstream Marketing, LLC Summit Permian Summit Midstream Permian, LLC Summit Utica Summit Midstream Utica, LLC the Company Summit Midstream Partners, LLC and its subsidiaries the Partnership Summit Midstream Partners, LP and its subsidiaries throughput volume the volume of natural gas, crude oil or produced water transported or passing through a pipeline, plant or other facility during a particular period; also referred to as volume throughput Tioga Midstream Tioga Midstream, LLC unconventional resource a basin where natural gas or crude oil production is developed from unconventional basin sources that require hydraulic fracturing as part of the completion process, for instance, natural gas produced from shale formations and coalbeds; also referred to as an unconventional resource play VOC volatile organic compound(s) wellhead the equipment at the surface of a well, used to control the well's pressure; also, the point at which the hydrocarbons and water exit the ground 6 Table of Contents PART I Item 1. Business. SMLP is a Delaware limited partnership that completed its IPO in October 2012. References to "we" or "our" refer collectively to SMLP and its subsidiaries. For additional information, see Note 1 to the consolidated financial statements. Item 1. Business is divided into the following sections: • Overview • Business Strategies • Competitive Strengths • Our Midstream Assets • Regulation of the Natural Gas and Crude Oil Industries • Environmental Matters • Other Information Overview We are a growth-oriented limited partnership focused on developing, owning and operating midstream energy infrastructure assets that are strategically located in the core producing areas of unconventional resource basins, primarily shale formations, in the continental United States. Our systems gather natural gas from pad sites, wells and central receipt points connected to our systems. Gathered natural gas volumes are then compressed, dehydrated, treated and/or processed for delivery to downstream pipelines serving processing plants and/or end users. We also contract with producers to gather crude oil and produced water from wells connected to our systems for delivery to downstream pipelines and third-party rail terminals in the case of crude oil and to third-party disposal wells in the case of produced water. We generally refer to all of the services our systems provide as gathering services. We are the owner-operator of, or have significant ownership interests in, the following gathering systems: • Summit Utica, a natural gas gathering system operating in the Appalachian Basin, which includes the Utica and Point Pleasant shale formations in southeastern Ohio; • Ohio Gathering, a natural gas gathering system and a condensate stabilization facility operating in the Appalachian Basin, which includes the Utica and Point Pleasant shale formations in southeastern Ohio; • Polar and Divide, crude oil and produced water gathering systems and transmission pipelines located in the Williston Basin, which includes the Bakken and Three Forks shale formations in northwestern North Dakota; • Tioga Midstream, crude oil, produced water and associated natural gas gathering systems operating in the Williston Basin, which includes the Bakken and Three Forks shale formations in northwestern North Dakota; • Bison Midstream, an associated natural gas gathering system operating in the Williston Basin, which includes the Bakken and Three Forks shale formations in northwestern North Dakota; • Grand River, a natural gas gathering and processing system located in the Piceance Basin, which includes the Mesaverde formation and the Mancos and Niobrara shale formations in western Colorado and eastern Utah; • Niobrara G&P, an associated natural gas gathering and processing system operating in the DJ Basin, which includes the Niobrara and Codell shale formations in northeastern Colorado; • DFW Midstream, a natural gas gathering system operating in the Fort Worth Basin, which includes the Barnett Shale formation in north-central Texas; 7 Table of Contents • Mountaineer Midstream, a natural gas gathering system operating in the Appalachian Basin, which includes the Marcellus Shale formation in northern West Virginia; and • Summit Permian, an associated natural gas gathering and processing system under development in the northern Delaware Basin in southeastern New Mexico. The systems that we operate and/or have a significant ownership interests in have a diverse group of customers and counterparties comprising affiliates and/or subsidiaries of some of the largest natural gas and crude oil producers in North America. Key customers are as follows: • XTO Energy Inc. ("XTO") and Ascent, the key customers for Summit Utica; • Gulfport Energy Corporation ("Gulfport") and Ascent Resources - Utica, LLC ("Ascent"), the key customers for Ohio Gathering; • Whiting Petroleum Corp. ("Whiting") and SM Energy Company ("SM Energy"), the key customers for Polar and Divide; • Hess Corp. ("Hess"), the key customer for Tioga Midstream; • Oasis Petroleum, Inc. ("Oasis") and a large U.S. independent crude oil and natural gas company, the key customers for Bison Midstream; • Caerus Oil & Gas LLC ("Caerus") and Terra Energy Partners LLC ("Terra"), the key customers for Grand River; • Fifth Creek Energy Operating Company, LLC ("Fifth Creek") and a large U.S. independent crude oil and natural gas company, the key customers for Niobrara G&P; • Total Gas & Power North America, Inc. ("Total"), the key customer for DFW Midstream; • Antero Resources Corp. ("Antero"), the key customer for Mountaineer Midstream; and • XTO, the key customer of Summit Permian, which is currently under development. We believe that the systems we operate and/or have significant ownership interests in are positioned for growth through increased utilization and further development. We intend to continue expanding our operations and diversifying our geographic footprint through asset acquisitions from third parties. We also intend to grow our business through the execution of new, and the expansion of existing, strategic partnerships with large producers to provide midstream services for their upstream exploration and production projects. In addition, we may participate in asset acquisitions with Summit Investments, although (i) Summit Investments has no current direct ownership interest in any operating assets, (ii) Summit Investments has no obligation to us to offer any assets that it may acquire or participate in any asset acquisitions that we may make and (iii) we have no obligation to acquire any assets offered. Our financial results are primarily driven by volume throughput across our gathering systems and expense management. During 2017, aggregate natural gas volume throughput averaged 1,748 MMcf/d and crude oil and produced water volume throughput averaged 75.2 Mbbl/d. A substantial majority of the volumes that we gather, treat and/or process have a fixed-fee rate structure thereby enhancing the stability of our cash flows by providing a revenue stream that is not directly subject to commodity price risk. Activities that expose us to direct commodity price risk include (i) the sale of physical natural gas and/or NGLs purchased under percentage-of-proceeds arrangements with certain of our customers on the Bison Midstream and Grand River systems, (ii) natural gas and crude oil marketing services in and around our gathering systems, (iii) the sale of natural gas we retain from certain DFW Midstream system customers and (iv) the sale of condensate we retain from our gathering services at Grand River. During the year ended December 31, 2017, less than 14% of our revenues were exposed to direct commodity price risk. In addition, the vast majority of our gathering and/or processing agreements include AMIs. Our AMIs cover approximately 3.3 million acres in the aggregate, which includes more than 0.8 million acres in Ohio Gathering. 8 Table of Contents Certain of our gathering and processing agreements also include MVCs. To the extent the customer does not meet its MVC, it must make an MVC shortfall payment to cover the shortfall of required volume throughput not shipped or processed, either on a monthly, quarterly or annual basis. We have designed our MVC provisions to ensure that we will generate a certain amount of revenue from each customer over the life of the associated gathering or processing agreement, whether by collecting gathering or processing fees on actual throughput or from cash payments to cover any MVC shortfall. As of December 31, 2017, we had remaining MVCs totaling 2.6 Tcfe. Our MVCs have a weighted-average remaining life of 7.4 years (assuming minimum throughput volume for the remainder of the term) and average approximately 1.0 Bcfe/d through 2022. We use a variety of financial and operational metrics to analyze our performance, including among others, throughput volume, revenues, operation and maintenance expenses and segment adjusted EBITDA. We view each of these operational and/or GAAP metrics as important factors in evaluating our profitability and determining the amounts of cash distributions we pay to our unitholders. For additional information on our results of operations, see Item 6. Selected Financial Data and the "Results of Operations" section included in the Item 7. MD&A. Financial Information About Segments. As of December 31, 2017, our reportable segments and their respective gathering systems were: • the Utica Shale, which is served by Summit Utica; • Ohio Gathering, which includes our ownership interest in OGC and OCC; • the Williston Basin, which includes Polar and Divide, Tioga Midstream and Bison Midstream; • the Piceance/DJ Basins, which includes Grand River and Niobrara G&P; • the Barnett Shale, which includes DFW Midstream; and • the Marcellus Shale, which includes Mountaineer Midstream; Our reportable segments reflect the way in which (i) we manage our operations and (ii) management uses the reported financial information to make decisions and allocate resources in connection therewith. The primary assets of our reportable segments consist of gathering systems and the related property, plant and equipment and intangible assets with the exception of the Ohio Gathering reportable segment, which holds our ownership interest in OGC and OCC. Year ended December 31, 2017 2016 2015 (In thousands) Property, plant and equipment, net $ 1,795,129 $ 1,853,671 $ 1,812,783 Intangible assets, net 301,345 421,452 461,310 For additional information on our reportable segments, see the "Results of Operations—Segment Overview for the Years Ended December 31, 2017, 2016 and 2015" section included in the Item 7. MD&A and Note 3 to the consolidated financial statements. For additional information on revenue and accounts receivable concentrations, see the "Liquidity and Capital Resources—Credit and Counterparty Concentration Risks" section included in Item 7. MD&A and Notes 3 and 10 to the consolidated financial statements. For additional information on long-lived assets, see Notes 4 and 5 to the consolidated financial statements. Our Sponsor and Summit Investments. Energy Capital Partners, together with its affiliated funds, is a private equity firm with over $13.0 billion in capital commitments that is focused on investing in North America's energy infrastructure. Energy Capital Partners has significant energy and financial expertise to complement its investment in us, including investments in the power generation, midstream oil and gas, electric transmission, energy equipment and services, environmental infrastructure and other energy-related sectors. Summit Investments, which was formed in 2009 by members of our management team and our Sponsor, is the ultimate owner of our General Partner. We are managed and operated by the Board of Directors and executive 9 Table of Contents officers of our General Partner, which is managed and operated by Summit Investments. As a result, due to its ownership interest in Summit Investments and its representation on Summit Investments' board of managers, Energy Capital Partners controls our General Partner and its activities, thereby controlling SMLP. In December 2015, Energy Capital Partners approved a unit purchase program of up to $100.0 million of SMLP common units (the "Purchase Program"). A wholly owned subsidiary of Summit Investments acquired 151,160 common units and Energy Capital Partners acquired 5,915,827 common units under the Purchase Program. The Purchase Program concluded in June 2016. Business Strategies Our principal business strategy is to increase the amount of cash distributions we make to our unitholders over time. Our plan for continuing to execute this strategy includes the following key components: • Maintaining our focus on fee-based revenue with minimal direct commodity price exposure. As we expand our business, we intend to maintain our focus on providing midstream energy services under fee- based arrangements. Our midstream services are provided under primarily long-term and fee-based contracts with original terms of up to 25 years. We believe that our focus on fee-based revenues with minimal direct commodity price exposure is essential to maintaining stable cash flows. • Capitalizing on organic growth opportunities to maximize throughput on our existing systems. We intend to continue to leverage our management team's expertise in constructing, developing and optimizing our midstream assets to grow our business through organic development projects. We believe that our broad and geographically diverse operating footprint provides us with a competitive advantage to pursue organic development projects that are designed to extend our geographic reach, diversify our customer base, expand our midstream service offerings, increase the number of our hydrocarbon receipt points and maximize volume throughput. • Diversifying our asset base by expanding our midstream service offerings to new geographic areas. Our gathering operations in the Utica, Bakken, Barnett and Marcellus shale plays and the Piceance and DJ basins currently represent our core business. We intend to pursue opportunities to diversify our operations into other geographic regions through both greenfield development projects and acquisitions from third parties. For example, in the third quarter of 2017, we began developing Summit Permian, an associated natural gas gathering and processing system, in the northern Delaware Basin in southeastern New Mexico. • Partnering with producers to provide midstream services for their development projects in high- growth, unconventional resource plays. We seek to promote commercial relationships with established and well-capitalized producers that are willing to serve as key customers and commit to long-term MVCs and/or AMIs. We will continue to pursue partnership opportunities with established producers to develop new midstream energy infrastructure in unconventional resource basins that we believe will complement our existing assets and/or enhance our overall business by facilitating our entry into new basins. These opportunities generally consist of a strategic acreage position in an unconventional resource play that is well-positioned for accelerated production but has limited existing midstream energy infrastructure to support such growth. Competitive Strengths We believe that we will be able to execute the components of our principal business strategy successfully because of the following competitive strengths: • Strategically located assets in core areas of prolific unconventional resource basins supported by partnerships with large producers. We believe our assets are strategically positioned within the core areas of six established unconventional resource basins including Summit Permian currently under development. The geologic formations in the basins served by our assets have either relatively low drilling 10