UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549

SCHEDULE 14A

Proxy Statement Pursuant to Section 14(a) of
the Securities Exchange Act of 1934

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☒Definitive Proxy Statement

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☐Soliciting Material under §240.14a-12

Summit Midstream Partners, LP

(Name of Registrant as Specified In Its Charter)

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

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☐Fee computed on table in exhibit required by Item 25(b) per Exchange Act Rules 14a-6(i)(1) and 0-11.

April 9, 2024

Dear Fellow Summit Investors,

As we invite you to attend our virtual 2024 Annual Meeting, we thank you for your investment in Summit Midstream Partners and are pleased to provide you with a brief update on the Partnership.

Summit delivered solid financial and operating results in 2023, increasing adjusted EBITDA in 2023 compared to 2022, while also decreasing our total leverage ratio from 5.5x at year-end 2022 to 5.4x by December 31, 2023. During the year, we achieved several critical milestones:

•Integration of 2022 DJ Acquisitions. In 2023, we were focused on integrating and optimizing the acquired Outrigger DJ and Sterling DJ businesses (the “2022 DJ Acquisitions”). We completed multiple de-bottlenecking projects which we expect to drive meaningful operational and financial synergies in 2024 and beyond.

•Refinancing of 2025 Unsecured Notes. In November 2023, we issued a total of $209.5 million aggregate principal amount of unsecured notes (the “2026 Unsecured Notes”) in exchange for $180.0 million aggregate principal amount of existing senior unsecured notes due 2025 (the “2025 Unsecured Notes”) and $29.5 million in cash. The new cash investment was used to repurchase existing 2025 Unsecured Notes, leaving approximately $49.9 million of 2025 Unsecured Notes outstanding (collectively, the “Transactions”). The Transactions eliminate any material maturities until May 2026 and provide additional runway to continue to de-lever, optimize the base business and continue to pursue value-enhancing and leverage-accretive opportunities.

•Business Development Enhancing Customer Base and Contract Life. We executed multiple contract extensions and new contracts in 2023, including a 15-year contract extension dedicating more than 30,000 leased acres with a key customer in the Williston, a new 10-year take-or-pay contract behind our Double E Joint Venture, connecting a new 300 MMcf/d processing plant, and a new 15-year contract with over 25,500 dedicated acres in the condensate window behind our Ohio Gathering Joint Venture. We also commissioned the Buckeye Compression Project behind the Utica gathering system, resulting in an incremental compression fee.

•Strategic Alternatives Review. In October 2023, we announced that our board of directors (“Board”) launched a strategic alternatives review in which the Board considered a wide range of opportunities to maximize value for SMLP unitholders. The Board concluded the comprehensive review on March 22, 2024 and we announced on the same day:

•the sale of our Utica position for $625.0 million, subject to customary post-closing adjustments; and

•the Board’s belief that converting the Partnership to a C-Corp would best position us to maximize value by enhancing trading liquidity, greatly expanding the universe of potential investors and creating long-term tax advantages to our unitholders. The Board and management intend to seek approval from Summit unitholders to convert at a special meeting of the unitholders later this year.

At this year’s meeting, you will be asked to (1) elect two Class III directors to the Board, (2) ratify the appointment of Deloitte & Touche LLP as our independent registered public accounting firm for 2024, and (3) approve an advisory resolution on our executive compensation. The Board unanimously recommends that you vote for each of the two nominees for director and approve each of the other proposals. Please read our proxy statement for further details about the proposals.

On or about April 9, 2024, we are sending limited partners who are holders of record at the close of business on March 18, 2024 a set of our proxy materials, including our proxy statement and our Annual Report on Form 10-K for the year ended December 31, 2023. On this date, you will have the ability to access all of our proxy materials over the Internet at www.astproxyportal.com/ast/23805.

Your vote is important to us and our business. Except for the proposal on the ratification of the appointment of Deloitte & Touche LLP as our independent registered public accounting firm for 2024, your broker cannot vote your common units on your behalf until it receives your voting instructions. Whether or not you plan to attend the 2024 Annual Meeting, please submit your proxy with voting instructions as soon as possible. You may submit your proxy over the Internet or by mail. To vote your common units electronically during the virtual 2024 Annual Meeting, you will need your control number found on your proxy card or voting instruction form.

We appreciate your investment in the Partnership and look forward to your participation at the 2024 Annual Meeting in May.

Sincerely,

J. Heath Deneke
Chairman of the Board, President
and Chief Executive Officer of
Summit Midstream GP, LLC

NOTICE OF 2024 ANNUAL MEETING OF LIMITED PARTNERS

By order of the Board of Directors,

James D. Johnston
Executive Vice President, General Counsel,
Chief Compliance Officer and Secretary of
Summit Midstream GP, LLC

Summit Midstream Partners, LP
910 Louisiana Street, Suite 4200
Houston, Texas 77002

April 9, 2024

Important Notice Regarding the Availability of Proxy Materials for the
Annual Meeting of Limited Partners to be Held on May 9, 2024:

Our proxy statement and our Annual Report on Form 10-K for the year ended
December 31, 2023 are available at www.astproxyportal.com/ast/23805.

TABLE OF CONTENTS

SUMMIT MIDSTREAM PARTNERS, LP
910 Louisiana Street, Suite 4200
Houston, Texas 77002

PROXY STATEMENT
2024 ANNUAL MEETING OF LIMITED PARTNERS
May 9, 2024

INFORMATION ABOUT SUMMIT MIDSTREAM PARTNERS, LP

About SMLP

Summit Midstream Partners, LP, a Delaware limited partnership (including its subsidiaries, collectively, “we,” “our,” “us,” “SMLP,” or “the Partnership”), is a value-driven limited partnership focused on developing, owning and operating midstream energy infrastructure assets that are strategically located in unconventional resource basins, primarily shale formations, in the continental United States. Our common units representing limited partner interests in the Partnership (the “common units”) are listed and traded on the New York Stock Exchange (the “NYSE”) under the ticker symbol “SMLP.”

The Partnership was formed in May 2012. The Partnership’s executive offices are located at 910 Louisiana Street, Suite 4200, Houston, Texas 77002, and can be reached by phone at (832) 413-4770. The Partnership also maintains regional field offices in close proximity to our areas of operation to support the operation and development of our midstream assets.

Our Business Strategies

We operate a differentiated midstream platform that is built for long-term, sustainable value creation. Our integrated assets are strategically located in production basins including the Williston, DJ, Marcellus, Barnett, Piceance and Permian. Our primary business objective is to maximize cash flow and provide cash flow stability for our stakeholders while growing prudently and profitably. We intend to accomplish this objective by executing the following strategies:

•Continuing to prioritize safe and reliable operations. We believe that providing safe, reliable and efficient operations is a key component of our business strategy. We place a strong emphasis on employee training, operational procedures and enterprise technology, and we intend to continue promoting a high standard with respect to the efficiency of our operations and the safety of all of our constituents.

•Capital structure optimization. We seek to maximize unitholder value. Our capital structure currently consists of common equity, preferred equity, and indebtedness that is comprised of debt securities and borrowings under our revolving credit facilities, a portion of which is secured by substantially all of the Partnership’s assets. We intend to optimize our capital structure in the future by reducing our indebtedness with free cash flow, and when appropriate, we may pursue opportunistic capital markets transactions or asset divestitures with the objective of increasing long-term unitholder value.

•Portfolio management. We seek to maximize unitholder value by strategically managing our portfolio of midstream assets and allocating capital based on appropriate risk-informed cash flow assumptions. This may include opportunistic divestitures and acquisitions, re-allocation of capital to new or existing areas, and development of joint ventures involving our existing midstream assets or new investment opportunities.

•Maintaining our focus on fee-based revenue with minimal direct commodity price exposure. We intend to maintain our focus on providing midstream services under primarily long-term and fee-based contracts. We believe that our focus on fee-based revenues with minimal direct commodity price exposure is essential to maintaining stable cash flows.

•Maintaining strong producer relationships to maximize utilization of all of our midstream assets. We have cultivated strong producer relationships by focusing on customer service and reliable project execution and by operating our assets safely and reliably over time. We believe that our strong producer relationships will create future opportunities to expand our midstream services reach and optimize the utilization of our midstream assets for our customers.

QUESTIONS AND ANSWERS ABOUT THE 2024 ANNUAL MEETING

Q1:Why am I receiving these materials?

A:On or about April 9, 2024, we are sending Unitholders (as defined herein) a set of our proxy materials, including our proxy statement and our Annual Report on Form 10-K for the year ended December 31, 2023. On this date, you will have the ability to access all of our proxy materials over the Internet at www.astproxyportal.com/ast/23805.

We are providing these materials in connection with the solicitation by the Board of proxies to be voted at our 2024 Annual Meeting of Limited Partners (the “2024 Annual Meeting”) and any adjournments thereof. We will hold the 2024 Annual Meeting on May 9, 2024 at 2:00 p.m. Central Time via live webcast at https://web.lumiagm.com/217371229 (password: summit2024).

Q2:Who is soliciting my proxy?

A:The Board is sending you these materials in connection with its solicitation of proxies for use at the 2024 Annual Meeting. Certain of our directors, officers and employees and Morrow Sodali LLC (our proxy solicitor) may also solicit proxies on our behalf by mail, phone, fax or other electronic means, or in person.

Q3:Who is entitled to attend and vote at the 2024 Annual Meeting?

A:Limited partners of the Partnership who are holders of record of our outstanding common units (the “Voting Units”) at the close of business on March 18, 2024 (the “Unitholders”) are entitled to attend and vote on the matters presented at the 2024 Annual Meeting. The Unitholders will vote together as a single class and are entitled to one vote for each common unit held on the March 18, 2024 record date. On March 18, 2024, 10,422,175 common units were outstanding.

Q4:Which common units are considered “outstanding”?

A:“Outstanding” means, with respect to common units, all common units that are issued by the Partnership and reflected as outstanding on the Partnership’s books and records as of the date of determination; provided, however, that if any person or group, other than the General Partner and its affiliates, acquires beneficial ownership of 20% or more of the outstanding common units, the common units owned by such person or group will cease to be considered outstanding and will therefore lose all their voting rights with respect to the 2024 Annual Meeting. This loss of voting rights does not apply to persons who acquired such common units from affiliates of the Partnership, their transferees and persons who acquired such common units with the prior approval of the Board.

In addition, any common units held by the Partnership or a subsidiary of the Partnership are not considered outstanding with respect to voting under the Partnership Agreement. However, should such securities be transferred to an entity that is not a subsidiary of the Partnership, such common units would then be considered outstanding with respect to voting.

Q5:How do I participate in the virtual 2024 Annual Meeting?

A:The 2024 Annual Meeting will be held via live webcast. You will be able to attend the 2024 Annual Meeting, vote your common units and submit your questions during the meeting by visiting https://web.lumiagm.com/217371229 and entering the password (summit2024) and your control number found on your proxy card or voting instruction form.

Questions may be submitted during the 2024 Annual Meeting through https://web.lumiagm.com/217371229. Your questions must be confined to matters properly before the 2024 Annual Meeting and of general concern regarding the Partnership. If there are questions pertinent to matters properly before the 2024 Annual Meeting that cannot be answered during the meeting due to time constraints, we will post answers to a representative set of such questions at the “Investors” section at www.summitmidstream.com. The questions and answers will be available as soon as practicable after the meeting and will remain available until we file our 2025 Proxy Statement.

The 2024 Annual Meeting will begin at 2:00 p.m. Central Time. We encourage you to access the 2024 Annual Meeting before it begins. Online check-in will start approximately 60 minutes before the start of the meeting on May 9, 2024. If you have difficulty accessing or participating in the Annual Meeting, please visit https://www.lumiglobal.com/faq for help and support.

Other interested parties may listen to the 2024 Annual Meeting by visiting https://web.lumiagm.com/217371229 and logging in as a guest. Guests will be able to hear the 2024 Annual Meeting but will not be able to vote or ask a question during the meeting.

Q6:What constitutes a quorum to conduct business at the 2024 Annual Meeting?

A:Holders representing a majority of our outstanding common units (including outstanding common units deemed owned by the General Partner), present in person (virtually) or by properly submitted proxy, will constitute a quorum.

Your common units will be counted as present at the 2024 Annual Meeting if:

• you are present in person (virtually) at the meeting; or

• you have submitted a proxy over the Internet or by mail.

Proxies received but marked as abstentions and broker non-votes (described below) will be counted as present for purposes of determining whether a quorum has been achieved.

Q7:If my common units are held in street name by my broker or other nominee, will my broker or other nominee vote my common units?

A:If you own common units through a broker or other nominee, then your common units are held in that broker’s or nominee’s name and you are considered the beneficial owner of common units held in street name.

If a broker does not receive specific voting instructions from the beneficial owner, NYSE rules govern whether or not the broker is permitted to vote on the beneficial owner’s behalf. The NYSE has designated certain categories of proposals as “routine,” and brokers are permitted to vote on routine matters at their discretion. However, brokers are prohibited from voting on any matter deemed non-routine, which results in a “broker non-vote” for such proposal. A broker non-vote is treated as “present” for purposes of determining the existence of a quorum. If a non-routine proposal requires approval by the vote of a majority of the Voting Units, voting as a single class, entitled to vote, a broker non-vote constitutes, in effect, a vote against such proposal. However, if a proposal requires approval by a plurality of the votes cast, a broker non-vote has no effect on the outcome.

The election of two Class III directors (Proposal No. 1) and the approval of the advisory resolution on executive compensation (Proposal No. 3) are considered non-routine under applicable NYSE rules. The ratification of the appointment of Deloitte & Touche LLP as our independent registered public accounting firm for 2024 (Proposal No. 2) is a matter considered routine under applicable NYSE rules.

Q8:How do I vote my common units?

A:You may submit your proxy over the Internet or by mail. If you submit your proxy over the Internet or by returning a signed proxy card by mail, your common units will be voted as you indicate. If you sign your proxy card without indicating your vote, your common units will be voted in accordance with the recommendations of the Board.

To vote your common units electronically during the virtual 2024 Annual Meeting, you will need your control number found on your proxy card or voting instruction form.

Q9:What vote is required for each proposal and what is the recommendation of the Board?

A:The table below summarizes the recommendation of the Board, the vote required and the effect of abstentions and broker non-votes with respect to each proposal at the 2024 Annual Meeting.

(1)As an advisory vote, the result of the vote on the advisory resolution on executive compensation is not binding on the Partnership, the Compensation Committee or the Board, whether or not the proposal is passed under the standards described above.

Q10:Can I change my vote after I have voted by proxy?

A:You may revoke a proxy at any time before voting is closed at the 2024 Annual Meeting by:

•submitting a written revocation to the Secretary of the General Partner at the address indicated on the cover page of this proxy statement (provided that revocation is received by the Secretary of the General Partner by 11:59 p.m. Eastern Time on May 8, 2024);

•submitting your valid, signed and later-dated proxy by mail (provided that later-dated proxy is received by 11:59 p.m. Eastern Time on May 8, 2024);

•submitting your valid proxy over the Internet by 11:59 p.m. Eastern Time on May 8, 2024; or

•voting during the 2024 Annual Meeting, as described in Q8 above.

If instructions to the contrary are not given, your common units will be voted as indicated on the proxy and your presence without voting during the 2024 Annual Meeting will not revoke your proxy.

Q11:What should I do if I receive more than one set of voting materials for the 2024 Annual Meeting?

A:You may receive more than one set of voting materials for the 2024 Annual Meeting, and the materials may include multiple proxy cards or voting instruction cards. If you hold common units in more than one brokerage account, you will receive voting materials for each account; further, if you hold common units directly, but in more than one name (e.g., Jane Smith and Jane A. Smith), you will receive voting materials for each variant. Please complete and submit each proxy card and voting instruction card that you receive, according to its instructions.

Q12:Who is paying the expense of soliciting proxies?

A:We pay the cost of soliciting proxies and holding the 2024 Annual Meeting. Morrow Sodali LLC will assist us in the distribution of proxy materials and the solicitation of votes for a fee of $12,500, as well as the reimbursement of out-of-pocket expenses. In addition to distributing the proxy materials, proxies may also be solicited by personal interview, phone and similar means by our, and our affiliates’, directors, officers or employees, who will not receive additional compensation for performing that service. We also will make arrangements with brokers, banks and other nominees for forwarding proxy materials to the beneficial owners of our common units, and we will reimburse them for any reasonable expenses that they incur.

Q13:Who do I contact if I have further questions about voting or the 2024 Annual Meeting?

A:You may contact our Investor Relations department at IR@summitmidstream.com or Morrow Sodali LLC at (800) 662-5200 (toll-free in North America) or +1 (203) 658-9400 (outside of North America) or by email at SMLP@info.morrowsodali.com.

CORPORATE GOVERNANCE

Board Leadership and Governance

The Partnership is managed by the directors and executive officers of Summit Midstream GP, LLC (the “General Partner”), a wholly owned subsidiary of the Partnership. The directors and officers of the General Partner perform all of our management functions, and we do not have directors or officers. However, for simplicity’s sake, in this proxy statement, we refer to the directors of the General Partner as our directors or our Board, and we refer to the officers of the General Partner as our officers.

Directors are appointed for a term of three years and hold office until their successors have been elected or qualified or until the earlier of their death, resignation, removal or disqualification. Officers serve at the discretion of the Board.

The Board is divided into three classes of directors. Two Class I directors were elected at our annual meeting of limited partners held in 2022 (the “2022 Annual Meeting”) to serve for a term that expires at our annual meeting of limited partners to be held in 2025 (the “2025 Annual Meeting”), three Class II directors were elected at our annual meeting of limited partners held in 2023 (the “2023 Annual Meeting”) to serve for a term that expires at our annual meeting of limited partners to be held in 2026 (the “2026 Annual Meeting”), and two Class III directors are serving a term that expires at the 2024 Annual Meeting. On February 23, 2023, the Partnership amended its Partnership Agreement to subject the President or Chief Executive Officer, in his capacity as a director, to public election by the limited partners as a Class II director. J. Heath Deneke, President and Chief Executive Officer (the “Chief Executive Officer” or “CEO”) of the General Partner, was appointed by the Board to serve as Chairman.

The Board is led by the Chairman of the Board. The Board does not have a policy regarding whether the roles of the Chief Executive Officer and the Chairman of the Board should be separate. The Board believes that this issue is properly addressed as part of the succession planning process and that it is in the best interests of the Partnership for the Board to make a determination on the matter when it elects a new Chief Executive Officer or at other times consideration is warranted by circumstances. Our Corporate Governance Guidelines provide for the selection of an independent director to serve as “Lead Director” if the positions of Chief Executive Officer and Chairman of the Board are combined. Effective January 1, 2022, the Board appointed Mr. James J. Cleary as the Lead Director to preside over any executive sessions at which the Chairman of the Board is not present and to serve as a liaison between the Board and stakeholders on investor matters.

The Board conducts its business through meetings of the Board and its committees. The Board has an Audit Committee, a Compensation Committee and a Nominating, Governance and Sustainability Committee, and may have such other committees as the Board shall determine from time to time.

The table below shows the current membership and chair of the Board and each standing committee of the Board, the director selected to serve as Lead Director of the Board, the class to which each director belongs, the independence determinations made by the Board with respect to each director and the number of Board and committee meetings held during 2023. Each member of the Board attended all of the quarterly meetings of the Board and his or her Board committees held during the period in which he or she was a member during 2023. No member of the Board attended fewer than 75% of the aggregate of the total number of meetings of the Board and the total number of meetings of the Board committees held during the period in which he or she was a member during 2023. All of the Board members are invited to attend the 2024 Annual Meeting.

Director Independence

The Board includes one member of management, Mr. Deneke, President and Chief Executive Officer of the General Partner, and six non-management directors. As a limited partnership, SMLP is not required by the NYSE to have a majority of independent directors. However, the Partnership Agreement and the Corporate Governance Guidelines require that each Board member, other than the President or Chief Executive Officer of the General Partner, if such officer is a director, meet the independence standards required of directors who

serve on an audit committee of a board of directors established by the Securities Exchange Act of 1934, as amended (the “Exchange Act”), and the rules and regulations of the SEC thereunder and by the NYSE. Under rules adopted by the NYSE, no Board member qualifies as independent unless the Board affirmatively determines that the director has no material relationship with us. In evaluating each director’s independence, the Board considers all relevant facts and circumstances in making a determination of independence. In particular, when assessing the materiality of a director’s relationship with us, the Board considers the issue not merely from the standpoint of the director, but also from the standpoint of persons or organizations with which the director has an affiliation. In addition, the NYSE listing standards contain a list of several specific relationships that preclude independence. Furthermore, pursuant to the SEC independence standards for directors who serve on an audit committee of a board of directors, Board members may not (i) accept directly or indirectly any consulting, advisory or other compensatory fee from the Partnership or any subsidiary, other than payments for Board service and the receipt of fixed amounts of compensation, including deferred compensation, under a retirement plan for prior service with the Partnership, provided that such compensation is not contingent in any way on continued service; or (ii) be an “affiliated” person (as defined in Exchange Act Rule 10A-3) of the Partnership or any subsidiary.

As illustrated in the table above, the Board has determined that all of its six current non-management directors meet these applicable independence standards.

The Board has also determined that each of the current members of the Audit, Compensation and Nominating, Governance and Sustainability Committees are independent under the applicable NYSE listing standards and rules of the Securities and Exchange Commission (the “SEC”) and the Corporate Governance Guidelines. For further information about the committees, see “—Committees of the Board.”

Committees of the Board

Audit Committee

Mr. Jacobe, Mr. McNally and Mr. Peters serve as the members of the Audit Committee, with Mr. Peters serving as the chair of the committee. Mr. Peters qualifies as an audit committee financial expert within the meaning of the regulations of the SEC. All members of the Audit Committee are financially literate, in accordance with NYSE rules.

The Audit Committee assists the Board in its oversight of the integrity of the Partnership’s financial statements and its compliance with legal and regulatory requirements and corporate policies and controls. The Audit Committee has the sole authority to retain and terminate the Partnership’s independent registered public accounting firm, approve all auditing services and related fees and the terms thereof and pre-approve any non-audit services to be rendered by the Partnership’s independent registered public accounting firm. The Audit Committee is also responsible for confirming the independence and objectivity of the Partnership’s independent registered public accounting firm. The Audit Committee also discusses the Partnership’s major risk exposures with management, including those related to financial reporting and disclosure and cybersecurity, along with steps taken by management to monitor and control such exposures. The Partnership’s independent registered public accounting firm has unrestricted access to the Audit Committee.

The Audit Committee has adopted an Audit Committee charter, which is publicly available on the Partnership’s website under the “Corporate Governance” subsection of the “Investors” section at www.summitmidstream.com.

Compensation Committee

Mr. Cleary, Mr. Jacobe and Ms. Woung-Chapman serve as the members of the Compensation Committee, with Mr. Jacobe serving as the chair of the committee. The Compensation Committee provides oversight, administers and makes decisions regarding the Partnership’s executive compensation policies and incentive plans. The Compensation Committee also makes recommendations to the Board regarding the compensation of the Partnership’s outside directors. The Compensation Committee may form and delegate authority to subcommittees. The Compensation Committee has adopted a Compensation Committee charter, which is publicly available on the Partnership’s website under the “Corporate Governance” subsection of the “Investors” section at www.summitmidstream.com.

Nominating, Governance and Sustainability Committee

Mr. Cleary, Mr. Oates, Mr. Peters and Ms. Woung-Chapman serve as the members of the Nominating, Governance and Sustainability Committee, with Ms. Woung-Chapman serving as the chair of the committee. The Nominating, Governance and Sustainability Committee identifies individuals qualified to become Board members consistent with criteria approved by the Board, assists the Board in selection of director nominees, oversees corporate governance principles, oversees the Partnership’s environmental, social and governance (“ESG”) matters and oversees the evaluation of the Board and management.

The Nominating, Governance and Sustainability Committee has adopted a Nominating, Governance and Sustainability Committee charter, which is publicly available on the Partnership’s website under the “Corporate Governance” subsection of the “Investors” section at www.summitmidstream.com.

Compensation Committee Interlocks and Insider Participation

The Compensation Committee consists of Mr. Cleary, Mr. Jacobe and Ms. Woung-Chapman. During 2023, no member of the Compensation Committee was an executive officer of another entity on whose compensation committee or board of directors any executive officer of the Partnership served.

Furthermore, except for compensation arrangements disclosed in this proxy statement, we have not participated in any contracts, loans, fees or awards, and do not have any financial interests, direct or indirect, with any Compensation Committee member. In addition, none of our management or Board members are aware of any means, directly or indirectly, by which a Compensation Committee member could receive a material benefit from SMLP.

The Chief Executive Officer participated in his capacity as a director in the deliberations of the Board concerning named executive officer compensation and made recommendations to the Compensation Committee regarding named executive officer compensation but abstained from any decisions regarding his compensation.

Risk Oversight

The Board as a whole typically discusses and addresses our key strategic risks at its meetings over the course of each year, both as they relate to particular projects or other topics being considered by the Board and in their own right as a separate agenda topic. The Board’s discussions specifically include strategic planning, identifying and addressing our strategic risks and potential opportunities, and evaluating matters such as ESG reporting and sustainability. The Board also receives detailed reports from management regarding a variety of matters, including operational, health, safety and environmental, financial, legal, governance and cybersecurity matters, as applicable.

Each committee of the Board also reports to the Board on a regular basis, including as appropriate with respect to each committee’s risk oversight activities. For example, as applicable, the Board and the Audit Committee discuss the guidelines and policies that govern the process by which risk assessment and management is undertaken and evaluate reports from various functions with the management team on risk assessment and management. The Audit Committee assists the Board in oversight of the integrity of SMLP’s financial statements and compliance with legal and regulatory requirements. The Audit Committee also reviews and assesses the performance of SMLP’s internal audit function and its independent registered public accounting firm. The Compensation Committee manages risk as it relates to our compensation plans, programs, and structure and also oversees executive succession planning. The Nominating, Governance and Sustainability Committee oversees risks related to corporate governance, such as director independence, the effectiveness of the Board and committees and director nominations and oversees SMLP’s ESG matters and the sustainability report to be published by SMLP. We believe that the Board’s role in risk oversight is consistent with our leadership structure, with the Chief Executive Officer and other members of management having responsibility for assessing and managing our risk exposure and the Board and its committees providing oversight in connection with those efforts.

Governance Documents

Code of Business Conduct and Ethics

The Board has adopted a Code of Business Conduct and Ethics that sets forth the Partnership’s policy with respect to business ethics and conflicts of interest. The Code of Business Conduct and Ethics is intended to ensure that the employees, officers and directors of the Partnership and its General Partner conduct business with the highest standards of integrity and in compliance with all applicable laws and regulations. It applies to the employees, officers and directors of the Partnership and its General Partner, including the principal executive officer, principal financial officer and principal accounting officer or controller, or persons performing similar functions (the “Senior Financial Officers”). The Code of Business Conduct and Ethics also incorporates expectations of the Senior Financial Officers that enable the Partnership to provide accurate and timely disclosure in its filings with the SEC and other public communications. We will post information regarding any amendments to, or waivers of, the provisions of the Code of Business Conduct and Ethics applicable to the Senior Financial Officers at the website location referred to under “—Website Availability of Documents.”

Corporate Governance Guidelines

The Partnership’s Corporate Governance Guidelines provide guidelines for the governance of the Partnership. These guidelines establish, among other things, the requirements for the composition of the Board and the committees of the Board, the responsibilities of Board members and the requirements for meetings of the Board. The Corporate Governance Guidelines specifically provide, among other things, that (i) the independent members of the Board will select an independent director to serve as Lead Director to preside over any executive sessions at which the Chairman of the Board is not present, and (ii) interested parties may communicate directly with the General Partner’s independent Board members as set forth under “—Communications with the Board.”

Prohibition on Insider Trading and Avoidance of Speculative Trading in SMLP Units

We have established policies prohibiting our officers, directors and employees from purchasing or selling our securities while in possession of material, nonpublic information or otherwise using such information for their personal benefit or in any manner that would violate applicable laws and regulations. All transactions in our securities by our directors, officers and certain employees must be precleared by the Chief Compliance Officer. Additionally, our directors, officers and certain employees are prohibited from trading in our securities for the period beginning one week before the end of any fiscal quarter of SMLP and ending two days after the public release of earnings data for such fiscal quarter. Our policies also call for our directors, officers and certain employees to avoid participating in transactions involving trading activities that, by their aggressive or speculative nature, may give rise to an appearance of impropriety. In addition, to the extent any directors, officers or certain other employees wish to sell our securities, we permit our directors, officers and certain employees to enter into pre-arranged trading plans that comply with Rule 10b5-1 under the Exchange Act, which, in addition to any requirements of applicable law, must be approved by the Chief Compliance Officer or his designee.

Website Availability of Documents

The following documents are publicly available on the Partnership’s website under the “Corporate Governance” subsection of the “Investors” section at www.summitmidstream.com:

•Audit Committee Charter

•Compensation Committee Charter

•Nominating, Governance and Sustainability Committee Charter

•Code of Business Conduct and Ethics

•Corporate Governance Guidelines

•Insider Trading Policy

•Whistleblower Policy

A printed copy of any of these documents is also available free of charge on written request to the Secretary of the General Partner at 910 Louisiana Street, Suite 4200, Houston, Texas 77002.

Additionally, on July 1, 2023, we published our annual ESG Report, showcasing our commitment to core principles that drive operational excellence, sustainability and value for our business. These principles include prioritizing safe and reliable operations, minimizing our environmental impact, protecting our employees’ health and wellbeing, and following responsible and ethical business practices. Our ESG Report is available on our website and can be found at www.summitmidstream.com/esg.

Our website and the ESG Report are not part of this proxy statement and are not incorporated by reference into this proxy statement. Our ESG goals are aspirational and may change. Statements regarding our goals are not guarantees or promises that our goals will be achieved.

Director Candidates

In selecting members of the Board, the Nominating, Governance and Sustainability Committee’s recommendation and the Board’s decisions take into account, in addition to the independence criteria:

•Personal and professional qualities, characteristics, attributes, accomplishments and reputation in the business community;

•Current knowledge and contacts in the communities in which the Partnership does business and in the Partnership’s industry or other industries relevant to the Partnership’s business;

•Ability and willingness to commit adequate time to Board and committee matters, including service on boards of other publicly-traded companies;

•The fit of the individual’s skills and personality, including with those of other Board members and potential Board members, to build a Board that is effective, collegial and responsive to the needs of the Partnership;

•Diversity of viewpoints, background, experience and other demographics as compared to those of other Board members and potential Board members; and

•Other relevant factors as the Board deems appropriate, including the current composition of the Board, the need for Audit Committee expertise and the Board’s evaluation of other director candidates.

The Nominating, Governance and Sustainability Committee has the sole authority to retain and terminate any director search firm to be used to identify director candidates.

Communications with the Board

Interested parties may communicate directly with the General Partner’s independent Board members by submitting a communication in an envelope marked “Confidential” addressed to the “Independent Members of the Board” in care of the Secretary of the General Partner at 910 Louisiana Street, Suite 4200, Houston, Texas 77002. Additional requirements for certain types of communications are set forth under “Additional Information—Advance Notice Required for Limited Partner Proposals and Nominations.”

PROPOSAL NO. 1
ELECTION OF DIRECTORS

(Item 1 on the Proxy Card)

The Board is divided into three classes of directors for purposes of election. Two Class III directors will be elected at the 2024 Annual Meeting to serve a three-year term that will expire at our annual meeting of limited partners to be held in 2027.

As described above under “Questions and Answers about the 2024 Annual Meeting,” the Partnership Agreement provides that the nominees for Class III director will be elected by a plurality of the votes cast by our Unitholders. Abstentions and broker non-votes will have no effect on the vote with respect to this proposal.

If any nominee is unavailable as a candidate at the time of the 2024 Annual Meeting, either the number of directors constituting the full Board will be reduced to eliminate any vacancy or the persons named as proxies will use their best judgment in voting for any available nominee. The Board has no reason to believe that the current nominees will be unable to serve.

Mr. Cleary and Mr. Oates are the nominees for election as Class III directors at the 2024 Annual Meeting. There is no family relationship among any of our executive officers or directors, and there is no arrangement or understanding between any director or other person pursuant to which the director was or is to be selected as a director or nominee.

Key Skills, Experience and Competencies of the Board

The Board collectively represents the following key skills, experience and competencies:

Information Concerning Nominees for Election as Class III Directors

The following sets forth information as of March 18, 2024 concerning the nominees for election as Class III directors at the 2024 Annual Meeting.

Information Concerning Other Directors

The following sets forth information as of March 18, 2024 concerning the Class I and Class II directors whose present terms of office will expire at the 2025 Annual Meeting and the 2026 Annual Meeting, respectively.

For detailed information regarding our directors’ respective holdings of our units, compensation and other arrangements, see “Security Ownership—Security Ownership of Certain Beneficial Owners and Management,” “Director Compensation” and “Certain Relationships and Related Party Transactions.”

EXECUTIVE OFFICERS

The officers of the General Partner perform all of our management functions, and we do not have officers.

The table below shows certain information for the executive officers of the General Partner as of March 18, 2024.

J. Heath Deneke has been President and Chief Executive Officer and a director of the General Partner since September 2019 and currently serves as Chairman of the Board. Mr. Deneke’s biography and experience are included under “—Information Concerning Other Directors” above.

William J. Mault has been the Executive Vice President and Chief Financial Officer of the General Partner since February 2022. Mr. Mault has been with the General Partner since 2016 and has held various senior management roles at the General Partner, including Vice President of Corporate Development, Finance and Treasurer. Prior to joining the General Partner, Mr. Mault spent nearly 10 years in mergers and acquisitions and investment research capacities, most recently at SunTrust Robinson Humphrey (now Truist Securities). Mr. Mault has over 10 years of oil and gas industry experience, is a Chartered Financial Analyst® charterholder and holds a Bachelor of Business Administration, majoring in Banking, Finance and Economics, from Northwood University.

James D. Johnston has been the Executive Vice President, General Counsel and Chief Compliance Officer of the General Partner since September 2020 and the Secretary of the General Partner since March 2021. Prior to joining the General Partner, Mr. Johnston worked in the corporate legal department for Crestwood Equity Partners as Senior Vice President and General Counsel, after serving as Vice President, Deputy General Counsel at Crestwood. Prior to joining Crestwood in 2013, Mr. Johnston served as Assistant General Counsel for Kinder Morgan and in various legal and commercial roles of increasing responsibility at Kinder Morgan, El Paso Corporation and Sonat, Inc. from 1997 to 2013. Mr. Johnston holds a bachelor’s degree from Western University in Ontario, Canada and a Doctor of Jurisprudence from Samford University’s Cumberland School of Law in Birmingham, Alabama.

Matthew B. Sicinski has been the Senior Vice President and Chief Accounting Officer of the General Partner since February 2022. Mr. Sicinski joined the General Partner in February 2020 as Vice President and Chief Accounting Officer. Prior to joining the General Partner, Mr. Sicinski was the Vice President and Controller at Venari Resources and he spent over eight years at Southwestern Energy in multiple accounting, finance and commercial development roles. Additionally, Mr. Sicinski worked in the Houston offices of Arthur Andersen and Ernst & Young, most recently as a manager. Mr. Sicinski has over 20 years of oil and gas industry experience, is a Certified Public Accountant and received Bachelor of Business Administration and Master of Business Administration degrees in Accounting from Angelo State University. Mr. Sicinski is also a Lieutenant Commander in the United States Navy Reserve and a veteran of the Afghanistan War.

COMPENSATION DISCUSSION AND ANALYSIS

This Compensation Discussion and Analysis (“CD&A”) provides information regarding the compensation of certain of our executive officers in 2023, as reported in the Summary Compensation Table and other tables in this proxy statement.

In this CD&A, we review the compensation decisions, and rationale for those decisions, relating to our principal executive officer and the two next most highly compensated executive officers, who are referred to as the “Named Executive Officers” or “NEOs.”

The following describes the material elements of the Partnership’s executive compensation program for the NEOs for fiscal year 2023.

The NEOs are employees of Summit Operating Services Company, LLC (“Summit Operating”), a wholly owned subsidiary of the Partnership, and executive officers of the General Partner. As a result of the Partnership’s acquisition in 2020 of Summit Midstream Partners, LLC, the privately-held parent company of the General Partner, the Partnership pays for 100% of the NEOs’ compensation.

The Compensation Committee provides oversight, administers and makes decisions regarding the Partnership’s compensation policies and plans.

Compensation Philosophy and Objectives

Our compensation program is based on the philosophy that our executive management team should be aligned with our unitholders, and that our executives should be incentivized and rewarded for performance that advances business goals and the creation of sustainable value in all business cycles, leading to unitholder value creation. Our overall compensation program is designed to achieve the following objectives:

•Attract and retain outstanding talent;

•Drive achievement of short-term and long-term goals;

•Reward successful execution of objectives;

•Reinforce our culture and leadership competencies;

•Advance our business strategy and create long-term value;

•Align our executives’ interests with the interests of our unitholders; and

•Discourage undue risk-taking.

We incorporate a pay-for-performance philosophy when designing executive compensation opportunities. Thus, a portion of an executive’s target compensation is performance-based through linkage to the achievement of safety, financial and other measures deemed to be drivers in the creation and preservation of unitholder value. While the allocation among the elements of total direct compensation may vary, a portion of the compensation opportunity available to each of our NEOs is, by design, tied to the Partnership’s annual and long-term performance.

The following table highlights some of the key features of our executive compensation program:

2023 Business Highlights

Our business is focused on developing, owning and operating midstream energy infrastructure assets that are strategically located in unconventional resource basins in the United States. We offer natural gas, crude oil and produced water gathering systems that generate revenue under primarily long-term and fee-based gathering agreements with our customers.

Demand for our services is influenced by the condition of the oil and gas industry and demand for fossil fuels. We operate in a market influenced by cyclicality in producer development plans, volatility in commodity prices, and a long-term trend toward sustainable forms of energy and policies that discourage longer-term investment in the fossil fuel industry.

In 2023, we completed integration of the 2022 DJ Acquisitions and opportunistically reduced the outstanding amount of our unsecured notes maturing in 2025. We intend to optimize our capital structure in the future by reducing our indebtedness with free cash flow, and when appropriate, we may continue to pursue opportunistic transactions, including acquisitions, divestitures, re-allocation of capital to new or existing areas, and development of joint ventures involving our existing midstream assets or new investment opportunities.

2023 Executive Compensation Highlights

The discussion set forth below in this CD&A describes the approach to executive compensation, and elaborates upon the various actions taken and adjustments made, with respect to our executive compensation program in 2023, the highlights of which include the following:

•Continued offering of salaries and other executive compensation at competitive levels as needed to attract and retain talent;

•At-risk compensation constituting a significant portion of overall executive compensation;

•Engagement of an independent compensation consultant to review and benchmark our executive compensation;

•Elimination of single-trigger vesting of long-term equity awards in connection with a change in control for long-term equity awards granted in 2023; and

•Introduction of performance-based vesting requirements for a significant portion of new long-term equity awards.

We believe that our 2023 executive compensation:

•Appropriately reflects SMLP’s financial performance for the year, as well as for longer-term value creation;

•Strives to create alignment of our NEOs’ interests with those of our unitholders;

•Includes an appropriate overall mix of short- and long-term incentives, and service-based and performance-based vesting requirements, to enhance unitholder value and motivate sustainable performance and decision-making;

•Takes into consideration the efforts, performance and successes of our NEOs in pursuing our business objectives in challenging market conditions;

•Advances our core business strategy; and

•Helps attract, motivate and retain the key talent needed to ensure SMLP’s long-term success.

Our Compensation Setting Process

The Compensation Committee establishes the target total direct compensation of our executives and administers other benefit programs. To assist with its oversight responsibilities, the Compensation Committee engages an independent compensation consultant (the “Compensation Consultant”) who provides the Compensation Committee with data, analysis and advice on the structure and level of executive compensation. The Compensation Consultant participates in Compensation Committee meetings and executive sessions of the Compensation Committee meetings as requested. The Compensation Consultant may work with our management on various matters for which the Compensation Committee is responsible. We consider the Compensation Consultant to be independent of the Partnership according to current NYSE listing requirements and SEC guidance. Willis Towers Watson has served as the Compensation Consultant since September 2019.

The exact level of targeted compensation for each NEO varies based on the individual’s role at SMLP, the individual’s experience and the individual’s contribution to our success. Partnership management, in consultation with the Compensation Committee chair and the Compensation Consultant, prepares materials for the Compensation Committee relevant to matters under consideration by the Compensation Committee, including market data provided by the Compensation Consultant and recommendations of our CEO regarding compensation of the other executives. The Compensation Committee works with the Compensation Consultant to determine the compensation of our CEO.

Based on market data, which we use as a reference, we believe compensation for our NEOs is reasonably competitive with opportunities available to officers holding similar positions at comparable companies. We seek to set compensation levels for each element of total direct compensation based on our assessment of market practices at or near the median. The Compensation Committee adjusts target compensation for each NEO above or below the median, taking into consideration experience, performance, internal equity and other relevant circumstances.

Selection of Compensation Comparative Data

For benchmarking purposes, the Compensation Committee compares the total compensation for each NEO position to the compensation paid for similar positions by companies in our peer group. With input from the Compensation Committee and management, the Compensation Consultant evaluates companies to be included in the peer group and the methodology for selecting that peer group. As part of the process, the Compensation Consultant may consult with management to ensure that the most appropriate companies are selected, including from the perspective of similarity of business lines and competition for talent. The Compensation Committee then reviews and, as it may deem appropriate, approves the proposed peer group for the applicable compensation year.

In determining our peer group, we strive to define the market for our executive talent using a sizeable group of companies that are comparable to us in both line of business and size, as measured by revenues and other key financial characteristics. In addition, the Compensation Consultant provides data from industry-specific compensation surveys that provide an additional reference point and insight that helps support the compensation decision-making process. We believe that the compensation surveys and companies identified in our peer group constitute the best and most appropriate approach for benchmarking comparisons, which helps attract and retain highly qualified, experienced and technically proficient executives with well-developed management, operational and marketing skills needed to excel in our industry. The Compensation Committee will continue to review and monitor the peer group and its methodology on an annual basis and select peers based on appropriate screening criteria, metrics and competition for executive talent.

During the Compensation Committee’s annual review of executive compensation, the Compensation Consultant conducted a competitive assessment for similar types of positions comparable to SMLP’s direct peer companies and available survey data. For this assessment, information from peer company public filings was compiled, including public company proxy statements and annual reports on Form 10-K. The peer group used for 2023 executive compensation consisted of publicly traded midstream companies with whom we compete for executive talent.

The peer group comprised the following companies for 2023:

Each year, the Compensation Committee reviews the companies in the peer group with its Compensation Consultant, making changes when appropriate, including for mergers and acquisitions that affect the availability and relevance of compensation information.

The compensation analysis encompassed the primary elements of total direct compensation, including annual base salary, annual short-term incentive and long-term incentive awards for the NEOs of these peer group companies. The Compensation Committee considered the information provided to ascertain whether the compensation of our NEOs is aligned with its compensation philosophy and competitive with the compensation for executive officers of the peer group companies. The Compensation Committee reviewed the compensation analysis to confirm our compensation programs were supporting a competitive total compensation approach that emphasizes incentive-based compensation and appropriately rewards achievement of our objectives. The Compensation Committee will continue to review and monitor the peer group and our methodology on an annual basis and will select peers based on appropriate screening criteria, metrics and competition for executive talent.

Elements of Executive Compensation

The primary elements of compensation for the NEOs for 2023 are base salary, annual incentive compensation and long-term compensation awards (subject to both service-based and performance-based vesting requirements) granted under the Partnership’s Long-Term Incentive Plan, as in effect from time to time and as may be amended (for purposes of this CD&A, the “SMLP LTIP”). The NEOs also receive certain retirement, health and welfare and additional benefits.

Our executive compensation program consists of the following primary elements:

We use each element of compensation to satisfy one or more of our stated compensation objectives. Our goal is to achieve the appropriate balance between short-term cash incentives for achievement of annual financial performance goals and long-term incentives to promote achievement of sustained value over the longer term and for retention purposes.

We believe that incentive awards based on Partnership equity serve to align the economic interests of our executive officers with those of the Partnership’s public unitholders. This alignment was enhanced in 2023 with approval of the new SMLP LTIP prior to the 2023 award cycle and the unit pool thereunder, which allowed us to grant the 2023 LTIP awards to our NEOs solely as phantom unit awards, rather than as a combination of phantom unit awards and dollar-denominated awards as was necessary since 2020 in recognition of the limited number of units available at such times under the prior SMLP LTIP. We believe that our phantom unit awards provide proper incentives to avoid undue risk taking while increasing long-term unitholder value. We also believe that these awards are an important retention tool with respect to our NEOs.

For 2023, the target total direct compensation for the NEOs as set by the Compensation Committee is summarized below. Each element is further discussed in this CD&A.

(1)The amounts reported in this column reflect each NEO’s annualized base salary that went into effect as of February 23, 2023. Prior to such date, the NEO’s annualized base salaries were as follows: Mr. Deneke - $624,000; Mr. Mault - $300,000; and Mr. Johnston - $364,000.

Relative Size of Primary Elements of Compensation

We believe it is important for executive pay to be strongly linked to company performance. Our executive compensation program emphasizes the alignment of executive interests with those of unitholders to ensure accountability and sustained long-term company growth. Compensation for our NEOs is comprised of a fixed base salary plus a combination of annual cash and long-term equity incentives. The majority of our NEOs’ total direct compensation is variable, or at-risk, and dependent on the achievement of company performance goals and sustained tenure.

Our CEO’s compensation in 2023 was comprised of, at target, approximately 15% base salary, 23% annual incentive bonus (“annual bonus”) and 62% long-term incentive plan awards, amounting to approximately 85% at-risk compensation.

Our other NEOs’ compensation in 2023 was comprised of, at target, approximately 24% base salary, 24% annual bonus and 52% long-term incentive plan awards, amounting to approximately 76% at-risk compensation.

Base Salary

Base salary serves as the minimum, fixed level of cash compensation provided to NEOs and is designed to accurately reflect each NEO’s relative skills, experience and other contributions to the Partnership. The base salaries of our NEOs are reviewed annually by the Compensation Committee to determine the levels deemed necessary to attract and retain individuals with superior talent. That review is conducted in light of the Partnership’s performance, external market factors and any changes to other elements of compensation. We aim to pay base salaries for our executives near the median level compared to information provided by the Compensation Consultant, and to allow our executives to earn greater levels of short-term and long-term compensation only when our financial performance and unitholder returns warrant compensation at those higher levels.

The base salaries of our NEOs are set forth in the following table:

In 2023, the Compensation Committee determined to make adjustments to the NEOs’ base salaries, as shown above, beginning on February 23, 2023 based on market data provided by the Compensation Consultant and the competitive market for talent that continued to exist.

Annual Incentive Compensation

We provide an annual bonus to drive the achievement of key business results and to recognize the NEOs based on their contributions to those results. The annual bonus plan is a cash-based incentive plan. Incentive amounts are intended to provide total cash compensation near the market range for executive officers in comparable positions when target performance is achieved. Annual bonus compensation levels are set above or below the market range to reflect actual performance results as appropriate when performance is greater or less than expectations. Pursuant to their employment agreements in effect in 2023, each NEO was eligible to receive an annual bonus payout ranging from 0% to, for Mr. Deneke, 300% of annual base salary and, for Messrs. Mault and Johnston, 200% of base salary, in each case as may be adjusted at the discretion of the Compensation Committee based on attainment of annual performance targets.

In early 2023, the Compensation Committee established the 2023 annual bonus plan target opportunities as a percentage of base salary for our NEOs. The 2023 target for Mr. Deneke was 150% of his base salary. For Messrs. Mault and Johnston, it was 100% of their base salaries.

The Compensation Committee establishes performance measures annually that align with our business strategy, as reflected in a corporate scorecard applicable to the senior leadership team (the “SLT Scorecard”) and in individual performance goals for each NEO. The amount of each NEO’s actual bonus earned is equal to the product of their target annual bonus, multiplied by the level of achievement of the SLT Scorecard, multiplied by the level of achievement of their individual performance goals.

The SLT Scorecard reflects our key business priorities, including financial goals; health, safety, environmental and regulatory (“HSER”) goals; and certain strategic initiatives and other key objectives for a given year. In 2023, the SLT Scorecard contained four factors, which are considered by the Board and management as key indicators of the successful execution of our business plan. Those factors were (i) adjusted EBITDA, (ii) goals for overall business development activity, (iii) generation of excess cash flow and (iv) HSER metrics.

In February 2024, the Compensation Committee and the Board reviewed the SLT Scorecard for 2023 and determined the level of achievement of each key factor. We exceeded our threshold goals for adjusted EBITDA and our target goals for (ii) overall business development activity and (ii) HSER metrics. We did not achieve our threshold goals for the generation of excess cash flow. These results yielded a calculated SLT Scorecard result of 80% of target. The 2023 goals and results for the SLT Scorecard factors are set forth in the following table:

(1)Adjusted EBITDA is a non-GAAP financial measure and is a supplemental financial measure used by management in evaluating our financial performance. Please see “Non-GAAP Financial Measure—Adjusted EBITDA” included as Appendix A to this proxy statement for an explanation of how adjusted EBITDA is calculated and why we use adjusted EBITDA.

(2)Achievement of the overall business development goals is based on the Compensation Committee’s assessment of performance for 2023, for categories consisting of (i) continued development and optimization projects, (ii) securing additional contracts and plant connections for the Double E Pipeline, (iii) continuing to develop ESG and energy transition opportunities, and (iv) strategic transactions, including the pursuit of key strategic M&A initiatives.

(3)Calculation of excess cash flow is based on the sweep feature of the 2026 Secured Notes indenture. The excess cash flow achieved in 2023 equated to 0% of the target.

(4)Achievement of the HSER goals is based on the Compensation Committee’s assessment of performance for 2023, for categories consisting of (i) major incidents, (ii) total recordable incident rates, (iii) lost time incidents, (iv) spill intensity, (v) HSE training and (vi) reports resolved.

(5)The Compensation Committee approved an assessment of the Partnership’s overall performance at 80%.

Each NEO’s individual performance goals included their performance with respect to their applicable departmental functions, their contributions to the Partnership’s and their department’s performance, their individual leadership capabilities and their contributions towards strategic initiatives. The annual bonuses paid to each NEO were approved by the Compensation Committee, as further described below.

Mr. Deneke’s annual bonus reflects the SLT Scorecard’s 80% achievement and 95% achievement of his individual performance goals. In determining the level of achievement of his individual performance goals, the Compensation Committee noted Mr. Deneke’s driving the culture of safety and compliance that contributed to HSER achievements, leading the Company’s commercial and business development activities, and overseeing the Board and management’s review of strategic alternatives.

Mr. Mault’s annual bonus reflects the SLT Scorecard’s 80% achievement and 115% achievement of his individual performance goals. In determining the level of achievement of his individual performance goals, the Compensation Committee noted Mr. Mault’s leading the refinancing of 2025 senior unsecured notes that eliminated material debt maturities until May 2026 and the successful integration of the December 2022 acquisition of Outrigger and Sterling assets with the Company’s assets in the DJ basin.

Mr. Johnston’s annual bonus reflects the SLT Scorecard’s 80% achievement and 100% achievement of his individual performance goals. In determining the level of achievement of his individual performance goals, the Compensation Committee noted Mr. Johnston’s overseeing the Company’s HSER, HR, ESG/Sustainability reporting, legal, and regulatory accomplishments in 2023.

Long-Term Equity-Based Compensation Awards

The General Partner and the common unitholders of the Partnership approved the SMLP LTIP, pursuant to which eligible officers (including the NEOs), employees, consultants and directors of the General Partner and its affiliates are eligible to receive awards with respect to our equity interests, thereby linking the recipients’ compensation directly to the value of our common units and enhancing our ability to attract and retain superior talent. The SMLP LTIP provides for the grant, from time to time at the discretion of the Board or the Compensation Committee, of a dollar-denominated award, unit awards, restricted units, phantom units, unit options, unit appreciation rights, distribution equivalent rights, profits interest units and other unit-based awards. The approval of the new SMLP LTIP in 2022 and the unit pool thereunder allowed us to grant the 2023 LTIP awards to our NEOs solely as phantom unit awards, rather than as a combination of phantom unit awards and dollar-denominated awards as was necessary in prior years in recognition of the limited number of units available at such times under the prior SMLP LTIP.

The SMLP LTIP is designed to promote our interests, as well as the interests of our unitholders, by aligning the interests of our eligible employees (including the NEOs) and directors with those of common unitholders, as well as by strengthening our ability to attract, retain and motivate qualified individuals to serve as directors and employees. Awards under the SMLP LTIP are typically granted once per fiscal year (during the quarterly period ending March 31st).

2023 Awards

SMLP LTIP award guidelines were determined using the Compensation Consultant’s analysis for individuals in comparable positions and an analysis of the scope of their roles and duties. These guidelines set an annual long-term incentive award target in the amount of 400% of base salary for Mr. Deneke and 220% of base salary for Messrs. Mault and Johnston in 2023.

Effective March 15, 2023, the Board approved a grant of phantom units to each of Messrs. Deneke, Mault and Johnston, in line with the annual award guidelines. In consultation with the Compensation Consultant, the Compensation Committee determined that, consistent with the practices of the Company’s peer companies, phantom units should be granted subject to both performance-based and service-based vesting conditions. Consistent with Summit, companies in our compensation peer group are generally using a combination of performance-based and time-based awards. As this was the Company’s first year granting performance-based equity awards, the Compensation Committee determined that forty percent (40%) of the phantom units award will vest based on the achievement of the performance measures over a three-year performance period, as discussed below, and the remaining sixty percent (60%) of the phantom unit award will vest ratably subject to continued service over a three-year period. Holders of phantom units are entitled to distribution equivalent rights for each phantom unit, if applicable, providing for a lump sum payment equal to any accrued distributions from the grant date of the phantom units to be paid in cash upon the vesting date. The Compensation Committee selected equity awards with three-year service-based and performance-based vesting requirements to foster increased unit ownership by the NEOs, as a retention incentive for continued employment with the Partnership and to continue to align our NEOs’ interests with the interests of our unitholders.

To calculate the number of phantom units granted to each NEO, in February 2023, the Compensation Committee determined the dollar amount of the long-term incentive compensation award and that 40% of such value would be granted in the form of phantom units subject to performance-based vesting requirements and 60% of such value would be granted in the form of phantom units subject to service-based vesting requirements and then granted the number of phantom units that had a fair market value equal to the determined value, based on the market price for a unit of common equity. Phantom unit awards granted under the SMLP LTIP in 2023 were as follows:

(1)The Compensation Committee determined the number of phantom units awarded under the SMLP LTIP on February 20, 2023 based on a per unit volume-weighted average closing price of approximately $17.3246 for the three trading days immediately preceding the grant date.

(2)The number and value of performance-based phantom units are included in this table at target performance.

Performance-based Phantom Units

The performance-based phantom units will vest to the extent the following performance measures are met over the three-year period beginning January 1, 2023 and ending December 31, 2025 (the “performance period”):

•Leverage ratio, weighted 50%

•Relative unitholder return, weighted 50%

As shown in the table below, payouts can range from 0% to 200% of the target number of phantom units.

The leverage ratio is based on the ratio of (i) Consolidated Net Debt as of the end of the performance period to (ii) EBITDA for the period of the four consecutive fiscal quarters most recently ended as of the calculation date. Such ratio will be calculated in accordance with terms of the Loan and Security Agreement, dated as of November 2, 2021 (which is filed as Exhibit 10.43 to our Annual Report on Form 10-K for the year ended December 31, 2023, the “Credit Agreement”) for the calculation of “Total Net Leverage Ratio” as defined therein. Consolidated Net Debt and EBITDA will have the applicable meaning ascribed thereto in the Credit Agreement.

The Company’s relative unitholder return will be compared to the total unitholder or total shareholder return, as applicable, of a performance peer group comprised of Archrock, Inc. Crestwood Equity Partners LP, DCP Midstream, DT Midstream Inc., LP, EnLink Midstream LLC, Equitrans Midstream Corp., Genesis Energy LP, Magellan Midstream Partners LP, NGL Energy Partners LP, NuStar Energy LP, Targa Resources Corp., USA Compression Partners LP and USD Partners LP. Total returns will be calculated as (i) the sum of (a) the average fair market value of a common unit or share of common stock, as applicable, at the end of the performance period plus (b) any dividends paid over the performance period, divided by (ii) the average fair market value of a share of common stock, as applicable, at the beginning of the performance period; where the average fair market value as of a given date will be the volume-weighted average price of a common unit or common share, as applicable, during the 20 consecutive trading days ending on and including such date. Companies in the performance peer group that, during the performance period, have undergone an acquisition, merger or other corporate transaction pursuant to which they are not the surviving entity will be removed from the peer group.

The performance-based phantom units granted to the NEOs in 2023 are subject to accelerated vesting on the occurrence of any of the following events: (i) a termination of the NEO’s employment other than for cause, (ii) a termination of the NEO’s employment by the NEO for good reason or (iii) a termination of the NEO’s employment by reason of the NEO’s death or disability. As described in more

detail in the “—Potential Payments” section below, depending on the timing of such terminations, the performance-based phantom units will either vest at the time of termination, with the performance measures deemed met at the target level, or will remain outstanding and eligible to vest in accordance with their terms, as discussed below in the “—Potential Payments” section below.

In the event of a change in control, the performance measures associated with the performance-based phantom units will be scored based on the level of performance achieved during the period beginning on the first day of the performance period and ending on the latest practicable date prior to the change in control. If the performance-based phantom units, as scored, are not continued, assumed, substituted or replaced with an award that is either based (i) on shares of common stock or common units that are traded on a national securities exchange and are registered under the Securities Exchange Act of 1934, as amended, or (ii) on a U.S. dollar-denominated cash award, in each case, that has no less than equivalent economic value as immediately prior to the change in control, such performance-based phantom units will become vested in connection with the change in control. Any continued, assumed, substituted or replaced performance-based phantom units remain subject to accelerated vesting provisions described in the paragraph above.

Time-based Phantom Units

The time-based phantom units will vest one-third on each of the first three anniversaries following the date of grant.

The time-based phantom units are subject to accelerated vesting on the occurrence of any of the following events: (i) a termination of the NEO’s employment other than for cause, (ii) a termination of the NEO’s employment by the NEO for good reason or (iii) a termination of the NEO’s employment by reason of the NEO’s death or disability.

In the event of a change in control, the time-based phantom units will become vested only to the extent they are not continued, assumed, substituted or replaced as described above in the “Performance-based Phantom Units” section, and like the performance-based phantom units, if continued, assumed, substituted or replaced, the time-based phantom units will remain subject to the accelerated provisions described in the paragraph above.

Prior Year Awards

Due to the limited number of units available under the SMLP LTIP at the time of grant, awards granted under the SMLP LTIP in 2020, 2021 and 2022 were granted, in part, in the form of a cash retention bonus. The 2020 and 2021 awards vested and vest ratably over a three-year period, and the 2022 awards vested and vest 20%, 60% and 20% over a three-year period. To continue to align the interests of the Partnership’s senior management with our unitholders, following the approval of the new SMLP LTIP in 2022 (and the additional units available thereunder), in November 2022, the Compensation Committee approved a program pursuant to which each member of the Partnership’s senior management, including the NEOs, were given the opportunity to forfeit a portion of each outstanding vesting tranche of cash retention bonus awards previously granted in exchange for phantom units generally subject to the same terms and conditions (the “cash-to-phantom program”). A maximum of 300,000 phantom units were made available by the Compensation Committee under the cash-to-phantom program.

To the extent not forfeited pursuant to the cash-to-phantom program, (i) the final one-third of the 2020 awards, the second one-third of the 2021 awards and the first 20% of the 2022 awards vested in 2023, (ii) the remaining one-third of the 2021 awards and an additional 60% of the 2022 awards will vest in 2024, and (iii) the remaining 20% of the 2022 awards will vest in 2024.

Retirement, Health and Welfare and Additional Benefits

Our NEOs receive few perquisites or additional benefits. The NEOs are eligible to participate in such employee benefit plans and programs we offer to our employees, subject to the terms and eligibility requirements of those plans, and receive some additional benefits pursuant to the terms of their employment agreements.

401(k) Plan

The NEOs are eligible to participate in a tax qualified 401(k) defined contribution plan to the same extent as all of our other employees. In 2023, we made a fully vested matching contribution on behalf of each of the 401(k) plan’s participants up to 5% of such participant’s eligible salary for the year.

Health Savings Account Program

The NEOs are eligible to participate in a tax qualified health savings account (“HSA”) if they are enrolled in the available high-deductible health plan. The HSA is a tax-free savings account owned by an individual and can be used to pay for current or future qualified medical expenses. Participants determine how much to contribute, when and how to spend the money on eligible medical expenses, and how to invest the balance. The balance remains in the account and is not subject to forfeiture. The Partnership makes annual contributions to all HSA-eligible employees who enroll in and contribute to an HSA. In 2023, we made tax-free HSA contributions of $600 to each of Messrs. Deneke, Mault and Johnston.

Unitholder Outreach and Engagement

Following our 2023 annual unitholder meeting, we reviewed the voting results as well as reports published by proxy advisory firms to gain an initial understanding of areas of focus and we reached out to shareholders to invite feedback and discussion. As described above, in 2023, our long-term incentive plan introduced awards denominated in units (rather than a combination of units and cash) and subject to both performance-based and time-based vesting requirements (rather than solely time-based requirements), to more closely aligning the interests of our eligible employees (including the NEOs) and directors with those of common unitholders.

Employment Agreements

In February 2023, each NEO’s employment agreement with Summit Operating was amended and restated. Elements of the NEOs’ total direct compensation are subject to periodic review and may be adjusted accordingly by the Compensation Committee.

Messrs. Deneke’s and Johnston’s amended and restated employment agreements have an effective date of February 23, 2023 and an initial term that expired on September 4, 2023 and Mr. Mault’s amended and restated employment agreement has an effective date of February 23, 2023 and an initial term that expires on January 30, 2024. The terms of each of Messrs. Deneke’s, Mault’s and Johnston’s amended and restated employment agreements are subject to automatic extension for successive one-year periods, unless either party gives notice of non-extension to the other no later than 30 days prior to the expiration of the then-applicable term.

Mr. Deneke’s employment agreement provides for an annual base salary of $650,000, a performance-based bonus ranging from 0% to 300% of base salary, with a target of 150% of base salary, and an annual equity award under the SMLP LTIP with a target value of 400%, provided that such value may vary in the Board’s discretion based on Mr. Deneke’s or our performance prior to each grant. Messrs. Mault’s and Johnston’s employment agreements provide for an annual base salary of $336,000, for Mr. Mault, and $386,000, for Mr. Johnston, a performance-based bonus ranging from 0% to 200% of base salary, with a target of 100% of base salary, and an annual equity award under the SMLP LTIP with a target value of 220%, provided that such value may vary in the Board’s discretion based on our performance or Mr. Mault’s and Mr. Johnston’s respective performance prior to each grant.

In addition, Messrs. Deneke’s, Mault’s and Johnston’s employment agreements also provide for reimbursement of certain business expenses incurred in connection with their employment, including company-paid tax preparation and advisory services of up to $12,000 per year, and Mr. Deneke’s employment agreement also provides for Young Presidents Organization membership dues of up to $15,000 per year.

Messrs. Deneke, Mault and Johnston are each entitled to receive a prorated annual bonus (based on target) if any of their employment is terminated (i) by either Messrs. Deneke, Mault or Johnston, as applicable, with good reason, or by us without cause (each a “Qualifying Termination”), (ii) as a result of a non-extension of the term by us (an “Employer Nonrenewal”), or (iii) due to death or disability, paid as a lump sum within 60 days of termination, subject, in the event of a Qualifying Termination, Employer Nonrenewal or disability to the applicable NEO’s execution and nonrevocation of a release of claims.

Messrs. Deneke’s, Mault’s and Johnston’s employment agreements provide for a cash severance payment upon a termination resulting from an Employer Nonrenewal or a Qualifying Termination, subject to the execution and nonrevocation of a release of claims within 60 days following their termination. Such severance payment will be equal to, for Mr. Deneke, three times, and for Mr. Mault and Mr. Johnston, two and one-half times the sum of (a) each of their respective annual base salaries and (b) the higher of each of their respective target annual bonuses and the annual bonuses actually paid to each in respect of the year immediately preceding their termination. The severance payment will be paid in equal installments generally over the period beginning on the date of their termination and ending on its first anniversary. Messrs. Deneke, Mault and Johnston would also be entitled to subsidized COBRA coverage for the lesser of the time during which they are eligible for COBRA coverage and 18 months. Messrs. Deneke’s, Mault’s and Johnston’s employment agreements provide that if following any of Messrs. Deneke’s, Mault’s or Johnston’s termination of employment, we discover that grounds for a termination for “cause” existed at the time of their termination, Messrs. Deneke’s, Mault’s or Johnston’s termination of employment will be recharacterized a termination for cause and any payment or benefit received in connection with their termination (whether or not pursuant to their employment agreements) shall be repaid, and they will not be eligible for any remaining severance payment or benefits under their employment agreements.

The amended and restated employment agreements generally define good reason as any of Messrs. Deneke’s, Mault’s or Johnston’s termination of employment within ninety days after the occurrence of (i) a material diminution in their authority, duties or responsibilities; (ii) a material diminution in the aggregated total of their base salary, target bonus opportunity and annual target long-term incentive award opportunity (provided that such target opportunity may vary year-to-year based upon each of Messrs. Deneke’s, Mault’s or Johnston’s, or our performance prior to such grant); (iii) a material change in the geographic location at which they must perform their services under the agreement; or (iv) any other action or inaction that constitutes a material breach of the employment agreement by us. For Mr. Deneke, good reason also includes a change in Mr. Deneke’s reporting relationship resulting in Mr. Deneke no longer reporting directly to the Board or if he is not elected as a director.

Following any termination of employment due to an Employer Nonrenewal or Qualifying Termination, Messrs. Deneke, Mault and Johnston will be subject to a post-termination non-competition covenant through the first anniversary of termination unless any of Messrs. Deneke, Mault or Johnston elect to forego any portion of his severance payment in exchange for a waiver of the corresponding non-competition period. Following Messrs. Deneke’s, Mault’s or Johnston’s termination of employment for any reason, Messrs. Deneke, Mault and Johnston will be subject to a one-year post-termination non-solicitation covenant.

Messrs. Deneke’s, Mault’s and Johnston’s employment agreements also provide that, in the event of a change in control, (1) all equity awards granted to them under the SMLP LTIP prior to the effective date of their amended and restated employment agreement and held by them as of immediately prior to a change in control of the Partnership or the General Partner will become fully vested immediately prior to the change in control and (2) if any portion of the payments or benefits provided to Messrs. Deneke, Mault or Johnston in connection with a change in control becomes (whether or not pursuant to their employment agreements) subject to the excise tax under Section 4999 of the Internal Revenue Code, then the payments and benefits will be reduced to the extent such reduction would result in a greater after-tax benefit to any of Messrs. Deneke, Mault or Johnston.

Hedging Policy

Our Insider Trading Policy calls for all members of the Board and all of our officers and employees to ordinarily avoid engaging in speculative trading, including the purchase of put or call options or the writing of such options. For more information on our Insider Trading Policy, see “Corporate Governance—Governance Documents—Prohibition on Insider Trading and Avoidance of Speculative Trading in SMLP Units.”

Equity Holding Guidelines

We believe that equity-based compensation aligns the economic interests of our directors and certain executive officers with those of common unitholders. In accordance with this goal, the Board has approved and adopted equity holding guidelines for our directors and certain executive officers as described below.

The holdings of the directors and executive officers subject to the equity holding guidelines were measured initially on March 31, 2022 and then annually based on the volume weighted average trading price for the five days ending on and including December 31 (the “Measurement Date”). Individuals subject to the equity holding guidelines are encouraged to meet the applicable guidelines by the Measurement Date on which such individual’s total prior LTIP grants made after such individual’s appointment to the position equals or exceeds the value applicable to such individual’s position as listed above. Individuals subject to the equity holding guidelines are expected to retain 100% of any units of common equity received from LTIP grants after appointment to the position until and unless they hold sufficient equity to meet the guidelines. As of December 31, 2023, each of the directors and executive officers subject to the equity holding guidelines exceeded (or was on track to exceed within the required time set forth in the guidelines) the equity holding set forth in the guidelines. The ownership levels for each of our directors and NEOs as of December 31, 2023, based on a volume-weighted price per unit of $18.1677, is set forth in the table below:

(1)Mr. Oates was appointed to the Board on February 28, 2022, and as of December 31, 2023, his total 2022 and 2023 LTIP grants had not yet met his required multiple, but after his 2024 LTIP grant (which was comprised of 6,581 units granted on January 18, 2024), Mr. Oates has met his required multiple within the timeframe specified in the guidelines.

For purposes of satisfying the guidelines, the following are considered equity holdings of an individual:

•common units owned outright (whether certificated, book-entry or held in street name), including units owned jointly with a spouse (including domestic partners under state law);

•common units owned (whether certificated, book-entry or held in street name) separately by a spouse (including domestic partners under state law) or children under the age of 21 that share the individual’s household;

•common units held in an individual retirement account;

•common units held in a private foundation or charitable trust, in each case established by the individual or where the individual serves as a trustee or director; and

•unvested LTIP grants held by the individual.

Impact of Accounting and Tax Treatments

In developing the compensation packages for our NEOs, we consider the potential accounting and tax implications thereof, but we balance such implications with our need to attract and retain talented management. While we consider the impact of Section 409A of the Internal Revenue Code and aim to structure our NEOs’ and other key employees’ compensation arrangements to be exempt from or compliant with the requirements thereunder, and while we consider the availability of tax deductions related to our NEOs’ and other key employees’ compensation, we do not provide Section 409A tax gross-ups in the event of adverse tax consequences thereunder nor do we view the deductibility of such compensation (or limitations thereon) as material compared to our ability to attract and retain key employees integral to the achievement of our business initiatives.

Risk Assessment Relative to Compensation Programs

The Compensation Committee manages risk as it relates to our compensation plans, programs, and structure (collectively, our “Compensation Practices”). The Compensation Committee meets with management to review whether any aspect of our Compensation Practices creates incentives for our employees to take inappropriate risks that could materially adversely affect the Partnership.

Our compensation policies contain a number of features that reflect sound risk management practices. Our compensation programs balance short- and long-term objectives, mitigating the potential incentive for unwarranted risk-taking for short-term, unsustainable results. Furthermore, the metrics we use to assess performance for our incentive compensation programs are broadly tailored to avoid distorting our NEOs’ incentives in pursuit of specific or individual performance goals. Our annual incentive compensation program is also capped, therefore not allowing for unlimited cash payouts.

Accordingly, we believe that the compensation practices for our NEOs and other employees are appropriately structured and do not pose a material risk to the Partnership. We believe these compensation practices are designed and implemented in a manner that does not promote excessive risk-taking that could damage the value of the Partnership or provide compensatory rewards for inappropriate decisions or behavior.

COMPENSATION COMMITTEE REPORT

The Compensation Committee provides oversight, administers and makes decisions regarding the Partnership’s compensation policies and plans. Additionally, the Compensation Committee generally reviews and discusses the Compensation Discussion and Analysis with senior management of the Partnership as a part of the Partnership’s governance practices. Based on this review and discussion, the Compensation Committee has recommended to the Board of the General Partner that the Compensation Discussion and Analysis be included in this proxy statement.

Members of the Compensation Committee:

Lee Jacobe (Chair)
James J. Cleary
Marguerite Woung-Chapman

EXECUTIVE COMPENSATION TABLES

Summary Compensation Table

The following table sets forth certain information with respect to the compensation paid to our NEOs for the years ended December 31, 2023, 2022 and 2021, as applicable.

(1)For 2023, the amounts shown reflect (i) the portion of the cash retention component of the LTIP awards granted to Messrs. Deneke and Mault in 2020 and to the NEOs in 2021 and 2022, in each case, that was not foregone as part of the 2022 cash-to-phantom program and that became vested in 2023 and (ii) for Messrs. Deneke and Johnston, the value of (a) the phantom unit awards granted under the 2022 cash-to-phantom program that vested in 2023 and (b) the amount by which the grant date fair value of such units exceeded the amount of the cash retention component foregone. For 2022 and 2021, the amounts shown reflect the portion of the cash retention components that became vested in 2022 and 2021, respectively.

(2)Amounts shown reflect the grant date fair value of the phantom unit awards granted to the NEOs pursuant to the annual LTIP program in 2023, 2022 and 2021, respectively, in accordance with FASB Accounting Standards Codification Topic 718, Compensation—Stock Compensation (“FASB ASC Topic 718”), with phantom units subject to performance-based vesting conditions valued based on probable performance as of the grant date. Assuming maximum performance, the grant date fair value of phantom units subject to performance-based vesting conditions would be: Mr. Deneke - $2,375,387; Mr. Mault - $676,093; and Mr. Johnston - $776,569. The amounts shown for 2022 do not reflect the grant date fair value of the phantom unit awards granted to the NEOs pursuant to the cash-to-phantom program as the portion of the grant date fair value of the cash-to-phantom units that replaced the NEOs’ foregone cash retention component are or will be reflected in the “Bonus” column of the Summary Compensation Table in the years such awards vest.

(3)Amounts shown represent the incentive bonus earned under the Partnership’s annual incentive bonus program in the fiscal year indicated but paid in the following fiscal year.

(4)The Company makes contributions to the Named Executive Officer’s health savings accounts and pays all employees, including the Named Executive Officers, a holiday bonus. Additionally, the amounts in this column include the following:

(a)Includes employer-paid medical and dental premiums.

(5)Mr. Deneke, the President and Chief Executive Officer, also served as a member of the Board but did not receive any additional compensation for serving on the Board.

(6)Mr. Mault was not a Named Executive Officer prior to 2022.

Grants of Plan-Based Awards for Fiscal Year 2023

The following table sets forth information concerning annual incentive awards and phantom unit awards granted to the Partnership’s NEOs in fiscal year 2023.

(1)Represents annual incentive opportunities that may be awarded pursuant to the Partnership’s annual incentive program for the year ended December 31, 2023 with payment based upon the Partnership’s achievement of pre-established performance goals and other factors. For additional information, please see “Compensation Discussion and Analysis—Elements of Executive Compensation—Annual Incentive Compensation.”

(2)Represents the number of performance-based phantom units (with distribution equivalent rights) under the SMLP LTIP that may be earned if the target and maximum performance levels are met. As discussed above in “Compensation Discussion and Analysis—Elements of Executive Compensation—Long-Term Equity-Based Compensation Awards, the performance-based phantom units do not provide for threshold performance levels, but are scored based on straight-line interpolation between levels of performance. 

(3)Amounts shown represent the fair value of the award on the date of the grant, in accordance with FASB ASC Topic 718. For the assumptions made in valuing these awards, see Note 15 to the consolidated financial statements in our Annual Report on Form 10-K for the year ended December 31, 2023.

(4)Represents the number of service-based phantom units with distribution equivalent rights under the SMLP LTIP.

Narrative Disclosure to the Summary Compensation Table and Grants of Plan-Based Awards for Fiscal Year 2023 Table

A description of material factors necessary to understand the information disclosed in the tables above with respect to salaries, bonuses, equity awards, non-equity incentive plan compensation and all other compensation can be found in the CD&A that precedes these tables.

Outstanding Equity Awards at Fiscal Year-End 2023

The following table presents information regarding the outstanding equity awards held by the Partnership’s NEOs at December 31, 2023.

(1)Phantom units granted to the NEOs vest as described below, subject to continued employment, and accelerated vesting as provided in the applicable award agreement. The NEOs also receive distribution equivalent rights for each phantom unit, if applicable, providing for a lump sum payment equal to any accrued distributions from the grant date of the phantom units to be paid in cash upon the vesting date.

(2)Amounts were calculated using the closing price of SMLP’s publicly traded common units ($17.91) on December 29, 2023, the last trading day of the year.

(3)Represents the performance-based phantom units granted to the NEOs in 2023, which vest based on the extent to which the associated performance measures are achieved at the end of a three-year period. The amounts set forth in the table above represent the number of phantom units that may vest based on the target level of performance.

(4)Represents the time-based phantom units granted to the NEOs in 2023, which vest ratably over a three-year period with the first tranche scheduled to vest on the first anniversary of the grant date.

(5)Represents the unvested portion of the phantom units received in exchange for the cancellation of all or a portion of the cash retention component of the 2022 annual LTIP award in connection with the cash-to-phantom program, which vest approximately 75% and 25% on each of March 15, 2024 and March 15, 2025.

(6)Represents the unvested portion of the phantom units received in exchange for the cancellation of all or a portion of the cash retention component of the 2021 annual LTIP award in connection with the cash-to-phantom program. These phantom units vest on March 15, 2024.

(7)Represents the unvested portion of the phantom units granted to the NEOs in 2022, which vest approximately 50% on each of March 15, 2024 and March 15, 2025.

(8)Represents the unvested portion of the phantom units granted to the NEOs in 2021, which vest on March 15, 2024.

Phantom Units Vested for Fiscal Year 2023

The following table represents information regarding the vesting of phantom units during the year ended December 31, 2023 with respect to the Partnership’s NEOs.

(1)Represents the number of phantom units that vested in 2023.

(2)Represents the value of the phantom units that vested in 2023. The value of the phantom units that vested was calculated using the closing price of SMLP’s publicly traded common units at the date of vesting.

Pension Benefits

Currently, the Partnership does not sponsor or maintain a pension or defined benefit program for its NEOs. This policy may change in the future.

Potential Payments upon Termination or Change in Control

SEC regulations require us to disclose potential payments to an NEO in connection with his or her termination or a change of control of SMLP. The following table sets forth information concerning potential amounts payable to the NEOs upon termination of employment under various circumstances, and upon a change in control, if such event took place on December 31, 2023.

(1)The NEOs’ employment agreements provide that upon an Employer Nonrenewal or a Qualifying Termination, the NEOs will receive a severance payment equal to, for Mr. Deneke, three times, and for Messrs. Mault and Johnston, two and one-half times, the sum of their respective annual base salary and the higher of their respective target annual bonus and the annual bonus actually paid to them in respect of the immediately preceding year.

(2)The NEOs’ employment agreements provide that the NEOs are entitled to receive a prorated annual bonus (based on target) if their employment is terminated by reason of death or disability or as a result of an Employer Nonrenewal or a Qualifying Termination.

(3)The NEOs’ employment agreements provide that the NEOs are entitled to subsidized COBRA coverage for the lesser of the time during which he is eligible for COBRA coverage and 18 months.

(4)Amounts represent the value of (a) the phantom units and (b) the cash retention component, in each case, that vests upon the occurrence of the triggering event. The value of the phantom units was calculated using the closing price of SMLP’s publicly traded common units on December 29, 2023.

•Unvested equity awards and cash retention components granted to the NEOs prior to February 2023 will immediately vest upon a termination without cause or by reason of death or disability, upon a change in control, or, if provided in the individual award agreement, upon a termination for good reason.

•In the event of a termination of employment, unvested equity awards granted in February 2023 will vest as follows: (i) unvested time-based awards will immediately vest upon a Qualifying Termination or a termination of employment by reason of death or disability; (ii) unvested performance-based awards will vest upon a Qualifying Termination in the first or second year of the performance period or upon a termination of employment by reason of death or disability prior to the end of the performance period, in each case, with the performance measures deemed met at the target level, and (iii) unvested performance-based awards will remain outstanding and eligible to vest in accordance with their terms at the end of the performance period upon a Qualifying Termination in the third year of the performance period or upon a termination of employment by reason of death or disability on or following the last day of the performance period.

•In the event of a change in control, unvested equity awards and cash retention components granted to the NEOs in February 2023 will vest in connection with a change in control only if not continued, assumed, substituted or replaced with an award that is either based (i) on shares of common stock or common units that are traded on a national securities exchange and are registered under the Securities Exchange Act of 1934, as amended, or (ii) on a U.S. dollar-denominated cash award, in each case, that has no less than equivalent economic value as immediately prior to the change in control. Where such unvested equity awards are so continued, assumed, substituted or replaced, the phantom units will remain outstanding subject to their terms, with the performance measures associated with the performance-based phantom units scored based on the level of performance achieved during the period beginning on the first day of the performance period and ending on the latest practicable date prior to the change in control and, regardless of whether time-based or performance-based, such phantom units will otherwise remain subject to the accelerated vesting provisions upon a Qualifying Termination or termination of employment by reason of death or disability. For purposes of this table, it is assumed that the Company undergoes a change in control on December 31, 2023 and the NEOs’ undergo a Qualifying Termination.

(5)If any portion of the payments or benefits provided to the NEOs in connection with a change in control becomes subject to the excise tax under Section 4999 of the Internal Revenue Code, then the payments and benefits will be reduced to the extent such reduction would result in a greater after-tax benefit to Messrs. Deneke, Mault and Johnston, respectively. Receipt of these separation payments and benefits are subject to the execution of a release of claims, compliance with restrictive covenant provisions and the payment timing and terms, as applicable, as described in “Compensation Discussion and Analysis—Employment Agreements.”

CEO Pay Ratio

The following is a reasonable estimate, prepared under applicable SEC rules, of the ratio of the annual total compensation of our CEO to the median of the annual total compensation of our other employees for our last completed fiscal year.

For 2023, we determined our median employee by ranking our employees (other than the CEO) employed as of December 31, 2023 (the “determination date”) by the sum of each employee’s annualized base salary, his or her actual cash bonus received in 2023 for 2022 performance, and his or her actual overtime pay received in 2023. In annualizing each employee’s base salary, we used each employee’s base salary rate as of the determination date. We made no full-time equivalent adjustment for any employee, we had no temporary or seasonal workers as of the determination date, and we made no cost-of-living adjustments. The annual total compensation of our median employee (other than the CEO) for 2023 was $142,644, inclusive of 401(k) matching contributions, insurance benefits and an annual bonus payment. To determine the annual total compensation of our CEO for purposes of this disclosure, we chose the person who was serving as CEO as of the determination date and used the total compensation he received in 2023 as set forth in the Summary Compensation Table above. Accordingly, for purposes of this disclosure, we determined that the CEO’s annual total compensation for 2023 was $6,268,338. Based on the foregoing, we calculated the ratio of the annual total compensation of our CEO to the median of the annual total compensation of all other employees to be 43.94 to 1. Given the different methodologies that various public companies will use to determine an estimated pay ratio, our estimated pay ratio should not be used as a basis for comparison with ratios disclosed by other companies.

Pay Versus Performance

SEC regulations require us to disclose the following information about the relationship between executive compensation paid for our CEO (“PEO” in the following tables) and the average paid for our other NEOs and the Partnership’s financial performance.