SMLP Summit Midstream Partners LP

FORM 4 [X] Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).         
UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES                                                                                   
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Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940                       

1. Name and Address of Reporting Person * ENERGY CAPITAL PARTNERS II, LLC	2. Issuer Name and Ticker or Trading Symbol Summit Midstream Partners, LP [ SMLP ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director                    __X__ 10% Owner _____ Officer (give title below)    _____ Other (specify below)
(Last)          (First)          (Middle) 40 BEECHWOOD ROAD	3. Date of Earliest Transaction (MM/DD/YYYY) 5/28/2020
(Street) SUMMIT, NJ 07901 (City)        (State)        (Zip)	4. If Amendment, Date Original Filed (MM/DD/YYYY)	6. Individual or Joint/Group Filing (Check Applicable Line) ___ Form filed by One Reporting Person _ X _ Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1.Title of Security (Instr. 3)	2. Trans. Date	2A. Deemed Execution Date, if any	3. Trans. Code (Instr. 8)		4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Units (Limited Partner Interests)	5/28/2020		D		5915827	D	(1)	0	I	By SMLP Holdings, LLC (2)(3)
Common Units (Limited Partner Interests)	5/28/2020		D		45318866	D	(1)	0	I	By Summit Midstream Partners, LLC (2)(3)

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivate Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Trans. Date	3A. Deemed Execution Date, if any	4. Trans. Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:
(1)	On May 28, 2020, pursuant to a purchase agreement, dated as of May 3, 2020, the Issuer purchased (i) all the outstanding limited liability company interests of Summit Midstream Partners, LLC ("Summit Investments"), which is the sole member of Summit Midstream Partners Holdings, LLC ("SMP Holdings"), which in turn owns 45,318,866 common units representing limited partner interests in the Issuer (the "Common Units"), and (ii) 5,915,827 Common Units held by SMLP Holdings, LLC ("SMLP") for a total purchase price of $35 million in cash and warrants to purchase up to 10 million Common Units. As a result of these transactions, Summit Investments became a wholly owned subsidiary of the Issuer.
(2)	Summit Investments is the sole member of SMP Holdings. Energy Capital Partners II, LLC ("ECP") indirectly controls Energy Capital Partners II, LP ("ECP II"), Energy Capital Partners II-A, LP ("ECP II-A"), Energy Capital Partners II-B IP, LP ("ECP II-B"), Energy Capital Partners II-C (Summit IP), LP ("ECP II-C"), and Energy Capital Partners II (Summit Co-Invest), LP ("ECP Summit Co-Invest" and together with ECP II, ECP II-A, ECP II-B and ECP II-C, the "ECP Funds").
(3)	Prior to the transactions reported herein, the ECP Funds owned a majority of the membership interests in Summit Investments and therefore may have been deemed to indirectly beneficially own the Common Units held of record by SMP Holdings. The ECP Funds, other than ECP Summit Co-Invest, hold all of the membership interests in SMLP. Accordingly, each of them, other than ECP Summit Co-Invest, may have been deemed to share beneficially ownership of the Common Units held by SMLP.

Reporting Owners
Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
ENERGY CAPITAL PARTNERS II, LLC 40 BEECHWOOD ROAD SUMMIT, NJ 07901		X
ENERGY CAPITAL PARTNERS II, LP 40 BEECHWOOD ROAD SUMMIT, NJ 07901		X
ENERGY CAPITAL PARTNERS II-A, LP 40 BEECHWOOD ROAD SUMMIT, NJ 07901		X
ENERGY CAPITAL PARTNERS II-B IP, LP 40 BEECHWOOD ROAD SUMMIT, NJ 07901		X
ENERGY CAPITAL PARTNERS II-C (SUMMIT IP), LP 40 BEECHWOOD ROAD SUMMIT, NJ 07901		X
Energy Capital Partners II (Summit Co-Invest), LP 40 BEECHWOOD ROAD SUMMIT, NJ 07901		X

Signatures
Energy Capital Partners II, LLC, By: /s/ Christopher M. Leininger, Partner and General Counsel		10/22/2021
**Signature of Reporting Person		Date
Energy Capital Partners II, LP, By: Energy Capital Partners GP II, LP Its: General Partner By: Energy Capital Partners II, LLC Its: General Partner By: /s/ Christopher M. Leininger, Partner and General Counsel		10/22/2021
**Signature of Reporting Person		Date
Energy Capital Partners II-A, LP, By: Energy Capital Partners GP II, LP Its: General Partner By: Energy Capital Partners II, LLC Its: General Partner By: Christopher M. Leininger, Partner and General Counsel		10/22/2021
**Signature of Reporting Person		Date
Energy Capital Partners II-B IP, LP, By: Energy Capital Partners GP II, LP Its: General Partner By: Energy Capital Partners II, LLC Its: General Partner By: /s/ Christopher M. Leininger, Partner and General Counsel		10/22/2021
**Signature of Reporting Person		Date
Energy Capital Partners II-C (Summit IP), LP, By: Energy Capital Partners GP II, LP Its: General Partner By: Energy Capital Partners II, LLC Its: General Partner By: /s/ Christopher M. Leininger, Partner and General Counsel		10/22/2021
**Signature of Reporting Person		Date
Energy Capital Partners II (Summit Co-Invest), LP, By: Energy Capital Partners GP II Co- Investment (Summit), LLC Its: General Partner By: Energy Capital Partners II, LLC Its: Managing Member By: /s/ Christopher M. Leininger, Partner and General Counsel		10/22/2021
**Signature of Reporting Person		Date