FORM 4 [ ] 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 * Johnston James David 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                    _____ 10% Owner
__X__ Officer (give title below)    _____ Other (specify below)
See remarks below.
(Last)         (First)         (Middle)
C/O SUMMIT MIDSTREAM PARTNERS, LP, 910 LOUISIANA STREET, SUITE 4200
3. Date of Earliest Transaction (MM/DD/YYYY)
3/31/2021
(Street)
HOUSTON, TX 77002
(City)       (State)       (Zip)
4. If Amendment, Date Original Filed (MM/DD/YYYY)
 
6. Individual or Joint/Group Filing (Check Applicable Line) _X _ Form filed by One Reporting Person
___ 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  3/31/2021    M    16667  A  (1) 16667 (2) D   
Common Units  3/31/2021    F    4058 (3) D $24.10  12609  D   

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
Phantom Units   (1) 3/31/2021    M        16667    (4)  (5) Common Units  16667  $0.00  16666 (2)(6) D   

Explanation of Responses:
(1)  Each phantom unit is the economic equivalent of one common unit.
(2)  On November 9, 2020, the Issuer effected a 1-for-15 reverse unit split (the "Reverse Unit Split"). Pursuant to the Reverse Unit Split, common unitholders received one common unit for every 15 common units owned at the close of business on November 9, 2020. All fractional units created by the Reverse Unit Split were rounded to the nearest whole unit. The common units began trading on a split-adjusted basis on November 10, 2020. After giving effect to the Reverse Unit Split, the number of issued and outstanding common units decreased to 3,774,992.
(3)  Common Units being withheld to pay tax liability.
(4)  One-half of the phantom units (rounded down to the nearest whole number of units, except in the case of the final vesting date) shall vest on March 31, 2021, and the other half shall vest on March 31, 2022, subject to continued employment and accelerated vesting as provided in the applicable award agreement. The Reporting Person will receive Distribution Equivalent Rights ("DERs") for each phantom unit, if applicable, providing for payment on the vesting date of a lump sum of cash equal to any accrued distributions from and after the grant date of the phantom units.
(5)  The phantom units and associated DERs do not expire. The phantom units are settled upon vesting in common units (on a one-for-one basis) or in cash, at the discretion of the Issuer.
(6)  Total excludes phantom units from other tranches with different vesting and expiration dates.

Remarks:
The Reporting Person is Executive Vice President, General Counsel, and Chief Compliance Officer of Summit Midstream GP, LLC, the general partner of the Issuer (the "General Partner"). The Issuer is managed by the directors and executive officers of the General Partner.

Reporting Owners
Reporting Owner Name / Address
Relationships
Director 10% Owner Officer Other
Johnston James David
C/O SUMMIT MIDSTREAM PARTNERS, LP
910 LOUISIANA STREET, SUITE 4200
HOUSTON, TX 77002


See remarks below.

Signatures
/s/ James D. Johnston 4/1/2021
**Signature of Reporting Person Date