SCHEDULE 13G

(Rule 13d-102)
Information to be Included in Statements Filed Pursuant

to § 240.13d-1(b), (c) and (d) and Amendments Thereto Filed

Pursuant to § 240.13d-2

Under the Securities Exchange Act of 1934
(Amendment No. 2)

(Name of Issuer)

(Title of Class of Securities)

(CUSIP Number)

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

*The remainder of this cover page shall be filled out for a reporting person's initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter the disclosures provided in a prior cover page.

The information required in the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

(1)        Represents 5,293,571 common units representing limited partner interests (“Common Units”), or 15.4% of the outstanding Common Units, and 24,409,850 subordinated units representing limited partner interests (“Subordinated Units”), or 100% of the outstanding Subordinated Units, in the Issuer held directly by Summit Midstream Partners Holdings, LLC (“SMP Holdings”), of which Summit Midstream Partners, LLC (“Summit Investments”) is the sole member. The Subordinated Units may be converted into Common Units on a one-for-one basis after expiration of the subordination period (as defined in the Issuer’s First Amended and Restated Agreement of Limited Partnership (the “Partnership Agreement”), which is incorporated by reference herein), and other circumstances as noted in the Partnership Agreement.

(2)        Based upon 34,423,997 Common Units and 24,409,850 Subordinated Units outstanding as of October 31, 2014, as reported in the Issuer’s most recent Form 10-Q filed on November 7, 2014.

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(1)        Represents 5,293,571 common units representing limited partner interests (“Common Units”), or 15.4% of the outstanding Common Units, and 24,409,850 subordinated units representing limited partner interests (“Subordinated Units”), or 100% of the outstanding Subordinated Units, in the Issuer held directly by Summit Midstream Partners Holdings, LLC (“SMP Holdings”), of which Summit Midstream Partners, LLC (“Summit Investments”) is the sole member. The Subordinated Units may be converted into Common Units on a one-for-one basis after expiration of the subordination period (as defined in the Issuer’s First Amended and Restated Agreement of Limited Partnership (the “Partnership Agreement”), which is incorporated by reference herein), and other circumstances as noted in the Partnership Agreement.

(2)        Based upon 34,423,997 Common Units and 24,409,850 Subordinated Units outstanding as of October 31, 2014, as reported in the Issuer’s most recent Form 10-Q filed on November 7, 2014.

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(1)        Represents 5,293,571 common units representing limited partner interests (“Common Units”), or 15.4% of the outstanding Common Units, and 24,409,850 subordinated units representing limited partner interests (“Subordinated Units”), or 100% of the outstanding Subordinated Units, in the Issuer held directly by Summit Midstream Partners Holdings, LLC (“SMP Holdings”), of which Summit Midstream Partners, LLC (“Summit Investments”) is the sole member. Energy Capital Partners II, LLC (“ECP II”) and its parallel and co-investment funds (the “ECP Funds” and, together with ECP II, “ECP”) hold, in the aggregate, greater than a majority of the membership interest in Summit Investments. ECP II is the general partner of the general partner of each ECP Fund that holds membership interests in Summit Investments and has voting and investment control over the securities held thereby. Accordingly, ECP may be deemed to indirectly beneficially own the Common Units and the Subordinated Units of the Issuer held by Summit Investments and SMP Holdings.

(2)         Based upon 34,423,997 Common Units and 24,409,850 Subordinated Units outstanding as of October 31, 2014, as reported in the Issuer’s most recent Form 10-Q filed on November 7, 2014.

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(1)   Represents 5,293,571 common units representing limited partner interests (“Common Units”) and 24,409,850 subordinated units representing limited partner interests (“Subordinated Units”) in the Issuer held directly by SMP Holdings, of which Summit Investments is the sole member.

(2)   The Subordinated Units may be converted into Common Units on a one-for-one basis after expiration of the subordination period (as defined in the Issuer’s First Amended and Restated Agreement of Limited Partnership (the “Partnership Agreement”), which is incorporated by reference herein), and other circumstances as noted in the Partnership Agreement.

(3)   SMP Holdings beneficially owns 5,293,571 Common Units, or 15.4% of the outstanding Common Units, and 24,409,850 Subordinated Units, or 100% of the outstanding Subordinated Units, in the Issuer. ECP II and its parallel and co-investment funds (the “ECP Funds” and, together with ECP II, “ECP”) hold, in the aggregate, greater than a majority of the membership interests in Summit Investments. ECP II is the general partner of the general partner of each ECP Fund that holds membership interests in Summit Investments and has voting and investment control over the securities held thereby. Accordingly, ECP may be deemed to indirectly beneficially own the Common Units and Subordinated Units of the Issuer held by Summit Investments and SMP Holdings.

(4)   Based upon 34,423,997 Common Units and 24,409,850 Subordinated Units outstanding as of October 31, 2014, as reported in the Issuer’s most recent Form 10-Q filed on November 7, 2014.

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SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

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