Sec Form 4 Filing - Magnolia Infrastructure Partners, LLC @ American Midstream Partners, LP - 2015-09-15

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 Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person Magnolia Infrastructure Partners, LLC 2. Issuer Name and Ticker or Trading Symbol American Midstream Partners, LP [ AMID] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director X __ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) C/O ARCLIGHT CAPITAL PARTNERS, LLC, 200 CLARENDON STREET, 55TH FLOOR 3. Date of Earliest Transaction (MM/DD/YY) 09/15/2015 (Street) BOSTON, MA02117 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) _____ Form filed by One Reporting Person __ X __ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction 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

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction 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 (MM/DD/YY) 7. Title and Amount of Underlying Securities (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 Common Units ( 1 ) 09/15/2015 J( 1 ) 618,921 ( 1 ) ( 1 ) Common Units 618,921 $ 11.31 618,921 ( 2 ) D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Magnolia Infrastructure Partners, LLC C/O ARCLIGHT CAPITAL PARTNERS, LLC 200 CLARENDON STREET, 55TH FLOOR BOSTON, MA02117 X X American Midstream GP, LLC ATTENTION: WILLIAM B. MATHEWS 1400 16TH STREET, SUITE 310 DENVER, CO80202 X X High Point Infrastructure Partners, LLC C/O ARCLIGHT CAPITAL PARTNERS, LLC 200 CLARENDON STREET, 55TH FLOOR BOSTON, MA02117 X X ArcLight Capital Holdings, LLC C/O ARCLIGHT CAPITAL PARTNERS, LLC 200 CLARENDON STREET, 55TH FLOOR BOSTON, MA02117 X X ArcLight Capital Partners, LLC 200 CLARENDON STREET, 55TH FLOOR BOSTON, MA02117 X X ARCLIGHT ENERGY PARTNERS FUND V, L.P. C/O ARCLIGHT CAPITAL PARTNERS, LLC 200 CLARENDON STREET, 55TH FLOOR BOSTON, MA02117 X X Revers Daniel R C/O ARCLIGHT CAPITAL PARTNERS, LLC 200 CLARENDON STREET, 55TH FLOOR BOSTON, MA02117 X X Signatures /s/ Daniel R. Revers, MAGNOLIA INFRASTRUCTURE PARTNERS, LLC, By: Daniel R. Revers, President 09/17/2015 Signature of Reporting Person Date /s/ Daniel R. Revers, HIGH POINT INFRASTRUCTURE PARTNERS, LLC, LLC, By: Daniel R. Revers, President 09/17/2015 Signature of Reporting Person Date /s/ William B. Mathews, AMERICAN MIDSTREAM GP, LLC, By: William B. Mathews, Senior Vice President 09/17/2015 Signature of Reporting Person Date /s/ Daniel R. Revers, ARCLIGHT CAPITAL HOLDINGS, LLC, By: Daniel R. Revers, President 09/17/2015 Signature of Reporting Person Date /s/ Daniel R. Revers, ARCLIGHT CAPITAL PARTNERS, LLC, By: Daniel R. Revers, President 09/17/2015 Signature of Reporting Person Date /s/ Daniel R. Revers, ARCLIGHT ENERGY PARTNERS FUND V, L.P., LLC, By: ArcLight PEF GP V, LLC, its General Partner, By: ArcLight Capital Holdings, LLC, its Manager, By: Daniel R. Revers, Managing Partner 09/17/2015 Signature of Reporting Person Date /s/ Daniel R. Revers 09/17/2015 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Represents common units representing limited partnership interests of the Issuer (the "Common Units") held directly by Magnolia Infrastructure Partners, LLC ("Magnolia"). Represents Common Units purchased by Magnolia in the Issuer's underwritten public offering of 7,500,000 Common Units, which closed on September 15, 2015. ( 2 )Represents the aggregate number of Common Units held after the acquisition of Common Units reported in Column 5 of this line item.

Remarks: ArcLight Capital Holdings, LLC ("ArcLight Holdings") is the sole manager and member of ArcLight Capital Partners, LLC ("ArcLight Partners"). ArcLight Partners is the investment adviser to ArcLight Energy Partners Fund V, L.P. ("Fund V" and together with ArcLight Holdings and ArcLight Partners, the "ArcLight Entities"). ArcLight Holdings is the manager of the general partner of Fund V. Mr. Revers is a manager of ArcLight Holdings and a managing partner of ArcLight Partners and has certain voting and dispositive rights as a member of ArcLight Partners' investment committee. Fund V indirectly owns Magnolia and, through indirectly controlled subsidiaries, Fund V owns approximately 90% of the ownership interest in HPIP, which in turn owns 95% of the General Partner. As a result, the ArcLight Entities and Mr. Revers may be deemed to indirectly beneficially own the securities of the Issuer held by Magnolia, HPIP and the General Partner, but disclaim beneficial ownership except to the extent of their respective pecuniary interests therein.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

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