F1This Form 4 is filed jointly by MRD WHR LA Midstream LLC ("MRD WHR LA"), MRD Midstream LLC ("MRD Midstream"), MRD Holdco LLC ("MRD Holdco"), Natural Gas Partners VIII, L.P. ("NGP VIII"), Natural Gas Partners IX, L.P. ("NGP IX"), NGP IX Offshore Holdings, L.P. ("NGP IX Offshore"), GFW VIII, L.L.C. ("GFW VIII"), G.F.W. Energy VIII, L.P. ("GFW Energy VIII"), GFW IX, L.L.C. ("GFW IX"), G.F.W. Energy IX, L.P. ("GFW Energy IX") and NGP Energy Capital Management, L.L.C. ("NGP ECM"), pursuant to the expiration of the underwriters' option to purchase additional common units of the Issuer in connection with the initial public offering of common units representing limited partner interests pursuant to a Registration Statement on Form S-1 (Registration No. 333-199020) (the "Registration Statement").
F2MRD Midstream is a wholly owned subsidiary of MRD Holdco. NGP VIII, NGP IX and NGP IX Offshore own a controlling interest in MRD Holdco. GFW VIII is the sole general partner of GFW Energy VIII, which is the general partner of NGP VIII, and GFW IX is the sole general partner of GFW Energy IX, which is the general partner of NGP IX and NGP IX Offshore. GFW VIII has delegated full power and authority to manage NGP VIII, and GFW IX has delegated full power and authority to manage NGP IX and NGP IX Offshore, respectively, to NGP ECM. Accordingly, each of MRD Midstream, MRD Holdco, NGP VIII, NGP IX, NGP IX Offshore, GFW VIII, GFW Energy VIII, GFW IX, GFW Energy IX and NGP ECM may be deemed to share voting and dispositive power over the reported units, and therefore may also be deemed to be the beneficial owner of these units but disclaims such ownership except to the extent of its pecuniary interest.
F3On June 18, 2015, the underwriters exercised, in part, their option to purchase additional common units as described in the Registration Statement. On July 6, 2015, as a result of the expiration of the underwriters' option to purchase additional common units, as described in the Registration Statement, the Issuer issued 391,140 common units to MRD WHR LA for no additional consideration. MRD WHR LA immediately distributed its entire interest in the Issuer to its members, consisting of 273,798 common units to MRD Midstream and 117,342 common units to WHR Midstream LLC. After giving effect to such deferred issuances, MRD Midstream owns 2,127,704 common units and 5,250,000 subordinated units, representing an approximate 18.4% limited partner interest in the Issuer.

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