Exhibit A

JOINT FILING AGREEMENT

The undersigned each agree that (i) the statement on Schedule 13D relating to the common units representing limited partnership interests of Eagle Rock Energy Partners, L.P., a Delaware limited partnership, has been adopted and filed on behalf of each of them, (ii) all future amendments to such statement on Schedule 13D will, unless written notice to the contrary is delivered as described below, be jointly filed on behalf of each of them, and (iii) the provisions of Rule 13d-1(k)(1) under the Securities Exchange Act of 1934 apply to each of them. This agreement may be terminated with respect to the obligation to jointly file future amendments to such statement on Schedule 13D as to any of the undersigned upon such person giving written notice thereof to each of the other persons signatory hereto, at the principal office thereof.

Dated: August 15, 2011

MONTIERRA MINERALS & PRODUCTION, L.P.
By its general partner, Montierra Management LLC
By:	/s/ Joseph A. Mills Joseph A. Mills
	Chief Executive Officer
MONTIERRA MANAGEMENT LLC
By:	/s/ Joseph A. Mills Joseph A. Mills
	Chief Executive Officer
NATURAL GAS PARTNERS VII, L.P.
By its general partner, G.F.W. Energy VII, L.P.
By its general partner, GFW VII, L.L.C.
By:	/s/ Kenneth A. Hersh Kenneth A. Hersh
	Authorized Member

NATURAL GAS PARTNERS VIII, L.P.
By its general partner, G.F.W. Energy VIII, L.P.
By its general partner, GFW VIII, L.L.C.
By:	/s/ Kenneth A. Hersh Kenneth A. Hersh
	Authorized Member
NGP INCOME MANAGEMENT L.L.C.
By:	/s/ Tony R. Weber Tony R. Weber
	President
EAGLE ROCK HOLDINGS NGP 7, LLC
By its sole member, Natural Gas Partners VII, L.P.
By its general partner, G.F.W. Energy VII, L.P.
By its general partner, GFW VII, L.L.C.
By:	/s/ Kenneth A. Hersh Kenneth A. Hersh
	Authorized Member

EAGLE ROCK HOLDINGS NGP 8, LLC
By its sole member, Natural Gas Partners VIII, L.P.
By its general partner, G.F.W. Energy VIII, L.P.
By its general partner, GFW VIII, L.L.C.
By:	/s/ Kenneth A. Hersh Kenneth A. Hersh
	Authorized Member
ERH NGP 7 SPV, LLLC
By:	/s/ Kenneth A. Hersh Kenneth A. Hersh
	Chief Executive Officer & President
ERH NGP 8 SPV, LLC
By:	/s/ Kenneth A. Hersh Kenneth A. Hersh
	Chief Executive Officer & President
/s/ Kenneth A. Hersh
Kenneth A. Hersh