Exhibit 99.5

SUMMIT MIDSTREAM PARTNERS, LP

UNAUDITED PRO FORMA CONDENSED COMBINED FINANCIAL INFORMATION

AS OF MARCH 31, 2013 AND FOR THE THREE MONTHS ENDED MARCH 31, 2013 AND

THE YEAR ENDED DECEMBER 31, 2012

Throughout this report, when we use the terms “we,” “us,” “SMLP,” or “the Partnership” we are referring to Summit Midstream Partners, LP, the partnership itself or to Summit Midstream Partners, LP and its subsidiaries collectively as the context requires.

Set forth below are our unaudited pro forma condensed combined financial statements as of and for the three months ended March 31, 2013 and for the year ended December 31, 2012 which reflect SMLP’s acquisition of the Bison Gas Gathering System from Summit Midstream Partners, LLC (“Summit Investments”) on June 4, 2013 (the “Bison Acquisition”) and our issuance of $300.0 million of new senior unsecured notes (the “Offering”).

The Bison Gas Gathering System was carved out from Summit Investments’ recent acquisition of Bear Tracker Energy, LLC (“BTE”) which closed on February 15, 2013.  Summit Investments accounted for its acquisition of BTE using the acquisition method of accounting.

The proceeds from the Offering are intended to repay borrowings under our revolving credit facility.

The unaudited pro forma condensed combined balance sheet as of March 31, 2013 and the unaudited pro forma condensed combined statement of operations for the three months ended March 31, 2013 were derived from the unaudited condensed consolidated financial statements of SMLP for the three months ended March 31, 2013 and the unaudited condensed financial statements of the Bison Gas Gathering System for the periods from January 1, 2013 through February 15, 2013 and February 16, 2013 through March 31, 2013.  The unaudited pro forma condensed combined statement of operations for the year ended December 31, 2012 was derived from the SMLP audited consolidated financial statements and the audited carve-out financial statements of the Bison Gas Gathering System for the year ended December 31, 2012. The pro forma financial statements do not include any historical or pro forma impacts of our pending acquisition of the Mountaineer Midstream System.

The unaudited pro forma condensed combined balance sheet reflects the Bison Acquisition and the Offering as if such transactions closed as of March 31, 2013 and the unaudited pro forma condensed combined statements of operations reflect the Bison Acquisition and the Offering as if such transactions had occurred as of January 1, 2012. Descriptions of the adjustments for the Bison Acquisition are presented in the notes to the unaudited pro forma condensed combined financial statements. The unaudited pro forma condensed combined financial statements and accompanying notes should be read in conjunction with SMLP’s historical financial statements filed with the Securities and Exchange Commission and included elsewhere in this offering memorandum.

The unaudited pro forma condensed combined balance sheet and the unaudited pro forma condensed combined statements of operations were derived by adjusting the historical financial statements of each entity based on currently available information and, therefore, the actual adjustments may materially differ from the pro forma adjustments. Because the Bison Acquisition was executed between entities under common control, the Bison Acquisition will be accounted for by SMLP on an “as if pooled” basis for all periods in which common control existed.  Common control began on February 15, 2013 concurrent with Summit Investments’ acquisition of BTE.  The assets acquired and liabilities assumed by SMLP in the Bison Acquisition have been reflected at historical cost.

The unaudited pro forma condensed combined financial statements do not purport to present our financial position or the results of operations had the Bison Acquisition actually been completed as of the dates indicated. Further, these unaudited pro forma condensed combined financial statements do not reflect the effects of any cost savings or other synergies that may be achieved as a result of this transaction, are based on assumptions that SMLP believes are reasonable under the circumstances, and are intended for informational purposes only.  Moreover, the statements do not project our financial position or results of operations for any future date or period.

SUMMIT MIDSTREAM PARTNERS, LP

UNAUDITED PRO FORMA CONDENSED COMBINED BALANCE SHEET

MARCH 31, 2013

The accompanying notes are an integral part of these unaudited pro forma condensed combined financial statements.

SUMMIT MIDSTREAM PARTNERS, LP

UNAUDITED PRO FORMA CONDENSED COMBINED STATEMENT OF OPERATIONS

THREE MONTHS ENDED MARCH 31, 2013

The accompanying notes are an integral part of these unaudited pro forma condensed combined financial statements.

SUMMIT MIDSTREAM PARTNERS, LP

UNAUDITED PRO FORMA CONDENSED COMBINED STATEMENT OF OPERATIONS

YEAR ENDED DECEMBER 31, 2012

The accompanying notes are an integral part of these unaudited pro forma condensed combined financial statements.

SUMMIT MIDSTREAM PARTNERS, LP

NOTES TO UNAUDITED PRO FORMA CONDENSED COMBINED FINANCIAL INFORMATION

AS OF MARCH 31, 2013 AND FOR THE THREE MONTHS ENDED MARCH 31, 2013 AND

THE YEAR ENDED DECEMBER 31, 2012

Pro forma adjustments

(a)  Reflects the total purchase price for Summit Midstream Partners, LP’s acquisition of 100% of the membership interests of Bison Midstream, LLC of $249.8 million, calculated as follows (in thousands):

(1) Number of units calculated using the five-day volume-weighted-average price as of June 3, 2013 of $31.53 per unit.

On February 15, 2013, Summit Investments acquired BTE (the “BTE Transaction”) and on June 4, 2013, SMLP entered into a purchase and sale agreement with Summit Investments to acquire certain associated natural gas gathering pipeline, dehydration and compression assets in the Williston Basin in North Dakota (the “Bison Gas Gathering System”) that were part of the BTE assets acquired in February 2013 (the “Bison Transaction”). The Bison Gas Gathering System was carved out from BTE.

Summit Investments accounted for the BTE Transaction under the acquisition method of accounting, whereby the various gathering systems’ identifiable tangible and intangible assets acquired and liabilities assumed were recorded based on their fair values as of February 15, 2013. The intangible assets that were acquired are composed of gas gathering agreement contract values and right-of-way easements. Their fair values were determined based upon assumptions related to future cash flows, discount rates, asset lives, and projected capital expenditures to complete the various systems.

SMLP acquired Bison at historical cost which is representative of Summit Investments recent fair value accounting for the BTE Transaction. The previous information is included because such basis adjustment will have a continuing effect on SMLP’s financial position and results of operations.

(b)  Reflects borrowings of $200.0 million under our revolving credit facility to partially fund the Bison Acquisition.

(c)  Reflects partner’s capital contribution by Summit Investments for the contribution of assets in excess of consideration paid by SMLP for Bison (in thousands):

The general partner interest allocation was calculated based on a 2% general partner interest in the contribution of assets in excess of consideration given by SMLP to Summit Investments.  Common and subordinated limited partner interests allocations were calculated as their respective percentages of total limited partner capital as of March 31, 2013 applied to the balance of the contribution by Summit Investments after giving effect to the general partner allocation.

(d)  Reflects the issuance of $300.0 million of senior notes, net of related transaction costs and expenses, of which the net proceeds were used to pay down our revolving credit facility.

(e)  Reflects pro forma adjustment of depreciation and amortization expense for the three months ended March 31, 2013 as follows (in thousands):

Depreciation is calculated on a straight-line basis for depreciable assets.  The estimated aggregate annual amortization of intangible assets expected to be recognized as of March 31, 2013 for the remainder of 2013 and each of the four succeeding fiscal years follows (in thousands).

(f)  Reflects a $100.0 million net reduction in principal and as a result, interest expense at 2.96% (i.e. the historical average rate for borrowings under our revolving credit facility during the three months ended March 31, 2013) and assumes that the interest expense impact of the reduced outstanding balance is partially offset by an increase in commitment fee expense (0.50%) for the same principal amount.

(g)  Reflects interest expense for the three months ended March 31, 2013 (assumed at 6.5% annually) associated with the Offering.  Assuming a 1/8% increase (decrease) in interest rates, interest expense would increase (decrease) by approximately $93,750.

(h)  The Company’s pro forma basic weighted-average number of common units outstanding for the three months ended March 31, 2013 and the year ended December 31, 2012 was calculated as follows:

(i)  The Company’s pro forma diluted weighted-average number of common units outstanding for the three months ended March 31, 2013 was calculated as follows:

(j)  Reflects pro forma adjustment of depreciation and amortization expense for contract intangibles. Depreciation is calculated on a straight-line basis for depreciable assets.  The estimated aggregate annual amortization of intangible assets expected to be recognized as of December 31, 2012 for each of the five succeeding fiscal years follows (in thousands).

(k)  Reflects a $100.0 million net reduction in principal and as a result, interest expense at 2.78% (i.e. the historical average rate for borrowings under our revolving credit facility during the year ended December 31, 2012) and assumes that the interest expense impact of the reduced outstanding balance is partially offset by an increase in commitment fee expense (0.50%) for the same principal amount.

(l)  Reflects interest expense for the year ended December 31, 2012 (assumed at 6.5% annually) associated with the Offering. Assuming a 1/8% increase (decrease) in interest rates, interest expense would increase (decrease) by approximately $375,000.

(m)  The Company’s pro forma diluted weighted-average number of common units outstanding for the year ended December 31, 2012 was calculated as follows:

(n)  Reflects amortization of deferred loan costs incurred in connection with the Offering.

(o)  Negative cash remaining after the effects of the Bison Acquisition and the Offering would be off-set with the cash flow from operations and amount drawn on our revolving credit facility in May 2013 that is not reflected herein. SMLP’s cash on hand as of May 31, 2013 was approximately $11.2 million.