The Partnership makes estimates and assumptions that affect the reported amounts of assets and liabilities at the balance sheet dates, including fair value measurements, the reported amounts of revenues and expenses and the disclosure of commitments and contingencies. Although management believes these estimates are reasonable, actual results could differ from its estimates.

The unaudited condensed consolidated financial statements contained in this report include the assets, liabilities and results of operations of SMLP and its subsidiaries. All intercompany transactions among the consolidated entities have been eliminated in consolidation. Comprehensive income or loss is the same as net income or loss for all periods presented.

There have been no changes to the Partnership’s significant accounting policies since December 31, 2022.2023.

During the quarterly period ended March 31, 20232024, the Partnership recognized a total gain on the disposition of Summit Utica of $212.5 million based on total cash proceeds received of $625.0 million and net assets sold of $412.5 million. A portion of the cash proceeds was used to reduce amounts outstanding under the provisional purchase accounting measurements initially recorded in December 2022ABL Facility (see Note 8 - Debt, for the Outrigger DJ acquisition. The provisional measurementsadditional information) and are subject to change duringfinal working capital adjustments.

The following table presents estimated revenue expected to be recognized during the remainder of 20232024 and over the remaining contract period related to performance obligations that are unsatisfied and are comprised of estimated minimum volume commitments.MVC shortfall payments.

Details on the Partnership’s property, plant and equipment follow.

Depreciation expense and capitalized interest for the Partnership follow.

TheAs of March 31, 2024, the Partnership has an equity method investmentsinvestment in Double E, and Ohio Gathering, the balancesbalance of which areis included in the Investment in equity method investees caption on the unaudited condensed consolidated balance sheets. On March 22, 2024, in connection with the Utica Sale, the Partnership sold its investment in Ohio Gathering and recognized an estimated $126.3 million gain, which is recorded within Gain on sale of equity method investment within the unaudited condensed consolidated statements of operations. See Note 3 - Divestitures for additional information.

Details of the Partnership’s equity method investments follow.

Certain of the Partnership’s gathering and/or processing agreements provide for monthly or annual MVCs. The amount of the shortfall payment is based on the difference between the actual throughput volume shipped and/or processed for the applicable period and the MVC for the applicable period, multiplied by the applicable gathering or processing fee.

Many of the Partnership’s gas gathering agreements contain provisions that can reduce or delay the cash flows that it expects to receive from MVCs to the extent that a customer's actual throughput volumes are above or below its MVC for the applicable contracted measurement period.

The balances in deferred revenue as of March 31, 20232024 and December 31, 20222023 are primarily related to contributions in aid of construction which will be recognized as revenue over the life of the contract.

An update of noncurrent deferred revenue follows.

Debt for the Partnership at March 31, 20232024 and December 31, 2022,2023, follows:

The ABL Facility will mature on May 1, 2026; provided that (a) if the outstanding amount of the 2025 Senior Notes (or any permitted refinancing indebtedness in respect thereof that has a final maturity, scheduled amortization or any other scheduled

repayment, mandatory prepayment, mandatory redemption or sinking fund obligation prior to the date that is 120 days after the Termination Date (as defined in the ABL Agreement)) on such date equals or exceeds $50.0 million, then the ABL Facility will mature on December 13, 2024. As of March 31, 2024, and (b) if both (i) any amountthe outstanding balance of the 2025 Senior Notes (or any permitted refinancing indebtedness in respect thereof that has a final maturity, scheduled amortization or any other scheduled repayment, mandatory prepayment, mandatory redemption or sinking fund obligation prior to the date that is 120 days after the Termination Date) is outstanding on such date and (ii) Liquidity (as defined in the ABL Agreement) is less than an amount equal to the sum of the then aggregate outstanding principal amount of the 2025 Senior Notes (or any permitted refinancing indebtedness in respect thereof that has a final maturity, scheduled amortization or any other scheduled repayment, mandatory prepayment, mandatory redemption or sinking fund obligation prior to the date that is 120 days after the Termination Date) plus the Threshold Amount (as defined in the ABL Agreement) on such date, then the ABL Facility will mature on January 14, 2025.was $49.8 million.

As of March 31, 2023,2024, the applicable margin under the adjusted LIBORSOFR borrowings was 3.50%3.25%, the interest rate was 8.42%8.69% and the available borrowing capacity of the ABL Facility totaled $78.7$383.7 million after giving effect to the issuance of $4.3 million in outstanding but undrawn irrevocable standby letters of credit.credit and $12.0 million of commitment reserves.

The ABL Facility also requires that Summit Holdings not permit (i) the First Lien Net Leverage Ratio (as defined in the ABL Agreement) as of the last day of any fiscal quarter to be greater than 2.50:1.00, or (ii) the Interest Coverage Ratio (as defined in the ABL Agreement) as of the last day of any fiscal quarter to be less than 2.00:1.00. As of March 31, 2023,2024, the First Lien Net

As of March 31, 2023,2024, the applicable margin under adjusted LIBORterm SOFR borrowings was 2.375%2.475%, the average interest rate was 6.76%7.79% and the unused portion of the Permian Transmission Credit Facilities totaled $4.5 million, subject to a commitment fee of 0.7% after giving effect to the issuance of $10.5 million in outstanding but undrawn irrevocable standby letters of credit. Summit Permian Transmission, LLC entered into interest rate hedges with notional amounts representing approximately 90% of the Permian Term Loan facility at a fixed LIBORSOFR rate of 1.49%1.23%. As of March 31, 2023,2024, the Partnership was in compliance with the financial covenants of the Permian Transmission Credit Facilities.

The 2026 Secured Notes are effectively subordinated to any of our or the guarantors’ current and future secured first lien indebtedness, including indebtedness incurred under the ABL Facility, to the extent of the value of the collateral securing such

indebtedness, and our and the guarantors’ current and future debt that is secured by liens on assets other than the collateral, to the extent of the value of such assets. The 2026 Secured Notes are structurally subordinated to all indebtedness and other liabilities of our subsidiaries that do not guarantee the 2026 Secured Notes. The 2026 Secured Notes are effectively equal to our and the guarantors’ obligations under any future second lien indebtedness and effectively senior to all of our future junior lien indebtedness and existing and future unsecured indebtedness, including our outstanding senior unsecured notes, to the extent of the value of the collateral, and senior to any of our future subordinated indebtedness. The 2026 Secured Notes will mature on October 15, 2026.

BeforeAt any time prior to October 15, 2023, the Co-Issuers may redeemcould have on any one or more occasions redeemed up to 35% of the aggregate principal amount of the 2026 Secured Notes in whole or in part,(including any additional notes) issued under the 2026 Secured Notes Indenture at a redemption price equal to 100% of their108.5% of the principal amount of the 2026 Secured Notes, plus a make-whole premium, together with accrued and unpaid interest, if any, to, but not including the redemption date.date, in an amount not greater than the net cash proceeds of certain equity offerings by the Partnership, provided that: (i) at least 65% of the initial aggregate principal amount of the 2026 Secured Notes (including any additional notes) remains outstanding immediately after the occurrence of such redemption (excluding notes held by the Partnership and its subsidiaries); and (ii) the redemption occurs within 180 days of the date of the closing of each such equity offering by the Partnership. On and after October 15, 2023, the Co-Issuers may redeem all or part of the 2026 Secured Notes at redemption prices (expressed as percentages of principal amount) equal to: (a) 104.250% for the twelve-month period beginning October 15, 2023; (b) 102.125% for the twelve-month period beginning October 15, 2024; and (c) 100.000% for the twelve-month period beginning on October 15, 2025 and at any time thereafter, in each case plus accrued and unpaid interest, if any, to, but not including the redemption date. As of March 31, 2023,2024, the Partnership was in compliance with the financial covenants governing its 2026 Secured Notes.

Starting in the first quarter of 2023 with respect to the fiscal year ended 2022, and continuing annually through the fiscal year ended 2025, the Partnership is required under the terms of the 2026 Secured Notes Indenture to, if it has Excess Cash Flow (as defined in the 2026 Secured Notes Indenture), and subject to its ability to make such an offer under the ABL Facility, offer to purchase an amount of the 2026 Secured Notes, at 100% of the principal amount plus accrued and unpaid interest, equal to

Generally, if the Partnership does not offer to purchase designated annual amounts of its 2026 Secured Notes or reduce its first lien capacity under the 2026 Secured Notes Indenture per annum from 2023 through 2025, the interest rate on the 2026 Secured Notes is subject to certain rate escalations. Per the terms of the 2026 Secured Notes Indenture, the designated amounts are to offer to purchase $50.0 million aggregate principal amount of the 2026 Secured Notes by April 1, 2023, otherwise the interest rate shall automatically increase by 50 basis points per annum; $100.0 million aggregate principal amount of the 2026 Secured Notes by April 1, 2024, otherwise the interest rate shall automatically increase by 100 basis points per annum (minus any amount previously increased); and $200.0 million aggregate principal amount of the 2026 Secured Notes by April 1, 2025, otherwise the interest rate shall automatically increase by 200 basis points per annum (minus any amount previously increased).

Based on the amount of the Partnership’sour Excess Cash Flow for the fiscal year ended 2022,2023, on March 27, 2024, the Partnership wascommenced a cash tender offer to purchase up to $19.3 million aggregate principal amount of the outstanding 2026 Secured Notes at 100% of the principal amount plus accrued and unpaid interest. The cash flow offer expired on April 24, 2024 with $13.6 million tendered and validly accepted. Accordingly, $13.6 million of the 2026 Secured Notes is reflected as current debt in the March 31, 2024 unaudited condensed consolidated balance sheet.

As of April 1, 2024, the Partnership had not able to makemade offers to purchase in the designatedrequired amount for the fiscal year ended 2022; as a result,of $100.0 million and the interest rate on the 2026 Secured Notes increased an incremental 50 basis points to 9.00%9.50% effective with the first payment on April 1, 2023.such date.

To the extent the Partnership makes an offer to purchase, and the offer is not fully accepted by the holders of the 2026 Secured Notes, the Partnership may use any remaining amount not accepted for any purpose not prohibited by the 2026 Secured Notes Indenture or the ABL Facility.

The Co-Issuers have the right to redeem all or part of the 2025 Senior Notes at a redemption price of 101.438% (with the redemption price declining ratably each year to 100.00% on April 15, 2023), plus accrued and unpaid interest, if any, to, but not including the redemption date.

As discussed above, in November, 2023, the Partnership exchanged $180.0 million aggregate principal amount of the 2025 Senior Notes and repurchased $29.7 million aggregate principal amount of the remaining 2025 Senior Notes that were not exchanged.

As of March 31, 2023,2024, the Partnership was in compliance with the financial covenants governing itsof the 2025 Senior Notes. The 2025 Senior Notes will mature on April 15, 2025.

The carrying values on the balance sheets of the ABL Facility and Permian Transmission Term Loan representsrepresent their fair value due to their floating interest rates. The fair values of the 2026 Unsecured Notes, 2026 Secured Notes and 2025 Senior Notes are based on an average of nonbinding broker quotes as of March 31, 20232024 and December 31, 2022.2023. The use of different market assumptions or valuation methodologies may have a material effect on their estimated fair value.value of the Senior Notes.

transactions are entered into, and the Partnership actively monitors the creditworthiness where applicable. However, there can be no assurance that a counterparty will be able to meet its obligations to the Partnership. The Partnership presents its derivative positions on a gross basis and does not net the asset and liability positions.

As of March 31, 20232024 and December 31, 2022,2023, the Partnership’s interest rate swap agreements had a fair value of $12.8$13.2 million and $15.2$11.9 million, respectively, and are recorded within other noncurrent assets within the unaudited condensed consolidated balance sheets. The derivative instruments’ fair value are determined using level 2 inputs from the fair value hierarchy. For the three months ended March 31, 2024 and 2023, the CompanyPartnership recorded a gain on interest rate swaps of $2.6 million and a loss on interest rate swaps of $1.3 million.million, respectively.

As of March 31, 2023,2024, the Partnership had 93,039 Subsidiary Series A Preferred Units issued and outstanding.

If the Subsidiary Series A Preferred Units were redeemed on March 31, 2023,2024, the redemption amount would be $121.2$127.1 million when considering the applicable multiple of invested capital metric and make-whole amount provisions contained in the Subsidiary Series A Preferred Unit agreement.Amended and Restated Limited Liability Company Agreement of Permian Holdco.

The following table shows the change in ourthe Partnership’s Subsidiary Series A Preferred Unit balance from January 1, 20232024 to March 31, 2023,2024, net of $2.1$1.6 million and $2.2$1.7 million of unamortized issuance costs at March 31, 20232024 and December 31, 2022,2023, respectively:

The following table details the components of EPU.

As of March 31, 2023,2024, the Partnership has recognized (i) a current liability for remediation effort expenditures expected to be incurred within the next 12 months and (ii) a noncurrent liability for estimated remediation expenditures expected to be incurred subsequent to March 31, 2024.2025. Each of these amounts represent the Partnership’s best estimate for costs expected to be incurred. Neither of these amounts have been discounted to their present value.

An update of the Partnership’s undiscounted accrued environmental remediation is as follows and is primarily related to the 2015 Blacktail Release and other environmental remediation activities, as detailed below.

In 2015, the Partnership learned of the rupture of a four-inch produced water gathering pipeline on the Meadowlark Midstream system near Williston, North Dakota (“2015 Blacktail Release”). On August 4, 2021, subsidiaries of the Partnership entered into the following agreements to resolve the U.S. federal and North Dakota state governments’ environmental claims with respect to the 2015 Blacktail Release: (i) a Consent Decree with the U.S. Department of Justice (“DOJ”), the U.S. Environmental Protection Agency (“EPA”), and the State of North Dakota (“Consent Decree”); (ii) a Plea Agreement with the United States (“Plea Agreement”); and (iii) a Consent Agreement with the North Dakota Industrial Commission (“Consent Agreement” together with the Consent Decree and Plea Agreement, the “Global Settlement”). As of March 31, 20232024 and December 31, 2022,2023, the accrued loss liability for the 2015 Blacktail Release was $28.3$21.7 million and are recorded within Other noncurrent liabilities and Accrued settlement payable within the unaudited condensed consolidated balance sheets.

Key terms of the Global Settlement included (i) payment of penalties and fines totaling $36.3 million, consisting of $1.25 million in natural resource damages payable to federal and state governments, a $25.0 million payable to the federal government over 5 years, and a $10.0 million payable to state governments over, for the federal and state civil amounts, six years and, for the federal criminal amounts, five years, with interest applied to unpaid amounts accruing at, for the federal and state civil amounts, a fixed rate of 3.25%, and, for the federal criminal amounts, a variable rate set by statute, and of which $6.7 million is expected to be paid within the next twelve months; (ii) continuation of remediation efforts at the site of the 2015 Blacktail Release; (iii) other injunctive relief including but not limited to control room management, environmental management system audit, training, and reporting; (iv) guilty pleas by Defendant subsidiary for (a) one charge of negligent

discharge of a harmful quantity of oil and (b) one charge of knowing failure to immediately report a discharge of oil; and (v) organizational probation for a minimum period of three years from sentencing on December 6, 2021, including payment in full of certain components of the fines and penalty amounts. The agreements comprising the Global Settlement were subject to the approval of the U.S. District Court for the District of North Dakota (the “U.S. District Court”). The U.S. District Court entered an order making the civil components of the Global Settlement effective on September 28, 2021 and accepted the sentencing in the Plea Agreement on December 6, 2021, completing approval of the Global Settlement.

As of March 31, 2023,2024, the Partnership’s reportable segments are:

Corporate and Other represents those results that: (i) are not specifically attributable to a reportable segment; (ii) are not individually reportable; or (iii) have not been allocated to aour reportable segment for the purpose of evaluating their performance,segments, including certain general and administrative expense items, transaction costs, acquisition integration costs and transaction costs.interest expense.