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| R            | QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934                                                                                                                                                                                                                                                                          |
|--------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
|         |                                                                                                                                                                                                                                                                                                                                                                  |
|         | For the quarterly period ended March 31, 2011                                                                                                                                                                                                                                                                                                                         |
|         |                                                                                                                                                                                                                                                                                                                                                                  |
|         | OR                                                                                                                                                                                                                                                                                                                                                                    |
|  £ |  TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934                                                                                                                                                                                                                                                                   |
|         |                                                                                                                                                                                                                                                                                                                                                                  |
|         | For the transition period from                                                       to |

| Delaware                                 | 63-0196650          |
|------------------------------------------|---------------------|
| (State or Other Jurisdiction             | (I.R.S. Employer    |
| of Incorporation or Organization)        | Identification No.) |
|                                     |                |
| El Paso Building                    |                |
| 1001 Louisiana Street                    |                |
| Houston, Texas                           | 77002               |
| (Address of Principal Executive Offices) | (Zip Code)          |

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TABLE OF CONTENTS

| Caption                              | Page                                                                                              |
|-------------------------------------------|--------------------------------------------------------------------------------------------------------|
| PART I — Financial Information |                                                                                                   |
|                                      |                                                                                                   |   |
| Item  1.                        | Financial Statements                                                                                   |   1 |
| Item  2.                        | Management’s Discussion and Analysis of Financial Condition and  Results of Operations |   8 |
| Item  3.                        | Quantitative and Qualitative Disclosures About Market Risk                                        | 12 |
| Item  4.                        | Controls and Procedures                                                                                | 12 |
|                                      |                                                                                                   |   |
| PART II — Other Information    |                                                                                                   |
|                                      |                                                                                                   |   |
| Item  1.                        | Legal Proceedings                                                                                      | 13 |
| Item  1A.                       | Risk Factors                                                                                           | 13 |
| Item  2.                        | Unregistered Sales of Equity Securities and Use of Proceeds                                            | 13 |
| Item  3.                        | Defaults Upon Senior Securities                                                                        | 13 |
| Item  4.                        | (Removed and Reserved)                                                                                 | 13 |
| Item  5.                        | Other Information                                                                                      | 13 |
| Item  6.                        | Exhibits                                                                                               | 14 |
|                                      | Signatures                                                                                             | 15 |

|   | Below is a list of terms that are common to our industry and used throughout this document:                                                                       |
|--------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
|   |                                                                                                                                                                   |
|   |                                                                                                                                                                   |
|   | /d = per day                                                                                                                                                 | BBtu = billion British thermal units |
|   |                                                                                                                                                                   |
|   | When we refer to “us”, “we”, “our”, or “ours”, we are describing Southern Natural Gas Company and/or our subsidiaries. |

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Table of Contents

PART I — FINANCIAL INFORMATION

Item 1. Financial Statements

|                                        |   | Quarter EndedMarch 31, |    |
|--------------------------------------------------|--------|-----------------------------|---------|
|                                             |   | 2011                        |    |   | 2010 |   |
|                                             |   |                        |    |   |   |   |   |   |
| Operating revenues                               |   | $                           | 145     |   |   | $ | 145 |   |
|                                             |   |                        |    |   |   |   |   |   |
| Operating expenses                               |   |                        |    |   |   |   |   |   |
|    Operation and maintenance      |   |                        | 34      |   |   |   | 37 |   |
|    Depreciation and amortization  |   |                        | 15      |   |   |   | 15 |   |
|    Taxes, other than income taxes |   |                        | 8       |   |   |   | 7 |   |
|                                             |   |                        | 57      |   |   |   | 59 |   |
| Operating income                                 |   |                        | 88      |   |   |   | 86 |   |
| Earnings from unconsolidated affiliate           |   |                        | 4       |   |   |   | 4 |   |
| Other income, net                                |   |                        | 2       |   |   |   | 1 |   |
| Interest and debt expense                        |   |                        | (16     | ) |   |   | (16 | ) |
| Affiliated interest income, net                  |   |                        | — |   |   |   | 1 |   |
| Net income                                       |   | $                           | 78      |   |   | $ | 76 |   |

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|                                                                                            |   | March 31,2011 |    |   | December 31,2010 |   |
|------------------------------------------------------------------------------------------------------|--------|---------------|---------|--------|-----------------------|--------|
| ASSETS                                                                                               |   |
| Current assets                                                                                       |   |          |    |   |                  |   |
|    Cash and cash equivalents                                                          |   | $             | 6       |   |                  | $      | 4 |   |
|    Accounts and note receivable                                                       |   |          |    |   |                  |   |   |   |
|          Customer                                       |   |          | 10      |   |                  |   | 3 |   |
|          Affiliates                                     |   |          | 2       |   |                  |   | — |   |
|          Other                                          |   |          | 21      |   |                  |   | 26 |   |
|    Materials and supplies                                                             |   |          | 16      |   |                  |   | 16 |   |
|    Regulatory assets                                                                  |   |          | 18      |   |                  |   | 14 |   |
|           Total current assets                     |   |          | 73      |   |                  |   | 63 |   |
| Property, plant and equipment, at cost                                                               |   |          | 3,903   |   |                  |   | 3,885 |   |
|    Less accumulated depreciation and amortization                                     |   |          | 1,385   |   |                  |   | 1,390 |   |
|           Total property, plant and equipment, net |   |          | 2,518   |   |                  |   | 2,495 |   |
| Other assets                                                                                         |   |          |    |   |                  |   |   |   |
|    Investment in unconsolidated affiliate                                             |   |          | 59      |   |                  |   | 56 |   |
|    Other                                                                              |   |          | 73      |   |                  |   | 73 |   |
|                                                                                                 |   |          | 132     |   |                  |   | 129 |   |
|           Total assets                             |   | $             | 2,723   |   |                  | $      | 2,687 |   |
|                                                                                                 |   |          |    |   |                  |   |   |   |
| LIABILITIES AND PARTNERS’ CAPITAL                                                              |   |
| Current liabilities                                                                                  |   |          |    |   |                  |   |   |   |
|    Accounts and note payable                                                          |   |          |    |   |                  |   |   |   |
|          Trade                                          |   | $             | 20      |   |                  | $      | 25 |   |
|          Affiliates                                     |   |          | 12      |   |                  |   | 28 |   |
|          Other                                          |   |          | 35      |   |                  |   | 31 |   |
|    Taxes payable                                                                      |   |          | 7       |   |                  |   | 13 |   |
|    Accrued interest                                                                   |   |          | 18      |   |                  |   | 18 |   |
|  Contractual deposits                                                                           |   |          | 9       |   |                  |   | 6 |   |
|    Asset retirement obligations                                                       |   |          | — |   |                  |   | 1 |   |
|           Total current liabilities                |   |          | 101     |   |                  |   | 122 |   |
| Long-term debt                                                                                       |   |          | 910     |   |                  |   | 910 |   |
| Other liabilities                                                                                    |   |          | 32      |   |                  |   | 31 |   |
|                                                                                                 |   |          |    |   |                  |   |   |   |
| Commitments and contingencies (Note 4)                                                               |   |          |    |   |                  |   |   |   |
| Partners’ capital                                                                              |   |          | 1,680   |   |                  |   | 1,624 |   |
| Total liabilities and partners’ capital                                                        |   | $             | 2,723   |   |                  | $      | 2,687 |   |

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|                                                                                                                     |   | Quarter EndedMarch 31, |    |
|-------------------------------------------------------------------------------------------------------------------------------|--------|-----------------------------|---------|
|                                                                                                                          |   | 2011                        |    |   | 2010 |   |
| Cash flows from operating activities                                                                                          |   |                        |    |   |   |   |
|    Net income                                                                                                  |   | $                           | 78      |   |   | $ | 76 |   |
|    Adjustments to reconcile net income to net cash from operating activities                                   |   |                        |    |   |   |   |   |   |
|       Depreciation and amortization                                                             |   |                        | 15      |   |   |   | 15 |   |
|       Earnings from unconsolidated affiliate, adjusted for cash distributions                   |   |                        | (3      | ) |   |   | (1 | ) |
|       Other non-cash income items                                                               |   |                        | (1      | ) |   |   | — |   |
|       Asset and liability changes                                                               |   |                        | (1      | ) |   |   | 2 |   |
|               Net cash provided by operating activities |   |                        | 88      |   |   |   | 92 |   |
|                                                                                                                          |   |                        |    |   |   |   |   |   |
| Cash flows from investing activities                                                                                          |   |                        |    |   |   |   |   |   |
|    Capital expenditures                                                                                        |   |                        | (51     | ) |   |   | (18 | ) |
|    Net change in note receivable from affiliate                                                                |   |                        | (4      | ) |   |   | 23 |   |
| Acquisition                                                                                                                   |   |                        | — |   |   |   | (18 | ) |
| Proceeds from the sale of assets                                                                                              |   |                        | — |   |   |   | 8 |   |
| Other                                                                                                                         |   |                        | 3       |   |   |   | — |   |
|               Net cash used in investing activities     |   |                        | (52     | ) |   |   | (5 | ) |
|                                                                                                                          |   |                        |    |   |   |   |   |   |
| Cash flows from financing activities                                                                                          |   |                        |    |   |   |   |   |   |
| Net change in note payable to affiliate                                                                                       |   |                        | (12     | ) |   |   | — |   |
|    Contributions from partners                                                                                 |   |                        | 25      |   |   |   | — |   |
|    Distributions to partners                                                                                   |   |                        | (47     | ) |   |   | (83 | ) |
|               Net cash used in financing activities     |   |                        | (34     | ) |   |   | (83 | ) |
|                                                                                                                          |   |                        |    |   |   |   |   |   |
| Net change in cash and cash equivalents                                                                                       |   |                        | 2       |   |   |   | 4 |   |
| Cash and cash equivalents                                                                                                     |   |                        |    |   |   |   |   |   |
|    Beginning of period                                                                                         |   |                        | 4       |   |   |   | — |   |
|    End of period                                                                                               |   | $                           | 6       |   |   | $ | 4 |   |

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|           |   | March 31, 2011 |   |   | December 31, 2010 |   |
|----------------|--------|----------------|--------|--------|-------------------|--------|
|      |   | CarryingAmount |   |   | FairValue         |   |   | CarryingAmount |   |   | FairValue |   |
|           |   | (In millions)  |   |
| Long-term debt |   | $              | 910    |   |              | $      | 1,031 |   |   | $ | 910 |   |   | $ | 984 |   |

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|                                                                        |   | Quarter EndedMarch 31, |    |
|-----------------------------------------------------------------------------|--------|------------------------|---------|
|                                                                        |   | 2011                   |    |   | 2010 |   |
|                                                                        |   | (In millions)          |    |
| Accounts receivable sold to the third-party financial institution (1)  |   | $                      | 162     |   |   | $ | 146 |   |
| Cash received for accounts receivable sold under the program                |   |                   | 96      |   |   |   | 123 |   |
| Deferred purchase price related to accounts receivable sold                 |   |                   | 66      |   |   |   | 23 |   |
| Cash received related to the deferred purchase price                        |   |                   | 73      |   |   |   | 57 |   |
| Amount paid in conjunction with terminated program (2)                 |   |                   | — |   |   |   | 30 |   |

|                                                                        |   | March 31,     |   |   | December 31, |   |
|-----------------------------------------------------------------------------|--------|---------------|--------|--------|--------------|--------|
|                                                                        |   | 2011          |   |   | 2010         |   |
|                                                                        |   | (In millions) |   |
| Accounts receivable sold and held by third-party financial institution      |   | $             | 50     |   |         | $      | 56 |   |
| Uncollected deferred purchase price related to accounts receivable sold (1) |   |          | 19     |   |         |   | 26 |   |

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|                                                               |   | 2011          |   |   | 2010   |   |
|--------------------------------------------------------------------|--------|---------------|--------|--------|--------|--------|
|                                                               |   | (In millions) |   |
| Operating results data:                                            |   |          |   |   |   |   |
|    Operating revenues                               |   | $             | 5      |   |   | $      | 5 |   |
|    Operating expenses                               |   |          | 1      |   |   |   | 1 |   |
|    Income from continuing operations and net income |   |          | 4      |   |   |   | 4 |   |

|                                 |   | 2011          |   |   | 2010   |   |
|--------------------------------------|--------|---------------|--------|--------|--------|--------|
|                                 |   | (In millions) |   |
| Revenues                             |   | $             | 2      |   |   | $      | 2 |   |
| Operation and maintenance expenses   |   |          | 27     |   |   |   | 30 |   |
| Reimbursements of operating expenses |   |          | 1      |   |   |   | 1 |   |

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Item 2. Management’s Discussion and Analysis of Financial Condition andResults of Operations

|                                   |   | 2011                             |    |   |  2010 |   |
|----------------------------------------|--------|----------------------------------|---------|--------|------------|--------|
|                                   |   | (In millions,except for volumes) |    |
|                                   |
| Operating revenues                     |   | $                                | 145     |   |       | $      | 145 |   |
| Operating expenses                     |   |                             | (57     | )      |       |   | (59 | ) |
|    Operating income     |   |                             | 88      |   |       |   | 86 |   |
| Earnings from unconsolidated affiliate |   |                             | 4       |   |       |   | 4 |   |
| Other income, net                      |   |                             | 2       |   |       |   | 1 |   |
|    Segment EBIT         |   |                             | 94      |   |       |   | 91 |   |
| Interest and debt expense              |   |                             | (16     | )      |       |   | (16 | ) |
| Affiliated interest income, net        |   |                             | — |   |       |   | 1 |   |
|    Net income           |   | $                                | 78      |   |       | $      | 76 |   |
| Throughput volumes (BBtu/d)(1)    |   |                             | 2,632   |   |       |   | 2,899 |   |

|                                              |   | Variance                |    |
|---------------------------------------------------|--------|-------------------------|---------|
|                                              |   | Operating               |    |   | Operating |   |   |   |   |   |   |   |
|                                              |   | Revenue                 |    |   | Expense |   |   | Other |   |   | Total |   |
|                                              |   | Favorable/(Unfavorable) |    |
|                                              |   | (In millions)           |    |
| Expansion                                         |   | $                       | 5       |   |   | $ | — |   |   | $ | 1 |   |   | $ | 6 |   |
| Reservation and other service revenues            |   |                    | (5      | ) |   |   | — |   |   |   | — |   |   |   | (5 | ) |
| Operating and general and administrative expenses |   |                    | — |   |   |   | 2 |   |   |   | — |   |   |   | 2 |   |
| Total impact on Segment EBIT                      |   | $                       | — |   |   | $ | 2 |   |   | $ | 1 |   |   | $ |  3 |   |

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|                             |   | 2011                            |    |   |  2010 |   |
|----------------------------------|--------|---------------------------------|---------|--------|------------|--------|
|                             |   | (In millions, except for rates) |    |   |
| Average advance due from El Paso |   | $                               | — |   |       | $      | 137 |   |
| Average advance due to EPB       |   |                            | 10      |   |       |   | — |   |
| Average short-term interest rate |   |                            | 0.8     | %      |       |   | 1.5 | % |

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|                                         |   |   |   |
|----------------------------------------------|--------|--------|--------|
| Cash Flow from Operations                    |   |   |   |
| Net income                                   |   | $      | 78     |   |
| Non-cash income adjustments                  |   |   | 11     |   |
| Change in assets and liabilities             |   |   | (1     | ) |
| Total cash flow from operations              |   |   | 88     |   |
|                                         |   |   |   |   |
| Other Cash Inflows                           |   |   |   |   |
| Investing activities                         |   |   |   |   |
| Other                                        |   |   | 3      |   |
|                                         |   |   |   |   |
| Financing activities                         |   |   |   |   |
| Contributions from partners                  |   |   | 25     |   |
|                                         |   |   |   |   |
| Total other cash inflows other cash inflows  |   |   | 28     |   |
|                                         |   |   |   |   |
| Cash Outflows                                |   |   |   |   |
| Investing activities                         |   |   |   |   |
| Capital expenditures                         |   |   | 51     |   |
| Net change in note receivable from affiliate |   |   | 4      |   |
|                                         |   |   | 55     |   |
| Financing activities                         |   |   |   |   |
| Net change in note payable to affiliate      |   |   | 12     |   |
| Distributions to partners                    |   |   | 47     |   |
|                                         |   |   | 59     |   |
|                                         |   |   |   |   |
| Total cash outflows                          |   |   | 114    |   |
| Net change in cash and cash equivalents      |   | $      | 2      |   |

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|    |   | Quarter EndedMarch 31, 2011 |   |   | 2011Remaining |   |   | Total  |   |
|--------------|--------|-----------------------------|--------|--------|---------------|--------|--------|--------|--------|
|         |   | (In millions)               |   |
| Expansion    |   | $                           | 40     |   |          | $      | 94     |   |   | $ | 134 |   |
| Maintenance  |   |                        | 11     |   |          |   | 53     |   |   |   | 64 |   |
|         |   | $                           | 51     |   |          | $      | 147    |   |   | $ | 198 |   |

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Item 3. Quantitative and Qualitative Disclosures About Market Risk

Item 4. Controls and Procedures

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PART II — OTHER INFORMATION

Item 1. Legal Proceedings

Item 1A. Risk Factors

Item 2. Unregistered Sales of Equity Securities and Use of Proceeds

Item 3. Defaults Upon Senior Securities

Item 4. (Removed and Reserved)

Item 5. Other Information

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Item 6. Exhibits

| •         | should not in all instances be treated as categorical statements of fact, but rather as a way of allocating the risk to one of the parties if those statements prove to be inaccurate;                     |
|---------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
|                      |                                                                                                                                                                                                       |
| •         | may have been qualified by disclosures that were made to the other party in connection with the negotiation of the applicable agreement, which disclosures are not necessarily reflected in the agreement; |
|                      |                                                                                                                                                                                                       |
| •         | may apply standards of materiality in a way that is different from what may be viewed as material to certain investors; and                                                                           |
|                      |                                                                                                                                                                                                       |
|  •   | were made only as of the date of the applicable agreement or such other date or dates as may be specified in the agreement and are subject to more recent developments.                                    |

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SIGNATURES

|                                | SOUTHERN NATURAL GAS COMPANY                                                                 |   |
|-------------------------------------|----------------------------------------------------------------------------------------------|--------|
|                                |                                                                                         |   |
|                                |                                                                                         |   |
|                                |                                                                                         |   |
| Date: May 6, 2011                   |  /s/ Norman G. Holmes                                                                   |   |
|                                | Norman G. HolmesPresident(Principal Executive Officer)                                       |   |
|                                |                                                                                         |   |
|                                |                                                                                         |   |
|                                |                                                                                         |   |
|                                |                                                                                         |   |
| Date: May 6, 2011    |  /s/ John R. Sult                                                                       |   |
|                                | John R. SultExecutive Vice President andChief Financial Officer(Principal Financial Officer) |   |
|                                |                                                                                         |   |
|                                |                                                                                         |   |

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| ExhibitNumber |  Description  |
|---------------|-------------------------|
|          | 3.A                     |   | Fifth Amendment to General Partnership Agreement of Southern Natural Gas Company, dated March 14, 2011.  |
|  *       | 12                      |   | Ratio of Earnings to Fixed Charges. |
|          | 31.A                    |   | Certification of Principal Executive Officer pursuant to Section 302 of the Sarbanes-Oxley Act of 2002. |
|          | 31.B                    |   | Certification of Chief Financial Officer pursuant to Section 302 of the Sarbanes-Oxley Act of 2002. |
|          | 32.A                    |   | Certification of Principal Executive Officer pursuant to Section 906 of the Sarbanes-Oxley Act of 2002. |
|          | 32.B                    |   | Certification of Chief Financial Officer pursuant to Section 906 of the Sarbanes-Oxley Act of 2002. |

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