----

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|   | x | QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 |
|--------|---|---------------------------------------------------------------------------------------------------|

|   | o | TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 |
|--------|---|----------------------------------------------------------------------------------------------------|

| New Mexico                                                     | 75-0575400                           |
|----------------------------------------------------------------|--------------------------------------|
| (State or other jurisdiction of incorporation or organization) | (I.R.S. Employer Identification No.) |
|                                                           |                                 |
| Tyler at NinthAmarillo, Texas                                  | 79101                                |
| (Address of principal executive offices)                       | (Zip Code)                           |

| Large accelerated filer o                   | Accelerated filer o         |
|---------------------------------------------|-----------------------------|
|                                        |                        |
| Non-accelerated filer x                     | Smaller reporting company o |
| (Do not check if smaller reporting company) |                        |

| Class                      |   | Outstanding at May 2, 2011 |
|----------------------------|--------|---------------------------------|
| Common Stock, $1 par value |   | 100 shares                      |

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TABLE OF CONTENTS

| PART I - FINANCIAL INFORMATION                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                        |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------|
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |                                                                                        |   |
| Item l.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                | Financial Statements (Unaudited)                                                            | 3 |
| Item 2.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                | Management’s Discussion and Analysis of Financial Condition and Results of Operations | 16 |
| Item 4.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                | Controls and Procedures                                                                     | 19 |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |                                                                                        |   |
| PART II - OTHER INFORMATION                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |                                                                                        |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |                                                                                        |   |
| Item 1.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                | Legal Proceedings                                                                           | 19 |
| Item 1A.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               | Risk Factors                                                                                | 19 |
| Item 6.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                | Exhibits                                                                                    | 19 |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |                                                                                        |   |
| SIGNATURES                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       | 20                                                                                          |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |                                                                                        |
| Certifications Pursuant to Section 302                                                                                                                                                        | 1                                                                                           |
| Certifications Pursuant to Section 906                                                                                                                                                        | 1                                                                                           |
| Statement Pursuant to Private Litigation                                                                                                                                                      | 1                                                                                           |

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TABLE OF CONTENTS

|                                                                                   |   | Three Months Ended March 31, |    |
|----------------------------------------------------------------------------------------|--------|------------------------------|---------|
|                                                                                   |   | 2011                         |    |   | 2010 |   |
|                                                                                   |   |                         |    |   |   |   |
| Operating revenues                                                                     |   | $                            | 381,209 |   |   | $ | 381,482 |   |
|                                                                                   |   |                         |    |   |   |   |   |   |
| Operating expenses                                                                     |   |                         |    |   |   |   |   |   |
| Electric fuel and purchased power                                                      |   |                         | 249,250 |   |   |   | 256,194 |   |
| Other operating and maintenance expenses                                               |   |                         | 62,753  |   |   |   | 56,705 |   |
| Demand side management program expenses                                                |   |                         | 3,429   |   |   |   | 1,946 |   |
| Depreciation and amortization                                                          |   |                         | 26,158  |   |   |   | 25,654 |   |
| Taxes (other than income taxes)                                                        |   |                         | 10,120  |   |   |   | 10,155 |   |
| Total operating expenses                                                               |   |                         | 351,710 |   |   |   | 350,654 |   |
|                                                                                   |   |                         |    |   |   |   |   |   |
| Operating income                                                                       |   |                         | 29,499  |   |   |   | 30,828 |   |
|                                                                                   |   |                         |    |   |   |   |   |   |
| Other income (expense), net                                                            |   |                         | 62      |   |   |   | (6 | ) |
| Allowance for funds used during construction – equity                            |   |                         | 1,926   |   |   |   | 433 |   |
|                                                                                   |   |                         |    |   |   |   |   |   |
| Interest charges and financing costs                                                   |   |                         |    |   |   |   |   |   |
| Interest charges – includes other financing costs of $660 and $650, respectively |   |                         | 15,798  |   |   |   | 16,146 |   |
| Allowance for funds used during construction – debt                              |   |                         | (1,349  | ) |   |   | (546 | ) |
| Total interest charges and financing costs                                             |   |                         | 14,449  |   |   |   | 15,600 |   |
|                                                                                   |   |                         |    |   |   |   |   |   |
| Income before income taxes                                                             |   |                         | 17,038  |   |   |   | 15,655 |   |
| Income taxes                                                                           |   |                         | 6,800   |   |   |   | 7,956 |   |
| Net income                                                                             |   | $                            | 10,238  |   |   | $ | 7,699 |   |

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TABLE OF CONTENTS

|                                                                          |   | Three Months Ended March 31, |     |
|-------------------------------------------------------------------------------|--------|------------------------------|----------|
|                                                                          |   | 2011                         |     |   | 2010 |   |
|                                                                          |   |                         |     |   |   |   |
| Operating activities                                                          |   |                         |     |   |   |   |
| Net income                                                                    |   | $                            | 10,238   |   |   | $ | 7,699 |   |
| Adjustments to reconcile net income to cash provided by operating activities: |   |                         |     |   |   |   |   |   |
| Depreciation and amortization                                                 |   |                         | 26,714   |   |   |   | 26,216 |   |
| Demand side management program amortization                                   |   |                         | 453      |   |   |   | 476 |   |
| Deferred income taxes                                                         |   |                         | 5,431    |   |   |   | 10,895 |   |
| Amortization of investment tax credits                                        |   |                         | (85      | ) |   |   | (74 | ) |
| Allowance for equity funds used during construction                           |   |                         | (1,926   | ) |   |   | (433 | ) |
| Net realized and unrealized hedging and derivative transactions               |   |                         | 66       |   |   |   | 66 |   |
| Changes in operating assets and liabilities:                                  |   |                         |     |   |   |   |   |   |
| Accounts receivable                                                           |   |                         | (734     | ) |   |   | (1,538 | ) |
| Accrued unbilled revenues                                                     |   |                         | 5,233    |   |   |   | 6,790 |   |
| Inventories                                                                   |   |                         | 5,658    |   |   |   | 4,982 |   |
| Prepayments and other                                                         |   |                         | (1,351   | ) |   |   | 6,880 |   |
| Accounts payable                                                              |   |                         | (1,872   | ) |   |   | (18,594 | ) |
| Net regulatory assets and liabilities                                         |   |                         | (5,721   | ) |   |   | (21,105 | ) |
| Other current liabilities                                                     |   |                         | 7,864    |   |   |   | 3,336 |   |
| Change in other noncurrent assets                                             |   |                         | (3,798   | ) |   |   | (1,172 | ) |
| Change in other noncurrent liabilities                                        |   |                         | (8,856   | ) |   |   | (814 | ) |
| Net cash provided by operating activities                                     |   |                         | 37,314   |   |   |   | 23,610 |   |
|                                                                          |   |                         |     |   |   |   |   |   |
| Investing activities                                                          |   |                         |     |   |   |   |   |   |
| Utility capital/construction expenditures                                     |   |                         | (91,010  | ) |   |   | (47,281 | ) |
| Allowance for equity funds used during construction                           |   |                         | 1,926    |   |   |   | 433 |   |
| Investments in utility money pool arrangement                                 |   |                         | —  |   |   |   | (189,900 | ) |
| Receipts from utility money pool arrangement                                  |   |                         | —  |   |   |   | 259,900 |   |
| Net cash (used in) provided by investing activities                           |   |                         | (89,084  | ) |   |   | 23,152 |   |
|                                                                          |   |                         |     |   |   |   |   |   |
| Financing activities                                                          |   |                         |     |   |   |   |   |   |
| Proceeds from short-term borrowings, net                                      |   |                         | 26,000   |   |   |   | — |   |
| Borrowings under utility money pool arrangement                               |   |                         | 154,500  |   |   |   | — |   |
| Repayment under utility money pool arrangement                                |   |                         | (154,500 | ) |   |   | — |   |
| Repayment of long-term debt                                                   |   |                         | —  |   |   |   | (25,000 | ) |
| Capital contributions from parent                                             |   |                         | 50,000   |   |   |   | — |   |
| Dividends paid to parent                                                      |   |                         | (16,358  | ) |   |   | (17,240 | ) |
| Net cash provided by (used in) financing activities                           |   |                         | 59,642   |   |   |   | (42,240 | ) |
|                                                                          |   |                         |     |   |   |   |   |   |
| Net increase in cash and cash equivalents                                     |   |                         | 7,872    |   |   |   | 4,522 |   |
| Cash and cash equivalents at beginning of period                              |   |                         | 1,778    |   |   |   | 7,363 |   |
| Cash and cash equivalents at end of period                                    |   | $                            | 9,650    |   |   | $ | 11,885 |   |
|                                                                          |   |                         |     |   |   |   |   |   |
| Supplemental disclosure of cash flow information:                             |   |                         |     |   |   |   |   |   |
| Cash paid for interest, net of amounts capitalized                            |   | $                            | (1,737   | ) |   | $ | (3,140 | ) |
| Cash (paid) received for income taxes, net                                    |   |                         | (4,268   | ) |   |   | 10,459 |   |
|                                                                          |   |                         |     |   |   |   |   |   |
| Supplemental disclosure of non-cash investing transactions:                   |   |                         |     |   |   |   |   |   |
| Property, plant and equipment additions in accounts payable                   |   | $                            | 8,528    |   |   | $ | 4,478 |   |

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|                                                                                  |   | March 31, 2011 |      |   | Dec. 31, 2010 |   |
|---------------------------------------------------------------------------------------|--------|----------------|-----------|--------|---------------|--------|
| Assets                                                                                |   |           |      |   |          |   |
| Current assets                                                                        |   |           |      |   |          |   |
| Cash and cash equivalents                                                             |   | $              | 9,650     |   |          | $      | 1,778 |   |
| Accounts receivable, net                                                              |   |           | 45,936    |   |          |   | 44,871 |   |
| Accounts receivable from affiliates                                                   |   |           | 1,279     |   |          |   | 1,610 |   |
| Accrued unbilled revenues                                                             |   |           | 104,951   |   |          |   | 110,184 |   |
| Inventories                                                                           |   |           | 24,191    |   |          |   | 29,849 |   |
| Regulatory assets                                                                     |   |           | 23,701    |   |          |   | 21,547 |   |
| Derivative instruments                                                                |   |           | 7,892     |   |          |   | 7,892 |   |
| Deferred income taxes                                                                 |   |           | 17,386    |   |          |   | 19,051 |   |
| Prepayments and other                                                                 |   |           | 6,357     |   |          |   | 5,006 |   |
| Total current assets                                                                  |   |           | 241,343   |   |          |   | 241,788 |   |
|                                                                                  |   |           |      |   |          |   |   |   |
| Property, plant and equipment, net                                                    |   |           | 2,463,522 |   |          |   | 2,401,266 |   |
|                                                                                  |   |           |      |   |          |   |   |   |
| Other assets                                                                          |   |           |      |   |          |   |   |   |
| Regulatory assets                                                                     |   |           | 281,622   |   |          |   | 283,207 |   |
| Derivative instruments                                                                |   |           | 62,760    |   |          |   | 64,734 |   |
| Other                                                                                 |   |           | 14,309    |   |          |   | 10,668 |   |
| Total other assets                                                                    |   |           | 358,691   |   |          |   | 358,609 |   |
| Total assets                                                                          |   | $              | 3,063,556 |   |          | $      | 3,001,663 |   |
|                                                                                  |   |           |      |   |          |   |   |   |
| Liabilities and Equity                                                                |   |           |      |   |          |   |   |   |
| Current liabilities                                                                   |   |           |      |   |          |   |   |   |
| Current portion of long-term debt                                                     |   | $              | 44,500    |   |          | $      | 44,500 |   |
| Short-term debt                                                                       |   |           | 75,000    |   |          |   | 49,000 |   |
| Accounts payable                                                                      |   |           | 145,576   |   |          |   | 134,322 |   |
| Accounts payable to affiliates                                                        |   |           | 10,389    |   |          |   | 24,525 |   |
| Regulatory liabilities                                                                |   |           | 51,957    |   |          |   | 53,197 |   |
| Taxes accrued                                                                         |   |           | 16,007    |   |          |   | 19,867 |   |
| Accrued interest                                                                      |   |           | 24,541    |   |          |   | 12,128 |   |
| Dividends payable                                                                     |   |           | 15,860    |   |          |   | 16,358 |   |
| Derivative instruments                                                                |   |           | 3,601     |   |          |   | 3,601 |   |
| Other                                                                                 |   |           | 20,479    |   |          |   | 21,349 |   |
| Total current liabilities                                                             |   |           | 407,910   |   |          |   | 378,847 |   |
|                                                                                  |   |           |      |   |          |   |   |   |
| Deferred credits and other liabilities                                                |   |           |      |   |          |   |   |   |
| Deferred income taxes                                                                 |   |           | 545,309   |   |          |   | 541,204 |   |
| Deferred investment tax credits                                                       |   |           | 1,966     |   |          |   | 2,051 |   |
| Regulatory liabilities                                                                |   |           | 128,767   |   |          |   | 134,952 |   |
| Asset retirement obligations                                                          |   |           | 21,480    |   |          |   | 21,131 |   |
| Derivative instruments                                                                |   |           | 44,091    |   |          |   | 44,991 |   |
| Pension and employee benefit obligations                                              |   |           | 48,357    |   |          |   | 52,280 |   |
| Other                                                                                 |   |           | 5,796     |   |          |   | 10,827 |   |
| Total deferred credits and other liabilities                                          |   |           | 795,766   |   |          |   | 807,436 |   |
|                                                                                  |   |           |      |   |          |   |   |   |
| Commitments and contingent liabilities                                                |   |           |      |   |          |   |   |   |
| Capitalization                                                                        |   |           |      |   |          |   |   |   |
| Long-term debt                                                                        |   |           | 853,347   |   |          |   | 853,267 |   |
| Common stock – authorized 200 shares of $1.00 par value; outstanding 100 shares |   |           | —   |   |          |   | — |   |
| Additional paid in capital                                                            |   |           | 743,531   |   |          |   | 693,531 |   |
| Retained earnings                                                                     |   |           | 264,634   |   |          |   | 270,257 |   |
| Accumulated other comprehensive loss                                                  |   |           | (1,632    | )      |          |   | (1,675 | ) |
| Total common stockholder’s equity                                               |   |           | 1,006,533 |   |          |   | 962,113 |   |
| Total liabilities and equity                                                          |   | $              | 3,063,556 |   |          | $      | 3,001,663 |   |

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| 1. | Summary of Significant Accounting Policies |
|----|--------------------------------------------|

| 2. | Accounting Pronouncements |
|----|---------------------------|

| 3. | Selected Balance Sheet Data |
|----|-----------------------------|

| (Thousands of Dollars)    |   | March 31, 2011 |       |   | Dec. 31, 2010 |   |
|-------------------------------------|--------|----------------|------------|--------|--------------------|--------|
| Accounts receivable, net            |   |           |       |   |               |   |
| Accounts receivable                 |   | $              | 50,661     |   |               | $      | 49,966 |   |
| Less allowance for bad debts        |   |           | (4,725     | )      |               |   | (5,095 | ) |
|                                |   | $              | 45,936     |   |               | $      | 44,871 |   |
| Inventories                         |   |           |       |   |               |   |   |   |
| Materials and supplies              |   | $              | 17,412     |   |               | $      | 15,093 |   |
| Fuel                                |   |           | 6,779      |   |               |   | 14,756 |   |
|                                |   | $              | 24,191     |   |               | $      | 29,849 |   |
| Property, plant and equipment, net  |   |           |       |   |               |   |   |   |
| Electric plant                      |   | $              | 3,872,541  |   |               | $      | 3,826,202 |   |
| Construction work in progress       |   |           | 252,245    |   |               |   | 221,025 |   |
| Total property, plant and equipment |   |           | 4,124,786  |   |               |   | 4,047,227 |   |
| Less accumulated depreciation       |   |           | (1,661,264 | )      |               |   | (1,645,961 | ) |
|                                |   | $              | 2,463,522  |   |               | $      | 2,401,266 |   |

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| 4. | Income Taxes |
|----|--------------|

| (Millions of Dollars)                    |   | March 31, 2011 |   |   | Dec. 31, 2010 |   |
|----------------------------------------------------|--------|----------------|--------|--------|---------------|--------|
| Unrecognized tax benefit - Permanent tax positions |   | $              | 0.2    |   |          | $      | 0.2 |   |
| Unrecognized tax benefit - Temporary tax positions |   |           | 4.1    |   |          |   | 4.1 |   |
| Unrecognized tax benefit balance                   |   | $              | 4.3    |   |          | $      | 4.3 |   |

| 5. | Rate Matters |
|----|--------------|

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| 6. | Commitments and Contingent Liabilities |
|----|----------------------------------------|

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| (Millions of Dollars)            |   | March 31, 2011 |   |   | Dec. 31, 2010 |   |
|---------------------------------------|--------|----------------|--------|--------|---------------|--------|
| Guarantees issued and outstanding (a) |   | $              | 87.0   |   |          | $      | 87.0 |   |

| (a) | SPS has provided indemnification to Lubbock for losses arising out of any breach of the representations, warranties and covenants under the related asset purchase agreement and for losses arising out of certain other matters, including pre-closing unknown liabilities.  The indemnification provisions are capped at the purchase price, $87 million, in the aggregate.  As of March 31, 2011 and Dec. 31, 2010, no claims have been made.  The indemnification provisions for most representations and warranties expire 12 months after the closing date.  Certain representations and warranties, including those having to do with transaction authorization survive indefinitely.  The indemnification for covenants survives until the applicable covenant is performed. |
|-----|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

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| (Millions of Dollars)                           |   | Three Months Ended March 31, 2011 |   |   | Twelve Months Ended Dec. 31, 2010 |   |
|-----------------------------------------------------------|--------|-----------------------------------|--------|--------|----------------------------------------|--------|
| Borrowing limit                                           |   | $                                 | 300    |   |                                   | $      | 248 |   |
| Amount outstanding at period end                     |   |                              | 75     |   |                                   |   | 49 |   |
| Average amount outstanding                                |   |                              | 60     |   |                                   |   | 8 |   |
| Maximum amount outstanding                                |   |                              | 110    |   |                                   |   | 65 |   |
| Weighted average interest rate, computed on a daily basis |   |                              | 0.37   | %      |                                   |   | 0.37 | % |
| Weighted average interest rate at end of period           |   |                              | 0.37   |   |                                   |   | 0.37 |   |

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|   | ● | The credit facility may be increased by up $50 million. |
|--------|---------|---------------------------------------------------------|

|   | ● | The credit facility has a financial covenant requiring that SPS’ debt-to-total capitalization ratio be less than or equal to 65 percent.  SPS was in compliance as its debt-to-total capitalization ratio was 49 percent and 50 percent at March 31, 2011 and Dec. 31, 2010, respectively.  If SPS does not comply with the covenant, an event of default may be declared, and if not remedied, any outstanding amounts due under the facility can be declared due by the lender. |
|--------|---------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

|   | ● | The credit facility has a cross-default provision that provides SPS will be in default on its borrowings under the facility if it, comprising 15 percent or more of the consolidated assets, defaults on any indebtedness in an aggregate principal amount exceeding $75 million. |
|--------|---------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

|   | ● | The interest rates under the line of credit are based on the Eurodollar rate, plus a borrowing margin based on the applicable credit ratings of 100 to 200 basis points per year. |
|--------|---------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

|   | ● | The commitment fees, also based on applicable long-term credit ratings, are calculated on the unused portion of the line of credit at a range of 10 to 35 basis points per year. |
|--------|---------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| Credit Facility |   |   | Drawn (a) |   |   | Available |   |
|-----------------|--------|--------|-----------|--------|--------|-----------|--------|
| $               | 300.0  |   |      | $      | 75.0   |      |   | $ | 225.0 |   |

| (Millions of Dollars)                           |   | Three Months Ended March 31, 2011 |    |   | Twelve Months Ended Dec. 31, 2010 |   |
|-----------------------------------------------------------|--------|----------------------------------------|---------|--------|-----------------------------------|--------|
| Borrowing limit                                           |   | $                                      | 100     |   |                              | $      | 100 |   |
| Amount outstanding at period end                     |   |                                   | — |   |                              |   | — |   |
| Average amount outstanding                                |   |                                   | 28      |   |                              |   | 16 |   |
| Maximum amount outstanding                                |   |                                   | 71      |   |                              |   | 77 |   |
| Weighted average interest rate, computed on a daily basis |   |                                   | 0.35    | %      |                              |   | 0.37 | % |
| Weighted average interest rate at end of period           |   |                                   | N/A     |   |                              |   | N/A |   |

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|                                                                                |   | Three Months Ended March 31, |   |
|-------------------------------------------------------------------------------------|--------|------------------------------|--------|
| (Thousands of Dollars)                                                    |   | 2011                         |   |   | 2010 |   |
| Accumulated other comprehensive loss related to cash flow hedges at Jan. 1          |   | $                            | (1,675 | ) |   | $ | (1,847 | ) |
| After-tax net realized losses on derivative transactions reclassified into earnings |   |                         | 43     |   |   |   | 43 |   |
| Accumulated other comprehensive loss related to cash flow hedges at March 31        |   | $                            | (1,632 | ) |   | $ | (1,804 | ) |

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|                                      |   | March 31, 2011 |    |   | Dec. 31, 2010 |   |
|-------------------------------------------|--------|----------------|---------|--------|---------------|--------|
|                                      |   | Carrying       |    |   |          |   |   | Carrying |   |   |   |   |
| (Thousands of Dollars)          |   | Amount         |    |   | Fair Value    |   |   | Amount |   |   | Fair Value |   |
| Long-term debt, including current portion |   | $              | 897,847 |   |          | $      | 997,967 |   |   | $ | 897,767 |   |   | $ | 989,789 |   |

|                             |   | Three Months Ended March 31, |   |
|----------------------------------|--------|------------------------------|--------|
| (Thousands of Dollars) |   | 2011                         |   |   | 2010 |   |
| Interest income                  |   | $                            | 144    |   |   | $ | 63 |   |
| Other nonoperating income        |   |                         | 2      |   |   |   | 1 |   |
| Insurance policy expense         |   |                         | (84    | ) |   |   | (70 | ) |
| Other income (expense), net      |   | $                            | 62     |   |   | $ | (6 | ) |

| 10.  | Segment Information |
|-----------|---------------------|

| 11. | Comprehensive Income |
|-----|----------------------|

|                                                                                |   | Three Months Ended March 31, |   |
|-------------------------------------------------------------------------------------|--------|------------------------------|--------|
| (Thousands of Dollars)                                                              |   | 2011                         |   |   | 2010 |   |
| Net income                                                                          |   | $                            | 10,238 |   |   | $ | 7,699 |   |
| Other comprehensive income:                                                         |   |                         |   |   |   |   |   |   |
| After-tax net realized losses on derivative transactions reclassified into earnings |   |                         | 43     |   |   |   | 43 |   |
| Comprehensive income                                                                |   | $                            | 10,281 |   |   | $ | 7,742 |   |

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|                                                                                      |   | Three Months Ended March 31, |    |
|-------------------------------------------------------------------------------------------|--------|------------------------------|---------|
|                                                                                      |   | 2011                         |    |   | 2010 |   |   | 2011 |   |   | 2010 |   |
|                                                                                      |   |                         |    |   |   |   |   | Postretirement Health |   |
| (Thousands of Dollars)                                                          |   | Pension Benefits             |    |   | Care Benefits |   |
| Xcel Energy                                                                               |   |                         |    |   |   |   |   |   |   |   |   |   |
| Service cost                                                                              |   | $                            | 18,112  |   |   | $ | 17,618 |   |   | $ | 1,315 |   |   | $ | 1,038 |   |
| Interest cost                                                                             |   |                         | 39,915  |   |   |   | 40,652 |   |   |   | 10,551 |   |   |   | 10,529 |   |
| Expected return on plan assets                                                            |   |                         | (55,286 | ) |   |   | (58,124 | ) |   |   | (7,968 | ) |   |   | (7,134 | ) |
| Amortization of transition obligation                                                     |   |                         | — |   |   |   | — |   |   |   | 3,611 |   |   |   | 3,611 |   |
| Amortization of prior service cost (credit)                                               |   |                         | 5,633   |   |   |   | 5,164 |   |   |   | (1,233 | ) |   |   | (1,233 | ) |
| Amortization of net loss                                                                  |   |                         | 18,729  |   |   |   | 11,024 |   |   |   | 3,343 |   |   |   | 2,709 |   |
| Net periodic benefit cost                                                                 |   |                         | 27,103  |   |   |   | 16,334 |   |   |   | 9,619 |   |   |   | 9,520 |   |
| Costs not recognized and additional cost recognized due to the effects of regulation |   |                         | (7,885  | ) |   |   | (7,326 | ) |   |   | 973 |   |   |   | 973 |   |
| Net benefit cost recognized for financial reporting                                       |   | $                            | 19,218  |   |   | $ | 9,008 |   |   | $ | 10,592 |   |   | $ | 10,493 |   |
|                                                                                      |   |                         |    |   |   |   |   |   |   |   |   |   |   |   |   |   |
| SPS                                                                                       |   |                         |    |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Net periodic benefit cost                                                                 |   | $                            | 2,604   |   |   | $ | 1,188 |   |   | $ | 836 |   |   | $ | 829 |   |
| Costs not recognized due to the effects of regulation                           |   |                         | (575    | ) |   |   | — |   |   |   | — |   |   |   | — |   |
| Net benefit cost recognized for financial reporting                                       |   | $                            | 2,029   |   |   | $ | 1,188 |   |   | $ | 836 |   |   | $ | 829 |   |

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Item 2 — MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS

|                              |   | Three Months Ended March 31 |   |
|-----------------------------------|--------|-----------------------------|--------|
| (Millions of Dollars)             |   | 2011                        |   |   | 2010 |   |
| Electric revenues                 |   | $                           | 381    |   |   | $ | 381 |   |
| Electric fuel and purchased power |   |                        | (249   | ) |   |   | (256 | ) |
| Electric margin                   |   | $                           | 132    |   |   | $ | 125 |   |

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| (Millions of Dollars)                                                       |   | 2011 vs. 2010 |    |
|-----------------------------------------------------------------------------|--------|---------------|---------|
| Fuel and purchased power cost recovery                                      |   | $             | (10     | ) |
| Retail sales decrease (excluding weather impact)                            |   |          | (3      | ) |
| Sales mix and demand revenues                                               |   |          | (1      | ) |
| Service and facility fees                                                   |   |          | (1      | ) |
| Transmission revenue                                                        |   |          | 6       |   |
| Firm wholesale                                                              |   |          | 5       |   |
| Demand side management revenue and incentive (partially offset by expenses) |   |          | 3       |   |
| Retail rate increase (Texas)                                                |   |          | 2       |   |
| Other, net                                                                  |   |          | (1      | ) |
| Total change in electric revenues                                           |   | $             | — |   |

| (Millions of Dollars)                                                       |   | 2011 vs. 2010 |   |
|-----------------------------------------------------------------------------|--------|---------------|--------|
| Firm wholesale                                                              |   | $             | 5      |   |
| Transmission revenue, net of expense                                        |   |          | 3      |   |
| Demand side management revenue and incentive (partially offset by expenses) |   |          | 3      |   |
| Retail rate increase (Texas)                                                |   |          | 2      |   |
| Retail sales decrease (excluding weather impact)                            |   |          | (3     | )  |
| Sales mix and demand revenues                                               |   |          | (1     | )  |
| Service and facility fees                                                   |   |          | (1     | )  |
| Other, net                                                                  |   |          | (1     | )  |
| Total increase in electric margin                                           |   | $             | 7      |   |

| (Millions of Dollars)                                      |   | 2011 vs. 2010 |   |
|------------------------------------------------------------|--------|---------------|--------|
| Higher plant generation costs                              |   | $             | 3      |   |
| Higher contract labor costs                                |   |          | 2      |   |
| Higher employee benefit costs                              |   |          | 1      |   |
| Total increase in other operating and maintenance expenses |   | $             | 6      |   |

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Item 4 — CONTROLS AND PROCEDURES

Item 1 —LEGAL PROCEEDINGS

Item 1A — RISK FACTORS

Item 6 — EXHIBITS

| 3.01*  |   | Amended and Restated Articles of Incorporation dated Sept. 30, 1997 (Exhibit 3(a)(2) to Form 10-K for the year ended Dec. 31, 1997 (file no. 001-03789) dated March 3, 1998).                                                                                                                                                                                                                                                                     |
|--------|--------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| 3.02*  |   | By-laws dated Sept. 29, 1997 (Exhibit 3(b)(2) to Form 10-K for the year ended Dec. 31, 1997 (file no. 001-03789) dated March 3, 1998).                                                                                                                                                                                                                                                                                                            |
| 10.01* |   | Credit Agreement, dated as of March 17, 2011 among SPS, as Borrower, the several lenders from time to time parties thereto, JPMorgan Chase Bank, N.A., as Administrative Agent, Bank of America, N.A., and Barclays Capital, the investment banking division of Barclays Bank Plc, as Syndication Agents, and Wells Fargo Bank, National Association, as Documentation Agent (Exhibit 99.05 to Form 8-K of Xcel Energy, file number 001-03034, dated March 23, 2011). |
| 10.02* |   | Stock Equivalent Plan for Non-Employee Directors of Xcel Energy as amended and restated effective Feb. 23, 2011 (Appendix A to the Xcel Energy Definitive Proxy Statement (file no. 001-03034) filed April 5, 2011).                                                                                                                                                                                                                                                  |
| 31.01  |   | Principal Executive Officer’s and Principal Financial Officer’s certifications pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 302 of the Sarbanes-Oxley Act of 2002.                                                                                                                                                                                                                                                        |
| 32.01  |   | Certification pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002.                                                                                                                                                                                                                                                                                                                                     |
| 99.01  |   | Statement pursuant to Private Securities Litigation Reform Act of 1995.                                                                                                                                                                                                                                                                                                                                                                                               |

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SIGNATURES

|        |   | Southwestern Public Service Company        |
|-------------|--------|--------------------------------------------|
| May 2, 2011 |   |                                       |
|        | By:    | /s/ TERESA S. MADDEN                       |
|        |   | Teresa S. Madden                           |
|        |   | Vice President and Controller              |
|        |   |                                       |
|        |   | /s/ DAVID M. SPARBY                        |
|        |   | David M. Sparby                            |
|        |   | Vice President and Chief Financial Officer |

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