10-Q

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C.  20549

FORM 10-Q

(Mark One)

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

For the quarterly period ended March 31, 2024

or

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

For the transition period from to

Commission File Number: 001-03140

Northern States Power Company

(Exact Name of Registrant as Specified in its Charter)

Wisconsin			39-0508315
(State or Other Jurisdiction of Incorporation or Organization)			(I.R.S Employer Identification No.)
1414 West Hamilton Avenue	Eau Claire	Wisconsin	54701
(Address of Principal Executive Offices)			(Zip Code)

(715)	852-5812
(Registrant’s Telephone Number, Including Area Code)

N/A

(Former name, former address and former fiscal year, if changed since last report)

Securities registered pursuant to Section 12(b) of the Act:

Title of each class	Trading Symbol(s)	Name of each exchange on which registered
N/A	N/A	N/A

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. ☒ Yes  ☐ No

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files). ☒ Yes  ☐ No

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

Large accelerated filer	☐	Accelerated filer	☐
Non-accelerated filer	☒	Smaller reporting company	☐
		Emerging growth company	☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). ☐ Yes ☒ No

Indicate the number of shares outstanding of each of the issuer’s classes of common stock, as of the latest practicable date.

Class	Outstanding at April 25, 2024
Common Stock, $100 par value	933,000 shares

Northern States Power Company meets the conditions set forth in General Instructions H(1)(a) and (b) of Form 10-Q and is therefore filing this Form 10-Q with the reduced disclosure format specified in General Instruction H(2) to such Form 10-Q.

TABLE OF CONTENTS

PART I	FINANCIAL INFORMATION
Item 1 —	Financial Statements (unaudited)	4
	Consolidated Statements of Income	4
	Consolidated Statements of Cash Flows	5
	Consolidated Balance Sheets	6
	Consolidated Statements of Common Stockholder's Equity	7
	Notes to Consolidated Financial Statements	8
Item 2 —	Management’s Discussion and Analysis of Financial Condition and Results of Operations	12
Item 4 —	Controls and Procedures	13
PART II	OTHER INFORMATION
Item 1 —	Legal Proceedings	14
Item 1A —	Risk Factors	14
Item 5 —	Other Information	14
Item 6 —	Exhibits	14
SIGNATURES		15

This Form 10-Q is filed by NSP-Wisconsin. NSP-Wisconsin is a wholly owned subsidiary of Xcel Energy Inc. Additional information on Xcel Energy is available in various filings with the SEC. This report should be read in its entirety.

Definitions of Abbreviations

Xcel Energy Inc.’s Subsidiaries and Affiliates (current and former)
e prime	e prime inc.
NSP-Minnesota	Northern States Power Company, a Minnesota corporation
NSP System	The electric production and transmission system of NSP-Minnesota and NSP-Wisconsin operated on an integrated basis and managed by NSP-Minnesota
NSP-Wisconsin	Northern States Power Company, a Wisconsin corporation
PSCo	Public Service Company of Colorado
SPS	Southwestern Public Service Company
Utility subsidiaries	NSP-Minnesota, NSP-Wisconsin, PSCo and SPS
Xcel Energy	Xcel Energy Inc. and its subsidiaries

Federal and State Regulatory Agencies
D.C. Circuit	United States Court of Appeals for the District of Columbia Circuit
EPA	United States Environmental Protection Agency
FERC	Federal Energy Regulatory Commission
MPUC	Minnesota Public Utilities Commission
MPSC	Michigan Public Service Commission
PSCW	Public Service Commission of Wisconsin
SEC	Securities and Exchange Commission

Other
C&I	Commercial and Industrial
CEO	Chief executive officer
CERCLA	Comprehensive Environmental Response, Compensation, and Liability Act
CFO	Chief financial officer
GAAP	United States generally accepted accounting principles
IRP	Integrated Resource Plan
MGP	Manufactured gas plant
MISO	Midcontinent Independent System Operator, Inc.
NOx	Nitrogen Oxides
PFAS	Per- and Polyfluoroalkyl Substances
O&M	Operating and maintenance
RFP	Request for proposal
ROE	Return on equity
RTO	Regional Transmission Organization
Measurements
MW	Megawatts

Forward-Looking Statements

Except for the historical statements contained in this report, the matters discussed herein are forward-looking statements that are subject to certain risks, uncertainties and assumptions. Such forward-looking statements, including those relating to future sales, future expenses, future tax rates, future operating performance, estimated base capital expenditures and financing plans, projected capital additions and forecasted annual revenue requirements with respect to rider filings, expected rate increases to customers, expectations and intentions regarding regulatory proceedings, and expected impact on our results of operations, financial condition and cash flows of resettlement calculations and credit losses relating to certain energy transactions, as well as assumptions and other statements are intended to be identified in this document by the words “anticipate,” “believe,” “could,” “estimate,” “expect,” “intend,” “may,” “objective,” “outlook,” “plan,” “project,” “possible,” “potential,” “should,” “will,” “would” and similar expressions. Actual results may vary materially. Forward-looking statements speak only as of the date they are made, and we expressly disclaim any obligation to update any forward-looking information. The following factors, in addition to those discussed in NSP-Wisconsin's Annual Report on Form 10-K for the fiscal year ended Dec. 31, 2023 and subsequent filings with the SEC, could cause actual results to differ materially from management expectations as suggested by such forward-looking information: operational safety; successful long-term operational planning; commodity risks associated with energy markets and production; rising energy prices and fuel costs; qualified employee workforce and third-party contractor factors; violations of our Codes of Conduct; our ability to recover costs; changes in regulation; reductions in our credit ratings and the cost of maintaining certain contractual relationships; general economic conditions, including recessionary conditions, inflation rates, monetary fluctuations, supply chain constraints and their impact on capital expenditures and/or the ability of NSP-Wisconsin to obtain financing on favorable terms; availability or cost of capital; our customers’ and counterparties’ ability to pay their debts to us; assumptions and costs relating to funding our employee benefit plans and health care benefits; tax laws; uncertainty regarding epidemics, the duration and magnitude of business restrictions including shutdowns (domestically and globally), the potential impact on the workforce, including shortages of employees or third-party contractors due to quarantine policies, vaccination requirements or government restrictions, impacts on the transportation of goods and the generalized impact on the economy; effects of geopolitical events, including war and acts of terrorism; cybersecurity threats and data security breaches; seasonal weather patterns; changes in environmental laws and regulations; climate change and other weather events; natural disaster and resource depletion, including compliance with any accompanying legislative and regulatory changes; costs of potential regulatory penalties and wildfire damages in excess of liability insurance coverage; regulatory changes and/or limitations related to the use of natural gas as an energy source; challenging labor market conditions and our ability to attract and retain a qualified workforce; and our ability to execute on our strategies or achieve expectations related to environmental, social and governance matters including as a result of evolving legal, regulatory and other standards, processes, and assumptions, the pace of scientific and technological developments, increased costs, the availability of requisite financing, and changes in carbon markets.

PART I — FINANCIAL INFORMATION

ITEM 1 — FINANCIAL STATEMENTS

NSP-WISCONSIN AND SUBSIDIARIES

CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED)

(amounts in millions)

	Three Months Ended March 31
	2024		2023
Operating revenues
Electric, non-affiliates	$	203	$	204
Electric, affiliates	53		50
Natural gas	54		77
Total operating revenues	310		331
Operating expenses
Electric fuel and purchased power, non-affiliates	4		4
Purchased power, affiliates	103		103
Cost of natural gas sold and transported	24		46
Operating and maintenance expenses	56		58
Conservation program expenses	3		3
Depreciation and amortization	45		41
Taxes (other than income taxes)	9		8
Total operating expenses	244		263
Operating income	66		68
Allowance for funds used during construction — equity	3		2
Interest charges and financing costs
Interest charges and other financing costs	14		13
Allowance for funds used during construction — debt	(1)		(1)
Total interest charges and financing costs	13		12
Income before income taxes	56		58
Income tax expense	13		13
Net income	$	43	$	45

See Notes to Consolidated Financial Statements

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NSP-WISCONSIN AND SUBSIDIARIES

CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED)

(amounts in millions)

	Three Months Ended March 31
	2024		2023
Operating activities
Net income	$	43	$	45
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation and amortization	46		42
Deferred income taxes	3		(2)
Allowance for equity funds used during construction	(3)		(2)
Provision for bad debts	1		2
Changes in operating assets and liabilities:
Accounts receivable	(13)		(16)
Accrued unbilled revenues	9		20
Inventories	3		15
Other current assets	5		13
Accounts payable	(7)		(10)
Net regulatory assets and liabilities	(1)		17
Other current liabilities	5		—
Pension and other employee benefit obligations	(7)		(3)
Other, net	2		1
Net cash provided by operating activities	86		122
Investing activities
Capital/construction expenditures	(121)		(101)
Net cash used in investing activities	(121)		(101)
Financing activities
Repayments of short-term borrowings, net	(60)		(35)
Borrowings under utility money pool arrangement	130		—
Repayments under utility money pool arrangement	(111)		—
Capital contributions from parent	106		36
Dividends paid to parent	(25)		(23)
Net cash provided (used in) by financing activities	40		(22)
Net change in cash, cash equivalents and restricted cash	5		(1)
Cash, cash equivalents and restricted cash at beginning of period	6		2
Cash, cash equivalents and restricted cash at end of period	$	11	$	1
Supplemental disclosure of cash flow information:
Cash paid for interest (net of amounts capitalized)	$	(12)	$	(13)
Cash paid for income taxes, net	(7)		(4)
Supplemental disclosure of non-cash investing and financing transactions:
Accrued property, plant and equipment additions	$	33	$	33
Inventory transfers to property, plant and equipment	2		2
Allowance for equity funds used during construction	3		2

See Notes to Consolidated Financial Statements

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NSP-WISCONSIN AND SUBSIDIARIES

CONSOLIDATED BALANCE SHEETS (UNAUDITED)

(amounts in millions, except share and per share data)

	March 31, 2024		Dec. 31, 2023
Assets
Current assets
Cash and cash equivalents	$	11	$	6
Accounts receivable, net	90		89
Accrued unbilled revenues	53		63
Inventories	24		29
Regulatory assets	23		24
Prepaid taxes	21		28
Prepayments and other	7		6
Total current assets	229		245
Property, plant and equipment, net	3,332		3,237
Other assets
Regulatory assets	181		185
Other	3		3
Total other assets	184		188
Total assets	$	3,745	$	3,670
Liabilities and Equity
Current liabilities
Current portion of long-term debt	$	200	$	200
Short-term debt	—		60
Borrowings under utility money pool arrangement	19		—
Accounts payable	61		64
Accounts payable to affiliates	20		21
Dividends payable to parent	18		25
Regulatory liabilities	41		42
Taxes accrued	19		16
Accrued interest	13		13
Other	24		23
Total current liabilities	415		464
Deferred credits and other liabilities
Deferred income taxes	336		330
Deferred investment tax credits	5		5
Regulatory liabilities	412		407
Customer advances	26		25
Pension and employee benefit obligations	20		27
Other	34		35
Total deferred credits and other liabilities	833		829
Commitments and contingencies
Capitalization
Long-term debt	1,011		1,011
Common stock — 1,000,000 shares authorized of $100 par value; 933,000 shares outstanding at March 31, 2024 and Dec. 31, 2023, respectively	93		93
Additional paid in capital	938		843
Retained earnings	455		430
Total common stockholder's equity	1,486		1,366
Total liabilities and equity	$	3,745	$	3,670

See Notes to Consolidated Financial Statements

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NSP-WISCONSIN AND SUBSIDIARIES

CONSOLIDATED STATEMENTS OF COMMON STOCKHOLDER'S EQUITY (UNAUDITED)

(amounts in millions, except share data)

	Common Stock Issued					Retained Earnings		Total Common Stockholder's Equity
	Shares	Par Value		Additional Paid In Capital
Three Months Ended March 31, 2024 and 2023
Balance at December 31, 2022	933,000	$	93	$	761	$	405	$	1,259
Net income						45		45
Common dividends declared to parent						(24)		(24)
Contribution of capital by parent				30				30
Balance at March 31, 2023	933,000	$	93	$	791	$	426	$	1,310
Balance at December 31, 2023	933,000	$	93	$	843	$	430	$	1,366
Net income						43		43
Common dividends declared to parent						(18)		(18)
Contribution of capital by parent				95				95
Balance at March 31, 2024	933,000	$	93	$	938	$	455	$	1,486

	Total Common Stockholder's Equity
See Notes to Consolidated Financial Statements

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NSP-WISCONSIN AND SUBSIDIARIES

Notes to Consolidated Financial Statements (UNAUDITED)

In the opinion of management, the accompanying unaudited consolidated financial statements contain all adjustments necessary to present fairly, in accordance with GAAP, the financial position of NSP-Wisconsin and its subsidiaries as of March 31, 2024 and Dec. 31, 2023; the results of NSP-Wisconsin's operations, including the components of net income, cash flows, and changes in stockholder's equity for the three months ended March 31, 2024 and 2023.

All adjustments are of a normal, recurring nature, except as otherwise disclosed. Management has also evaluated the impact of events occurring after March 31, 2024 up to the date of issuance of these consolidated financial statements. These statements contain all necessary adjustments and disclosures resulting from that evaluation. The Dec. 31, 2023 balance sheet information has been derived from the audited 2023 consolidated financial statements included in the NSP-Wisconsin Annual Report on Form 10-K for the year ended Dec. 31, 2023.

Notes to the consolidated financial statements have been prepared pursuant to the rules and regulations of the SEC for Quarterly Reports on Form 10-Q. Certain information and note disclosures normally included in financial statements prepared in accordance with GAAP on an annual basis have been condensed or omitted pursuant to such rules and regulations. For further information, refer to the consolidated financial statements and notes thereto included in the NSP-Wisconsin Annual Report on Form 10-K for the year ended Dec. 31, 2023, filed with the SEC on Feb. 21, 2024. Due to the seasonality of NSP-Wisconsin’s electric and natural gas sales, interim results are not necessarily an appropriate base from which to project annual results.

1. Summary of Significant Accounting Policies

The significant accounting policies set forth in Note 1 to the consolidated financial statements in the NSP-Wisconsin Annual Report on Form 10-K for the year ended Dec. 31, 2023 appropriately represent, in all material respects, the current status of accounting policies and are incorporated herein by reference.

2. Accounting Pronouncements

Recently Issued

Segment Reporting — In November 2023, the FASB issued ASU 2023-07 – Segment Reporting (Topic 280) – Improvements to Reportable Segment Disclosures, which extends the existing requirements for annual disclosures to quarterly periods, and requires that both annual and quarterly disclosures present segment expenses using line items consistent with information regularly provided to the chief operating decision maker. The ASU is effective for annual periods beginning after Dec. 15, 2023 and quarterly periods beginning after Dec. 15, 2024, and Xcel Energy does not expect implementation of the new disclosure guidance to have a material impact to its consolidated financial statements.

Income Taxes — In December 2023, the FASB issued ASU 2023-09 – Income Taxes (Topic 740) – Improvements to Income Tax Disclosures, with new disclosure requirements including presentation of prescribed line items in the effective tax rate reconciliation and disclosures regarding state and local tax payments. The ASU is effective for annual periods beginning after Dec. 15, 2024, and Xcel Energy does not expect implementation of the new disclosure guidance to have a material impact to its consolidated financial statements.

Climate-Related Disclosures — In March 2024, the SEC issued Final Rule 33-11275 – The Enhancement and Standardization of Climate-Related Disclosures for Investors. This rule requires registrants to provide standardized disclosures in Form 10-K related to climate-related risks, Scope 1 and 2 greenhouse gas emissions, as well as to include in a footnote to the consolidated financial statements the financial impact of severe weather events and other natural conditions. The rule requires implementation in phases between 2025 and 2033. In April 2024, the SEC announced that it would voluntarily stay its final climate disclosure rules pending judicial review. Xcel Energy does not expect implementation of the new guidance to have a material impact on the consolidated financial statements.

3. Selected Balance Sheet Data

(Millions of dollars)	March 31, 2024		Dec. 31, 2023
Accounts receivable, net
Accounts receivable	$	98	$	98
Less allowance for bad debts	(8)		(9)
Accounts receivable, net	$	90	$	89

(Millions of dollars)	March 31, 2024		Dec. 31, 2023
Inventories
Materials and supplies	$	12	$	11
Fuel	10		10
Natural gas	2		8
Total inventories	$	24	$	29

(Millions of dollars)	March 31, 2024		Dec. 31, 2023
Property, plant and equipment, net
Electric plant	$	3,895	$	3,845
Natural gas plant	504		502
Common and other property	287		278
Construction work in progress	306		252
Total property, plant and equipment	4,992		4,877
Less accumulated depreciation	(1,660)		(1,640)
Property, plant and equipment, net	$	3,332	$	3,237

4. Borrowings and Other Financing Instruments

Short-Term Borrowings

NSP-Wisconsin meets its short-term liquidity requirements primarily through the issuance of commercial paper and borrowings under its credit facility and the money pool.

Money Pool — Xcel Energy Inc. and its utility subsidiaries have established a money pool arrangement that allows for short-term investments in and borrowings between the utility subsidiaries. Xcel Energy Inc. may make investments in the utility subsidiaries at market-based interest rates; however, the money pool arrangement does not allow the utility subsidiaries to make investments in Xcel Energy Inc.

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Money pool borrowings:

(Amounts in Millions, Except Interest Rates)	Three Months Ended March 31, 2024			Year Ended Dec. 31, 2023
Borrowing limit	$	150		$	150
Amount outstanding at period end	19			—
Average amount outstanding	12			6
Maximum amount outstanding	54			43
Weighted average interest rate, computed on a daily basis	5.33		%	4.98		%
Weighted average interest rate at period end	5.33			N/A

Commercial Paper — Commercial paper outstanding:

(Amounts in Millions, Except Interest Rates)	Three Months Ended March 31, 2024			Year Ended Dec. 31, 2023
Borrowing limit	$	150		$	150
Amount outstanding at period end	—			60
Average amount outstanding	41			15
Maximum amount outstanding	99			93
Weighted average interest rate, computed on a daily basis	5.49		%	4.85		%
Weighted average interest rate at period end	N/A			5.50

Letters of Credit — NSP-Wisconsin uses letters of credit, generally with terms of one year, to provide financial guarantees for certain obligations. At both March 31, 2024 and Dec. 31, 2023, there were immaterial letters of credit outstanding under the credit facility.

Revolving Credit Facility — In order to issue its commercial paper, NSP-Wisconsin must have a revolving credit facility equal to or greater than the commercial paper borrowing limit and cannot issue commercial paper exceeding available capacity under this credit facility. The credit facility provides short-term financing in the form of notes payable to banks, letters of credit and back-up support for commercial paper borrowings.

NSP-Wisconsin has the right to request an extension of the revolving credit facility termination date for an additional one-year period. All extension requests are subject to majority bank group approval.

As of March 31, 2024, NSP-Wisconsin had the following committed revolving credit facility available (in millions of dollars):

Credit Facility (a)		Outstanding (b)		Available
$	150	$	—	$	150

(a)Expires in September 2027.

(b)Includes outstanding commercial paper.

All credit facility bank borrowings, outstanding letters of credit and outstanding commercial paper reduce the available capacity under the credit facility. NSP-Wisconsin had no direct advances on the credit facility outstanding at March 31, 2024 and Dec. 31, 2023.

Other Short-Term Borrowings — Clearwater Investments, Inc., a NSP-Wisconsin subsidiary, had an immaterial note payable to Xcel Energy Inc. as of March 31, 2024 and Dec. 31, 2023, respectively.

5. Revenues

Revenue is classified by the type of goods/services rendered and market/customer type. NSP-Wisconsin’s operating revenues consisted of the following:

	Three Months Ended March 31, 2024
(Millions of Dollars)	Electric		Natural Gas		Total
Major revenue types
Revenue from contracts with customers:
Residential	$	77	$	30	$	107
C&I	118		22		140
Other	2		—		2
Total retail	197		52		249
Interchange and other	56		1		57
Total revenue from contracts with customers	253		53		306
Alternative revenue and other	3		1		4
Total revenues	$	256	$	54	$	310

	Three Months Ended March 31, 2023
(Millions of Dollars)	Electric		Natural Gas		Total
Major revenue types
Revenue from contracts with customers:
Residential	$	82	$	41	$	123
C&I	120		34		154
Other	2		—		2
Total retail	204		75		279
Interchange and other	47		1		48
Total revenue from contracts with customers	251		76		327
Alternative revenue and other	3		1		4
Total revenues	$	254	$	77	$	331

6. Income Taxes

Reconciliation between the statutory rate and effective tax rate:

	Three Months Ended March 31
	2024		2023
Federal statutory rate	21.0	%	21.0	%
State tax (net of federal tax effect)	6.2		6.2
(Decreases) increases:
Plant regulatory differences (a)	(4.3)		(3.5)
Other (net)	0.3		(1.3)
Effective income tax rate	23.2	%	22.4	%

(a)Plant regulatory differences primarily relate to the credit of excess deferred taxes to customers through the average rate assumption method. Income tax benefits associated with the credit are offset by corresponding revenue reductions.

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7. Fair Value of Financial Assets and Liabilities

Fair Value Measurements

Accounting guidance for fair value measurements and disclosures provides a hierarchical framework for disclosing the observability of the inputs utilized in measuring assets and liabilities at fair value.

•Level 1 — Quoted prices are available in active markets for identical assets or liabilities as of the reporting date. The types of assets and liabilities included in Level 1 are actively traded instruments with observable actual trading prices.

•Level 2 — Pricing inputs are other than actual trading prices in active markets, but are either directly or indirectly observable as of the reporting date. The types of assets and liabilities included in Level 2 are typically either comparable to actively traded securities or contracts or priced with models using highly observable inputs.

•Level 3 — Significant inputs to pricing have little or no observability as of the reporting date. The types of assets and liabilities included in Level 3 include those valued with models requiring significant judgment or estimation.

Specific valuation methods include:

Commodity Derivatives — Methods used to measure the fair value of commodity derivative forwards and options utilize forward prices and volatilities, as well as pricing adjustments for specific delivery locations, and are generally assigned a Level 2 classification. When contracts relate to inactive delivery locations or extend to periods beyond those readily observable on active exchanges, the significance of the use of less observable inputs on a valuation is evaluated, and may result in Level 3 classification.

Derivative Activities and Fair Value Measurements

NSP-Wisconsin enters into derivative instruments, including forward contracts, futures, swaps and options, to manage risk in connection with changes in utility commodity prices.

Commodity Derivatives — NSP-Wisconsin enters into derivative instruments to manage variability of future cash flows from changes in commodity prices in its electric and natural gas operations. This could include the purchase or sale of natural gas to generate electric energy and natural gas for resale.

As of March 31, 2024, NSP-Wisconsin had no commodity contracts designated as cash flow hedges.

Consideration of Credit Risk and Concentrations — NSP-Wisconsin continuously monitors the creditworthiness of counterparties to its interest rate derivatives and commodity derivative contracts prior to settlement, and assesses each counterparty’s ability to perform on the transactions set forth in the contracts. Impact of credit risk was immaterial to the fair value of unsettled commodity derivatives presented on the consolidated balance sheets.

Recurring Derivative Fair Value Measurements

Impact of derivative activity:

Changes in the fair value of natural gas commodity derivatives resulted in immaterial and $1 million of net gains for the three months ended March 31, 2024 and 2023, respectively, which were recognized as regulatory assets and liabilities. The classification as a regulatory asset or liability is based on commission approved regulatory recovery mechanisms.

During the three months ended March 31, 2024 and 2023, $1 million and $2 million, respectively, of pre-tax losses were recognized during the period related to option premium amortization subject to natural gas cost recovery mechanisms and reclassified out of income to a regulatory asset, as appropriate.

NSP-Wisconsin had immaterial outstanding derivative assets or liabilities measured at fair value as of March 31, 2024 and Dec. 31, 2023.

Fair Value of Long-Term Debt

As of March 31, 2024, other financial instruments for which the carrying amount did not equal fair value:

	March 31, 2024				Dec. 31, 2023
(Millions of Dollars)	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Long-term debt, including current portion	$	1,211	$	1,104	$	1,211	$	1,117

Fair value of NSP-Wisconsin’s long-term debt is estimated based on recent trades and observable spreads from benchmark interest rates for similar securities. Fair value estimates are based on information available to management as of March 31, 2024 and Dec. 31, 2023, and given the observability of the inputs, fair values presented for long-term debt were assigned as Level 2.

8. Benefit Plans and Other Postretirement Benefits

Components of Net Periodic Benefit Cost

	Three Months Ended March 31
	2024		2023
(Millions of Dollars)	Pension Benefits
Service cost	$	1	$	1
Interest cost (a)	2		2
Expected return on plan assets (a)	(2)		(2)
Net periodic benefit cost	$	1	$	1

(a)The components of net periodic cost other than the service cost component are included in the line item “Other income (expense), net” in the consolidated statements of income or capitalized on the consolidated balance sheets as a regulatory asset.

In January 2024, contributions totaling $100 million were made across Xcel Energy’s pension plans, of which $7 million was attributable to NSP-Wisconsin. Xcel Energy does not expect additional pension contributions during 2024.

9. Commitments and Contingencies

Legal

NSP-Wisconsin is involved in various litigation matters in the ordinary course of business. The assessment of whether a loss is probable or is a reasonable possibility, and whether the loss or a range of loss is estimable, often involves a series of complex judgments about future events. Management maintains accruals for losses probable of being incurred and subject to reasonable estimation. Management is sometimes unable to estimate an amount or range of a reasonably possible loss in certain situations, including but not limited to when (1) the damages sought are indeterminate, (2) the proceedings are in the early stages, or (3) the matters involve novel or unsettled legal theories.

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In such cases, there is considerable uncertainty regarding the timing or ultimate resolution, including a possible eventual loss. For current proceedings not specifically reported herein, management does not anticipate that the ultimate liabilities, if any, would have a material effect on NSP-Wisconsin’s consolidated financial statements. Legal fees are generally expensed as incurred.

Gas Trading Litigation — e prime is a wholly owned subsidiary of Xcel Energy. e prime was in the business of natural gas trading and marketing but has not engaged in natural gas trading or marketing activities since 2003. Multiple lawsuits involving multiple plaintiffs seeking monetary damages were commenced against e prime and its affiliates, including Xcel Energy, between 2003 and 2009 alleging fraud and anticompetitive activities in conspiring to restrain the trade of natural gas and manipulate natural gas prices. Cases were all consolidated in the U.S. District Court in Nevada.

One case remains active which includes a multi-district litigation matter consisting of a Wisconsin purported class (Arandell Corp.). The Court issued a ruling in June 2022 granting plaintiffs’ class certification. In April 2023, the Seventh Circuit Court of Appeals heard the defendants’ appeal challenging whether the district court properly assessed class certification. A decision relating to class certification is expected imminently. Xcel Energy considers the reasonably possible loss associated with this litigation to be immaterial.

Rate Matters

NSP-Wisconsin is involved in various regulatory proceedings arising in the ordinary course of business. Until resolution, typically in the form of a rate order, uncertainties may exist regarding the ultimate rate treatment for certain activities and transactions. Amounts have been recognized for probable and reasonably estimable losses that may result. Unless otherwise disclosed, any reasonably possible range of loss in excess of any recognized amount is not expected to have a material effect on the financial statements.

Environmental

New and changing federal and state environmental mandates can create financial liabilities for NSP-Wisconsin, which are normally recovered through the regulated rate process.

Site Remediation

Various federal and state environmental laws impose liability where hazardous substances or other regulated materials have been released to the environment. NSP-Wisconsin may sometimes pay all or a portion of the cost to remediate sites where past activities of their predecessors or other parties have caused environmental contamination.

Environmental contingencies could arise from various situations, including sites of former MGPs; and third-party sites, such as landfills, for which NSP-Wisconsin is alleged to have sent wastes to that site.

MGP, Landfill and Disposal Sites

NSP-Wisconsin is investigating, remediating or performing post-closure actions at one MGP, landfill or other disposal sites across its service territories.

NSP-Wisconsin has recognized approximately $13 million of costs/liabilities from final resolution of these issues, however, the outcome and timing are unknown. In addition, there may be regulatory recovery, insurance recovery and/or recovery from other potentially responsible parties, offsetting a portion of costs incurred.

Environmental Requirements — Water and Waste

Federal Clean Water Act Section 316(b) — The Federal Clean Water Act requires the EPA to regulate cooling water intake structures to assure they reflect the best technology available for minimizing impingement and entrainment of aquatic species. NSP-Wisconsin estimates capital expenditures of approximately $5 million may be required to comply with the requirements. NSP-Wisconsin believes two plants could be required to make improvements to reduce impingement and entrainment. NSP-Wisconsin anticipates these costs will be recoverable through regulatory mechanisms.

Environmental Requirements — Air

Clean Air Act NOx Allowance Allocations — In June 2023, the EPA published final regulations under the "Good Neighbor" provisions of the Clean Air Act. The final rule applies to generation facilities in Wisconsin, as well as other states outside of our service territory. The rule establishes an allowance trading program for NOx that will impact NSP-Wisconsin’s fossil fuel-fired electric generating facilities. Subject facilities will have to secure additional allowances, install NOx controls and/or develop a strategy of operations that utilizes the existing allowance allocations. Guidelines are also established for allowance banking and emission limit backstops.

While the financial impacts of the final rule are uncertain and dependent on market forces and anticipated generation, NSP-Wisconsin anticipates the costs would be recoverable through regulatory mechanisms.

10. Segment Information

NSP-Wisconsin evaluates performance based on profit or loss generated from the product or service provided. These segments are managed separately because the revenue streams are dependent upon regulated rate recovery, which is separately determined for each segment.

NSP-Wisconsin has the following reportable segments:

•Regulated Electric — The regulated electric utility segment generates electricity, which is transmitted and distributed in Wisconsin and Michigan.

•Regulated Natural Gas — The regulated natural gas utility segment purchases, transports, stores and distributes natural gas in portions of Wisconsin and Michigan.

Asset and capital expenditure information is not provided for NSP-Wisconsin's reportable segments. As an integrated electric and natural gas utility, NSP-Wisconsin operates significant assets that are not dedicated to a specific business segment. Reporting assets and capital expenditures by business segment would require arbitrary and potentially misleading allocations, which may not necessarily reflect the assets that would be required for the operation of the business segments on a stand-alone basis.

Certain costs, such as common depreciation, common O&M expenses and interest expense are allocated based on cost causation allocators across each segment. In addition, a general allocator is used for certain general and administrative expenses, including office supplies, rent, property insurance and general advertising.

11

NSP-Wisconsin's segment information:

	Three Months Ended March 31
(Millions of Dollars)	2024		2023
Regulated Electric
Total revenues (a)	$	256	$	254
Net income	33		33
Regulated Natural Gas
Total revenues	$	54	$	77
Net income	10		11
All Other
Net income	$	—	$	1
Consolidated Total
Total revenues (a)	$	310	$	331
Net income	43		45

(a)Total revenues include $53 million and $50 million of affiliate electric revenue for the three months ended March 31, 2024 and 2023, respectively.

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

Discussion of financial condition and liquidity for NSP-Wisconsin is omitted per conditions set forth in General Instructions H(1)(a) and (b) of Form 10-Q for wholly owned subsidiaries. It is replaced with management’s narrative analysis of the results of operations set forth in General Instruction H(2)(a) of Form 10-Q for wholly owned subsidiaries (reduced disclosure format).

Non-GAAP Financial Measures

The following discussion includes financial information prepared in accordance with GAAP, as well as certain non-GAAP financial measures such as ongoing earnings. Generally, a non-GAAP financial measure is a measure of a company’s financial performance, financial position or cash flows that adjusts measures calculated and presented in accordance with GAAP.

NSP-Wisconsin’s management uses non-GAAP measures for financial planning and analysis, for reporting of results to the Board of Directors, in determining performance-based compensation and communicating its earnings outlook to analysts and investors. Non-GAAP financial measures are intended to supplement investors’ understanding of our performance and should not be considered alternatives for financial measures presented in accordance with GAAP. These measures are discussed in more detail below and may not be comparable to other companies’ similarly titled non-GAAP financial measures.

Earnings Adjusted for Certain Items (Ongoing Earnings)

Ongoing earnings reflect adjustments to GAAP earnings (net income) for certain items.

We use this non-GAAP financial measure to evaluate and provide details of NSP-Wisconsin’s core earnings and underlying performance. We believe this measurement is useful to investors to evaluate the actual and projected financial performance and contribution of NSP-Wisconsin. For the three months ended March 31, 2024 and 2023, there were no such adjustments to GAAP earnings and therefore GAAP earnings equal ongoing earnings.

Results of Operations

NSP-Wisconsin's net income was $43 million and $45 million for the three months ended March 31, 2024 and 2023, respectively, as lower O&M expenses were offset by increased depreciation.

Electric Revenue

Electric revenues are impacted by fluctuations in the price of natural gas, coal and uranium, regulatory outcomes, market prices and seasonality. Electric revenues increased $2 million for the first quarter.

(Millions of Dollars)	Three Months Ended March. 31, 2024 vs. 2023
Estimated impact of weather	$	(3)
Sales and demand	(2)
Regulatory rate outcomes	4
Interchange agreement revenue from NSP-Minnesota	3
Total increase	$	2

Natural Gas Revenues

Natural gas revenues vary with changing sales and the cost of natural gas and regulatory outcomes. Natural gas revenues decreased $23 million in the first quarter.

(Millions of Dollars)	Three Months Ended March. 31, 2024 vs. 2023
Recovery of lower cost of natural gas	$	(21)
Estimated impact of weather	(3)
Other (net)	1
Total decrease	$	(23)

Electric Fuel and Purchased Power — Expenses incurred for electric fuel and purchased power are impacted by fluctuations in market prices of natural gas, coal and uranium, as well as seasonality. However, these incurred expenses are generally recovered through various regulatory recovery mechanisms. As a result, changes in these expenses are generally offset in operating revenues and have minimal earnings impact.

Electric fuel and purchased power expenses remained flat for the first quarter of 2024.

Cost of Natural Gas Sold and Transported — Expenses incurred for the cost of natural gas sold are impacted by market prices and seasonality. These costs are generally recovered through various regulatory recovery mechanisms. As a result, changes in these expenses are generally offset in operating revenues and have minimal earnings impact.

Natural gas sold and transported decreased $22 million for the first quarter of 2024. The decrease is primarily due to lower commodity prices and lower volumes.

Non-Fuel Operating Expenses and Other Items

O&M Expenses — O&M expenses decreased $2 million year to date, primarily due to lower storm costs.

Depreciation and Amortization — Depreciation and amortization increased $4 million year to date, primarily due to system expansion.

Public Utility Regulation and Other

The FERC and various state and local regulatory commissions regulate NSP-Wisconsin. The electric and natural gas rates charged to customers of NSP-Wisconsin are approved by the FERC or the regulatory commissions in the states in which it operates.

Rates are designed to recover plant investment, operating costs and an allowed return on investment. NSP-Wisconsin requests changes in utility rates through commission filings.

12

Changes in operating costs can affect NSP-Wisconsin’s financial results, depending on the timing of rate case filings and implementation of final rates. Other factors affecting rate filings are new investments, sales, conservation and demand side management efforts, and the cost of capital. In addition, the regulatory commissions authorize the ROE, capital structure and depreciation rates in rate proceedings. Decisions by these regulators can significantly impact NSP-Wisconsin’s results of operations.

Except to the extent noted below, the circumstances set forth in Public Utility Regulation included in Item 7 of NSP-Wisconsin’s Annual Report on Form 10-K for the year ended Dec. 31, 2023 appropriately represent, in all material respects, the current status of public utility regulation and are incorporated herein by reference.

Pending Regulatory Proceedings - NSP-System

2022 Upper Midwest IRP Resource Acquisition

Following the MPUC’s approval of NSP-Minnesota and NSP-Wisconsin’s latest IRP in April 2022, NSP-Minnesota and NSP-Wisconsin have been engaged in multiple resource acquisition processes and proceedings to meet the need identified in the IRP.

•In the second quarter of 2023, NSP-Minnesota initiated the process with the MPUC for acquisition of 800 MW of firm dispatchable resources. In January 2024, NSP-Minnesota and other companies submitted proposed resources and filed for project approval with the MPUC. NSP-Minnesota expects a decision by the second quarter of 2025.

•In July 2023, NSP-Wisconsin issued an RFP seeking approximately 650 MW of solar and/or solar plus storage development assets that will be developed in the 2027-2029 timeframe to replace the capacity from the retiring King Generating Station. The RFP closed in September 2023 and bids are being evaluated.

•In October 2023, NSP-Minnesota issued an RFP seeking approximately 1,200 MW of wind development assets to replace capacity and reutilize interconnection rights associated with the retiring Sherco coal facilities. The RFP closed in December 2023 and NSP-Minnesota expects to file for approval of recommended projects by mid-2024.

2024 Upper Midwest Resource Plan

In February 2024, NSP-Minnesota filed its Upper Midwest Resource Plan with the MPUC which included the following key items:

•Reduced carbon emissions by more than 80%, potentially up to 88%, by 2030.

•Extends the operation of Prairie Island and Monticello through the early 2050s.

•Adds 3,600 MWs of new wind and solar resources by 2030.

•Adds 600 MWs of battery energy storage by 2030.

•Adds more than 2,200 MWs of dispatchable resources by 2030.

These proposed resources are in addition to projects already approved by the MPUC. NSP-Minnesota anticipates a MPUC decision in 2025.

Emerging Environmental Regulation

Clean Air Act

Power Plant Greenhouse Gas Regulations — In April 2024, the EPA published final rules addressing control of CO2 emissions from the power sector. The rules regulate new natural gas generating units and emission guidelines for existing coal and certain natural gas generation. The rules create subcategories of coal units based on planned retirement date and subcategories of natural gas combustion turbines and combined cycle units based on utilization. The CO2 control requirements vary by subcategory. NSP-Wisconsin continues to evaluate the impact of these rules and believes that the cost of these initiatives or replacement generation would be recoverable through rates based on prior state commission practices.

Waste-to-Energy Air Regulations — In January 2024, the EPA proposed air regulations addressing new and existing large municipal waste combustors. The proposed rules lower current emission standards for certain pollutants and would require installation of new pollution controls and/or more intense use of existing pollution controls at French Island Generating Station. Until final rules are issued, it is not certain what the impact will be on NSP-Wisconsin. NSP-Wisconsin believes that the cost of these initiatives or replacement generation would be recoverable through rates based on prior state commission practices.

Emerging Contaminants of Concern

PFAS are man-made chemicals that are widely used in consumer products and can persist and bio-accumulate in the environment. NSP-Wisconsin does not manufacture PFAS but because PFAS are so ubiquitous in products and the environment, it may impact our operations.

In September 2022, the EPA proposed to designate two types of PFAS as “hazardous substances” under the CERCLA.

In March 2023, the EPA published a proposed rule that would establish enforceable drinking water standards for certain PFAS chemicals.

In February 2024, the EPA proposed to change the Resource Conservation and Recovery Act by adding nine PFAS to its list of hazardous constituents.

Final rules for all three proposals are expected in 2024 which could result in new obligations. Potential costs are uncertain until final rules are published and/or agency action is taken.

ITEM 4 — CONTROLS AND PROCEDURES

Disclosure Controls and Procedures

NSP-Wisconsin maintains a set of disclosure controls and procedures designed to ensure that information required to be disclosed in reports that it files or submits under the Securities Exchange Act of 1934 is recorded, processed, summarized, and reported within the time periods specified in SEC rules and forms.

In addition, the disclosure controls and procedures ensure that information required to be disclosed is accumulated and communicated to management, including the CEO and CFO, allowing timely decisions regarding required disclosure.

As of March 31, 2024, based on an evaluation carried out under the supervision and with the participation of NSP-Wisconsin’s management, including the CEO and CFO, of the effectiveness of its disclosure controls and procedures, the CEO and CFO have concluded that NSP-Wisconsin’s disclosure controls and procedures were effective.

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Internal Control Over Financial Reporting

No changes in NSP-Wisconsin’s internal control over financial reporting occurred during the most recent fiscal quarter that materially affected, or are reasonably likely to materially affect, NSP-Wisconsin’s internal control over financial reporting.

PART II — OTHER INFORMATION

ITEM 1 — LEGAL PROCEEDINGS

NSP-Wisconsin is involved in various litigation matters in the ordinary course of business. The assessment of whether a loss is probable or is a reasonable possibility, and whether the loss or a range of loss is estimable, often involves a series of complex judgments about future events. Management maintains accruals for losses probable of being incurred and subject to reasonable estimation.

Management is sometimes unable to estimate an amount or range of a reasonably possible loss in certain situations, including but not limited to, when (1) the damages sought are indeterminate, (2) the proceedings are in the early stages, or (3) the matters involve novel or unsettled legal theories. In such cases, there is considerable uncertainty regarding the timing or ultimate resolution of such matters, including a possible eventual loss.

For current proceedings not specifically reported herein, management does not anticipate that the ultimate liabilities, if any, would have a material effect on NSP-Wisconsin’s consolidated financial statements. Legal fees are generally expensed as incurred.

See Note 9 to the consolidated financial statements and Part I Item 2 for further information.

ITEM 1A — RISK FACTORS

NSP-Wisconsin's risk factors are documented in Item 1A of Part I of its Annual Report on Form 10-K for the year ended Dec. 31, 2023, which is incorporated herein by reference. There have been no material changes from the risk factors previously disclosed in the Form 10-K.

ITEM 5 — OTHER INFORMATION

None of the Company’s directors or officers adopted, modified, or terminated a Rule 10b5-1 trading arrangement or a non-Rule 10b5-1 trading arrangement during the Company’s fiscal quarter ended March 31, 2024.

ITEM 6 — EXHIBITS

* Indicates incorporation by reference

Exhibit Number	Description	Report or Registration Statement	Exhibit Reference
3.01*	Amended and Restated Articles of Incorporation of NSP-Wisconsin, dated May 28, 1998	NSP-Wisconsin Form S-4 dated Jan. 21, 2004	3.01
3.02*	Amended and Restated Bylaws of NSP-Wisconsin, dated Jan. 25, 2019	NSP-Wisconsin Form 10-K for the year ended Dec. 31, 2018	3.02
31.01	Principal Executive Officer’s certifications pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 302 of the Sarbanes-Oxley Act of 2002
31.02	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	Certifications pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002
101.INS	Inline XBRL Instance Document - the instance document does not appear in the Interactive Data File because its XBRL tags are embedded within the Inline XBRL document.
101.SCH	Inline XBRL Schema
101.CAL	Inline XBRL Calculation
101.DEF	Inline XBRL Definition
101.LAB	Inline XBRL Label
101.PRE	Inline XBRL Presentation
104	Cover Page Interactive Data File (formatted as Inline XBRL and contained in Exhibit 101)

14

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

		Northern States Power Company (a Wisconsin corporation)
4/25/2024	By:	/s/ MELISSA L. OSTROM
		Melissa L. Ostrom
		Vice President, Controller
		(Principal Accounting Officer)
	By:	/s/ BRIAN J. VAN ABEL
		Brian J. Van Abel
		Executive Vice President, Chief Financial Officer
		(Principal Financial Officer)

15

EX-31.01

Exhibit 31.01

CERTIFICATION

I, Robert C. Frenzel, certify that:

1.I have reviewed this report on Form 10-Q of Northern States Power Company (a Wisconsin corporation);

2.Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3.Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4.The registrant’s other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

a)Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

b)Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

c)Evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

d)Disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5.The registrant’s other certifying officer and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant’s auditors and the audit committee of the registrant’s board of directors (or persons performing the equivalent functions):

a)All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and

b)Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

Date: 4/25/2024

/s/ ROBERT C. FRENZEL

Robert C. Frenzel

Chairman, Chief Executive Officer and Director

(Principal Executive Officer)

1

EX-31.02

Exhibit 31.02

CERTIFICATION

I, Brian J. Van Abel, certify that:

1.I have reviewed this report on Form 10-Q of Northern States Power Company (a Wisconsin corporation);

2.Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3.Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4.The registrant’s other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

a)Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

b)Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

c)Evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

d)Disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5.The registrant’s other certifying officer and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant’s auditors and the audit committee of the registrant’s board of directors (or persons performing the equivalent functions):

a)All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and

b)Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

Date: 4/25/2024

/s/ BRIAN J. VAN ABEL

Brian J. Van Abel

Executive Vice President, Chief Financial Officer and Director

(Principal Financial Officer)

2

EX-32.01

Exhibit 32.01

OFFICER CERTIFICATION

CERTIFICATION PURSUANT TO

18 U.S.C. SECTION 1350,

AS ADOPTED PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the Quarterly Report of Northern States Power Company, a Wisconsin Corporation (NSP-Wisconsin) on Form 10-Q for the quarter ended March 31, 2024, as filed with the SEC on the date hereof (Form 10-Q), each of the undersigned officers of NSP-Wisconsin certifies, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that, to such officer’s knowledge:

(1)The Form 10-Q fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934; and

(2)The information contained in the Form 10-Q fairly presents, in all material respects, the financial condition and results of operations of NSP-Wisconsin as of the dates and for the periods expressed in the Form 10-Q.

Date: 4/25/2024

/s/ ROBERT C. FRENZEL

Robert C. Frenzel

Chairman, Chief Executive Officer and Director

(Principal Executive Officer)

/s/ BRIAN J. VAN ABEL

Brian J. Van Abel

Executive Vice President, Chief Financial Officer and Director

(Principal Financial Officer)

The foregoing certification is being furnished solely pursuant to 18 U.S.C. Section 1350 and is not being filed as part of the Report or as a separate disclosure document.

A signed original of this written statement required by Section 906, or other document authenticating, acknowledging or otherwise adopting the signature that appears in typed form within the electronic version of this written statement required by Section 906, has been provided to NSP-Wisconsin and will be retained by NSP-Wisconsin and furnished to the SEC or its staff upon request.

1

XML

Cover Page - shares	3 Months Ended
	Mar. 31, 2024	Apr. 25, 2024
Cover [Abstract]
Entity Registrant Name	NORTHERN STATES POWER CO /WI/
Entity Central Index Key	0000072909
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q1
Amendment Flag	false
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2024
Document Transition Report	false
Entity File Number	001-03140
Entity Incorporation, State or Country Code	WI
Entity Tax Identification Number	39-0508315
Entity Address, Address Line One	1414 West Hamilton Avenue
Entity Address, City or Town	Eau Claire
Entity Address, State or Province	WI
Entity Address, Postal Zip Code	54701
City Area Code	(715)
Local Phone Number	852-5812
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		933,000

XML

CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Operating revenues
Electric, non-affiliates	$ 203	$ 204
Electric, affiliates	53	50
Natural gas	54	77
Total operating revenues	310	331
Operating expenses
Electric fuel and purchased power, non-affiliates	4	4
Purchased power, affiliates	103	103
Cost of natural sold and transported	24	46
Operating and maintenance expenses	56	58
Conservation program expenses	3	3
Depreciation and amortization	45	41
Taxes (other than income taxes)	9	8
Total operating expenses	244	263
Operating income	66	68
Allowance for funds used during construction — equity	3	2
Interest charges and financing costs
Interest charges and other financing costs	14	13
Allowance for funds used during construction — debt	(1)	(1)
Total interest charges and financing costs	13	12
Income before income taxes	56	58
Income tax expense	13	13
Net income	$ 43	$ 45

XML

CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Operating activities
Net income	$ 43	$ 45
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation and amortization	46	42
Deferred income taxes	3	(2)
Allowance for equity funds used during construction	3	2
Provision for bad debts	1	2
Changes in operating assets and liabilities:
Accounts receivable	(13)	(16)
Accrued unbilled revenues	9	20
Inventories	3	15
Other current assets	5	13
Accounts payable	(7)	(10)
Net regulatory assets and liabilities	(1)	17
Other current liabilities	5	0
Pension and other employee benefit obligations	(7)	(3)
Other, net	2	1
Net cash provided by operating activities	86	122
Investing activities
Capital/construction expenditures	(121)	(101)
Net cash used in investing activities	(121)	(101)
Financing activities
Repayments of short-term borrowings, net	(60)	(35)
Borrowings under utility money pool arrangement	130	0
Repayments under utility money pool arrangement	(111)	0
Capital contributions from parent	106	36
Dividends paid to parent	(25)	(23)
Net cash provided (used in) by financing activities	40	(22)
Net change in cash, cash equivalents and restricted cash	5	(1)
Cash, cash equivalents and restricted cash at beginning of period	6	2
Cash, cash equivalents and restricted cash at end of period	11	1
Supplemental disclosure of cash flow information:
Cash paid for interest (net of amounts capitalized)	(12)	(13)
Cash paid for income taxes, net	(7)	(4)
Supplemental disclosure of non-cash investing and financing transactions:
Accrued property, plant and equipment additions	33	33
Inventory transfers to property, plant and equipment	2	2
Allowance for equity funds used during construction	$ 3	$ 2

XML

CONSOLIDATED BALANCE SHEETS (UNAUDITED) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Current assets
Cash and cash equivalents	$ 11	$ 6
Accounts receivable, net	90	89
Accrued unbilled revenues	53	63
Inventories	24	29
Regulatory assets	23	24
Prepaid taxes	21	28
Prepayments and other	7	6
Total current assets	229	245
Property, Plant and Equipment, Net [Abstract]
Property, plant and equipment, net	3,332	3,237
Other assets
Regulatory assets	181	185
Other	3	3
Total other assets	184	188
Total assets	3,745	3,670
Current liabilities
Current portion of long-term debt	200	200
Short-term debt	0	60
Borrowings under utility money pool arrangement	19	0
Dividends payable to parent	18	25
Regulatory liabilities	41	42
Taxes accrued	19	16
Accrued interest	13	13
Other	24	23
Total current liabilities	415	464
Deferred credits and other liabilities
Deferred income taxes	336	330
Deferred investment tax credits	5	5
Regulatory liabilities	412	407
Customer advances	26	25
Pension and employee benefit obligations	20	27
Other	34	35
Total deferred credits and other liabilities	833	829
Commitments and contingencies
Capitalization
Long-term debt	1,011	1,011
Common stock — 1,000,000 shares authorized of $100 par value; 933,000 shares outstanding at March 31, 2024 and Dec. 31, 2023, respectively	$ 93	$ 93
Common stock, shares authorized (in shares)	1,000,000	1,000,000
Common stock, par value (in dollars per share)	$ 100	$ 100
Common stock, shares outstanding (in shares)	933,000	933,000
Additional paid in capital	$ 938	$ 843
Retained earnings	455	430
Total common stockholder's equity	1,486	1,366
Total liabilities and equity	3,745	3,670
Related Party
Current liabilities
Accounts payable	61	64
Affiliated Entity
Current liabilities
Accounts payable	$ 20	$ 21

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CONSOLIDATED STATEMENTS OF COMMON STOCKHOLDER'S EQUITY - USD ($) $ in Millions	Total	Common stock	Additional Paid In Capital	Retained Earnings
Balance (in shares) at Dec. 31, 2022		933,000
Beginning Balance at Dec. 31, 2022	$ 1,259	$ 93	$ 761	$ 405
Increase (Decrease) in Stockholder's Equity
Net income	45			45
Common dividends declared to parent	(24)			(24)
Contribution of capital by parent	30		30
Balance (in shares) at Mar. 31, 2023		933,000
Ending Balance at Mar. 31, 2023	$ 1,310	$ 93	791	426
Balance (in shares) at Dec. 31, 2023	933,000	933,000
Beginning Balance at Dec. 31, 2023	$ 1,366	$ 93	843	430
Increase (Decrease) in Stockholder's Equity
Net income	43			43
Common dividends declared to parent	(18)			(18)
Contribution of capital by parent	$ 95		95
Balance (in shares) at Mar. 31, 2024	933,000	933,000
Ending Balance at Mar. 31, 2024	$ 1,486	$ 93	$ 938	$ 455

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Management's Opinion

3 Months Ended

Mar. 31, 2024

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Management's Opinion

In the opinion of management, the accompanying unaudited consolidated financial statements contain all adjustments necessary to present fairly, in accordance with GAAP, the financial position of NSP-Wisconsin and its subsidiaries as of March 31, 2024 and Dec. 31, 2023; the results of NSP-Wisconsin's operations, including the components of net income, cash flows, and changes in stockholder's equity for the three months ended March 31, 2024 and 2023.

All adjustments are of a normal, recurring nature, except as otherwise disclosed. Management has also evaluated the impact of events occurring after March 31, 2024 up to the date of issuance of these consolidated financial statements. These statements contain all necessary adjustments and disclosures resulting from that evaluation. The Dec. 31, 2023 balance sheet information has been derived from the audited 2023 consolidated financial statements included in the NSP-Wisconsin Annual Report on Form 10-K for the year ended Dec. 31, 2023.

Notes to the consolidated financial statements have been prepared pursuant to the rules and regulations of the SEC for Quarterly Reports on Form 10-Q. Certain information and note disclosures normally included in financial statements prepared in accordance with GAAP on an annual basis have been condensed or omitted pursuant to such rules and regulations. For further information, refer to the consolidated financial statements and notes thereto included in the NSP-Wisconsin Annual Report on Form 10-K for the year ended Dec. 31, 2023, filed with the SEC on Feb. 21, 2024. Due to the seasonality of NSP-Wisconsin’s electric and natural gas sales, interim results are not necessarily an appropriate base from which to project annual results.

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Summary of Significant Accounting Policies

3 Months Ended

Mar. 31, 2024

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

The significant accounting policies set forth in Note 1 to the consolidated financial statements in the NSP-Wisconsin Annual Report on Form 10-K for the year ended Dec. 31, 2023 appropriately represent, in all material respects, the current status of accounting policies and are incorporated herein by reference.

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Accounting Pronouncements

3 Months Ended

Mar. 31, 2024

Accounting Standards Update and Change in Accounting Principle [Abstract]

Accounting Pronouncements

Recently Issued

Segment Reporting — In November 2023, the FASB issued ASU 2023-07 – Segment Reporting (Topic 280) – Improvements to Reportable Segment Disclosures, which extends the existing requirements for annual disclosures to quarterly periods, and requires that both annual and quarterly disclosures present segment expenses using line items consistent with information regularly provided to the chief operating decision maker. The ASU is effective for annual periods beginning after Dec. 15, 2023 and quarterly periods beginning after Dec. 15, 2024, and Xcel Energy does not expect implementation of the new disclosure guidance to have a material impact to its consolidated financial statements.

Income Taxes — In December 2023, the FASB issued ASU 2023-09 – Income Taxes (Topic 740) – Improvements to Income Tax Disclosures, with new disclosure requirements including presentation of prescribed line items in the effective tax rate reconciliation and disclosures regarding state and local tax payments. The ASU is effective for annual periods beginning after Dec. 15, 2024, and Xcel Energy does not expect implementation of the new disclosure guidance to have a material impact to its consolidated financial statements.

Climate-Related Disclosures — In March 2024, the SEC issued Final Rule 33-11275 – The Enhancement and Standardization of Climate-Related Disclosures for Investors. This rule requires registrants to provide standardized disclosures in Form 10-K related to climate-related risks, Scope 1 and 2 greenhouse gas emissions, as well as to include in a footnote to the consolidated financial statements the financial impact of severe weather events and other natural conditions. The rule requires implementation in phases between 2025 and 2033. In April 2024, the SEC announced that it would voluntarily stay its final climate disclosure rules pending judicial review. Xcel Energy does not expect implementation of the new guidance to have a material impact on the consolidated financial statements.

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Selected Balance Sheet Data

3 Months Ended

Mar. 31, 2024

Balance Sheet Related Disclosures [Abstract]

Selected Balance Sheet Data

(Millions of dollars)	March 31, 2024		Dec. 31, 2023
Accounts receivable, net
Accounts receivable	$	98	$	98
Less allowance for bad debts	(8)		(9)
Accounts receivable, net	$	90	$	89

(Millions of dollars)	March 31, 2024		Dec. 31, 2023
Inventories
Materials and supplies	$	12	$	11
Fuel	10		10
Natural gas	2		8
Total inventories	$	24	$	29

(Millions of dollars)	March 31, 2024		Dec. 31, 2023
Property, plant and equipment, net
Electric plant	$	3,895	$	3,845
Natural gas plant	504		502
Common and other property	287		278
Construction work in progress	306		252
Total property, plant and equipment	4,992		4,877
Less accumulated depreciation	(1,660)		(1,640)
Property, plant and equipment, net	$	3,332	$	3,237

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Borrowings and Other Financing Instruments

3 Months Ended

Mar. 31, 2024

Debt Disclosure [Abstract]

Borrowings and Other Financing Instruments

Short-Term Borrowings

NSP-Wisconsin meets its short-term liquidity requirements primarily through the issuance of commercial paper and borrowings under its credit facility and the money pool.

Money Pool — Xcel Energy Inc. and its utility subsidiaries have established a money pool arrangement that allows for short-term investments in and borrowings between the utility subsidiaries. Xcel Energy Inc. may make investments in the utility subsidiaries at market-based interest rates; however, the money pool arrangement does not allow the utility subsidiaries to make investments in Xcel Energy Inc.

Money pool borrowings:

(Amounts in Millions, Except Interest Rates)	Three Months Ended March 31, 2024			Year Ended Dec. 31, 2023
Borrowing limit	$	150		$	150
Amount outstanding at period end	19			—
Average amount outstanding	12			6
Maximum amount outstanding	54			43
Weighted average interest rate, computed on a daily basis	5.33		%	4.98		%
Weighted average interest rate at period end	5.33			N/A

Commercial Paper — Commercial paper outstanding:

(Amounts in Millions, Except Interest Rates)	Three Months Ended March 31, 2024			Year Ended Dec. 31, 2023
Borrowing limit	$	150		$	150
Amount outstanding at period end	—			60
Average amount outstanding	41			15
Maximum amount outstanding	99			93
Weighted average interest rate, computed on a daily basis	5.49		%	4.85		%
Weighted average interest rate at period end	N/A			5.50

Letters of Credit — NSP-Wisconsin uses letters of credit, generally with terms of one year, to provide financial guarantees for certain obligations. At both March 31, 2024 and Dec. 31, 2023, there were immaterial letters of credit outstanding under the credit facility.

Revolving Credit Facility — In order to issue its commercial paper, NSP-Wisconsin must have a revolving credit facility equal to or greater than the commercial paper borrowing limit and cannot issue commercial paper exceeding available capacity under this credit facility. The credit facility provides short-term financing in the form of notes payable to banks, letters of credit and back-up support for commercial paper borrowings.

NSP-Wisconsin has the right to request an extension of the revolving credit facility termination date for an additional one-year period. All extension requests are subject to majority bank group approval.

As of March 31, 2024, NSP-Wisconsin had the following committed revolving credit facility available (in millions of dollars):

Credit Facility (a)		Outstanding (b)		Available
$	150	$	—	$	150

(a)Expires in September 2027.

(b)Includes outstanding commercial paper.

All credit facility bank borrowings, outstanding letters of credit and outstanding commercial paper reduce the available capacity under the credit facility. NSP-Wisconsin had no direct advances on the credit facility outstanding at March 31, 2024 and Dec. 31, 2023.

Other Short-Term Borrowings — Clearwater Investments, Inc., a NSP-Wisconsin subsidiary, had an immaterial note payable to Xcel Energy Inc. as of March 31, 2024 and Dec. 31, 2023, respectively.

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Revenues

3 Months Ended

Mar. 31, 2024

Revenue from Contract with Customer [Abstract]

Revenues

Revenue is classified by the type of goods/services rendered and market/customer type. NSP-Wisconsin’s operating revenues consisted of the following:

	Three Months Ended March 31, 2024
(Millions of Dollars)	Electric		Natural Gas		Total
Major revenue types
Revenue from contracts with customers:
Residential	$	77	$	30	$	107
C&I	118		22		140
Other	2		—		2
Total retail	197		52		249
Interchange and other	56		1		57
Total revenue from contracts with customers	253		53		306
Alternative revenue and other	3		1		4
Total revenues	$	256	$	54	$	310

	Three Months Ended March 31, 2023
(Millions of Dollars)	Electric		Natural Gas		Total
Major revenue types
Revenue from contracts with customers:
Residential	$	82	$	41	$	123
C&I	120		34		154
Other	2		—		2
Total retail	204		75		279
Interchange and other	47		1		48
Total revenue from contracts with customers	251		76		327
Alternative revenue and other	3		1		4
Total revenues	$	254	$	77	$	331

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Income Taxes

3 Months Ended

Mar. 31, 2024

Income Tax Disclosure [Abstract]

Income Taxes

6. Income Taxes

Reconciliation between the statutory rate and effective tax rate:

	Three Months Ended March 31
	2024		2023
Federal statutory rate	21.0	%	21.0	%
State tax (net of federal tax effect)	6.2		6.2
(Decreases) increases:
Plant regulatory differences (a)	(4.3)		(3.5)
Other (net)	0.3		(1.3)
Effective income tax rate	23.2	%	22.4	%

(a)Plant regulatory differences primarily relate to the credit of excess deferred taxes to customers through the average rate assumption method. Income tax benefits associated with the credit are offset by corresponding revenue reductions.

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Fair Value of Financial Assets and Liabilities

3 Months Ended

Mar. 31, 2024

Fair Value Disclosures [Abstract]

Fair Value of Financial Assets and Liabilities

7. Fair Value of Financial Assets and Liabilities

Fair Value Measurements

Accounting guidance for fair value measurements and disclosures provides a hierarchical framework for disclosing the observability of the inputs utilized in measuring assets and liabilities at fair value.

•Level 1 — Quoted prices are available in active markets for identical assets or liabilities as of the reporting date. The types of assets and liabilities included in Level 1 are actively traded instruments with observable actual trading prices.

•Level 2 — Pricing inputs are other than actual trading prices in active markets, but are either directly or indirectly observable as of the reporting date. The types of assets and liabilities included in Level 2 are typically either comparable to actively traded securities or contracts or priced with models using highly observable inputs.

•Level 3 — Significant inputs to pricing have little or no observability as of the reporting date. The types of assets and liabilities included in Level 3 include those valued with models requiring significant judgment or estimation.

Specific valuation methods include:

Commodity Derivatives — Methods used to measure the fair value of commodity derivative forwards and options utilize forward prices and volatilities, as well as pricing adjustments for specific delivery locations, and are generally assigned a Level 2 classification. When contracts relate to inactive delivery locations or extend to periods beyond those readily observable on active exchanges, the significance of the use of less observable inputs on a valuation is evaluated, and may result in Level 3 classification.

Derivative Activities and Fair Value Measurements

NSP-Wisconsin enters into derivative instruments, including forward contracts, futures, swaps and options, to manage risk in connection with changes in utility commodity prices.

Commodity Derivatives — NSP-Wisconsin enters into derivative instruments to manage variability of future cash flows from changes in commodity prices in its electric and natural gas operations. This could include the purchase or sale of natural gas to generate electric energy and natural gas for resale.

As of March 31, 2024, NSP-Wisconsin had no commodity contracts designated as cash flow hedges.

Consideration of Credit Risk and Concentrations — NSP-Wisconsin continuously monitors the creditworthiness of counterparties to its interest rate derivatives and commodity derivative contracts prior to settlement, and assesses each counterparty’s ability to perform on the transactions set forth in the contracts. Impact of credit risk was immaterial to the fair value of unsettled commodity derivatives presented on the consolidated balance sheets.

Recurring Derivative Fair Value Measurements

Impact of derivative activity:

Changes in the fair value of natural gas commodity derivatives resulted in immaterial and $1 million of net gains for the three months ended March 31, 2024 and 2023, respectively, which were recognized as regulatory assets and liabilities. The classification as a regulatory asset or liability is based on commission approved regulatory recovery mechanisms.

During the three months ended March 31, 2024 and 2023, $1 million and $2 million, respectively, of pre-tax losses were recognized during the period related to option premium amortization subject to natural gas cost recovery mechanisms and reclassified out of income to a regulatory asset, as appropriate.

NSP-Wisconsin had immaterial outstanding derivative assets or liabilities measured at fair value as of March 31, 2024 and Dec. 31, 2023.

Fair Value of Long-Term Debt

As of March 31, 2024, other financial instruments for which the carrying amount did not equal fair value:

	March 31, 2024				Dec. 31, 2023
(Millions of Dollars)	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Long-term debt, including current portion	$	1,211	$	1,104	$	1,211	$	1,117

Fair value of NSP-Wisconsin’s long-term debt is estimated based on recent trades and observable spreads from benchmark interest rates for similar securities. Fair value estimates are based on information available to management as of March 31, 2024 and Dec. 31, 2023, and given the observability of the inputs, fair values presented for long-term debt were assigned as Level 2.

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Benefit Plans and Other Postretirement Benefits

3 Months Ended

Mar. 31, 2024

Retirement Benefits [Abstract]

Benefit Plans and Other Postretirement Benefits

Components of Net Periodic Benefit Cost

	Three Months Ended March 31
	2024		2023
(Millions of Dollars)	Pension Benefits
Service cost	$	1	$	1
Interest cost (a)	2		2
Expected return on plan assets (a)	(2)		(2)
Net periodic benefit cost	$	1	$	1

(a)The components of net periodic cost other than the service cost component are included in the line item “Other income (expense), net” in the consolidated statements of income or capitalized on the consolidated balance sheets as a regulatory asset.

In January 2024, contributions totaling $100 million were made across Xcel Energy’s pension plans, of which $7 million was attributable to NSP-Wisconsin. Xcel Energy does not expect additional pension contributions during 2024

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Commitments and Contingencies

3 Months Ended

Mar. 31, 2024

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

Legal

NSP-Wisconsin is involved in various litigation matters in the ordinary course of business. The assessment of whether a loss is probable or is a reasonable possibility, and whether the loss or a range of loss is estimable, often involves a series of complex judgments about future events. Management maintains accruals for losses probable of being incurred and subject to reasonable estimation. Management is sometimes unable to estimate an amount or range of a reasonably possible loss in certain situations, including but not limited to when (1) the damages sought are indeterminate, (2) the proceedings are in the early stages, or (3) the matters involve novel or unsettled legal theories.

In such cases, there is considerable uncertainty regarding the timing or ultimate resolution, including a possible eventual loss. For current proceedings not specifically reported herein, management does not anticipate that the ultimate liabilities, if any, would have a material effect on NSP-Wisconsin’s consolidated financial statements. Legal fees are generally expensed as incurred.

Gas Trading Litigation — e prime is a wholly owned subsidiary of Xcel Energy. e prime was in the business of natural gas trading and marketing but has not engaged in natural gas trading or marketing activities since 2003. Multiple lawsuits involving multiple plaintiffs seeking monetary damages were commenced against e prime and its affiliates, including Xcel Energy, between 2003 and 2009 alleging fraud and anticompetitive activities in conspiring to restrain the trade of natural gas and manipulate natural gas prices. Cases were all consolidated in the U.S. District Court in Nevada.

One case remains active which includes a multi-district litigation matter consisting of a Wisconsin purported class (Arandell Corp.). The Court issued a ruling in June 2022 granting plaintiffs’ class certification. In April 2023, the Seventh Circuit Court of Appeals heard the defendants’ appeal challenging whether the district court properly assessed class certification. A decision relating to class certification is expected imminently. Xcel Energy considers the reasonably possible loss associated with this litigation to be immaterial.

Rate Matters

NSP-Wisconsin is involved in various regulatory proceedings arising in the ordinary course of business. Until resolution, typically in the form of a rate order, uncertainties may exist regarding the ultimate rate treatment for certain activities and transactions. Amounts have been recognized for probable and reasonably estimable losses that may result. Unless otherwise disclosed, any reasonably possible range of loss in excess of any recognized amount is not expected to have a material effect on the financial statements.

Environmental

New and changing federal and state environmental mandates can create financial liabilities for NSP-Wisconsin, which are normally recovered through the regulated rate process.

Site Remediation

Various federal and state environmental laws impose liability where hazardous substances or other regulated materials have been released to the environment. NSP-Wisconsin may sometimes pay all or a portion of the cost to remediate sites where past activities of their predecessors or other parties have caused environmental contamination.

Environmental contingencies could arise from various situations, including sites of former MGPs; and third-party sites, such as landfills, for which NSP-Wisconsin is alleged to have sent wastes to that site.

MGP, Landfill and Disposal Sites

NSP-Wisconsin is investigating, remediating or performing post-closure actions at one MGP, landfill or other disposal sites across its service territories.

NSP-Wisconsin has recognized approximately $13 million of costs/liabilities from final resolution of these issues, however, the outcome and timing are unknown. In addition, there may be regulatory recovery, insurance recovery and/or recovery from other potentially responsible parties, offsetting a portion of costs incurred.

Environmental Requirements — Water and Waste

Federal Clean Water Act Section 316(b) — The Federal Clean Water Act requires the EPA to regulate cooling water intake structures to assure they reflect the best technology available for minimizing impingement and entrainment of aquatic species. NSP-Wisconsin estimates capital expenditures of approximately $5 million may be required to comply with the requirements. NSP-Wisconsin believes two plants could be required to make improvements to reduce impingement and entrainment. NSP-Wisconsin anticipates these costs will be recoverable through regulatory mechanisms.

Environmental Requirements — Air

Clean Air Act NOx Allowance Allocations — In June 2023, the EPA published final regulations under the "Good Neighbor" provisions of the Clean Air Act. The final rule applies to generation facilities in Wisconsin, as well as other states outside of our service territory. The rule establishes an allowance trading program for NOx that will impact NSP-Wisconsin’s fossil fuel-fired electric generating facilities. Subject facilities will have to secure additional allowances, install NOx controls and/or develop a strategy of operations that utilizes the existing allowance allocations. Guidelines are also established for allowance banking and emission limit backstops.

While the financial impacts of the final rule are uncertain and dependent on market forces and anticipated generation, NSP-Wisconsin anticipates the costs would be recoverable through regulatory mechanisms.

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Segment Information

3 Months Ended

Mar. 31, 2024

Segment Reporting [Abstract]

Segment Information

NSP-Wisconsin evaluates performance based on profit or loss generated from the product or service provided. These segments are managed separately because the revenue streams are dependent upon regulated rate recovery, which is separately determined for each segment.

NSP-Wisconsin has the following reportable segments:

•Regulated Electric — The regulated electric utility segment generates electricity, which is transmitted and distributed in Wisconsin and Michigan.

•Regulated Natural Gas — The regulated natural gas utility segment purchases, transports, stores and distributes natural gas in portions of Wisconsin and Michigan.

Asset and capital expenditure information is not provided for NSP-Wisconsin's reportable segments. As an integrated electric and natural gas utility, NSP-Wisconsin operates significant assets that are not dedicated to a specific business segment. Reporting assets and capital expenditures by business segment would require arbitrary and potentially misleading allocations, which may not necessarily reflect the assets that would be required for the operation of the business segments on a stand-alone basis.

Certain costs, such as common depreciation, common O&M expenses and interest expense are allocated based on cost causation allocators across each segment. In addition, a general allocator is used for certain general and administrative expenses, including office supplies, rent, property insurance and general advertising.

NSP-Wisconsin's segment information:

	Three Months Ended March 31
(Millions of Dollars)	2024		2023
Regulated Electric
Total revenues (a)	$	256	$	254
Net income	33		33
Regulated Natural Gas
Total revenues	$	54	$	77
Net income	10		11
All Other
Net income	$	—	$	1
Consolidated Total
Total revenues (a)	$	310	$	331
Net income	43		45

(a)Total revenues include $53 million and $50 million of affiliate electric revenue for the three months ended March 31, 2024 and 2023, respectively.

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Pay vs Performance Disclosure - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Pay vs Performance Disclosure
Net income	$ 43	$ 45

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Insider Trading Arrangements	3 Months Ended
	Mar. 31, 2024
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

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Selected Balance Sheet Data (Tables)

3 Months Ended

Mar. 31, 2024

Balance Sheet Related Disclosures [Abstract]

Accounts Receivable, Net

(Millions of dollars)	March 31, 2024		Dec. 31, 2023
Accounts receivable, net
Accounts receivable	$	98	$	98
Less allowance for bad debts	(8)		(9)
Accounts receivable, net	$	90	$	89

Inventories

(Millions of dollars)	March 31, 2024		Dec. 31, 2023
Inventories
Materials and supplies	$	12	$	11
Fuel	10		10
Natural gas	2		8
Total inventories	$	24	$	29

Property, Plant and Equipment, Net

(Millions of dollars)	March 31, 2024		Dec. 31, 2023
Property, plant and equipment, net
Electric plant	$	3,895	$	3,845
Natural gas plant	504		502
Common and other property	287		278
Construction work in progress	306		252
Total property, plant and equipment	4,992		4,877
Less accumulated depreciation	(1,660)		(1,640)
Property, plant and equipment, net	$	3,332	$	3,237

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Borrowings and Other Financing Instruments (Tables)

3 Months Ended

Mar. 31, 2024

Borrowings and Other Financing Instruments [Abstract]

Credit Facilities

As of March 31, 2024, NSP-Wisconsin had the following committed revolving credit facility available (in millions of dollars):

Credit Facility (a)		Outstanding (b)		Available
$	150	$	—	$	150

(a)Expires in September 2027.

(b)Includes outstanding commercial paper.

Money Pool

Borrowings and Other Financing Instruments [Abstract]

Short-Term Borrowings

Money pool borrowings:

(Amounts in Millions, Except Interest Rates)	Three Months Ended March 31, 2024			Year Ended Dec. 31, 2023
Borrowing limit	$	150		$	150
Amount outstanding at period end	19			—
Average amount outstanding	12			6
Maximum amount outstanding	54			43
Weighted average interest rate, computed on a daily basis	5.33		%	4.98		%
Weighted average interest rate at period end	5.33			N/A

Commercial Paper

Borrowings and Other Financing Instruments [Abstract]

Short-Term Borrowings

Commercial paper outstanding:

(Amounts in Millions, Except Interest Rates)	Three Months Ended March 31, 2024			Year Ended Dec. 31, 2023
Borrowing limit	$	150		$	150
Amount outstanding at period end	—			60
Average amount outstanding	41			15
Maximum amount outstanding	99			93
Weighted average interest rate, computed on a daily basis	5.49		%	4.85		%
Weighted average interest rate at period end	N/A			5.50

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Revenues (Tables)

3 Months Ended

Mar. 31, 2024

Revenue from Contract with Customer [Abstract]

Disaggregation of revenue

NSP-Wisconsin’s operating revenues consisted of the following:

	Three Months Ended March 31, 2024
(Millions of Dollars)	Electric		Natural Gas		Total
Major revenue types
Revenue from contracts with customers:
Residential	$	77	$	30	$	107
C&I	118		22		140
Other	2		—		2
Total retail	197		52		249
Interchange and other	56		1		57
Total revenue from contracts with customers	253		53		306
Alternative revenue and other	3		1		4
Total revenues	$	256	$	54	$	310

	Three Months Ended March 31, 2023
(Millions of Dollars)	Electric		Natural Gas		Total
Major revenue types
Revenue from contracts with customers:
Residential	$	82	$	41	$	123
C&I	120		34		154
Other	2		—		2
Total retail	204		75		279
Interchange and other	47		1		48
Total revenue from contracts with customers	251		76		327
Alternative revenue and other	3		1		4
Total revenues	$	254	$	77	$	331

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Income Taxes (Tables)

3 Months Ended

Mar. 31, 2024

Income Tax Disclosure [Abstract]

Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]

Reconciliation between the statutory rate and effective tax rate:

	Three Months Ended March 31
	2024		2023
Federal statutory rate	21.0	%	21.0	%
State tax (net of federal tax effect)	6.2		6.2
(Decreases) increases:
Plant regulatory differences (a)	(4.3)		(3.5)
Other (net)	0.3		(1.3)
Effective income tax rate	23.2	%	22.4	%

(a)Plant regulatory differences primarily relate to the credit of excess deferred taxes to customers through the average rate assumption method. Income tax benefits associated with the credit are offset by corresponding revenue reductions.

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Fair Value of Financial Assets and Liabilities (Tables)

3 Months Ended

Mar. 31, 2024

Fair Value Disclosures [Abstract]

Carrying Amount and Fair Value of Long-term Debt

	March 31, 2024				Dec. 31, 2023
(Millions of Dollars)	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Long-term debt, including current portion	$	1,211	$	1,104	$	1,211	$	1,117

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Benefit Plans and Other Postretirement Benefits (Tables)

3 Months Ended

Mar. 31, 2024

Retirement Benefits [Abstract]

Components of Net Periodic Benefit Cost

Components of Net Periodic Benefit Cost

	Three Months Ended March 31
	2024		2023
(Millions of Dollars)	Pension Benefits
Service cost	$	1	$	1
Interest cost (a)	2		2
Expected return on plan assets (a)	(2)		(2)
Net periodic benefit cost	$	1	$	1

(a)The components of net periodic cost other than the service cost component are included in the line item “Other income (expense), net” in the consolidated statements of income or capitalized on the consolidated balance sheets as a regulatory asset.

In January 2024, contributions totaling $100 million were made across Xcel Energy’s pension plans, of which $7 million was attributable to NSP-Wisconsin. Xcel Energy does not expect additional pension contributions during 2024.

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Segment Reporting (Tables)

3 Months Ended

Mar. 31, 2024

Segment Reporting [Abstract]

Schedule of Segment Reporting Information, by Segment

NSP-Wisconsin's segment information:

	Three Months Ended March 31
(Millions of Dollars)	2024		2023
Regulated Electric
Total revenues (a)	$	256	$	254
Net income	33		33
Regulated Natural Gas
Total revenues	$	54	$	77
Net income	10		11
All Other
Net income	$	—	$	1
Consolidated Total
Total revenues (a)	$	310	$	331
Net income	43		45

(a)Total revenues include $53 million and $50 million of affiliate electric revenue for the three months ended March 31, 2024 and 2023, respectively.

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Selected Balance Sheet Data - Accounts Receivable (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Accounts Receivable, Net
Accounts receivable	$ 98	$ 98
Less allowance for bad debts	(8)	(9)
Accounts receivable, net	$ 90	$ 89

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Selected Balance Sheet Data - Inventories (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Inventory [Line Items]
Total Inventories	$ 24	$ 29
Materials and supplies
Inventory [Line Items]
Inventories	12	11
Fuel
Inventory [Line Items]
Inventories	10	10
Natural gas
Inventory [Line Items]
Inventories	$ 2	$ 8

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Selected Balance Sheet Data - Property, Plant and Equipment (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Public Utility, Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 4,992	$ 4,877
Less accumulated depreciation	(1,660)	(1,640)
Property, plant and equipment, net	3,332	3,237
Electric plant
Public Utility, Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	3,895	3,845
Natural gas plant
Public Utility, Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	504	502
Common and other property
Public Utility, Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	287	278
Construction work in progress
Public Utility, Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 306	$ 252

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Borrowings and Other Financing Instruments, Commercial Paper (Details) - USD ($)		3 Months Ended	12 Months Ended
		Mar. 31, 2024	Dec. 31, 2023
Short-term Debt [Line Items]
Amount outstanding at period end		$ 0	$ 60,000,000
Credit Facility
Short-term Debt [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	[1]	150,000,000
Long-term Line of Credit		0	0
Commercial Paper
Short-term Debt [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		150,000,000	150,000,000
Amount outstanding at period end		0	60,000,000
Average amount outstanding		41,000,000	15,000,000
Maximum amount outstanding		$ 99,000,000	$ 93,000,000
Weighted average interest rate, computed on a daily basis		5.49%	4.85%
Weighted average interest rate at period end			5.50%
Money Pool
Short-term Debt [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		$ 150,000,000	$ 150,000,000
Amount outstanding at period end		19,000,000	0
Average amount outstanding		12,000,000	6,000,000
Maximum amount outstanding		$ 54,000,000	$ 43,000,000
Weighted average interest rate, computed on a daily basis		5.33%	4.98%
Weighted average interest rate at period end		5.33%

[1] Expires in September 2027.

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Borrowings and Other Financing Instruments, Letters of Credit (Details) - USD ($)	3 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Line of Credit Facility [Line Items]
Line of Credit Facility, Expiration Period	1 year
Amount outstanding at period end	$ 0	$ 60,000,000
Credit Facility
Line of Credit Facility [Line Items]
Long-term Line of Credit	$ 0	$ 0

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Borrowings and Other Financing Instruments, Credit Facility (Details) - USD ($)		Mar. 31, 2024	Dec. 31, 2023
Payable to Affiliates
Line of Credit Facility [Line Items]
Notes Payable, Current		$ 0	$ 0
Credit Facility
Line of Credit Facility [Line Items]
Credit Facility	[1]	150,000,000
Outstanding	[2]	0
Available		150,000,000
Direct advances on the credit facility outstanding		$ 0	$ 0

[1] Expires in September 2027.

[2] Includes outstanding commercial paper.

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Revenues (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Total revenues
Disaggregation of Revenue [Line Items]
Total revenues	$ 310	$ 331
Regulated Electric | Total revenues
Disaggregation of Revenue [Line Items]
Total revenues	256	254
Regulated Natural Gas | Total revenues
Disaggregation of Revenue [Line Items]
Total revenues	54	77
Retail
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	249	279
Retail | Residential
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	107	123
Retail | C&I
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	140	154
Retail | Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	2	2
Retail | Regulated Electric
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	197	204
Retail | Regulated Electric | Residential
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	77	82
Retail | Regulated Electric | C&I
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	118	120
Retail | Regulated Electric | Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	2	2
Retail | Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	52	75
Retail | Regulated Natural Gas | Residential
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	30	41
Retail | Regulated Natural Gas | C&I
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	22	34
Retail | Regulated Natural Gas | Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Interchange
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	57	48
Interchange | Regulated Electric
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	56	47
Interchange | Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1	1
Total revenue from contracts with customers
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	306	327
Total revenue from contracts with customers | Regulated Electric
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	253	251
Total revenue from contracts with customers | Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	53	76
Alternative revenue and other
Disaggregation of Revenue [Line Items]
Alternative revenue and other	4	4
Alternative revenue and other | Regulated Electric
Disaggregation of Revenue [Line Items]
Alternative revenue and other	3	3
Alternative revenue and other | Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Alternative revenue and other	$ 1	$ 1

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Income Taxes (Details)		3 Months Ended
		Mar. 31, 2024	Mar. 31, 2023
Income Tax Disclosure [Abstract]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent		21.00%	21.00%
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent		6.20%	6.20%
Effective Income Tax Rate Reconciliation, Other Regulatory Items, Percent	[1]	(4.30%)	(3.50%)
Effective Income Tax Rate Reconciliation, Other Adjustments, Percent		0.30%	(1.30%)
Effective Income Tax Rate Reconciliation, Percent		23.20%	22.40%

[1] Plant regulatory differences primarily relate to the credit of excess deferred taxes to customers through the average rate assumption method. Income tax benefits associated with the credit are offset by corresponding revenue reductions.

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Fair Value of Financial Assets and Liabilities - Commodity Derivatives (Details) $ in Millions	Mar. 31, 2024 USD ($)
cash flow hedge commodity
Derivative [Line Items]
Commodity contracts designated as cash flow hedges	$ 0

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Fair Value of Financial Assets and Liabilities - Impact of Derivative Activities on Income (Details) - Other Derivative Instruments - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Natural Gas Commodity
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	$ 1	$ 2
Natural Gas Commodity [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pre-tax fair value gains (losses) recognized during the period in regulatory (assets) and liabilities		$ 1

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Fair Value of Financial Assets and Liabilities - Fair Value of Long-Term Debt (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Carrying Amount	$ 1,211	$ 1,211
Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value	$ 1,104	$ 1,117

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Benefit Plans and Other Postretirement Benefits (Details) - Pension Plan [Member] - USD ($) $ in Millions		1 Months Ended	3 Months Ended
		Jan. 31, 2024	Mar. 31, 2024	Mar. 31, 2023
Components of Net Periodic Benefit Cost [Abstract]
Service cost			$ 1	$ 1
Interest cost (a)	[1]		2	2
Expected return on plan assets (a)	[1]		(2)	(2)
Net periodic benefit cost			$ 1	$ 1
Contributions to pension plans		$ 7
Parent Company [Member]
Components of Net Periodic Benefit Cost [Abstract]
Contributions to pension plans		$ 100

[1] The components of net periodic cost other than the service cost component are included in the line item “Other income (expense), net” in the consolidated statements of income or capitalized on the consolidated balance sheets as a regulatory asset.

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Commitments and Contingencies Gas Trading Litigation (Details)	Mar. 31, 2024
Gas Trading Litigation
Loss Contingencies [Line Items]
Loss Contingency, Pending Claims, Number	1

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Commitments and Contingencies (Details) - Enviromental Requirements $ in Millions	Mar. 31, 2024 USD ($)
Loss Contingencies [Line Items]
Cost of identified MGP, landfill, or disposal sites under current investigation and/or remediation	$ 13.0
Liability for estimated cost to comply with regulation	$ 5.0
Plants required for improvements	2
Other MGP, Landfill, or Disposal Sites [Domain]
Loss Contingencies [Line Items]
Number of identified MGP sites under current investigation and/or remediation	1

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Segment Information (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2024	Mar. 31, 2023
Segment Reporting Information [Line Items]
Net income		$ 43	$ 45
Regulated and Unregulated Operating Revenue		310	331
Affiliate Revenue		53	50
Natural gas		54	77
Cost of identified MGP, landfill, or disposal sites under current investigation and/or remediation		13
Total revenues
Segment Reporting Information [Line Items]
Regulated and Unregulated Operating Revenue	[1]	310	331
Regulated Electric
Segment Reporting Information [Line Items]
Net income		33	33
Regulated Electric | Total revenues
Segment Reporting Information [Line Items]
Regulated Operating Revenue, Electric	[1]	256	254
Regulated Natural Gas
Segment Reporting Information [Line Items]
Net income		10	11
Revenues Including Intersegment Revenues		54	77
All Other
Segment Reporting Information [Line Items]
Net income		$ 0	$ 1

[1] Total revenues include $53 million and $50 million of affiliate electric revenue for the three months ended March 31, 2024 and 2023, respectively.