UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 10-K

ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d)

OF THE SECURITIES EXCHANGE ACT OF 1934

For the Fiscal Year EndedDecember 31, 2004

Securities registered pursuant to Section 12 (b) of the Act:       None

Securities registered pursuant to Section 12 (g) of the Act:       None

Indicate by check mark if the registrant is a well known seasoned issuer, as defined in Rule 405 of the Securities Act.    Yes [  ]    No [X]

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or 15 (d) of the Act.    Yes [  ]    No [X]

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.  Yesx [X]    No¨ [  ]

Indicate by check mark if disclosure of delinquent filers pursuant to Item 405 of Regulation S-K (Section 229.405 of this Chapter) is not contained herein, and will not be contained, to the best of the registrant’sregistrant's knowledge, in the definitive proxy or information statements incorporated by reference in Part III of this Form 10-K or any amendment to this Form 10-K.    x[X]

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, or a non-accelerated filer. See definition of "accelerated filer and large accelerated filer" in Rule 12b-2 of the Exchange Act. (Check one):    Large accelerated filer [  ]    Accelerated filer [  ]    Non-accelerated filer[X]

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act).    Yes¨ [  ]    Nox

[X]

The aggregate market value of the common equity of Wisconsin Gas LLC held by non-affiliates as of June 30, 20042005 was zero. All of the membership interests of Wisconsin Gas LLC are held by Wisconsin Energy Corporation.

Indicate the number of shares outstanding of each of the Registrant’sRegistrant's classes of common stock, as of the latest practicable date (January 31, 2005)2006):

1,125 Common Membership Interests

Documents Incorporated by Reference

None.

Reduced Disclosure Format

The Registrant meets the conditions set forth in General Instructions I(1)(a) and (b) of Form 10-K and is therefore filing with the reduced disclosure format.

2004 Form 10-K

WISCONSIN GAS LLC

FORM 10-K REPORT FOR THE YEAR ENDED DECEMBER 31, 2004

TABLE OF CONTENTS

2004 Form 10-K

2.  Properties ..........................................................................................................................................		7
3.  Legal Proceedings .............................................................................................................................		8
4.  Submission of Matters to a Vote of Security Holders ......................................................................		8
Executive Officers of the Registrant ..................................................................................................		9
PART II
5.  Market for Registrant's Common Equity, Related Stockholder Matters and Issuer Purchases      of Equity Securities.............................................................................................................................	10
6.  Selected Financial Data ......................................................................................................................	10
7.  Management's Discussion and Analysis of Financial Condition and Results of Operations .............	11
7A.Quantitative and Qualitative Disclosures About Market Risk ..........................................................	24
8.  Financial Statements and Supplementary Data ..................................................................................	25
9.  Changes in and Disagreements with Accountants on Accounting and Financial Disclosure ............	46
9A. Controls and Procedures ..................................................................................................................	46
9B. Other Information .............................................................................................................................	46

PART III
10. Directors and Executive Officers of the Registrant ..........................................................................	46
11. Executive Compensation ..................................................................................................................	46
12. Security Ownership of Certain Beneficial Owners and Management       and Related Stockholder Matters.......................................................................................................	46
13. Certain Relationships and Related Transactions ...............................................................................	47
14. Principal Accountant Fees and Services ............................................................................................	47

PART IV
15. Exhibits and Financial Statement Schedules .....................................................................................	48
Schedule II -- Valuation and Qualifying Accounts ............................................................................	49
Signatures ............................................................................................................................................	50
Exhibit Index .......................................................................................................................................	E-1

INTRODUCTION

INTRODUCTION

Wisconsin Gas LLC, formerly Wisconsin Gas Company, is a natural gas distribution public utility which serves approximately 577,000583,300 gas customers in Wisconsin. Wisconsin Gas is a single member limited liability company organized under the laws of the state of Wisconsin and is a wholly owned subsidiary of Wisconsin Energy Corporation (Wisconsin Energy). Wisconsin Energy hasWe have integrated Wisconsin Gas’many of our operations with the gas operations and corporate support areas of Wisconsin Electric Power Company (Wisconsin Electric), Wisconsin Energy’sEnergy's wholly-owned electric, gas and steam utility. In April 2002, Wisconsin Electric and Wisconsin Gas began doing business under the trade name “We Energies”"We Energies". Unless qualified by their context when used in this document, the terms Wisconsin Gas, the Company, our, us or we refer to Wisconsin Gas.

We maintain our principal executive offices in Milwaukee, Wisconsin. We are the largest natural gas distribution public utility operating throughout Wisconsin. We are subject to the regulation of the Public Service Commission of Wisconsin (PSCW) as to various phases of our operations, including rates, service and issuance of long-term securities.

General Information About our Business:Our business is highly seasonal, particularly as to residential and commercial sales of gas for space heating purposes, with a substantial portion of our sales occurring in the winter heating season. The following table sets forth the volumes of natural gas we delivered to our customers. The sales volumes represent quantities we sold and delivered to customers. The volumes shown as transported represent customer-owned gas that we delivered to customers.customers for the years ended December 31, 2005 and 2004.

Cautionary Factors:Factors Regarding Forward -- Looking Statements:   Certain statements contained herein are “Forward-Looking Statements”"Forward-Looking Statements" within the meaning of the Private Securities Litigation Reform Act of 1995. Forward-Looking Statements include, among other things, statements regarding management’smanagement's expectations and projections regarding regulatory matters, gas deliveries, remediation costs, environmental and other capital expenditures, liquidity and capital resources and other matters. Also, Forward-Looking Statements may be identified by reference to a future period or periods or by the use of forward looking terminology such as “anticipates,” “believes,” “estimates,” “expects,” “forecasts,” “intends,” “may,” “objectives,” “plans,” “possible,” “potential,” “projects”"anticipates," "believes," "estimates," "expects," "forecasts," "intends," "may," "objectives," "plans," "possible," "potential," "projects" or similar terms or variations of these terms. Actual results may differ materially from those set forth in Forward-Looking Statements as a result of certain risks and uncertainties, including but not limited to, those risks and uncertainties described under the heading “Cautionary Factors”Cautionary Factors in Item 7 of this report, as well as other matters described under the heading “FactorsFactors Affecting Results, Liquidity and Capital Resources”Resources in Item 7 of this report, and other risks and uncertainties detailed from time to time in our filings with the Securities and Exchange Commission (SEC) or otherwise described throughout this document. We disclaim any responsibility to update these forward-looking statements.

GAS UTILITY OPERATIONS

We are authorized to provide retail gas distribution service in designated territories in the state of Wisconsin, as established by indeterminate permits, certificates of public convenience and necessity or boundary agreements with other utilities. We also transport customer-owned gas. We are the largest natural gas distribution utility in

2004 Form 10-K

Wisconsin. Our largest concentration of customers is in Wisconsin, operating throughout the state including the City of Milwaukee, Wisconsin and surrounding suburban communities..

Gas Deliveries

Our gas utility business is highly seasonal due to the heating requirements of residential and commercial customers. Annual gas sales are also impacted by the variability of winter temperatures.

See “ResultsResults of Operations”Operations in Item 7 for selected gas operating information by customer class during each of the three years in the period ended December 31, 2004.

2005.

We delivered approximately 1,2331,266 million therms of gas during 2004,2005, including customer-owned transported gas, a 3.9% decrease2.7% increase compared with 2003.2004. As of December 31, 2004,2005, we were transporting gas for approximately 1,1051,124 customers who purchased gas directly from other suppliers. Transported gas accounted for approximately 39%42% of the total volumes delivered by us during 2005, 39% during 2004 and 38% during 2003 and 39% during 2002.2003. We had approximately 577,000583,300 customers at December 31, 2004,2005, an increase of approximately 1.3%1.1% since December 31, 2003.

2004.

Our maximum daily send-out in 20042005 was 922,076902,071 dekatherms on January 29, 2004.17, 2005. A dekatherm is equivalent to ten therms or one million British thermal units.

Sales to Large Gas Customers:We provide gas utility service to a diversified base of industrial customers. Major industries served include the paper, food products and fabricated metal products industries. Fuel used for Wisconsin Electric's electric energy supply represents our largest transportation customer.

In late February 2001, Wisconsin Energy filed a petition with the PSCW starting the regulatory review process for a 10-year strategy, originally proposed in September 2000, to improve the supply and reliability of electricity in Wisconsin. As part of Wisconsin Energy’sEnergy'sPower the Future strategy, Wisconsin Energy is investing in new natural gas-fired and coal-fired generating capacity. WeThe first natural gas-fired facility is a transport customer of ours; we expect the second natural gas-fired facilitiesfacility, which is scheduled to go into service in 2008, to also be a transport customers of ours.customer.

Gas Deliveries Growth:   We currently forecast our total therm deliveries of natural gas to grow at an annual rate of approximately 4.8%2.6% over the next five-years.five-year period ending December 31, 2010. This forecast reflects a current year normalized sales level and assumes moderate growth in the economy of our service territory, normal weather and incrementalPower the Future demand.

Competition

Competition in varying degrees exists between natural gas and other forms of energy available to consumers. Many of our large commercial and industrial customers are dual-fuel customers that are equipped to switch between natural gas and alternate fuels. We are allowed to offer lower-priced interruptible ratesgas sales and transportation services for these customers to enable them to reduce their energy costs and use gas rather than other fuels.dual-fuel customers. Under gas transportation agreements, customers purchase gas directly from gas marketers and arrange with interstate pipelines and us to have the gas transported to the facilities where it is used. We earn substantially the same margin (difference between revenue and cost of gas) whether we sell and transport gas to customers or only transport their gas.

Our future ability to maintain our present share of the industrial dual-fuel market (the market that is equipped to use gas or other fuels) depends on our success and the success of third-party gas marketers in obtaining long-term and short-term supplies of natural gas at competitive prices compared to other sources and in arranging or facilitating competitively-priced transportation service for those customers that desire to buy their own gas supplies.

Federal and state regulators continue to implement policies to bring more competition to the gas industry. For information concerning proceedings by the PSCW to consider how its regulation of gas distribution utilities should change to reflect the changing competitive environment in the gas industry, see “FactorsFactors Affecting Results, Liquidity and Capital Resources”Resources in Item 7. While the gas utility distribution function is expected to remain a highly regulated, monopoly function, the sales of the natural gas commodity and related services are expected to become increasingly subject to competition from third parties. However, itIt remains uncertain if and when the current economic

2004 Form 10-K

disincentives for small customers to choose an alternative gas commodity supplier may be removed such that we begin to face competition for the sale of gas to our smaller firm customers.

Gas Supply, Pipeline Capacity and Storage

We have been able to meet our contractual obligations with both our suppliers and our customers despite periods of severe cold and unseasonably warm weather.

Pipeline Capacity and Storage:Our natural gas originates in three major gas producing areas of North America: the Oklahoma and Texas basins, the Gulf of Mexico and western Canada. We have contracted for long-term firm capacity from each of these areas. This strategy reflects management’smanagement's belief that overall supply security is enhanced by geographic diversification of the supply portfolios and that Canada represents an important long-term source of reliable, competitively-priced gas. Wisconsin Energy also has a one-third ownership interest in the Guardian Pipeline which receives gas supply in the Joliet, Illinois market hub.

Because of the daily and seasonal variations in gas usage in Wisconsin, we have also contracted for substantial underground storage capacity, primarily in Michigan. Storage capacity enables us to manage significant changes in daily demand and to optimize our overall gas supply and capacity costs. We generally inject gas into storage during the spring and summer months and withdraw it in the winter months. As a result, we can contract for less long-line pipeline capacity than would otherwise be necessary and can purchase gas on a more uniform daily basis from suppliers year-round. Each of these capabilities enables us to reduce our overall costs.

We also maintain high deliverability storage in the mid-continent and Southeast production areas, as well as in our market area. This storage capacity is designed to deliver gas when other supplies cannot be delivered during extremely cold weather in the producing areas, which can reduce long-line supply.

We hold firm daily transportation and storage capacity entitlements from pipelines and other service providers under long-term contracts.

Term Gas Supply:We currently have contracts for firm supplies with terms in excess of 30 days with 12 gas suppliers for gas acquired in the Joliet, Illinois market hub and in the three producing areas discussed above. The pricing of the term contracts is based upon first of the month indices. ManagementCombined with our storage capability, management believes that the volume of gas under contract is sufficient to meet our forecasted firm peak day demand.

Secondary Market Transactions:Capacity release is a mechanism by which pipeline long-line and storage capacity and gas supplies under contract can be resold in the secondary market. Local distribution companies, such as us, must contract for capacity and supply sufficient to meet the firm peak day demand of their customers. Peak or near peak demand days generally occur only a few times each year. Capacity release facilitates higher utilization of contracted capacity and supply during those times when the full contracted capacity and supply are not needed by the utility, helping to mitigate the fixed costs associated with maintaining peak levels of capacity and gas supply. Through pre-arranged agreements and day-to-day electronic bulletin board postings, interested parties can purchase this excess capacity and supply. The proceeds from these transactions are passed through to ratepayers, subject to our gas cost incentive mechanism pursuant to which we have an opportunityopportunit y to share in the cost savings. See “FactorsFactors Affecting Results, Liquidity and Capital Resources –-- Rates and Regulatory Matters”Matters in Item 7 for information on the gas cost recovery mechanism (GCRM) and gas cost incentive mechanism. During 2004,2005, we continued our active participation in the capacity release market.

Spot Market Gas Supply:We expect to continue to make gas purchases in the 30-day spot market as price and other circumstances dictate. We have supply relationships with a number of sellers from whom we purchase spot gas.

Hedging Gas Supply Prices:   We have PSCW approval to hedge (i) up to 50%45% of planned flowing gas supply using NYMEX based natural gas options, (ii) up to 10%15% of planned flowing gas supply using NYMEX based natural gas future contracts and (iii) up to 33%35% of planned storage withdrawals using NYMEX based natural gas options. That approval allows us to pass 100% of the hedging costs (premiums and brokerage fees) and proceeds (gains and losses) through our purchase gas adjustment mechanism. Hedge targets (volumes) are provided annually to the PSCW as part of our five-year gas supply plan filing.

2004 Form 10-K

To the extent that opportunities develop and our physical supply operating plans will support them, we also have PSCW approval to utilize NYMEX-based natural gas derivatives to capture favorable forward market price differentials. That approval provides for 100% of the related proceeds to accrue to our GCRM.

Guardian Pipeline:Wisconsin Energy has a one-third ownership interest in a joint venture,the Guardian Pipeline, L.L.C. (Guardian). Two unaffiliated companies also have one-third interests. Guardian owns an interstate natural gas pipeline

WATER UTILITY OPERATIONS

In November 1998, we entered into the water distribution business to leverage off of operational similarities with our natural gas business. As of December 31, 2004,2005, we served approximately 2,7002,800 water customers in the suburban Milwaukee area compared with approximately 2,6002,700 customers at December 31, 2003.2004. We also provide contract services to local municipalities and businesses within our service territory for water system repair and maintenance. Our water revenues totaled $2.3 million and $1.9 million in 2005 and $1.8 million in 2004, and 2003, respectively.

UTILITY RATE MATTERS

See “FactorsFactors Affecting Results, Liquidity and Capital Resources –-- Rates and Regulatory Matters”Matters in Item 7.

REGULATION

REGULATION

We are subject to the regulation of the PSCW as to retail gas and water rates in the state of Wisconsin, standards of service, issuance of long-term securities, construction of certain new facilities, transactions with affiliates, billing practices and various other matters.

We are also subject to regulations, where applicable, of the United States Environmental Protection Agency (EPA) and the Wisconsin Department of Natural Resources (WDNR).

Gas Cost Recovery:Our rates traditionally contain clauses providing for periodic rate adjustments, with PSCW approval, to reflect changes in purchased gas costs.

The PSCW approved a new performance-based GCRM which became effective April 1, 2001. See “RatesRates and Regulatory Matters”Matters in Item 7.

Changing Regulatory Environment:The PSCW has instituted generic proceedings to consider how its regulation of gas distribution utilities should change to reflect the changing competitive environment in the natural gas industry. To date, the PSCW has made a policy decision to deregulate the sale of natural gas in customer segments with workably competitive market choices and has adopted standards for transactions between a utility and its gas marketing affiliates. However, work on deregulation of the gas distribution industry by the PSCW is presently on hold. Currently, we are unable to predict the impact of potential future deregulation on our results of operations or financial position.

2004 Form 10-K

ENVIRONMENTAL COMPLIANCE

Environmental Expenditures

ENVIRONMENTAL COMPLIANCE

Environmental Expenditures

Expenditures for environmental compliance and remediation issues are included in anticipated capital expenditures described in Liquidity and Capital Resources in Item 7. For discussion of additional environmental issues, see “Environmental Matters”Environmental Matters in Item 3.

Manufactured Gas Plant Sites

We are reviewing and addressing environmental conditions at a number of former manufactured gas plant sites. See “Note K –Note L -- Commitments and Contingencies”Contingencies in the Notes to Financial Statements in Item 8.

OTHER

Research and Development:We had immaterial research and development expenditures in the last three years, primarily for improvement of service. Research and development activities include specific projects performedwork done by employees, consultants and contractors, plus sponsorship of research by industry associations.

Employees:   At December 31, 2004,2005, we had 674619 total employees, of which 529481 were represented under labor agreements.

The employees represented under labor agreements were with the following bargaining units as of December 31, 2004.2005.

2004 Form 10-K(a) Effective January 1, 2006, these bargaining units became a part of the Local 2006. These former locals are now individual bargaining units of Local 2006. We will continue to honor our bargaining agreements with each of these units as negotiated.

ITEM 1B. UNRESOLVED STAFF COMMENTS

ITEM 2. PROPERTIES

We own our principal properties outright except that the major portion of gas utility distribution mains and services are located, for the most part, on or in streets and highways and on land owned by others.

We own a distribution system which, as of December 31, 2004,2005, included approximately 10,40010,600 miles of distribution and transmission mains connected at gate stations to the pipeline transmission systems of ANR Pipeline Company, Guardian, Northern Natural Pipeline Company, Viking Gas Transmission and Michigan Consolidated Gas Company. We have a liquefied natural gas storage plant which converts and stores in liquefied form natural gas received during periods of low consumption. The liquefied natural gas storage plant has a send-out capability of 3,600 dekatherms per day. We also have a propane air system for peaking purposes. This propane air system will provide approximately 2,400 dekatherms per day of supply to the system. Our distribution system consists almost entirely of plastic and coated steel pipe. We own office buildings in certain communities in which it serves,we serve, gas regulating and metering stations, peaking facilities and itsour major service centers, including garage and warehousewareh ouse facilities.

Where distribution mains and services occupy private property, in some, but not all, instances we have obtained consents, permits or easements for such installations from the apparent owners or those in possession, generally without an examination of title.

In addition to those legal proceedings discussed below, we are currently, and from time to time, subject to claims and suits arising in the ordinary course of business. Although the results of such legal proceedings cannot be predicted with certainty, we believe, after consultation with legal counsel, that the ultimate resolution of these proceedings will not have a material adverse effect on our financial statements.

ENVIRONMENTAL MATTERS

We are subject to federal, state and certain local laws and regulations governing the environmental aspects of our operations. We believe that, perhaps with immaterial exceptions, our existing facilities are in compliance with applicable environmental requirements.

EPA Information Requests:   We responded to an EPAa U.S. Environmental Protection Agency (EPA) request for information pursuant to Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) Section 104(e) for the Solvay Coke and Gas Site located in Milwaukee, Wisconsin. All potentially responsive records and corporate legal files have been reviewed and responsive information was provided in October 2004. A predecessor company of ours had a customer and corporate relationship with the entity that owned and operated the site, Milwaukee Solvay Coke Company. In July 2005, we received a general notice letter from the EPA identifying us as a potentially responsible party under CERCLA. We responded to the EPA in July 2005, stating that we will participate in negotiations regarding the site, but that we do not admit to any liability for the site. Although we have not accepted responsibility for costs of any sort related to the property, remediation cost estimates and reserves continue to be included in the estimated manufactured gas plant values reported in “Note K –Note L -- Commitments and Contingencies”Contingencies in the Notes to Financial Statements in Item 8.

See “ManufacturedManufactured Gas Plant Sites”Sites in Note K –L -- Commitments and Contingencies”Contingencies in the Notes to Financial Statements in Item 8, which is incorporated by reference herein, for a discussion of matters related to certain manufactured gas plant sites.

UTILITY RATE MATTERS

See “FactorsFactors Affecting Results, Liquidity and Capital Resources –-- Rates and Regulatory Matters”Matters in Item 7 for information concerning rate matters in the jurisdictionsjurisdiction where we do business.

Omitted pursuant to General Instruction I(2)(c).

2004 Form 10-K

EXECUTIVE OFFICERS OF THE REGISTRANT

The names, ages at December 31, 20042005 and positions of our executive officers are listed below along with their business experience during the past five years. All officers are appointed until they resign, die or are removed pursuant to the Limited Liability Company Operating Agreement. There are no family relationships among these officers, nor is there any agreement or understanding between any officer and any other person pursuant to which the officer was selected. Reference to Wisconsin Gas LLC includes the time spent with the Company prior to its predecessor, Wisconsin Gas Company.conversion from a corporation to a limited liability company.

Gale E. Klappa.Age 54.55.

Charles R. Cole.Age 58.Cole.Age 59.

Stephen P. Dickson.Age 44.Dickson.Age 45.

Frederick D. Kuester.Age 54.55.

Allen L. Leverett.Age 38.39.

2004 Form 10-K

EXECUTIVE OFFICERS OF THE REGISTRANT – (Cont’d)

Kristine A. Rappé.Age 48..Age 49.

Larry Salustro.Age 57.Salustro.Age 58.