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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 ENDED DECEMBER

For the fiscal year ended December 31, 1998 COMMISSION FILE NUMBER2003

Commission File Number 1-7850

SOUTHWEST GAS CORPORATION (EXACT NAME OF REGISTRANT AS SPECIFIED IN ITS CHARTER) CALIFORNIA 88-0085720 (STATE OR OTHER JURISDICTION OF (I.R.S. EMPLOYER INCORPORATION OR ORGANIZATION) IDENTIFICATION NO.) 5241 SPRING MOUNTAIN ROAD POST OFFICE BOX 98510 LAS VEGAS, NEVADA 89193-8510 (ADDRESS OF PRINCIPAL EXECUTIVE OFFICES) (ZIP CODE) REGISTRANT'S TELEPHONE NUMBER, INCLUDING AREA CODE:

(Exact name of registrant as specified in its charter)

California88-0085720

(State or other jurisdiction of

incorporation or organization)

(I.R.S. Employer

Identification No.)

5241 Spring Mountain Road

Post Office Box 98510

Las Vegas, Nevada

89193-8510
(Address of principal executive offices)(Zip Code)

Registrant’s telephone number, including area code: (702) 876-7237 SECURITIES REGISTERED PURSUANT TO SECTION

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

NAME OF EACH EXCHANGE TITLE OF EACH CLASS ON WHICH REGISTERED ------------------- -------------------

Title of each class


Name of each exchange

on which registered


Common Stock, $1 par value

New York Stock Exchange, Inc.
Pacific Stock Exchange, Inc. 9.125%

7.70% Preferred Trust Originated Preferred Securities

New York Stock Exchange, Inc. Pacific Stock Exchange, Inc. Stock Purchase Rights New York Stock Exchange, Inc. Pacific Stock Exchange, Inc.

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 Y NO --- --- Yesþ No¨

Indicate by check mark if disclosure of delinquent filers pursuant to Item 405 of Regulation S-K is not contained herein, and will not be contained, to the best of registrant'sregistrant’s knowledge, in definitive proxy or information statements incorporated by reference in Part III of this Form 10-K or any amendment to this Form 10-K. [ ] AGGREGATE MARKET VALUE OF THE VOTING STOCK HELD BY NONAFFILIATES OF THE REGISTRANT: $824,362,704 at March 15, 1999 THE NUMBER OF SHARES OUTSTANDING OF COMMON STOCK: þ

Indicate by check mark whether the registrant is an accelerated filer.Yesþ No¨

Aggregate market value of the voting and non-voting common stock held by nonaffiliates of the registrant:

$715,068,782 as of June 30, 2003

The number of shares outstanding of common stock:

Common Stock, $1 Par Value, 30,531,95234,517,481 shares as of March 15, 1999 1, 2004

DOCUMENTS INCORPORATED BY REFERENCE

DESCRIPTION PART INTO WHICH INCORPORATED ----------- ----------------------------

Description


Part Into Which Incorporated


Annual Report to Shareholders for the Year Ended December 31, 1998 2003

Parts I, II, and IV

2004 Proxy Statement

Part III
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TABLE OF CONTENTS

PART I

PAGE ---- ITEM

Item 1. BUSINESS......................................................................

BUSINESS1

Natural Gas Operations........................................................ Operations

1

General Description......................................................... 2 Description

1

Rates and Regulation........................................................ Regulation

2 Recent Regulatory and Legislative Developments.............................. 3 Competition................................................................. 4

Demand for Natural Gas...................................................... 5 Gas

3

Natural Gas Supply.......................................................... 5 Supply

3

Competition

4

Environmental Matters....................................................... 6 Employees................................................................... 6 Matters

5

Employees

5

Construction Services......................................................... Services

5

Company Risk Factors

6 ITEM

Item 2. PROPERTIES.................................................................... 7 ITEM

PROPERTIES

8

Item 3.

LEGAL PROCEEDINGS............................................................. 9 ITEMPROCEEDINGS

10

Item 4.

SUBMISSION OF MATTERS TO A VOTE OF SECURITY HOLDERS........................... 9 HOLDERS

10
PART II ITEM

Item 5.

MARKET FOR THE REGISTRANT'SREGISTRANT’S COMMON EQUITY, AND RELATED STOCKHOLDER MATTERS........................................................... 9 ITEM
MATTERS AND ISSUER PURCHASES OF EQUITY SECURITIES
10

Item 6.

SELECTED FINANCIAL DATA....................................................... 9 ITEMDATA

10

Item 7. MANAGEMENT'S

MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION
AND RESULTS OF OPERATIONS..................................................... OPERATIONS
10 ITEM

Item 7A.

QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK.................... RISK

10 ITEM

Item 8.

FINANCIAL STATEMENTS AND SUPPLEMENTARY DATA................................... DATA

10 ITEM

Item 9.

CHANGES IN AND DISAGREEMENTS WITH ACCOUNTANTS ON ACCOUNTING
AND FINANCIAL DISCLOSURE...................................................... 10 DISCLOSURE
11

Item 9A.

CONTROLS AND PROCEDURES

11
PART III ITEM

Item 10.

DIRECTORS AND EXECUTIVE OFFICERS OF THE REGISTRANT............................ 10 ITEMREGISTRANT

12

Item 11.

EXECUTIVE COMPENSATION........................................................ 15 ITEMCOMPENSATION

13

Item 12.

SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT.................................................................... 20 ITEM
MANAGEMENT AND RELATED STOCKHOLDER MATTERS
13

Item 13.

CERTAIN RELATIONSHIPS AND RELATED TRANSACTIONS................................ 22 TRANSACTIONS

14

Item 14.

PRINCIPAL ACCOUNTANT FEES AND SERVICES

14
PART IV ITEM 14.

Item 15.

EXHIBITS, FINANCIAL STATEMENT SCHEDULES, AND REPORTS ON FORM 8-K ..................................................................... 22

15

List of Exhibits............................................................ 23 SIGNATURES............................................................................. 27 Exhibits

16

SIGNATURES

20
3


PART I ITEM

Item 1.    BUSINESS The registrant,

Southwest Gas Corporation (the Company), is“Company”) was incorporated, effective March 1931, under the laws of the Statestate of California effective March 1931. The executive offices of the Company are located at 5241 Spring Mountain Road, P.O. Box 98510, Las Vegas, Nevada, 89193-8510, telephone number (702) 876-7237.California. The Company is principallycomprised of two business segments: natural gas operations (“Southwest” or the “natural gas operations” segment) and construction services. Southwest is engaged in the business of purchasing, transporting, and distributing natural gas to residential, commercial, and industrial customers in geographically diverse portions of Arizona, Nevada, and California (Southwest orCalifornia. Southwest is the largest distributor in Arizona, selling and transporting natural gas operations segment).in most of central and southern Arizona, including the Phoenix and Tucson metropolitan areas. Southwest is also the largest distributor and transporter of natural gas in Nevada, serving the Las Vegas metropolitan area and northern Nevada. In April 1996,addition, Southwest distributes and transports natural gas in portions of California, including the Company acquired all ofLake Tahoe area and the outstanding stock of high desert and mountain areas in San Bernardino County.

Northern Pipeline Construction Co. (Northern(“NPL” or the construction services“construction services” segment) pursuant to, a definitive agreement dated November 1995. The Company issued approximately 1,439,000 shares of common stock valued at $24 million in connection with the acquisition. The acquisition was accounted for aswholly owned subsidiary, is a purchase. The construction services segmentfull-service underground piping contractor that provides utility companies with trenching and installation, replacement, and maintenance services for energy distribution systems. In July 1996, the Company completed the sale of the assets and liabilities of PriMerit Bank, Federal Savings Bank (PriMerit), a wholly owned subsidiary, to Norwest Corporation (Norwest) for $191 million pursuant to a definitive agreement dated January 1996. For consolidated financial reporting purposes, the financial services activities are disclosed as discontinued operations.

Financial information with respect to industryconcerning the Company’s business segments is included in Note 1411 of the Notes to Consolidated Financial Statements which is included in the 19982003 Annual Report to Shareholders and is incorporated herein by reference. In December 1998, the Boards of Directors of the

The Company and ONEOK, Inc. (ONEOK), headquartered in Tulsa, Oklahoma, announcedmaintains a definitive agreementwebsite (www.swgas.com) for the benefit of shareholders, investors, customers, and other interested parties. The Company makes its annual report on Form 10-K, quarterly reports on Form 10-Q, current reports on Form 8-K, and all amendments to be merged into ONEOK. The agreement calls for ONEOKthose reports available, free of charge, through its website as soon as reasonably practicable after such material is electronically filed with, or furnished to, pay cash of $28.50 for each share of Company common stock outstanding. The transaction is subject to customary conditions, including approvals from shareholders of the CompanySecurities and state regulators in Arizona, California, and Nevada. ONEOK expects to account for the merger using the purchase method of accounting. If the merger is consummated, the Company would operate as a division of ONEOK. In February 1999, the Company announced that it had received an unsolicited proposal from Southern Union Company (Southern Union), headquartered in Austin, Texas, offering to acquire the Company for $32.00 per share in cash. The proposal is preliminary in nature and subject to a number of contingencies and uncertainties. Under the terms of the agreement with ONEOK, as a result of certain preliminary determinations made by the Board of Directors of the Company, the Board of Directors has authorized management to commence substantive discussions with Southern Union regarding its proposal. No assurances can be given that any agreement will be reached with Southern Union. The merger agreement with ONEOK remains in full force and effect. 1 4 Exchange Commission (“SEC”).

NATURAL GAS OPERATIONS GENERAL DESCRIPTION

General Description

Southwest is subject to regulation by the Arizona Corporation Commission (ACC)(“ACC”), the Public Utilities Commission of Nevada (PUCN)(“PUCN”), and the California Public Utilities Commission (CPUC)(“CPUC”). These commissions regulate public utility rates, practices, facilities, and service territories in their respective states. The CPUC also regulates the issuance of all securities by the Company, with the exception of short-term borrowings. Certain accounting practices, transmission facilities, and rates are subject to regulation by the Federal Energy Regulatory Commission (FERC)(“FERC”). NPL is not regulated by the state utilities commissions in any of its operating areas.

As of December 31, 2003, Southwest purchases, transports,purchased, transported, and distributesdistributed natural gas to 1,209,0001,531,000 residential, commercial, and industrial customers in geographically diverse portions of Arizona, Nevada, and California. There were 58,00067,000 customers added to the system during 1998. 2003 (and an additional 9,000 in central Arizona associated with the acquisition of Black Mountain Gas Company (“BMG”) in October 2003).

The table below lists the percentage of Southwest operating margin (operating revenues less net cost of gas) by major customer class for the years indicated:
RESIDENTIAL AND OTHER FOR THE YEAR ENDED SMALL COMMERCIAL SALES CUSTOMERS TRANSPORTATION ------------------ ---------------- --------------- -------------- December 31, 1998 84% 5% 11% December 31, 1997 83 5 12 December 31, 1996 80 6 14

   Distribution

  Transportation

For the Year Ended


  

Residential and

Small Commercial


  

Other Sales

Customers


  

December 31, 2003

  84%  6%  10%

December 31, 2002

  83%  7%  10%

December 31, 2001

  82%  8%  10%

Southwest is not dependent on any one or a few customers to the extent that the loss of any one or several would have a significant adverse impact on earnings.

Transportation of customer-secured gas to end-users on the Southwest system accounted for 4854 percent of total system throughput in 1998.2003. Although the volumes were significant, these customers provide a much smaller proportionate share of operating margin. In 1998, customersCustomers who utilized this service transported 100134 million dekatherms. dekatherms in 2003, 133 million dekatherms in 2002, and 127 million dekatherms in 2001.

The demand for natural gas is seasonal. Variability in weather from normal temperatures can materially impact results of operations. It is the opinion of management that comparisons of earnings for interim periods do not reliably reflect overall trends and changes in Southwest operations. Also, earnings for interim periods can be significantly affected by the timing of general rate relief. RATES AND REGULATION

Rates and Regulation

Rates that Southwest is authorized to charge its distribution system customers are determined by the ACC, CPUC,PUCN, and PUCNCPUC in general rate cases and are derived using rate base, cost of service, and cost of capital experienced in a historical test year, as adjusted in Arizona and Nevada, and projected for a future test year in California. The FERC regulates the northern Nevada transmission and liquefied natural gas (LNG)(“LNG”) storage facilities of Paiute Pipeline Company (Paiute)(“Paiute”), a wholly owned subsidiary, and the rates it charges for transportation of gas directly to certain end-users and to various local distribution companies (LDCs)(“LDCs”). The LDCs transporting on the Paiute system are: Sierra Pacific Power Company (serving Reno and Sparks, Nevada), Avista Utilities (serving South Lake Tahoe, California), and Southwest Gas Corporation (serving Truckee and North Lake Tahoe, California and various locations throughout northern Nevada).

Rates charged to customers vary according to customer class and rate jurisdiction and are set at levels allowingthat are intended to allow for the recovery of all prudently incurred costs, including a return on rate base sufficient to pay interest on debt, preferred securities distributions, and a reasonable return on common equity. Rate base consists generally of the original cost of utility plant in service, plus certain other assets such as working capital and inventories, less accumulated depreciation on utility 2 5 plant in service, net deferred income tax liabilities, and certain other deductions. Rate schedules in all of the Southwest service areas contain purchased gas adjustment (PGA)(“PGA”) clauses, which allow Southwest to file for rate adjustments as the cost of purchased gas changes. Generally, SouthwestIn Nevada, tariffs provide for annual adjustment dates for changes in purchased gas costs. However, Southwest may requestmake additional requests to adjust its rates, more often than once each year, if market conditions warrant. TheseIn Arizona, Southwest adjusts rates monthly for changes in purchased gas costs, within pre-established limits. In California, a monthly gas cost adjustment based on forecasted monthly prices is used to adjust rates. PGA rate changes affect cash flows but have no direct impact on profit margin. Filings to change rates in accordance with PGA clauses are subject to audit by the appropriate state regulatory commission staffs.staff. Information with respect to recent general rate cases and PGA filings is included in the Rates and Regulatory Proceedings section of Management'sManagement’s Discussion and Analysis (MD&A), which is included(“MD&A”) in the 19982003 Annual Report to Shareholders.

The table below lists the docketed general rate filings last initiated and/or completedand the status of such filing within each ratemaking area:

MONTH FINAL RATES RATEMAKING AREA TYPE OF FILING MONTH FILED EFFECTIVE - --------------- -------------- ----------- --------- Arizona: Central and Southern.........

Ratemaking Area


Type of Filing


Month Filed


Month Final Rates

Effective


Arizona

General rate caseMay 2000November 1996 September 1997 2001

California: Northern .................... Operational attrition November 1997 January 1998 Nevada:

    Northern and Southern........ Southern

General rate case December 1995 July 1996 FERC: Paiute....................... February 2002Pending

Nevada:

    Northern and Southern

General rate caseMarch 2004Pending

FERC:

    Paiute

General rate caseJuly 1996January 1997
- ------------------- RECENT REGULATORY AND LEGISLATIVE DEVELOPMENTS Nevada In 1997, the Nevada Legislature passed, and the Governor signed into law, Assembly Bill (AB) 366. AB 366 provides the statutory framework

Demand for restructuring both the natural gas and electric industries in the State of Nevada to allow competition. The legislature left most of the decision making on restructuring to the PUCN. In addition to several organizational changes, AB 366 required the PUCN to create an alternative plan of regulation by July 1, 1998. The PUCN issued two decisions during 1998. The first identified the distinct componentsNatural Gas

Deliveries of natural gas service.by Southwest are made under a priority system established by state regulatory commissions. The second establishedpriority system is intended to ensure that the gas requirements of higher-priority customers, primarily residential customers and other customers who use 500 therms of gas per day or less, are fully satisfied on a proceduredaily basis before lower-priority customers, primarily electric utility and large industrial customers able to use alternative fuels, are provided any quantity of gas or capacity.

Demand for natural gas is greatly affected by which partiestemperature. On cold days, use of gas by residential and commercial customers may requestbe as much as six times greater than on warm days because of increased use of gas for space heating. To fully satisfy this increased high-priority demand, gas is withdrawn from storage in certain service areas, or peaking supplies are purchased from suppliers. If necessary, service to interruptible lower-priority customers may be curtailed to provide the needed delivery system capacity. No curtailment occurred during the latest peak heating season. Southwest maintains no significant backlog on its orders for gas service.

Natural Gas Supply

Southwest is responsible for acquiring (purchasing) and arranging delivery of (transporting) natural gas to its system for all sales customers.

The primary objective of Southwest with respect to acquiring gas supply is to ensure that adequate, as well as economical, supplies of natural gas are available from reliable sources. Gas is acquired from a wide variety of sources and a mix of purchase provisions, including spot market purchases and firm supplies with a variety of terms. During 2003, Southwest acquired gas supplies from 48 suppliers. This practice mitigates the risk of nonperformance by any one supplier.

Balancing reliable supply assurances with the associated costs results in a continually changing mix of purchase provisions within the supply portfolios. To address the unique requirements of its various market areas, Southwest assembles and administers a separate natural gas supply portfolio for each of its jurisdictional areas. Firm and spot market natural gas purchases are made in a competitive bid environment. Southwest has experienced price volatility over the past five years, as the weighted average delivered cost of natural gas has ranged from a low of 28 cents per therm in 1999 to a high of 55 cents per therm in 2001. During 2003, Southwest paid an average of 46 cents per therm. To mitigate customer exposure to market price volatility, Southwest continues to purchase a significant percentage of its forecasted annual normal weather requirements under firm, fixed-price arrangements that are secured periodically throughout the year.

The firm, fixed-price arrangements are structured such that a servicestated volume of gas is required to be classifiedscheduled by Southwest and delivered by the supplier. If the gas is not needed by Southwest or cannot be procured by the supplier, the contract provides for fixed or market-based penalties to be paid by the non-performing party. In the event that demand on Southwest’s system is lower than expected, Southwest may have the opportunity to forego the purchase at a negotiated price in excess of the contracted price during periods of extreme price volatility. Any savings would reduce the overall cost of gas for the purchase period.

In managing its gas supply portfolios, Southwest uses the fixed-price arrangements noted above, but does not currently utilize other stand-alone derivative financial instruments. In the future stand-alone derivatives may be used to hedge against possible price increases. However, any such change would be undertaken with the knowledge of Southwest’s various regulatory commissions.

Storage capability can influence the average annual price of gas, as "potentially competitive." Oncestorage allows a servicecompany to purchase natural gas in larger quantities during the off-peak season and store it for use in high demand periods when prices may be greater. Southwest currently has been considered potentially competitiveno storage availability in its Arizona or southern Nevada rate jurisdictions. Limited storage capabilities exist in southern and northern California and northern Nevada. A contract with Southern California Gas Company is intended for delivery only within Southwest’s southern California rate jurisdiction. In addition, a contract with Paiute for its LNG facility in northern Nevada and northern California allows for peaking capability only. Gas is purchased for injection during the off-peak period for use in the high demand months, but is again limited in its impact on the overall price. The LNG plant is currently leased from a third party, and the PUCN has authorized other companiescontract expires in July 2005. While

negotiations continue between the owner of the plant and Paiute to allow for the purchase of the facility, preparations are being made to provide alternatives to the leased facility to be in service underby July 2005.

Gas supplies for the southern system of Southwest (Arizona, southern Nevada, and southern California properties) are primarily obtained from producing regions in Colorado and New Mexico (San Juan basin), Texas (Permian basin), and Rocky Mountain areas. For its northern system (northern Nevada and northern California properties), Southwest primarily obtains gas from Rocky Mountain producing areas and from Canada.

Southwest arranges for transportation of gas to its Arizona, Nevada, and California service territories through the pipeline systems of El Paso Natural Gas Company (“El Paso”), Kern River Gas Transmission Company (“Kern River”), Transwestern Pipeline Company, Northwest Pipeline Corporation, Southern California Gas Company and Paiute. Supply and pipeline capacity availability on both short- and long-term bases is continually monitored by Southwest to ensure the reliability of service to its customers. Southwest currently receives firm transportation service, both on a short- and long-term basis, for all of its service territories on the pipeline systems noted above, and also has interruptible contracts in place that allow additional capacity to be acquired should an alternative planunforeseen need arise.

The Company believes that the current level of regulation, Southwest could continuecontracted firm interstate capacity is sufficient to provideserve each of its service under its regulated rates, or set up a new subsidiary and file for an affiliateterritories. As the need arises to offer service. The detailsacquire additional capacity on one of the PUCN restructuring plan are not fully developed at this time. Also remaining are numerous issues such as unbundling rates, licensing of alternative sellers, the utility's obligationinterstate pipeline transmission systems, primarily due to serve, and recovery of stranded costs. California In January 1998, the CPUC opened a rulemaking proceeding designed to reform the California natural gas industry by expanding opportunities for residential and small commercial customers to have access to competing natural gas suppliers. To accomplish this, the CPUC requested comments from interested parties, such ascustomer growth, Southwest to assess the current market and regulatory framework for the California natural gas industry and to develop reforms which emphasize market-oriented policies to benefit all California natural gas consumers. Southwest filed written comments with the CPUC in February 1998 addressing such issues as regulatory streamlining, unbundling, consumer protection and other competitive issues. The CPUC Division of Strategic Planning recommended that gas utilities fully unbundle services and exit the gas merchant (gas supply) business. 3 6 The CPUC established working groups to address safety concerns associated with introducing competition in providing billing, metering, and services on the customer side of the meter, and to develop consistency in policies, programs, tariffs, rules, and procedures used by gas utilities throughout the state. Reports from the working groups were submitted in August 1998. While the CPUC initially adopted an aggressive timetable for restructuring the gas industry, legislation was enacted late in 1998 delaying the CPUC ability to restructure the gas industry for residential customers until 2000 and requiring the CPUC to report to the legislature whether such restructuring is in the public interest. The CPUC will continue to hold hearings and take evidence in preparationconsider available options to obtain that capacity, either through the use of firm contracts with a pipeline company or by purchasing capacity on the open market.

Southwest is dependent upon the El Paso pipeline system for the reporttransportation of gas to virtually all of its Arizona service territories. Historically, Southwest received transportation service from El Paso to its Arizona service territories under a full requirements contract. Under full requirements service, El Paso was obligated to transport all of a customer’s gas requirements each day, and the legislature regarding naturalcustomer was obligated to have El Paso, and only El Paso, transport its requirements. Virtually all of El Paso’s customers in Arizona, New Mexico, and Texas have been full requirements customers, while El Paso has transported gas restructuring. Arizona Southwest agreed, as partfor its customers in California and Nevada subject to a specific maximum daily quantity, or contract demand limitation.

Since November 1999, the Federal Energy Regulatory Commission has been examining capacity allocation issues on the El Paso system in several proceedings. This examination resulted in a series of orders by the FERC in which all of the 1997major full requirements transportation service agreements on the El Paso system, including the agreement by which Southwest obtained the transportation of gas supplies to its Arizona rate case settlement,service areas, were converted to contract demand-type service agreements, with fixed maximum service limits, effective September 2003. At that time, all of the transportation capacity on the system was allocated among the shippers. In order to help ensure that the converting full requirements shippers would have adequate capacity to meet their needs, El Paso was authorized to expand the eligibilitycapacity on its system by adding compression.

The FERC is continuing to examine issues related to the implementation of the full requirements conversion. Petitions for customersjudicial review of the FERC’s orders mandating the conversion have been filed.

Management believes that it is difficult to qualifypredict the ultimate outcome of the proceedings or the impact of the FERC action on Southwest. Southwest has had adequate capacity for transportation service. Southwest also supported a proposalits customers’ needs during the 2003/2004 heating season to open an investigationdate and management believes adequate capacity exists for the remainder of the heating season. Additional costs may be incurred to address competitionacquire capacity in the natural gas industry, including the unbundling of rates and services, which was filed in May 1998 by a potential competitor of Southwest. No action has been taken on this proposal to date. In July 1998, Southwest filed a proposal that would provide all customers with the option of choosing their own gas suppliers by January 2000. The proposal was suspended into 1999 to allow gas marketers and other interested parties additional time to study the proposal. In May 1998, the Arizona Legislature approved House Bill 2663 (Bill), providing for electric generation service competition and confirming the authority of the ACC to open the service territories of the electric companies within the state to competition. The customer choice provisions of the Bill directed that during the initial construction of a residential structure, electric and natural gas facilities, at a minimum, shall be installed in and to the structure in a manner that provides the retail energy consumer with the capability to choose between electricity and natural gas as an energy source for each appliance application. Therefore,future as a result of this provision of the Bill, Southwest and other natural gas utilities inFERC order. However, it is anticipated that any additional costs would be collected from customers principally through the state of Arizona are assured that a natural gas option is available to all future customers. COMPETITION PGA mechanism.

Competition

Electric utilities are Southwest'sthe principal competitors of Southwest for the residential and small commercial markets throughout its service areas. Competition for space heating, general household, and small commercial energy needs generally occurs at the initial installation phase when the customer/builder typically makes the decision as to which type of equipment to install and operate. The customer will generally continue to use the chosen energy source for the life of the equipment. As a result of its success in these markets, Southwest has experienced consistent growth among the residential and small commercial customer classes.

Unlike residential and small commercial customers, certain large commercial, industrial, and electric generation customers have the capability to switch to alternative energy sources. To date, Southwest has been successful in retaining most of these customers by setting rates at levels competitive with alternative energy sources such as electricity, fuel oils, and coal. As a result,However, increases in natural gas prices, if sustained for an extended period of time, may impact Southwest’s ability to retain some of these customers. Overall, management does not anticipate any material adverse impact on its operating margin from fuel switching.

Southwest continues to compete with interstate transmission pipeline companies, such as El Paso, Natural Gas Company (El Paso), Kern River, Gas Transmission Company (Kern River), and Tuscarora Gas Transmission Company, to provide service to certain large end-users. End-use customers located in close proximity to these interstate pipelines pose a potential bypass threat and, therefore, requirethreat. Southwest attempts to closely monitor each customer situation and provide competitive service in order to retain the customer. Southwest has maintained an intensive effort to mitigate theseremained competitive threats through the use of discountednegotiated transportation contract rates, special long-term contracts with electric generation and cogeneration customers, and newother tariff programs. One such program provides an opportunity for potential bypass customers in Arizona to purchase natural gas-related services as a bundled package, including the procurement of gas supply. Southwest enters into gas 4 7 supply contracts for eligible customers, which are not included in its system supply portfolio, and provides nomination and balancing services on behalf of the customer. This program, as well as otherThese competitive response initiatives and otherwise competitive rates, has helped mitigatehave mitigated the financial impact from the threat of bypass and the potential loss of margin currently earned from large customers. DEMAND FOR NATURAL GAS Deliveries of natural gas by Southwest are made under a priority system established by each regulatory commission having jurisdiction over Southwest. The priority system is intended to ensure that the gas requirements of higher-priority customers, primarily residential customers and nonresidential customers who use 500 therms of gas per day or less, are fully satisfied on a daily basis before lower-priority customers, primarily electric utility and large industrial customers able to use alternative fuels, are provided any quantity of gas or capacity. Demand for natural gas is greatly affected by temperature. On cold days, use of gas by residential and commercial customers may be as much as eight times greater than on warm days because of increased use of gas for space heating. To fully satisfy this increased high-priority demand, gas is withdrawn from storage or peaking supplies are purchased from suppliers. If necessary, service to interruptible lower-priority customers may be curtailed to provide the needed delivery system capacity. Southwest maintains no backlog on its orders for gas service. Natural gas vehicles (NGVs) represent a nontraditional source of demand for natural gas. Southwest encourages the use of NGVs throughout its service territories. As of December 31, 1998, there were 48 public- and nonpublic-access fueling stations and approximately 5,500 NGVs in use throughout Southwest service territories. As more public fueling stations come on-line and stricter vehicle emission standards are adopted, the demand for NGVs should increase. NATURAL GAS SUPPLY Southwest is responsible to acquire (purchase) and arrange delivery of (transport) natural gas to its system for all sales customers. Southwest believes that natural gas supplies and pipeline capacity for transportation will remain plentiful and readily available. The primary objective of Southwest with respect to gas supply is to ensure that adequate, as well as economical, supplies of natural gas are available from reliable sources. Gas is acquired from a wide variety of sources, including suppliers on the spot market and those who provide firm supplies over short-term and longer-term durations. During 1998, Southwest acquired gas supplies from approximately 70 suppliers. This practice provides security against nonperformance by any one supplier. Balancing firm supply assurances against the associated costs dictates a continually changing natural gas purchasing mix within the supply portfolios. The current purchasing strategy of Southwest primarily involves competitively-bid firm volumetric contracts with variable or index-based pricing. This strategy allows Southwest to acquire gas at current market prices but can result in price volatility. In managing its gas supply portfolio, Southwest does not currently utilize stand-alone derivative financial instruments, but may do so in the future to hedge against possible price increases and help mitigate the regulatory risk of a gas cost disallowance during periods of rising prices. Any such change would be undertaken only with regulatory commission authorization. Natural gas prices have historically demonstrated seasonal volatility with higher prices in the heating season and lower prices during the summer or off-peak consumption period. The latter part of 1996 and early 1997 witnessed particularly steep price increases, whereas the two most recent winter periods experienced more typical seasonal price volatility. Gas supplies for the Southwest southern system (Arizona, southern Nevada, and southern California properties) are primarily obtained from producing regions in New Mexico (San Juan basin), Texas (Permian basin), and Rocky 5 8 Mountain areas. For its northern system (northern Nevada and northern California properties), Southwest primarily obtains gas from Rocky Mountain producing areas and from Canada. Southwest arranges for transportation of gas to its Arizona, Nevada, and California service territories through the pipeline systems of El Paso, Kern River, Northwest Pipeline Corporation, and Southern California Gas Company. Supply and pipeline capacity availability on both short- and long-term bases are continually monitored by Southwest to ensure the continued reliability of service to its customers. Southwest currently receives firm transportation service, both on a short- and long-term basis, for all of its service territories on the four pipeline systems noted above, and has interruptible contracts in place that allow additional capacity to be acquired as needed. The current level of contracted firm interstate capacity is sufficient to serve each of the service territories. As the need arises to acquire additional capacity on one of the interstate pipeline transmission systems, primarily due to customer growth, Southwest considers available options to obtain the capacity, either through the use of firm contracts with a pipeline company or by purchasing capacity on the open market. While firm contracts provide stability and guaranteed rights to capacity, they are generally a more expensive alternative. Southwest continues to evaluate natural gas storage as an option to enable it to take advantage of seasonal price differentials in obtaining natural gas from a variety of sources to meet the growing demand of its customers. ENVIRONMENTAL MATTERS

Environmental Matters

Federal, state, and local laws and regulations governing the discharge of materials into the environment have had little direct impact upon Southwest. Environmental efforts, with respect to matters such as protection of endangered species and archeological finds, have increased the complexity and time required to obtain pipeline rights-of-way and construction permits. However, increased environmental legislation and regulation are also beneficial to the natural gas industry. Because natural gas is one of the most environmentally safe fossil fuels currently available, its use helpscan help energy users to comply with stricter environmental standards. EMPLOYEES

Employees

At December 31, 1998,2003, the natural gas operations segment had 2,4292,550 regular full-time equivalent employees.employees, of which 507 full-time equivalent non-exempt employees in central Arizona were represented by the International Brotherhood of Electrical Workers. No other natural gas operations segment employees are represented by a union. Southwest believes it has a good relationship with its employees. Noemployees and that compensation, benefits, and working conditions afforded its employees are represented by a union. Reference is hereby madecomparable to Item 10those generally found in Part III of this report on Form 10-K for information relative to the executive officers of the Company. utility industry.

CONSTRUCTION SERVICES

Northern Pipeline Construction Co. (Northern or the construction services segment) is a full-service underground piping contractor whichthat provides utility companies with trenching and installation, replacement, and maintenance services for energy distribution systems. NorthernNPL contracts primarily with LDCs to install, repair, and maintain energy distribution systems from the town border station to the end-user meter.end-user. The primary focus of business operations is main and service replacement as well as new business installations. Construction work varies from relatively small projects to the piping of entire communities. Construction activity is seasonal.seasonal in most areas. Peak construction periods are the summer and fall months in colder climate areas, such as the Midwest.midwest. In the warmer climate areas, such as the southwestern United States, construction continues year round. Northern

NPL business activities are often concentrated in utility service territories where existing gasenergy lines are scheduled for replacement. An LDC will typically contract with NorthernNPL to provide pipe replacement services and new line installations. Contract terms generally specify unit priceunit-price or fixed-price arrangements. Unit priceUnit-price contracts establish prices for all of the various services to be performed during the contract period. These contracts often have annual 6 9 pricing reviews. During 1998, more than 892003, approximately 94 percent of revenue was earned under unit priceunit-price contracts. As of December 31, 19982003 no significant backlog existsexisted with respect to outstanding construction contracts.

Materials used by NPL in its pipeline construction activities are typically specified, purchased, and supplied by NPL’s customers. Construction contracts also contain provisions which make customers generally liable for remediating environmental hazards encountered during the construction process. Such hazards might include digging in an area that was contaminated prior to construction, finding endangered animals, digging in historically significant sites, etc.

Otherwise, NPL’s operations have minimal environmental impact (dust control, normal waste disposal, handling harmful materials, etc.).

Competition within the industry ishas traditionally been limited to several regional competitors in what can be characterized ashas been a largely fragmented industry. NorthernSeveral national competitors also exist within the industry. NPL currently operates in approximately 1517 major markets nationwide. Its customers are the primary LDCs in those markets. Construction companies typically depend on a fewDuring 2003, NPL served 41 major customers, with Southwest accounting for approximately 30 percent of their business. During 1998, Southwestrevenues. With the exception of one other customer that accounted for 32approximately 12 percent of Northernrevenue, no other customer had a relatively significant contribution to NPL revenues. No other customers contributed more than 10 percent of revenues.

Employment fluctuates between seasonal construction periods, which are normally heaviest in the summer and fall months. At December 31, 1998, Northern2003, NPL had 1,2671,822 regular full-time equivalent employees. Employment peaked in November 1998May 2003 when there were 1,6212,040 employees. The majority of the employees are represented by unions and are covered by collective bargaining agreements, which is typical of the utility construction industry.

Operations are conducted from 17 field locations with corporate headquarters located in Phoenix, Arizona. All buildings are leased from third parties. The lease terms are typically two to three years.five years or less. Field location facilities consist of a small building for repairs and acreageland to store equipment. ITEM

NPL is not directly affected by regulations promulgated by the ACC, PUCN, CPUC or FERC in its construction services. NPL is an unregulated construction subsidiary of Southwest Gas Corporation. However, because NPL performs work for the regulated natural gas segment of the Company, its construction costs are subject indirectly to “prudency reviews” just as any other capital work that is performed by third parties or directly by Southwest. However, such “prudency reviews” would not bring NPL under the regulatory jurisdiction of any of the commissions noted above.

COMPANY RISK FACTORS

Although the Company is not able to predict all factors that may affect future results, described below are some of the risk factors identified by the Company that may have a negative impact on our future financial performance or affect whether we achieve the goals or expectations expressed or implied in any forward-looking statements contained herein. Unless indicated otherwise, references below to “we,” “us” and “our” should be read to refer to Southwest Gas Corporation and its subsidiaries.

Our liquidity, and in certain circumstances our earnings, may be reduced during periods in which natural gas prices are rising significantly or are more volatile.

Rate schedules in each of our service territories contain purchased gas adjustment clauses which permit us to file for rate adjustments to recover increases in the cost of purchased gas. Increases in the cost of purchased gas have no direct impact on our profit margins, but do affect cash flows and can therefore impact the amount of our capital resources. We have used short-term borrowings in the past to temporarily finance increases in purchased gas costs, and we expect to do so during 2004, if the need again arises.

We may file requests for rate increases to cover the rise in the costs of purchased gas. Due to the nature of the regulatory process, there is a risk of a disallowance of full recovery of these costs during any period in which there has been a substantial run-up of these costs or our costs are more volatile. Any disallowance of purchased gas costs may reduce cash flow and earnings.

Increases in the cost of natural gas may arise from a variety of factors, including weather, changes in demand, the level of production and availability of natural gas, transportation constraints, transportation capacity cost increases, federal and state energy and environmental regulation and legislation, the degree of market liquidity, natural disasters, wars and other catastrophic events, and the success of our strategies in managing price risk.

Governmental policies and regulatory actions can reduce our earnings.

Governmental policies and regulatory actions, including those of the ACC, the CPUC, the FERC, and the PUCN relating to allowed rates of return, rate structure, purchased gas and investment recovery, operation and construction of

facilities, present or prospective wholesale and retail competition, changes in tax laws and policies, and changes in and compliance with environmental and safety laws and policies, can reduce our earnings. Risks and uncertainties relating to delays in obtaining regulatory approvals, conditions imposed in regulatory approvals, or determinations in regulatory investigations can also impact financial performance.

We are unable to predict what types of conditions might be imposed on Southwest or what types of determinations might be made in pending or future regulatory proceedings or investigations. We nevertheless believe that it is not uncommon for conditions to be imposed in regulatory proceedings, for Southwest to agree to conditions as part of a settlement of a regulatory proceeding, or for determinations to be made in regulatory investigations that will reduce our earnings and liquidity. For example, we may request recovery of a particular operating expense in a general rate case filing that a regulator disallows.

Significant customer growth in Arizona and Nevada could strain our capital resources.

We continue to experience significant population and customer growth throughout our service territories. During 2003, we added 67,000 customers, a five percent growth rate. Another 9,000 customers were added in October 2003 with the BMG acquisition. Over the past ten years, customer growth has averaged five percent per year. This growth has required large amounts of capital to finance the investment in new transmission and distribution plant. In 2003, our natural gas construction expenditures totaled $228 million. Approximately 72 percent of these current-period expenditures represented new construction, and the balance represented costs associated with routine replacement of existing transmission, distribution, and general plant.

Cash flows from operating activities (net of dividends) have been inadequate, and are expected to continue to be inadequate, to fund all necessary capital expenditures. We have funded this shortfall through the issuance of additional debt and equity securities, and expect to continue to do so. However, our ability to issue additional securities is dependent upon, among other things, conditions in the capital markets, regulatory authorizations, and our level of earnings.

Significant customer growth in Arizona and Nevada could also impact earnings.

Our ability to earn the rates of return authorized by the ACC and the PUCN is also more difficult because of significant customer growth. The rates we charge our distribution customers in Arizona and Nevada are derived using rate base, cost of service, and cost of capital experienced in a historical test year, as adjusted. This results in “regulatory lag” which delays our recovery of some of the costs of capital improvements and operating costs from customers in Arizona and Nevada.

Our earnings are greatly affected by variations in temperature during the winter heating season.

The demand for natural gas is seasonal and is greatly affected by temperature. Variability in weather from normal temperatures can materially impact results of operations. On cold days, use of gas by residential and commercial customers may be as much as six times greater than on warm days because of the increased use of gas for space heating. Weather has been and will continue to be one of the dominant factors in our financial performance.

Uncertain economic conditions may affect our ability to finance capital expenditures.

Our ability to finance capital expenditures and other matters will depend upon general economic conditions in the capital markets. The direction of interest rates is uncertain. Declining interest rates are generally believed to be favorable to utilities while rising interest rates are believed to be unfavorable because of the high capital costs of utilities. In addition, our authorized rate of return is based upon certain assumptions regarding interest rates. If interest rates are lower than assumed rates, our authorized rate of return in the future could be reduced. If interest rates are higher than assumed rates, it will be more difficult for us to earn our currently authorized rate of return.

A significant reduction in our credit ratings could materially and adversely affect our business, financial condition and results of operations.

We cannot be certain that any of our current ratings will remain in effect for any given period of time or that a rating will not be lowered or withdrawn entirely by a rating agency if, in its judgment, circumstances in the future so

warrant. Any downgrade could increase our borrowing costs, which would diminish our financial results. We would likely be required to pay a higher interest rate in future financings, and our potential pool of investors and funding sources could decrease. A downgrade could require additional support in the form of letters of credit or cash or other collateral and otherwise adversely affect our business, financial condition and results of operations.

Item 2.    PROPERTIES

The plant investment of Southwest consists primarily of transmission and distribution mains, compressor stations, peak shaving/storage plants, service lines, meters, and regulators, which comprise the pipeline systems and facilities located in and around the communities served. Southwest also includes other properties such as land, buildings, furnishings, work equipment, vehicles, and vehiclessoftware systems in plant investment. The northern Nevada and northern California properties of Southwest are referred to as the northern system; the Arizona, southern Nevada, and southern California properties are referred to as the southern system. Several properties are leased by Southwest, including an LNG storage plant on itsin northern Nevada, system and a portion of the corporate headquarters office complex located in Las Vegas, Nevada.Nevada, and the administrative offices in Phoenix, Arizona. Total gas plant, exclusive of leased property, at December 31, 1998,2003 was $2.1$3.1 billion, including construction work in progress. It is the opinion of management that the properties of Southwest are suitable and adequate for its purposes.

Substantially all gas main and service lines of Southwest are constructed across property owned by others under right-of-way grants obtained from the record owners thereof, on the streets and grounds of municipalities under authority conferred by franchises or otherwise, or on public highways or public lands under authority of various federal and state statutes. None of the numerous county and municipal franchises are exclusive, and some are of limited duration. These franchises are renewed regularly as they expire, and Southwest anticipates no serious difficulties in obtaining future renewals.

With respect to the right-of-way grants, Southwest has had continuous and uninterrupted possession and use of all such rights-of-way, and the associated gas mains and service lines, commencing with the initial stages of the construction of such facilities. Permits have been obtained from public authorities and other governmental entities in certain instances to cross or to lay facilities along roads and highways. These permits typically are revocable at the election of the grantor and Southwest occasionally must relocate its facilities when requested to do so by the grantor. Permits have also been obtained from railroad companies to cross over or under railroad lands or rights-of-way, which in some instances require annual or other periodic payments and are revocable at the grantors' elections. election of the grantors.

Southwest operates two primary pipeline transmission systems: (i) a system owned by Paiute, a wholly owned subsidiary, extending from the Idaho-Nevada border to the Reno, Sparks, and Carson City areas and communities in the Lake Tahoe area in both California and Nevada and other communities in northern and western Nevada; and (ii) a system extending from the Colorado River at the southern tip of Nevada to the Las Vegas distribution area. 7 10

The following map below shows the locations of major Southwest facilities and transmission lines, and principal communities to which Southwest supplies gas either as a wholesaler or distributor. The map also shows major supplier transmission lines that are interconnected with the Southwest systems. [MAP] [THE FOLLOWING TEXT TO BE INSERTED IN EDGAR VERSION ONLY] [DESCRIPTION: Map

Information on properties of Arizona, Nevada, and California indicating the locationNPL can be found on page 6 of Southwest service areas. Service areas in Arizona include most of the central and southern areas of the state including Phoenix, Tucson, Yuma, and surrounding communities. Service areas in northern Nevada include Carson City, Yerington, Fallon, Lovelock, Winnemucca, and Elko. Service areas in southern Nevada include the Las Vegas valley (including Henderson and Boulder City) and Laughlin. Service areas in southern California include Barstow, Big Bear, Needles, and Victorville. Service areas in northern California include the north shore of Lake Tahoe and portions of Truckee. Companies providing gas transportation services for the Company are indicated by showing the location of their pipelines. Major transporters include El Paso Natural Gas Company, Kern River Gas Transmission Company, Northwest Pipeline Corporation, and Southern California Gas Company. The location of the Paiute Pipeline Company transmission pipeline (extending from the Idaho/Nevada border to the Reno/Tahoe area) and Southwest's pipeline (extending from Laughlin/Bullhead City to the Las Vegas valley) are indicated. The LNG facility is located near Lovelock, Nevada.] 8 11 The information appearing in Part I, this Form 10-K under Construction Services.

Item 1, pages 6 and 7 with respect to the construction services segment is incorporated herein by reference. ITEM 3.    LEGAL PROCEEDINGS

The Company has beenis named as a defendant in various legal proceedings. The ultimate dispositions of these proceedings are not presently determinable; however, it is the opinion of management that nonone of this litigation to whichindividually or in the Company is subjectaggregate will have a material adverse impact on itsthe Company’s financial position or results of operations. On December 16, 1998, Arthur Klein, a purported shareholder of the Company, filed a Complaint in the Superior Court of the State of California in San Diego County (Case No. 726615) against the Company and its directors alleging one cause of action for breach of fiduciary duty. The plaintiff alleges that the consideration for the proposed merger with ONEOK is unfair and inadequate because the Company's Board of Directors approved the definitive agreement with ONEOK without conducting any auction or using another "market check" mechanism. Plaintiff is proposing to represent a class of all shareholders of the Company (excluding defendants and their affiliates and families). On March 22, 1999, the plaintiff filed an Amended Complaint in which he alleges causes of action for breach of fiduciary duty of loyalty and due care and breach of duty of candor. By his Amended Complaint, plaintiff seeks * to enjoin the merger with ONEOK, * to rescind the definitive agreement with ONEOK, * to implement an auction of the Company or similar process, * to void the $30 million termination fee in the definitive agreement with ONEOK in the event the definitive agreement with ONEOK is terminated, the Company's Board of Directors recommends another transaction, such as the merger proposed by Southern Union Company, or in other similar circumstances, and * unspecified damages. The court has ordered the parties to conduct limited discovery and set a preliminary injunction schedule, which, if followed, would result in a telephonic ruling on plaintiff's motion for a preliminary injunction in May 1999. The Company believes that it has valid defenses to plaintiff's claims. ITEM

Item 4.    SUBMISSION OF MATTERS TO A VOTE OF SECURITY HOLDERS

None.

PART II ITEM

Item 5.    MARKET FOR REGISTRANT'SREGISTRANT’S COMMON EQUITY, AND RELATED STOCKHOLDER MATTERS AND ISSUER PURCHASES OF EQUITY SECURITIES

The principal markets on which the common stock of the Company is traded are the New York Stock Exchange and the Pacific Stock Exchange. At March 15, 1999,1, 2004, there were 24,18623,259 holders of record of common stock, and the market price of the common stock was $27.$23.45. The quarterly market price of, and dividends on, Company common stock required by this item are included in the 19982003 Annual Report to Shareholders filed as an exhibit hereto and are incorporated herein by reference. ITEM

The Company has a common stock dividend policy which states that common stock dividends will be paid at a prudent level that is within the normal dividend payout range for its respective businesses, and that the dividend will be established at a level considered sustainable in order to minimize business risk and maintain a strong capital structure throughout all economic cycles. The quarterly common stock dividend was 20.5 cents per share throughout 2003. The dividend of 20.5 cents per share has been paid quarterly since September 1994.

Item 6.    SELECTED FINANCIAL DATA

Information required by this item is included in the 19982003 Annual Report to Shareholders and is incorporated herein by reference. 9 12 ITEM

Item 7.    MANAGEMENT'SMANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS

Information required by this item is included in the 19982003 Annual Report to Shareholders and is incorporated herein by reference. ITEM

Item 7A.    QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK Not applicable. ITEM

Information required by this item is included in the 2003 Annual Report to Shareholders under the heading “Management’s Discussion and Analysis” and under Notes 6 and 7 of the Notes to Consolidated Financial Statements and is incorporated herein by reference. Other risk information is included under the heading “Company Risk Factors” inItem 1. Business of this report.

Item 8.    FINANCIAL STATEMENTS AND SUPPLEMENTARY DATA

The Consolidated Financial Statements of Southwest Gas Corporation and Notes thereto, together with the reportreports of PricewaterhouseCoopers LLP, Independent Auditors, and Arthur Andersen LLP, Independent Public Accountants, are included in the 19982003 Annual Report to Shareholders and are incorporated herein by reference. ITEM

Item 9.    CHANGES IN AND DISAGREEMENTS WITH ACCOUNTANTS ON ACCOUNTING AND FINANCIAL DISCLOSURE None.

On May 28, 2002, the Company dismissed Arthur Andersen LLP as its independent auditor. The decision to dismiss Arthur Andersen was recommended by the Company’s Audit Committee and approved by its Board of Directors.

Arthur Andersen’s report on the financial statements of the Company for the year ended December 31, 2001 did not contain an adverse opinion or a disclaimer of opinion and was not qualified or modified as to uncertainty, audit scope, or accounting principles.

During the years ended December 31, 2000 and 2001, and the interim period between December 31, 2001 and May 28, 2002, there were no disagreements between the Company and Arthur Andersen on any matter of accounting principles or practices, financial statement disclosure or auditing scope or procedure, which disagreements, if not resolved to the satisfaction of Arthur Andersen, would have caused it to make reference to the subject matter of the disagreements in connection with its report. During the years ended December 31, 2000 and 2001, and the interim period between December 31, 2001 and May 28, 2002, there were no reportable events (as defined in Item 304(a)(1)(v) of Regulation S-K promulgated by the SEC). In May 2002, Arthur Andersen furnished the Company with a letter addressed to the SEC stating that it agrees with the statements above. A copy of the letter was included as an exhibit to the Form 8-K filed by the Company in May 2002.

The Company engaged PricewaterhouseCoopers LLP as its independent auditor, effective May 28, 2002. During the years ended December 31, 2000 and 2001, and the interim period between December 31, 2001 and May 28, 2002, neither the Company nor anyone on its behalf consulted with PricewaterhouseCoopers LLP regarding (i) the application of accounting principles to a specified transaction, either completed or proposed, (ii) the type of audit opinion that might be rendered on the Company’s financial statements, or (iii) any matter that was either the subject of a disagreement (as described above) or a reportable event.

The Company has not been able to obtain, after reasonable efforts, the written consent of Arthur Andersen to the incorporation by reference in the Company’s previously filed Form S-3 Registration Statements (Nos. 333-98995 and 333-106419) and Form S-8 Registration Statements (Nos. 333-31223, 333-106762 and 333-111034) of the report of Arthur Andersen on the 2001 financial statements included in this Annual Report, as required by the Securities Act of 1933. Therefore, in reliance on Rule 437a promulgated under the Securities Act of 1933, the Company has dispensed with the requirement to file a written consent from Arthur Andersen with this Annual Report. As a result, the ability of persons who purchase the Company’s securities pursuant to these Registration Statements to assert claims against Arthur Andersen may be limited.

Because the Company has not been able to obtain the written consent of Arthur Andersen, such persons may not have an effective remedy against Arthur Andersen for any untrue statements of a material fact contained in Arthur Andersen’s report or the financial statements covered thereby or any omissions to state a material fact required to be stated therein.

Item 9A.    CONTROLS AND PROCEDURES

The Company has established disclosure controls and procedures that are designed to provide reasonable assurance that information required to be disclosed in reports filed or submitted under the Securities Exchange Act of 1934 is recorded, processed, summarized, and reported within the time periods specified in the SEC’s rules and forms. A control system, no matter how well conceived and operated, can provide only reasonable, not absolute, assurance that the objectives of the control system are met. Further, the design of a control system must reflect the fact that there are resource constraints, and benefits of controls must be considered relative to their costs. Additionally, controls can be circumvented by the individual acts of some persons, by collusion of two or more people, or management override of the control. Because of the inherent limitations in a cost-effective control system, misstatements due to error or fraud may occur and not be detected.

Based on the most recent evaluation, as of December 31, 2003, management of the Company, including the Chief Executive Officer and Chief Financial Officer, believe the Company’s disclosure controls and procedures are effective at attaining the level of reasonable assurance noted above.

There have been no changes in the Company’s internal controls over financial reporting during the fourth quarter that have materially affected, or are likely to materially affect, the Company’s internal controls over financial reporting.

PART III ITEM

Item 10.    DIRECTORS AND EXECUTIVE OFFICERS OF THE REGISTRANT

(a)Identification of Directors. The names Information with respect to Directors is set forth under the heading “Election of the members of the Board of Directors, the principal occupation of each member and his or her employer for the last five years or longer, and the principal business of the corporation or other organization, if any, in which such occupation or employment is carried on, follow. GEORGE C. BIEHL Senior Vice President, Chief Financial Officer & Corporate Secretary Southwest Gas Corporation Director Since: 1998 Board Committees: Finance Mr. Biehl, 51, joined the Company in 1990 as Senior Vice President and Chief Financial Officer after serving in a number of capacities with Deloitte Haskins & Sells (now Deloitte & Touche) for sixteen years and as chief financial officer for PriMerit Bank for the five years before joining the Company. He also assumed the responsibilities as Corporate Secretary for the Company in 1996. Mr. Biehl graduated from Ohio State University with a degree in accounting and earned his MBA with an emphasis in finance from Columbia University. He is a licenced CPA in several states and is a member of the American Institute of Certified Public Accountants. He is also a member of the Las Vegas Chamber of Commerce Leadership Las Vegas Program, and serves on the finance committees of several trade association groups. 10 13 MANUEL J. CORTEZ President and Chief Executive Officer Las Vegas Convention and Visitors Authority Director Since: 1991 Board Committees: Audit (Chairman), Compensation, Pension Plan Investment Mr. Cortez, 60, served four terms (1977-1990) on the Clark County Commission and is a former chairman of the Commission. He has been active on various boards, including the Environmental Quality Policy Review Board, the Las Vegas Valley Water District Board of Directors, and the University Medical Center Board of Trustees, and served as chairman of the Liquor and Gaming Licensing Board and the Clark County Sanitation District. He has also held leadership roles with numerous civic and charitable organizations such as Boys and Girls Clubs of Clark County, Lied Discovery Childrens Museum, and Boys Town. Currently, Mr. Cortez holds professional membershipsDirectors” in the American Society of Association Executives, the Professional Convention Managers Association, the International Association of Convention and Visitors Bureaus, the American Society of Travel Agents, anddefinitive 2004 Proxy Statement, which by this reference is on the board of directors for the Travel Industry Association of America. LLOYD T. DYER Retired President and Chief Executive Officer Harrah's Director Since: 1978 Board Committees: Executive, Compensation (Chairman), Nominating Mr. Dyer, 71, obtained a degree in banking and finance from the University of Utah prior to his employment with Harrah's, a hotel/gaming corporation with its principal facilities in Reno and Lake Tahoe, in 1957. He was elected president and chief operating officer of Harrah's in 1975, and elected president and chief executive officer in 1978. He remained in those positions with Harrah's until his retirement in April 1980. Mr. Dyer is a trustee of the William F. Harrah Trusts. THOMAS Y. HARTLEY Chairman of the Board, Southwest Gas Corporation President and Chief Operating Officer, Colbert Golf Design and Development Director Since: 1991 Board Committees: Executive (Chairman), Compensation, Nominating Mr. Hartley, 65, obtained his degree in business from Ohio University in 1955, and was employed in various capacities by Deloitte Haskins & Sells (now Deloitte & Touche) from 1959 until his retirement as an area managing partner in 1988. He joined Southwest Gas Corporation as Director in 1991 and was elected Chairman of the Board of Directors in 1997. Mr. Hartley is actively involved in numerous business and civic activities. He is a past chairman of the UNLV Foundation and the Nevada Development Authority, and past president of the Las Vegas Founders Club. He has also held voluntary executive positions with the Las Vegas Founders Golf Foundation, the Las Vegas Chamber of Commerce, and the Boulder Dam Area Council of the Boy Scouts of America. He is a director of Sierra Health Services, Inc. and AmeriTrade Holdings Corporation. 11 14 MICHAEL B. JAGER Private Investor Director Since: 1989 Board Committees: Audit, Finance, Pension Plan Investment (Chairman) Mr. Jager, 67, obtained a degree in petroleum geology from Stanford University in 1955. After a four-year employment with the Richfield Oil Corporation as a petroleum geologist, he joined Frank H. Ayres & Son Construction Company and was involved in the construction of subdivisions and homes in southern California until 1979. Since that time he has consulted in the single family residential development industry, and owns and manages a number of businesses in Nevada. LEONARD R. JUDD Former President, Chief Operating Officer, and Director Phelps Dodge Corporation Director Since: 1988 Board Committees: Executive, Compensation, Nominating (Chairman) Mr. Judd, 60, former president, chief operating officer, and director of Phelps Dodge Corporation, joined Phelps Dodge in 1963 and worked at that company's operations in Arizona, New Mexico, and New York City. He was elected to the Phelps Dodge board of directors in 1987, president of Phelps Dodge Mining Company in 1988, and became president and chief operating officer of Phelps Dodge in 1989. He remained in those positions until the end of 1991. Mr. Judd is a member of various professional organizations and is active in numerous civic groups. He serves as a director of Morrison-Knudsen Corporation. JAMES J. KROPID President of James J. Kropid Investments Director Since: 1997 Board Committees: Executive, Compensation, Finance Mr. Kropid, 61, received his undergraduate degree from DePaul University and participated in the executive development program at the University of Illinois. He joined Centel Corporation in 1961 and became president of its Central Telephone Company-Nevada/Texas division in 1987. In 1993, the Governor of Nevada appointed him to the position of general manager of the Nevada State Industrial Insurance System, a position in which he served for almost two years. He is currently president of his own investment company. Mr. Kropid holds executive and board positions with various civic and charitable organizations including the National Conference for Community and Justice (formerly known as the National Conference of Christians and Jews), Las Vegas YMCA, and the Boy Scouts of America. He was formerly a board member for the Nevada Development Authority, United Way of Southern Nevada, and treasurer of St. Jude's Ranch for Children. He is a director of the Golf Company of Nevada. 12 15 MICHAEL O. MAFFIE President and Chief Executive Officer Southwest Gas Corporation Director Since: 1988 Board Committees: Executive Mr. Maffie, 51, joined the Company in 1978 as Treasurer after seven years with Arthur Andersen & Co. He was named Vice President/Finance and Treasurer in 1982, Senior Vice President and Chief Financial Officer in 1984, Executive Vice President in 1987, President and Chief Operating Officer in 1988, and President and Chief Executive Officer in 1993. He received his undergraduate degree in accounting and his MBA degree in finance from the University of Southern California. He serves as a director of Del Webb Corporation, Boyd Gaming Corporation, and Norwest Bank/Nevada Division. A member of various civic and professional organizations, he serves as chairman of the board of United Way of Southern Nevada and trustee and treasurer of the UNLV Foundation. He also is a director of the Pacific Coast Gas Association and the Institute of Gas Technology. CAROLYN M. SPARKS Co-Founder International Insurance Services, Ltd. Director Since: 1988 Board Committees: Audit, Finance (Chairperson), Pension Plan Investment Mrs. Sparks, 57, graduated from the University of California Berkeley in 1963, and with her husband, co-founded International Insurance Services, Ltd., in 1966 in Las Vegas. She served on the University and Community College System of Nevada Board of Regents from 1984 to 1996, and in 1991 was elected to a two-year term as chair of the Board of Regents. Mrs. Sparks is actively involved with numerous charitable and civic organizations, including founding and chairing the University Medical Center Foundation and the Children's Miracle Network Telethon. She is currently chair of the Nevada Children's Center Foundation and has been elected to the Foundation Boards of the University of Nevada Las Vegas and the Community College of Southern Nevada. ROBERT S. SUNDT Retired President Sundt Corp. Director Since: 1987 Board Committees: Executive, Finance, Nominating, Pension Plan Investment Mr. Sundt, 72, has been associated with Sundt Corp. in a variety of positions since 1948. He was named President of Sundt Corp. in 1983. He is now retired and has no continuing association with Sundt Corp. He is a member of the American Institute of Constructors, Consulting Constructors Council of America, and a life director of the Associated General Contractors of America. He was a member of the American Arbitration Association and has served as an arbitrator on disputes concerning the construction industry. He is a past member of the Construction Industry Presidents Forum. Mr. Sundt is affiliated with a number of community organizations and is past chairman of the Tucson Metropolitan Chamber of Commerce. 13 16 TERRANCE "TERRY" L. WRIGHT President and Chief Executive Officer Nevada Title Insurance Company Director Since: 1997 Board Committees: Audit, Compensation, Pension Plan Investment Mr. Wright, 49, received his undergraduate degree in business administration and his juris doctorate from DePaul University. He joined Chicago Title Insurance Company while in law school and after graduation remained with the company and eventually moved to the Las Vegas, Nevada office. In 1978, he acquired the assets of Western Title to form what is now known as Nevada Title Insurance Company. Mr. Wright is also associate general counsel for A.G. Spanos Enterprises, Inc., one of the nation's largest apartment complex builders. He is a member of the California and Illinois bar associations and is affiliated professionally with the Las Vegas Board of Realtors, Nevada Land Title Association, Las Vegas Executives, Opportunity Village, TPC board of governors, Young President's Organization, and is past-chairman of the Nevada Development Authority. Mr. Wright is also a trustee and an executive committee member of the UNLV Foundation. incorporated herein.

(b)Identification of Executive Officers. The name, age, position, and period position held during the last five years for each of the Executive Officers of the Company are as follows:

PERIOD POSITION NAME AGE POSITION HELD ---- --- -------- ---------------

Name


Age

Position


Period Position
Held


Michael O. Maffie 51

56Chief Executive Officer2003-Present
President and Chief Executive Officer 1994-Present 1999-2003

Jeffrey W. Shaw

45President2003-Present
Senior Vice President/Gas Resources and Pricing2002-2003
Senior Vice President/Finance and Treasurer2000-2002
Vice President/Treasurer1999-2000

George C. Biehl 51

56Executive Vice President/Chief Financial Officer and
Corporate Secretary2000-Present
Senior Vice President/Chief Financial Officer and 1996-Present
Corporate Secretary Senior Vice President and Chief Financial Officer 1994-1996 1999-2000

James P. Kane 52

57Executive Vice President/Operations2000-Present
Senior Vice President/Operations 1997-Present Vice President/Southern Arizona Division 1994-1997 James F. Lowman 52 Senior Vice President/Central Arizona Division 1994-Present Dudley J. Sondeno 46 Senior Vice President/Chief Knowledge and Technology Officer 1994-Present 1999-2000

Edward S. Zub 50

55Executive Vice President/Consumer Resources and
Energy Services2000-Present
Senior Vice President/Regulation and Product Pricing 1996-Present1999-2000

James F. Lowman

57Senior Vice President/Rates & Regulation 1994-1996 Central Arizona Division1999-Present

Thomas R. Sheets

53Senior Vice President/Legal Affairs and General Counsel2000-Present
Vice President/General Counsel1999-2000

Dudley J. Sondeno

51Senior Vice President/Chief Knowledge and
Technology Officer1999-Present

Roy R. Centrella

46Vice President/Controller and Chief Accounting Officer2002-Present
Controller2001-2002
 ��Assistant Controller1999-2001

Kenneth J. Kenny

41Treasurer2003-Present
Assistant Treasurer/Director Financial Services2000-2003
Senior Manager/Treasury1999-2000

(c)Identification of Certain Significant Employees.Employees. None.

(d)Family Relationships. None of the No Directors or Executive Officers are related to any other either by blood, marriage, or adoption.

(e)Business Experience. Information with respect to Directors is describedset forth under the heading “Election of Directors” in (a) above.the definitive 2004 Proxy Statement, which by this reference is incorporated herein. All Executive Officers have held responsible positions with the Company for at least five years as described in (b) above.

(f)Involvement in Certain Legal Proceedings. None.

(g)Promoters and Control Persons. None.

(h) Audit Committee Financial Expert. Information with respect to the financial expert of the Board of Directors’ audit committee is set forth under the heading “Committees of the Board” in the definitive 2004 Proxy Statement, which by this reference is incorporated herein.

(i) Identification of the Audit Committee. Information with respect to the composition of the Board of Directors’ audit committee is set forth under the heading “Committees of the Board” in the definitive 2004 Proxy Statement, which by this reference is incorporated herein.

Section 16(a) Beneficial Ownership Reporting Compliance. Section 16(a) of the Securities Exchange Act of 1934 requires officers and directors, and persons who own more than ten percent of a registered class of equity securities, to file reports of ownership and changes in ownership with the Securities and Exchange Commission (SEC)SEC and the New York Stock Exchange. Officers, directors, and beneficial owners of more than ten percent of any class of equity securities are required by SEC regulation to furnish the Company with copies of all Section 16(a) forms they file. 14 17

The Company has adopted procedures to assist its directors and executive officers in complying with Section 16(a) of the Securities and Exchange Act of 1934, as amended, which includes assisting in the preparation of forms for filing. For 19982003, all but onereports were timely filed.

Code of Business Conduct and Ethics.The Company has adopted a code of business conduct and ethics for its employees, including its chief executive officer, chief financial officer, chief accounting officer, and non-employee directors. A code of ethics is defined as written standards that are reasonably designed to deter wrongdoing and to promote: 1) honest and ethical conduct; 2) full, fair, accurate, timely, and understandable disclosure in reports and documents that a registrant files; 3) compliance with applicable governmental laws, rules, and regulations; 4) the prompt internal reporting of violations of the required reports were filed timely.code to an appropriate person or persons identified in the code; and 5) accountability for adherence to the code. The Form 4 listing acquisitions by Carolyn Sparks, as trustee and beneficiaryCompany’s Code of Business Conduct & Ethics can be viewed on the Company’s website (www.swgas.com). If any substantive amendments to the Code of Business Conduct & Ethics are made or any waivers are granted, including any implicit waiver, from a provision of the Sparks Family Trust,Code of 4,000 shares of Common Stock was not filed timely. An amended Form 4 for Mrs. Sparks listingBusiness Conduct & Ethics, to the August 1998 purchase was filed in January 1999. ITEM 11. EXECUTIVE COMPENSATION DIRECTORS COMPENSATION Outside directors receive an annual retainer of $24,000, plus $1,000 for each Board of Directors or committee meeting attended. Committee chairpersons receive an additional $500 for each committee meeting attended. The Chairman of the Board of Directors receives an additional $50,000 annually for serving in that capacity. Directors who are full-time employees ofCompany’s chief executive officer, chief financial officer and chief accounting officer, the Company will disclose the nature of such amendment or its subsidiaries receive no additional compensation for servicewaiver on the Board. Each outside director received in May 1998, options to purchase 2,000 shares of the Common Stock under the provisions of the Option Plan. Under the terms of the Option Plan, each outside director is entitled to receive additional options to purchase 2,000 shares of the Common Stock on the date of each Annual Meeting during the ten-year term of the Option Plan. The purchase price for the options is the market price of the Common Stock on the date of the grant and will become exercisable, in increments over three years, commencing with the first anniversary of the grant. All options granted to the outside directors will expire ten years after the date of each grant. The Option Plan contains change in control provisions. Outside directors may defer their compensation until retirement or termination of their status as directors. Any cash they receive from the cancellation of any outstanding options as a result of a change in control of the Company may also be deferred. At retirement or termination, amounts deferred will be paid out over 5, 10, 15, or 20 years. Amounts deferred receive interest at 150 percent of the Moody's Composite Bond Rate. The Company also provides a retirement plan for its outside directors. With a minimum of 10 years of service, an outside director can retire and receive an annual benefit for life equal to the annual retainer, at retirement, for serving on the Company's Board. Directors who retire before age 65, after satisfying the minimum service obligation, will receive retirement benefits upon reaching age 65. Upon a change in control of the Company, each of the directors of the Company with at least eight years of service will be entitled to receive retirement benefits. 15 18 EXECUTIVE COMPENSATION The following table provides compensation earned by the Company's Chief Executive Officer and each of the four most highly compensated executive officers of the Company, at year-end 1998, for the years ended December 31, 1998, 1997, and 1996. SUMMARY COMPENSATION TABLE (1) Company’s website, www.swgas.com.

LONG-TERM
Item 11.EXECUTIVE COMPENSATION -------------------------------------------- AWARDS PAYOUTS ANNUAL COMPENSATION ---------------------- -------------------- ------------------------------------------------------ RESTRICTED BONUS ($) STOCK LTIP ALL OTHER NAME AND ---------------------- OTHER ANNUAL AWARD(S) OPTIONS/ PAYOUTS COMPENSATION PRINCIPAL POSITION YEAR SALARY($) UTILITY(2) NON-UTILITY COMPENSATION($) ($)(2)(3)(4) SARS(#) ($) ($) (5) ------------------ ---- -------- ---------- ----------- --------------- ------------ -------- ------- ------------ Michael O. Maffie 1998 486,301 234,005 0 0 350,997 25,000 N/A 59,410 President & C.E.O. 1997 462,192 132,015 0 0 198,022 25,000 N/A 54,036 1996 435,479 129,602 500,000 0 194,403 90,000 N/A 46,210 George C. Biehl 1998 225,425 72,385 0 0 108,577 7,500 N/A 19,830 Senior Vice President/ 1997 214,877 40,762 0 0 61,143 7,500 N/A 17,329 Chief Financial Officer 1996 204,773 40,324 200,000 0 60,485 30,000 N/A 13,700 & Corporate Secretary Edward S. Zub 1998 180,137 59,283 0 0 88,928 7,500 N/A 20,352 Senior Vice President/ 1997 160,729 56,871 0 0 47,807 7,500 N/A 16,583 Regulation & Product 1996 138,484 28,802 0 0 43,223 25,000 N/A 12,723 Pricing James F. Lowman 1998 169,116 54,136 0 0 81,206 3,750 N/A 13,702 Senior Vice President/ 1997 161,401 35,665 0 0 45,998 3,750 N/A 12,279 Central Arizona Division 1996 154,015 29,336 0 0 44,004 15,000 N/A 10,316 Dudley J. Sondeno 1998 167,616 53,669 0 0 80,514 6,250 N/A 14,218 Senior Vice President/ 1997 159,901 30,387 0 0 45,581 6,250 N/A 13,983 Chief Knowledge & 1996 152,529 29,952 0 0 44,928 25,000 N/A 11,209 Technology Officer
(1) All compensation reflected in the Summary Compensation Table is reported on an earned basis for each fiscal year. (2) Utility bonuses and restricted stock awards earned for calendar years 1996, 1997, and 1998 were paid and awarded in 1997, 1998, and 1999, respectively. Restricted stock awards are paid in Common Stock following successful completion of a three-year restriction period. (3) Dividends equal to the dividends paid on the Common Stock will be accrued on the restricted stock during the restriction period. (4) The total number of restricted stock awards granted in 1996, 1997, and 1998, for calendar years 1995, 1996, and 1997, and their value based on the closing price of the Common Stock on the New York Stock Exchange on December 31, 1998, for the named executive officers are as follows:
Shares Value ------ ----- Mr. Maffie 33,564 $893,642 Mr. Biehl 10,465 278,631 Mr. Zub 7,504 199,794 Mr. Lowman 7,737 205,998 Mr. Sondeno 7,777 207,063
(5) The amounts shown in this column for each year consist of above-market interest on deferred compensation (in excess of 120 percent of the Applicable Federal Long-term Rate) and matching contributions under the Company's executive deferral plan. Under the plan, executive officers may defer up to 100 percent of their annual cash compensation. Interest on such deferrals is set at 150 percent of the Moody's Seasoned Corporate Bond Rate. As part of the plan, the Company provides matching contributions that parallel the contributions 16 19 made under the Company's 401(k) plan, which is available to all Company employees, equal to one-half of the deferred amount, up to six percent of their annual salary. The breakdown of this compensation for each named executive officer is as follows:
Above-market Matching Interest Contributions -------- ------------- Mr. Maffie $44,842 $14,568 Mr. Biehl 13,078 6,752 Mr. Zub 14,963 5,389 Mr. Lowman 8,635 5,067 Mr. Sondeno 9,196 5,022
- ---------------- OPTIONS/SARS GRANTED IN 1998 The following table sets forth the number of shares of the Company's Common Stock subject to stock options granted under the 1996 Stock Incentive Plan (Option Plan) to the named executive officers listed in the Summary Compensation Table during 1998, together with related information. OPTION/SAR GRANTS IN LAST FISCAL YEAR
POTENIAL REALIZABLE INDIVIDUAL GRANTS VALUE AT ASSUMED ------------------------------------------------------------ ANNUAL RATES NUMBER OF PERCENT OF TOTAL OF STOCK PRICE SECURITIES OPTIONS/SARS EXERCISE APPRECIATION FOR UNDERLYING GRANTED TO OR BASE OPTION TERM (2) OPTIONS/SARS EMPLOYEES IN PRICE EXPIRATION ---------------------- NAME GRANTED (#) (1) FISCAL YEAR ($/SH) DATE 5 PERCENT 10 PERCENT ---- --------------- ---------------- -------- ---------- --------- ---------- Michael O. Maffie 25,000 25.00 $23.06 7/20/08 $363,234 $916,734 George C. Biehl 7,500 7.50 23.06 7/20/08 108,970 275,020 Edward S. Zub 7,500 7.50 23.06 7/20/08 108,970 275,020 James F. Lowman 3,750 3.75 23.06 7/20/08 54,485 137,510 Dudley J. Sondeno 6,250 6.25 23.06 7/20/08 90,809 229,184 - ---------------
(1) Forty percent of the options become exercisable one year after the grant. Thirty percent of the options become exercisable two years after the grant, with the remaining becoming exercisable on the third anniversary of the grant. (2) The 5 percent and 10 percent growth rates for the period ending July 20, 2008, which were determined in accordance with the rules of the SEC, illustrate that the potential future value of the granted options is linked to future increases in growth of the price of the Common Stock. Because the exercise price for the options equals the market price of the Common Stock on the date of the grant, there will be no gain to the named executive officers without an increase in the stock price. The 5 percent and 10 percent growth rates are for illustration only and are not intended to be predictive of future growth. - ------------------- 17 20 OPTIONS/SAR EXERCISES AND YEAR-END VALUES Shown below is information

Information with respect to unexercised options grantedexecutive compensation is set forth under the Option Plan to the named executive officersheading “Executive Compensation and held by them at December 31, 1998. AGGREGATED OPTION/SAR EXERCISES IN 1998 AND YEAR-END OPTION/SAR VALUES
NO. OF NO. OF SECURITIES VALUE OF UNEXERCISED SHARES UNDERLYING UNEXERCISED IN-THE-MONEY ACQUIRED OPTIONS/SARS AT OPTIONS/SARS AT ON VALUES DECEMBER 31, 1998 DECEMBER 31, 1998 (1) NAME EXERCISE REALIZED EXERCISABLE UNEXERCISABLE(2) EXERCISABLE UNEXERCISABLE (2) ---- -------- -------- ----------- ---------------- ----------- ----------------- Michael O. Maffie 0 $0 73,000 67,000 $807,375 $515,438 George C. Biehl 0 0 24,000 21,000 266,625 165,094 Edward S. Zub 0 0 20,500 19,500 225,938 147,656 James F. Lowman 0 0 12,000 10,500 133,313 82,547 Dudley J. Sondeno 0 0 20,000 17,500 222,188 137,578
- ---------------- (1) Represents the difference between the exercise prices for in-the-money options and the closing price of $26.63 for the Company's Common Stock on the New York Stock Exchange on December 31, 1998, times the number of in-the-money options. (2) Unexercisable options are those options which have been granted but cannot yet be exercised due to the Code restrictions on the value of incentive options, restrictions incorporated into the Option Plan, and the specific option agreements. - ----------------- BENEFIT PLANS Southwest Gas Basic Retirement Plan. The named executive officers participateBenefits” in the Company's non-contributory, defined benefit retirement plan,definitive 2004 Proxy Statement, which by this reference is available to all employees of the Company and its subsidiaries (other than Northern Pipeline Construction Co.). Benefits are based upon an employee's years of service, up to a maximum of 30 years, and the employee's highest 5 consecutive years salary, excluding bonuses, within the final 10 years of service. 18 21 PENSION PLAN TABLE (1) incorporated herein.

YEARS
Item 12.

SECURITY OWNERSHIP OF SERVICE ANNUAL -------------------------------------------------------------- COMPENSATION 10 15 20 25 30 (2) ------------ -- -- -- -- ------ $50,000 $ 8,750 $13,125 $ 17,500 $21,875 $26,250 100,000 17,500 26,250 35,000 43,750 52,500 150,000 26,250 39,375 52,500 65,625 78,750 200,000 35,000 52,500 70,000 87,500 105,000 250,000 43,750 65,625 87,500 109,375 131,250 300,000 52,500 78,750 105,000 131,250 157,500 350,000 61,250 91,875 122,500 153,125 183,750 400,000 70,000 105,000 140,000 175,000 210,000 450,000 78,750 118,125 157,500 196,875 236,250 500,000 87,500 131,250 175,000 218,750 262,500 550,000 96,250 144,375 192,500 240,625 288,750 600,000 105,000 157,500 210,000 262,500 315,000 CERTAIN BENEFICIAL OWNERS AND MANAGEMENT AND

RELATED STOCKHOLDER MATTERS

- ------------------ (1) For 1999, the maximum annual compensation that can be considered in determining benefits under the Plan is $160,000. For future years the maximum annual compensation will be adjusted to reflect changes in the cost of living as established by the Internal Revenue Service. (2) Years of service beyond 30 years will not increase benefits under the basic retirement plan. - ----------------- Compensation covered under the basic retirement plan is based on salary depicted in the Summary Compensation Table. As of December 31, 1998, the credited years of service for the named executive officers shown in the Summary Compensation Table are as follows: Mr. Maffie, 20 years; Mr. Biehl, 13 years; Mr. Zub, 20 years; Mr. Lowman, 29 years; and Mr. Sondeno, 19 years. Amounts shown in the pension plan table are straight life annuity amounts notwithstanding the availability of joint survivorship benefit provisions. Benefits paid under the basic and supplemental retirement plans are not reduced by any Social Security benefits received. Supplemental Retirement Plan. The named executive officers also participate in the Company's supplemental retirement plan (SERP). Such officers with 10 or more years of service may retire at age 55 or older and will receive benefits under the SERP. Benefits from the SERP, when added to benefits received under the basic retirement plan, will equal 60 percent of each officer's highest 12-months of salary, as depicted in the Summary Compensation Table. For Mr. Maffie, compensation used to determine such benefits includes salary, cash bonuses other than the 1996 non-utility bonus, and the payment of restrictive stock awards depicted in the Summary Compensation Table. The cost to the Company for benefits under the SERP for any one of the named executive officers cannot generally be properly allocated or determined because of the overall plan assumptions and options available. SEVERANCE AND CHANGE IN CONTROL ARRANGEMENTS In July 1998, the Company amended the existing employment agreements with seven of its designated officers (including the named executive officers), and entered into change in control agreements with its remaining officers. The employment agreements generally provide for the payment, upon termination of employment by the Company without cause, as defined therein, of up to one and one-half years of the amount of total annual compensation (base salary, a predetermined level of incentive compensation and fringe benefits), and up to three years of total annual compensation for Mr. Maffie. The employment agreements further provide for the payment, upon the termination of employment for 19 22 "good reason," as defined therein, within two years following a change in control of the Company, of an amount equal to two to two and one-half times total annual compensation for each of these officers, other than Mr. Maffie who would receive three times total annual compensation. The change in control agreements for the other officers parallel the change in control provisions of the employment agreements. Restricted stock awards, stock options, or stock appreciation rights will vest and become immediately exercisable upon a change in control. Benefits under the SERP will also vest and/or accelerate. If any payment under these agreements would constitute a "parachute payment" subject to excise tax under the Code, the officer will be entitled to an additional "gross-up" payment. The terms of these agreements are for 24 months for each of the officers, other than Mr. Maffie whose agreement is for 36 months. Each of the agreements will be automatically extended annually for successive one-year periods, unless canceled by the Company. COMPENSATION COMMITTEE INTERLOCKS AND INSIDER PARTICIPATION The directors who served on the Company's Compensation Committee during 1998 were Lloyd T. Dyer (Chairman), Manuel J. Cortez, Thomas Y. Hartley, Leonard R. Judd, James J. Kropid, and James R. Lincicome. Director Kropid joined the committee after the retirement of James R. Lincicome at last year's Annual Meeting of Shareholders. Mr. Lincicome served on the committee during 1998 until his retirement in May 1998. ITEM 12. SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT

(a)Security Ownership of Certain Beneficial Owners. A group Information with respect to security ownership of investment companies headedcertain beneficial owners is set forth under the heading “Securities Ownership by Mario J. Gabelli reportedDirectors, Director Nominees, Executive Officers, and Certain Beneficial Owners” in February 1999, that it owned 3,023,883 shares of the Common Stock (approximately 9.9 percent as of March 15, 1999). The Company has been advised that the investment companies hold the shares as investment advisors for other beneficial owners. definitive 2004 Proxy Statement, which by this reference is incorporated herein.

(b)Security Ownership of Management. The following table discloses all Common Stock Information with respect to security ownership of management is set forth under the heading “Securities Ownership by Directors, Director Nominees, Executive Officers, and Certain Beneficial Owners” in the definitive 2004 Proxy Statement, which by this reference is incorporated herein.

(c)Changes in Control. None.

(d)Securities Authorized for Issuance Under Equity Compensation Plans.

At December 31, 2003, the Company had two stock-based compensation plans. With respect to the first plan, the Company may grant options to purchase shares of common stock to key employees and outside directors.

Equity Compensation Plan Information

Plan category


  

Number of securities

to be issued upon

exercise of

outstanding options,

warrants and rights


  

Weighted average

exercise price of

outstanding options,

warrants and rights


  

Number of securities

remaining available

for future issuance


(Thousands of shares)

          

Equity compensation plans approved by security holders

  1,502  $21.83  1,016

Equity compensation plans not approved by security holders

  —     —    —  
   
  

  

Total

  1,502  $21.83  1,016
   
  

  

Pursuant to the terms of the management incentive plan, the Company beneficially owned bymay issue restricted stock in the directorsform of performance shares to encourage key employees to remain in its employment to achieve short-term and long-term performance goals.

Plan category


  

Number of securities

to be issued upon

vesting of

performance shares


  

Weighted-average

grant date fair value

of award


  

Number of securities

remaining available

for future issuance


(Thousands of shares)

          

Equity compensation plans approved by security holders

  381  $21.41  —  

Equity compensation plans not approved by security holders

  —     —    —  
   
  

  

Total

  381  $21.41  —  
   
  

  

Additional information regarding the executive officerstwo equity compensation plans is included in Note 9 of the Company, as of March 15, 1999.
NO. OF SHARES PERCENT OF OUTSTANDING DIRECTOR/EXECUTIVE OFFICER BENEFICIALLY OWNED (1) COMMON STOCK (2) -------------------------- ---------------------- ---------------------- George C. Biehl 49,220 (3)(4) * Manuel J. Cortez 6,259 (5) * Lloyd T. Dyer 8,881 (5)(6) * Thomas Y. Hartley 17,630 (5)(7) * Michael B. Jager 8,620 (5)(8) * Leonard R. Judd 6,300 (5)(9) * James J. Kropid 3,098 (10) * Michael O. Maffie 134,276 (3)(11) * Carolyn M. Sparks 10,820 (5)(12) * Robert S. Sundt 9,300 (5)(13) * Terrance L. Wright 1,714 (14) * James F. Lowman 30,811 (15) * Dudley J. Sondeno 33,392 (16) * Edward S. Zub 38,893 (17) * Other Executive Officers 70,560 (18) * ------- Total 429,774 1.4 ======= ===
- --------------- 20 23 (1) The Common Stock holdings listedNotes to Consolidated Financial Statements in this column include performance shares grantedthe 2003 Annual Report to the Company's executive officers under the Company's Management Incentive Plan (MIP) for 1996, 1997, and 1998 and exercisable options issued under the 1996 Stock Incentive Plan (Option Plan). (2) As of March 15, 1999, the directors and executive officers of the Company beneficially owned, including exercisable options and MIP performance shares, 429,774 shares, which represent 1.4 percent of the Company's outstanding shares. No individual officer or director owned more than 1 percent of the Common Stock. (3) Number of shares does not include 6,618 shares held by the Southwest Gas Corporation Foundation, which is a charitable trust. Messrs. Maffie and Biehl are trustees of the Foundation but disclaim beneficial ownership of said shares. (4) The holdings include 24,000 shares which Mr. Biehl has the right to acquire through the exercise of options under the Option Plan. (5) The holdings include 4,300 shares which the non-employee directors have the right to acquire through the exercise of options under the Option Plan. (6) Number of shares include 4,581 shares over which Mr. Dyer has shared voting and investment control with his spouse through a family trust. (7) Number of shares include 311 shares over which Mr. Hartley has shared voting and investment control with his spouse through a family trust. (8) Number of shares includes 2,320 shares over which Mr. Jager has shared voting and investment control with his spouse through a family trust and 2,000 shares held in trust for Mr. Jager's spouse, over which Mr. Jager has no control. (9) Number of shares includes 2,000 shares over which Mr. Judd has shared voting and investment control with his spouse. (10) The holdings include 1,464 shares which Mr. Kropid has the right to acquire through the exercise of options under the Option Plan and 1,634 shares over which he has shared voting and investment power with his spouse through a family trust. The family trust also holds 1,500 shares of Trust Originated Preferred Securities issued by the Company's financing subsidiary, Southwest Gas Capital I. (11) The holdings include 73,000 shares which Mr. Maffie has the right to acquire through the exercise of options under the Option Plan and 3,044 shares over which he has shared voting and investment control with his spouse. (12) Number of shares includes 5,000 shares over which Mrs. Sparks has shared voting and investment control with her spouse through a family trust and 1,520 shares held as joint tenants with her spouse. (13) Number of shares includes 5,000 shares over which Mr. Sundt has shared voting and investment control with his spouse. (14) The holdings include 1,464 shares which Mr. Wright has the right to acquire through the exercise of options under the Option Plan. (15) The holdings include 12,000 shares which Mr. Lowman has the right to acquire through the exercise of options under the Option Plan. 21 24 (16) The holdings include 20,000 shares which Mr. Sondeno has the right to acquire through the exercise of options under the Option Plan. (17) The holdings include 20,500 shares which Mr. Zub has the right to acquire through the exercise of options under the Option Plan and 105 shares held solely by his spouse. (18) The holdings of other executive officers include 42,000 shares that can be acquired through the exercise of options under the Option Plan. - ---------------- (c) Changes in Control. In December 1998, the Company announced a definitive agreement to be acquired by ONEOK, Inc. See ITEM 1. BUSINESS. ITEMShareholders.

Item 13.    CERTAIN RELATIONSHIPS AND RELATED TRANSACTIONS

None.

Item 14.    PRINCIPAL ACCOUNTANT FEES AND SERVICES

Information with respect to accounting fees and services associated with PricewaterhouseCoopers LLP is set forth under the heading “Selection of Independent Accountants” in the definitive 2004 Proxy Statement, which by this reference is incorporated herein.

PART IV ITEM 14.

Item 15.    EXHIBITS, FINANCIAL STATEMENT SCHEDULES, AND REPORTS ON FORM 8-K

(a) The following documents are filed as part of this report on Form 10-K: (1) The Consolidated Financial Statements of the Company (including the Report of Independent Public Accountants) required to be reported herein are incorporated by reference to the information reported in the 1998 Annual Report to Shareholders under the following captions: Report of Independent Public Accountants.....................39 Consolidated Balance Sheets..................................40 Consolidated Statements of Income............................41 Consolidated Statements of Cash Flows........................42 Consolidated Statements of Stockholders' Equity..............43 Notes to Consolidated Financial Statements...................44 (2) All schedules have been omitted because the required information is either inapplicable or included in the Notes to Consolidated Financial Statements. (3) See List of exhibits.

(1)The Consolidated Financial Statements of the Company (including the Reports of Independent Auditors) required to be reported herein are incorporated by reference to the information reported in the 2003 Annual Report to Shareholders under the following captions:

Consolidated Balance Sheets

37

Consolidated Statements of Income

39

Consolidated Statements of Cash Flows

40

Consolidated Statements of Stockholders’ Equity

41

Notes to Consolidated Financial Statements

42

Report of Independent Auditors

62

Report of Independent Public Accountants

63

(2)All schedules have been omitted because the required information is either inapplicable or included in the Notes to Consolidated Financial Statements.

(3)SeeLIST OF EXHIBITS.

(b) Reports on Form 8-K. The

On February 17, 2004, the Company filed a Form 8-K, dated February 10, 1999, reportingfurnished summary financial information for the quarter and year ended December 31, 1998. 2003 pursuant to Item 12 of Form 8-K.

(c) See List of exhibits. 22 25 LIST OF EXHIBITS.

LIST OF EXHIBITS EXHIBIT NUMBER DESCRIPTION OF DOCUMENT - ------- ----------------------- 2.01(15) Agreement between Southwest Gas Corporation, The Southwest Companies and PriMerit Bank, Federal Savings Bank, as sellers and Norwest Corporation as buyer, dated April 10, 1996, regarding sale of assets and liabilities of PriMerit Bank. 2.02(24) Agreement and Plan of Merger by and among ONEOK, Inc., Oasis Acquisition Corporation, and Southwest Gas Corporation dated as of December 14, 1998. 3(i)(20) Restated Articles of Incorporation, as amended. 3(ii) Amended Bylaws of Southwest Gas Corporation. 4.01(1) Indenture between the Company and Bank of America National Trust and Savings Association, as successor by merger to Security Pacific National Bank, as Trustee, dated August 1, 1986, with respect to 9% Series A and Series B and 8 3/4% Series C Debentures. 4.02(6) Sixth Supplemental Indenture of the Company to Bank of America National Trust and Savings Association, as successor by merger to Security Pacific National Bank, as Trustee, dated as of June 16, 1992, supplementing and amending the Indenture dated as of August 1, 1986, with respect to 9 3/4% Debentures, Series F, due 2002. 4.03(7) Indenture between Clark County, Nevada, and Bank of America Nevada as Trustee, dated September 1, 1992, with respect to the issuance of $130,000,000 Industrial Development Revenue Bonds (Southwest Gas Corporation), $30,000,000 1992 Series A, due 2027, and $100,000,000 1992 Series B, due 2032. 4.04(8) Indenture between Clark County, Nevada, and Harris Trust and Savings Bank as Trustee, dated December 1, 1993, with respect to the issuance of $75,000,000 Industrial Development Revenue Bonds (Southwest Gas Corporation), 1993 Series A, due 2033. 4.05(8) Indenture between City of Big Bear Lake, California, and Harris Trust and Savings Bank as Trustee, dated December 1, 1993, with respect to the issuance of $50,000,000 Industrial Development Revenue Bonds (Southwest Gas Corporation Project), 1993 Series A, due 2028. 4.06(16) Indenture between the Company and Harris Trust and Savings Bank dated July 15, 1996, with respect to Debt Securities. 4.07(17) First Supplemental Indenture of the Company to Harris Trust and Savings Bank dated August 1, 1996, supplementing and amending the Indenture dated as of July 15, 1996, with respect to 7 1/2% and 8% Debentures, due 2006 and 2026, respectively. 4.08(19) Second Supplemental Indenture of the Company to Harris Trust and Savings Bank dated December 30, 1996, supplementing and amending the Indenture dated as of July 15, 1996, with respect to Medium-Term Notes. 4.09(3) Certificate of Trust of Southwest Gas Capital I. 4.10(11) Amended and Restated Declaration of Trust of Southwest Gas Capital I. 23 26 4.11(11) Form of Preferred Security (attached as Annex I to Exhibit A to the Amended and Restated Declaration of Trust of Southwest Gas Capital I included as Exhibit 4.10 hereto). 4.12(4) Form of Guarantee with respect to Preferred Securities. 4.13(10) Southwest Gas Capital I Preferred Securities Guarantee by the Company and Harris Trust and Savings Bank, dated as of October 31, 1995. 4.14(10) Form of Subordinated Debt Security (included in the First Supplemental Indenture included as Exhibit 4.16 hereto). 4.15(10) Subordinated Debt Securities Indenture between the Company and Harris Trust and Savings Bank, dated as of October 31, 1995. 4.16(10) First Supplemental Indenture between the Company and Harris Trust and Savings Bank, dated as of October 31, 1995, supplementing and amending the Indenture dated as of October 31, 1995, with respect to the 9.125% Subordinated Debt Securities. 4.17(2) Form of Deposit Agreement. 4.18(2) Form of Depositary Receipt (attached as Exhibit A to Deposit Agreement included as Exhibit 4.17 hereto). 4.19 Amended and Restated Rights Agreement between the Company and Harris Trust Company, as Rights Agent, dated as of February 9, 1999. 4.20 The Company hereby agrees to furnish to the SEC, upon request, a copy of any instruments defining the rights of holders of long-term debt issued by Southwest Gas Corporation or its subsidiaries. 10.01(5) Participation Agreement among the Company and General Electric Credit Corporation, Prudential Insurance Company of America, Aetna Life Insurance Company, Merrill Lynch Interfunding, Bank of America through purchase of Valley Bank of Nevada, Bankers Trust Company and First Interstate Bank of Nevada, dated as of July 1, 1982. 10.02(18) Amended and Restated Lease Agreement between the Company and Spring Mountain Road Associates, dated as of July 1, 1996. 10.03(8) Financing Agreement between the Company and Clark County, Nevada, dated September 1, 1992. 10.04(8) Financing Agreement between the Company and Clark County, Nevada, dated as of December 1, 1993. 10.05(8) Project Agreement between the Company and City of Big Bear Lake, California, dated as of December 1, 1993. 10.06(9) Southwest Gas Corporation Executive Deferral Plan, amended and restated as of May 10, 1994. 10.07(14) Southwest Gas Corporation Directors Deferral Plan, together with first amendment dated March 5, 1996. 10.08(8) Southwest Gas Corporation Board of Directors Retirement Plan, amended and restated as of October 1, 1993. 10.09(22) Southwest Gas Corporation Management Incentive Plan, amended and restated January 1, 1995. 24 27 10.10(9) Southwest Gas Corporation Supplemental Retirement Plan, amended and restated as of May 10, 1994. 10.11(23) Form of Employment Agreement with Company Officers. 10.12(23) Form of Change in Control Agreement with Company Officers. 10.13(12) Merger Agreement among the Company and Northern Pipeline Construction Co., dated as of November 13, 1995. 10.14(13) Southwest Gas Corporation 1996 Stock Incentive Plan. 10.15(21) $350 million Revolving Credit Agreement among the Company, Union Bank of Switzerland, et al., dated as of June 12, 1997. 12.01 Computation of Ratios of Earnings to Fixed Charges and Ratios of Earnings to Combined Fixed Charges and Preferred Stock Dividends of the Company. 13.01 Portions of 1998 Annual Report incorporated by reference to the Form 10-K. 21.01 List of subsidiaries of Southwest Gas Corporation. 23.01 Consent of Arthur Andersen LLP, Independent Public Accountants. 27.01 Financial Data Schedule (filed electronically only). - ----------------- (1) Incorporated herein by reference to the Registration Statement on Form S-3, No. 33-7931. (2) Incorporated herein by reference to the Registration Statement on Form S-3, No. 33-55621. (3) Incorporated herein by reference to the Registration Statement on Form S-3, No. 33-62143. (4) Incorporated herein by reference to Amendment No. 1 to Registration Statement on Form S-3, No. 33-62143. (5) Incorporated herein by reference to the report on Form 10-K for the year ended December 31, 1982. (6) Incorporated herein by reference to the report on Form 10-Q for the quarter ended June 30, 1992. (7) Incorporated herein by reference to the report on Form 10-Q for the quarter ended September 30, 1992. (8) Incorporated herein by reference to the report on Form 10-K for the year ended December 31, 1993. (9) Incorporated herein by reference to the report on Form 10-Q for the quarter ended June 30, 1994 (10) Incorporated herein by reference to the report on Form 10-Q for the quarter ended September 30, 1995. (11) Incorporated herein by reference to the report on Form 8-K dated October 26, 1995. (12) Incorporated herein by reference to the report on Form 10-K for the year ended December 31, 1995. 25 28 (13) Incorporated herein by reference to the Proxy Statement dated May 30, 1996. (14) Incorporated herein by reference to the report on Form 10-Q for the quarter ended June 30, 1996. (15) Incorporated herein by reference to the report on Form 8-K dated July 19, 1996. (16) Incorporated herein by reference to the report on Form 8-K dated July 26, 1996. (17) Incorporated herein by reference to the report on Form 8-K dated July 31, 1996. (18) Incorporated herein by reference to the report on Form 10-Q for the quarter ended September 30, 1996. (19) Incorporated herein by reference to the report on Form 8-K dated December 30, 1996. (20) Incorporated herein by reference to the report on Form 10-Q for the quarter ended March 31, 1997. (21) Incorporated herein by reference to the report on Form 10-Q for the quarter ended June 30, 1997. (22) Incorporated herein by reference to the report on Form 10-K for the year ended December 31, 1997. (23) Incorporated herein by reference to the report on Form 10-Q for the quarter ended September 30, 1998. (24) Incorporated herein by reference to the report on Form 8-K dated December 14, 1998. 26 29

Exhibit
Number


Description of Document


3(i)Restated Articles of Incorporation, as amended. Incorporated herein by reference to the report on Form 10-Q for the quarter ended March 31, 1997.
3(ii)Amended Bylaws of Southwest Gas Corporation. Incorporated herein by reference to the report on Form 10-Q for the quarter ended September 30, 2003.
4.01Indenture between Clark County, Nevada, and Harris Trust and Savings Bank as Trustee, dated December 1, 1993, with respect to the issuance of $75,000,000 Industrial Development Revenue Bonds (Southwest Gas Corporation), 1993 Series A, due 2033. Incorporated herein by reference to the report on Form 10-K for the year ended December 31, 1993.
4.02Indenture between City of Big Bear Lake, California, and Harris Trust and Savings Bank as Trustee, dated December 1, 1993, with respect to the issuance of $50,000,000 Industrial Development Revenue Bonds (Southwest Gas Corporation Project), 1993 Series A, due 2028. Incorporated herein by reference to the report on Form 10-K for the year ended December 31, 1993.
4.03Form of Deposit Agreement. Incorporated herein by reference to the Registration Statement on Form S-3, No. 33-55621.
4.04Form of Depositary Receipt (attached as Exhibit A to Deposit Agreement included as Exhibit 4.03 hereto). Incorporated herein by reference to the Registration Statement on Form S-3, No. 33-55621.
4.05Indenture between the Company and Harris Trust and Savings Bank dated July 15, 1996, with respect to Debt Securities. Incorporated herein by reference to the report on Form 8-K dated July 26, 1996.
4.06First Supplemental Indenture of the Company to Harris Trust and Savings Bank dated August 1, 1996, supplementing and amending the Indenture dated as of July 15, 1996, with respect to 7 1/2% and 8% Debentures, due 2006 and 2026, respectively. Incorporated herein by reference to the report on Form 8-K dated July 31, 1996.
4.07Second Supplemental Indenture of the Company to Harris Trust and Savings Bank dated December 30, 1996, supplementing and amending the Indenture dated as of July 15, 1996, with respect to Medium-Term Notes. Incorporated herein by reference to the report on Form 8-K dated December 30, 1996.
4.08Indenture between Clark County, Nevada, and Harris Trust and Savings Bank as Trustee, dated as of October 1, 1999, with respect to the issuance of $35,000,000 Industrial Development Revenue Bonds (Southwest Gas Corporation), Series 1999A and Taxable Series 1999B or convertibles of Series B (Series C and D), due 2038. Incorporated herein by reference to the report on Form 10-K for the year ended December 31, 1999.
4.09Third Supplemental Indenture between the Company and The Bank of New York, dated as of February 13, 2001, supplementing and amending the Indenture dated as of July 15, 1996, with respect to the $200,000,000, 8.375% Notes, due 2011. Incorporated herein by reference to the report on Form 8-K dated February 8, 2001.
4.10Fourth Supplemental Indenture of the Company to The Bank of New York as successor to Harris Trust and Savings Bank dated as of May 6, 2002, supplementing and amending the Indenture dated as of

July 15, 1996, with respect to the 7.625% Senior Unsecured Notes due 2012. Incorporated herein by reference to the report on Form 8-K dated May 1, 2002.
4.11Certificate of Trust of Southwest Gas Capital II. Incorporated herein by reference to the Registration Statement on Form S-3, No. 333-106419.
4.12Certificate of Trust of Southwest Gas Capital III. Incorporated herein by reference to the Registration Statement on Form S-3, No. 333-106419.
4.13Certificate of Trust of Southwest Gas Capital IV. Incorporated herein by reference to the Registration Statement on Form S-3, No. 333-106419.
4.14Trust Agreement of Southwest Gas Capital III. Incorporated herein by reference to the Registration Statement on Form S-3, No. 333-106419.
4.15Trust Agreement of Southwest Gas Capital IV. Incorporated herein by reference to the Registration Statement on Form S-3, No. 333-106419.
4.16Form of Common Stock certificate. Incorporated herein by reference to the report on Form 8-K dated July 22, 2003.
4.17Form of Preferred Trust Security. Incorporated herein by reference to the report on Form 8-K dated August 20, 2003.
4.18Form of Indenture with respect to the 7.70% Junior Subordinated Debentures. Incorporated herein by reference to the report on Form 8-K dated August 20, 2003.
4.19Form of 7.70% Junior Subordinated Debenture. Incorporated herein by reference to the report on Form 8-K dated August 20, 2003.
4.20Form of Amended and Restated Trust Agreement of Southwest Gas Capital II. Incorporated herein by reference to the report on Form 8-K dated August 20, 2003.
4.21Form of Guarantee Agreement with respect to the Preferred Trust Securities. Incorporated herein by reference to the report on Form 8-K dated August 20, 2003.
4.22The Company hereby agrees to furnish to the SEC, upon request, a copy of any instruments defining the rights of holders of long-term debt issued by Southwest Gas Corporation or its subsidiaries; the total amount of securities authorized thereunder does not exceed 10 percent of the consolidated total assets of Southwest Gas Corporation and its subsidiaries.
10.01Participation Agreement among the Company and General Electric Credit Corporation, Prudential Insurance Company of America, Aetna Life Insurance Company, Merrill Lynch Interfunding, Bank of America through purchase of Valley Bank of Nevada, Bankers Trust Company and First Interstate Bank of Nevada, dated as of July 1, 1982. Incorporated herein by reference to the report on Form 10-K for the year ended December 31, 1982.
10.02Financing Agreement between the Company and Clark County, Nevada, dated as of December 1, 1993. Incorporated herein by reference to the report on Form 10-K for the year ended December 31, 1993.
10.03Project Agreement between the Company and City of Big Bear Lake, California, dated as of December 1, 1993. Incorporated herein by reference to the report on Form 10-K for the year ended December 31, 1993.

10.04Amended and Restated Lease Agreement between the Company and Spring Mountain Road Associates, dated as of July 1, 1996. Incorporated herein by reference to the report on Form 10-Q for the quarter ended September 30, 1996.
10.05*Southwest Gas Corporation Supplemental Retirement Plan, amended and restated as of March 1, 1999. Incorporated herein by reference to the report on Form 10-K for the year ended December 31, 1999.
10.06*Southwest Gas Corporation Board of Directors Retirement Plan, amended and restated as of March 1, 1999. Incorporated herein by reference to the report on Form 10-K for the year ended December 31, 1999.
10.07Financing Agreement between the Company and Clark County, Nevada, dated as of October 1, 1999. Incorporated herein by reference to the report on Form 10-K for the year ended December 31, 1999.
10.08*Amended Form of Employment Agreement with Company Officers. Incorporated herein by reference to the reports on Form 10-Q for the quarters ended September 30, 1998, September 30, 2000 and September 30, 2001.
10.09*Amended Form of Change in Control Agreement with Company Officers. Incorporated herein by reference to the reports on Form 10-Q for the quarters ended September 30, 1998, September 30, 2000 and September 30, 2001.
10.10*Southwest Gas Corporation Management Incentive Plan, amended and restated January 1, 2002. Incorporated herein by reference to the Proxy Statement dated April 2, 2002.
10.11*Southwest Gas Corporation 2002 Stock Incentive Plan. Incorporated herein by reference to the Proxy Statement dated April 2, 2002.
10.12Multi-Year Revolving Credit Agreement among the Company, The Bank of New York, et al., dated as of May 10, 2002. Incorporated herein by reference to the report on Form 10-Q for the quarter ended September 30, 2002.
10.13*Southwest Gas Corporation Executive Deferral Plan, amended and restated as of November 19, 2002. Incorporated herein by reference to the Report on Form 10-K for the year ended December 31, 2002.
10.14*Southwest Gas Corporation Directors Deferral Plan, amended and restated as of November 19, 2002. Incorporated herein by reference to the Report on Form 10-K for the year ended December 31, 2002.
10.15Lease Supplement (attached as a supplement to Exhibit 10.01) as of December 12, 2002. Incorporated herein by reference to the Report on Form 10-K for the year ended December 31, 2002.
10.16Financing agreement dated as of March 1, 2003 by and between Clark County, Nevada and Southwest Gas Corporation relating to Clark County, Nevada Industrial Development Revenue Bonds Series 2003A, Series 2003B, Series 2003C, Series 2003D and Series 2003E. Incorporated herein by reference to the report on Form 10-Q for the quarter ended September 30, 2003.
12.01Computation of Ratios of Earnings to Fixed Charges of Southwest Gas Corporation.
13.01Portions of 2003 Annual Report incorporated by reference to the Form 10-K.

16.01Letter of Arthur Andersen LLP regarding change in certifying accountant. Incorporated herein by reference to the report on Form 8-K dated May 28, 2002.
21.01List of subsidiaries of Southwest Gas Corporation.
23.01Consent of PricewaterhouseCoopers LLP, Independent Accountants.
31.01Section 302 Certifications.
32.01Section 906 Certifications.

*Compensation Plans

SIGNATURES

Pursuant to the requirements of Section 13 or 15(d) 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. SOUTHWEST GAS CORPORATION Date: March 25, 1999 By /s/ MICHAEL O. MAFFIE ---------------------------- Michael O. Maffie, President and Chief Executive Officer

SOUTHWEST GAS CORPORATION
Date: March 11, 2004By/s/    MICHAEL O. MAFFIE        

Michael O. Maffie

Chief Executive Officer

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, this report has been signed below by the following persons on behalf of the Registrant and in the capacities and on the dates indicated.

SIGNATURE TITLE DATE --------- ----- ---- /s/ GEORGE

Signature


Title


Date


/s/    GEORGE C. BIEHL SeniorBIEHL        


(George C. Biehl)

Director, Executive Vice President, March 25, 1999 - ------------------------------------ Chief Financial Officer, and (GeorgeCorporate Secretary

March 11, 2004

/s/    MANUEL J. CORTEZ        


(Manuel J. Cortez)

Director

March 11, 2004

/s/    MARK M. FELDMAN        


(Mark M. Feldman)

Director

March 11, 2004

/s/    DAVID H. GUNNING        


(David H. Gunning)

Director

March 11, 2004

/s/    THOMAS Y. HARTLEY        


(Thomas Y. Hartley)

Chairman of the Board of Directors

March 11, 2004

/s/    LEROY C. Biehl) Corporate Secretary /s/ EDWARD A. JANOV HANNEMAN, JR.       


(LeRoy C. Hanneman, Jr.)

Director

March 11, 2004

/s/    MICHAEL B. JAGER        


(Michael B. Jager)

Director

March 11, 2004

/s/    LEONARD R. JUDD        


(Leonard R. Judd)

Director

March 11, 2004

/s/    JAMES J. KROPID        


(James J. Kropid)

Director

March 11, 2004

/s/    MICHAEL O. MAFFIE        


(Michael O. Maffie)

Director and Chief Executive Officer

March 11, 2004

/s/    CAROLYN M. SPARKS        


(Carolyn M. Sparks)

Director

March 11, 2004

/s/    TERRENCE L. WRIGHT        


(Terrence L. Wright)

Director

March 11, 2004

/s/    ROY R. CENTRELLA        


Roy R. Centrella

Vice President, Controller, and March 25, 1999 - ------------------------------------ Chief Accounting Officer (Edward A. Janov)

27 30 SIGNATURES Pursuant to the requirements of the Securities Exchange Act of 1934, this report has been signed below by the following persons on behalf of the Registrant and in the capacities and on the dates indicated.
SIGNATURE TITLE DATE --------- ----- ---- /s/ GEORGE C. BIEHL Director, Senior Vice President,

March 25, 1999 -------------------- Chief Financial Officer and (George C. Biehl) Corporate Secretary /s/ MANUEL J. CORTEZ Director March 25, 1999 -------------------- (Manuel J. Cortez) /s/ LLOYD T. DYER Director March 25, 1999 ----------------- (Lloyd T. Dyer) /s/ THOMAS Y. HARTLEY Chairman11, 2004

EXHIBIT INDEX

Exhibit

Number


Description of the Board March 25, 1999 ---------------------Document


12.01Computation of Directors (Thomas Y. Hartley) /s/ MICHAEL B. JAGER Director March 25, 1999 -------------------- (Michael B. Jager) /s/ LEONARD R. JUDD Director March 25, 1999 ------------------- (Leonard R. Judd) /s/ JAMES J. KROPID Director March 25, 1999 ------------------- (James J. Kropid) /s/ MICHAEL O. MAFFIE Director, President and March 25, 1999 --------------------- Chief Executive Officer (Michael O. Maffie) /s/ CAROLYN M. SPARKS Director March 25, 1999 --------------------- (Carolyn M. Sparks) /s/ ROBERT S. SUNDT Director March 25, 1999 ------------------- (Robert S. Sundt) /s/ TERRANCE L. WRIGHT Director March 25, 1999 ---------------------- (Terrance L. Wright) Ratios of Earnings to Fixed Charges of Southwest Gas Corporation.
13.01Portions of 2003 Annual Report to Shareholders incorporated by reference to Form 10-K.
21.01List of Subsidiaries of Southwest Gas Corporation.
23.01Consent of PricewaterhouseCoopers LLP, Independent Accountants.
31.01Section 302 Certifications.
32.01Section 906 Certifications.
28 31 EXHIBITS INDEX EXHIBIT NUMBER DESCRIPTION OF DOCUMENT - ------- ----------------------- 3(ii) Amended Bylaws of Southwest Gas Corporation. 4.19 Amended and Restated Rights Agreement between the Company and Harris Trust Company, as Rights Agent, dated as of February 9, 1999. 12.01 Computation of Ratios of Earnings to Fixed Charges and Ratios of Earnings to Combined Fixed Charges and Preferred Stock Dividends of the Company. 13.01 Portions of 1998 Annual Report incorporated by reference to the Form 10-K. 21.01 List of subsidiaries of Southwest Gas Corporation. 23.01 Consent of Arthur Andersen LLP, Independent Public Accountants. 27.01 Financial Data Schedule (filed electronically only).

22