<PAGE>

                                                                 EXHIBIT 10.4(c)

                                                          Contract No. 33182000D

                                                                    GGC-10476-CO

                      Firm Transportation Service Agreement
                               Rate Schedule TF-1

                                     between

                        COLORADO INTERSTATE GAS COMPANY

                                       and

                            ATMOS ENERGY CORPORATION

                              Dated: APRIL 1, 2003

<PAGE>

                                                          Contract No. 33182000D

                        TRANSPORTATION SERVICE AGREEMENT
                               RATE SCHEDULE TF-1

     The Parties identified below, in consideration of their mutual promises,
     agree as follows:

1.   TRANSPORTER: COLORADO INTERSTATE GAS COMPANY

2.   SHIPPER: ATMOS ENERGY CORPORATION

3.   APPLICABLE TARIFF: Transporter's FERC Gas Tariff, First Revised Volume No.
     1, as the same may be amended or superseded from time to time ("the
     Tariff).

4.   CHANGES IN RATES AND TERMS: Transporter shall have the right to propose to
     the FERC changes in its rates and terms of service, and this Agreement
     shall be deemed to include any changes which are made effective pursuant to
     FERC Order or regulation or provisions of law, without prejudice to
     Shipper's right to protest the same.

5.   TRANSPORTATION SERVICE: Transportation Service at and between Primary
     Point(s) of Receipt and Primary Point(s) of Delivery shall be on a firm
     basis. Receipt and Delivery of quantities at Secondary Point(s) of Receipt
     and/or Secondary Point(s) of Delivery shall be in accordance with the
     Tariff.

6.   POINTS OF RECEIPT AND DELIVERY: Shipper agrees to Tender Gas for
     Transportation Service and Transporter agrees to accept Receipt Quantities
     at the Primary Point(s) of Receipt identified in Exhibit "A." Transporter
     agrees to provide Transportation Service and Deliver Gas to Shipper (or for
     Shipper's account) at the Primary Point(s) of Delivery identified in
     Exhibit "A." Minimum and maximum receipt and delivery pressures, as
     applicable, are listed on Exhibit "A."

7.   RATES AND SURCHARGES: As set forth in Exhibit "B." For example, Transporter
     and Shipper may agree that a specified discount rate will apply: (a) only
     to certain specified firm service entitlements under this Agreement; (b)
     only if specified quantity levels are actually achieved under this
     Agreement (with higher rates, charges, and fees applicable to all
     quantities above those levels, or to all quantities under the Agreement if
     the specified levels are not achieved); (c) only to production reserves
     committed by the Shipper; (d) only during specified time periods; (e) only
     to specified Point(s) of Receipt, Pomt(s) of Delivery, mainline area
     segments, supply areas, Transportation routes, or defined geographical
     areas; or (f) in a specified relationship to the quantities actually
     Delivered (i.e., that the rates shall be adjusted in a specified
     relationship to quantities actually Delivered); provided, however, that any
     such discounted rates set forth above shall be between the minimum and
     maximum rates applicable to the sendee provided under this Agreement.

     In addition, the discount agreement may include a provision that if one
     rate component which was at or below the applicable maximum rate at the
     time the discount agreement was executed subsequently exceeds the
     applicable maximum rate due to a change in Transporter's maximum rates so
     that such rate component must be adjusted downward to equal the new
     applicable maximum rate, then other rate components may be adjusted upward
     to achieve the agreed overall rate, so long as none of the resulting rate
     components exceed the maximum rate applicable to that rate component. Such
     changes to rate components shall be applied prospectively, commencing with
     the date a Commission order accepts revised tariff sheets. However, nothing
     contained herein shall be construed to alter a refund obligation under
     applicable law for any period during which rates that had been charged
     under a discount agreement exceeded rates which ultimately are found to be
     just and reasonable.

8.   NEGOTIATED RATE AGREEMENT: YES____ NO X

9.   MAXIMUM DAILY QUANTITY (MDQ):

<TABLE>
<CAPTION>
MDQ (Dth/d)        EFFECTIVE
--------------------------------
<S>             <C>
6,121           4/01/03-9/30/06
</TABLE>

10.  TERM OF AGREEMENT:         Beginning:              APRIL 1, 2003

                                Extending through:      SEPTEMBER 30, 2006

<PAGE>

                                                          Contract No. 33182000D

11. NOTICES, STATEMENTS, AND BILLS:

        TO SHIPPER:
             INVOICES FOR TRANSPORTATION:
                 Atmos Energy Corporation
                 1301 Pennsylvania, Suite 800
                 Denver, Colorado 80203-5015
                 Attention: Gas Supply Colorado-Kansas Service Area

             ALL NOTICES:
                 Atmos Energy Corporation
                 P. O. Box 650205
                 Dallas, Texas 75265-0205
                 Attention: Contract Administration Colorado-Kansas Service Area

        TO TRANSPORTER:
                 See Payments, Notices, Nominations, and Points of Contact
                 sheets in the Tariff.

12.  SUPERSEDES AND CANCELS PRIOR AGREEMENT: When this Agreement becomes
     effective, it shall cancel and supersede the following agreement between
     the Parties: The Firm Transportation Service Agreement between Transporter
     and Shipper dated OCTOBER 1, 2001, referred to as Transporter's Agreement
     No. 33182000C.

13.  ADJUSTMENTS TO RATE SCHEDULE TF-1 AND/OR GENERAL TERMS AND CONDITIONS: N/A.

14.  INCORPORATION BY REFERENCE: This Agreement in all respects shall be subject
     to the provisions of Rate Schedule TF-1 and to the applicable provisions of
     the General Terms and Conditions of the Tariff as filed with, and made
     effective by, the FERC as same may change from time to time (and as they
     may be amended pursuant to Section 13 of the Agreement).

     IN WITNESS WHEREOF, the parties hereto have executed this Agreement.

TRANSPORTER:                                   SHIPPER:

COLORADO INTERSTATE GAS COMPANY                ATMOS ENERGY CORPORATION

By: /s/ Thomas L. Price                        By: /s/ Gary L. Schlessman
    ------------------                             ---------------------
    Thomas L. Price                            Name: Gary L. Schlessman
    Vice President                             Title: President
                                                      (Colorado-Kansas Division)
[STAMP OF LEGAL DEBT]                          Accepted and agreed to this
                                               19 day of May, 2003.
Accepted and agreed to this
21 day of April, 2003.
<PAGE>

                                                          Contract No. 33182000D

                                   EXHIBIT "A"

                      Firm Transportation Service Agreement
                                     between
                         COLORADO INTERSTATE GAS COMPANY
                                       and
                            ATMOS ENERGY CORPORATION

                              Dated: APRIL 1, 2003

1. Shippers Maximum Delivery Quantity ("MDQ"): 6,121 Dth per Day.

<TABLE>
<CAPTION>
                                                    Primary Point(s) of
                                                     Receipt Quantity
Primary Point(s) of Receipt                           (Dth per Day)          Minimum Receipt        Maximum Receipt
         (Note 1)               Effective Dates         (Note 2)           Pressure (p.s.i.g.)     Pressure (p.s.i.g.)
---------------------------     ----------------    -------------------    -------------------    --------------------
<S>                             <C>                 <C>                    <C>                    <C>
NORTHERN SYSTEM:

Echo Springs MM                 4/01/03 - 9/30/06            300                                           850

Lost Cabin                      4/01/03 - 9/30/06          1,200                                         1,100

Uintah                          4/01/03 - 9/30/06            593                                           940
                                                       ---------
     TOTAL Northern:                                       2,093

CENTRAL SYSTEM:

Lakin MM                        4/01/03 - 9/30/06            491                                           220

SOUTHERN SYSTEM:

Big Canyon                      4/01/03 - 9/30/06            491                   350                     955

Mocane                          4/01/03 - 9/30/06          1,260                                            65
                                                       ---------
      TOTAL Southern:                                      1,751
                                                       ---------
      TOTAL                                                6,121
</TABLE>

<TABLE>
<CAPTION>
                                                    Primary Point(s) of
 Primary Point(s) of Delivery                        Delivery Quantity      Minimum Delivery        Maximum Delivery
          (Note 1)               Effective Dates       (Dth per Day)       Pressure (p.s.i.g.)     Pressure (p.s.i.g.)
-----------------------------   -----------------   -------------------    -------------------    --------------------
<S>                             <C>                 <C>                    <C>                    <C>
CANON CITY GROUP:

Canon City                      4/01/03 - 9/30/06          4,231                    100                   LP

Colorado State Penitentiary     4/01/03 - 9/30/06            298                                         100

Engineering Station 476+78      4/01/03 - 9/30/06              5                                          LP

Florence City Gate              4/01/03 - 9/30/06            989                                          60

Fremont Cty. Industrial Park    4/01/03 - 9/30/06              9                                          LP

Penrose City Gate               4/01/03 - 9/30/06            135                                          60

Penrose PBS-2                   4/01/03 - 9/30/06            129                                          LP

Portland City Gate              4/01/03 - 9/30/06             35                                         100

Pritchett City Gate             4/01/03 - 9/30/06             35                                         150
                                                       ---------
     TOTAL Canon City Group                                5,866
</TABLE>
<PAGE>

                                                          Contract No. 33182000D

                                   EXHIBIT "A"

<TABLE>
<CAPTION>
                                                         Primary Point(s) of
Primary Point(s) of Delivery                              Delivery Quantity       Minimum Delivery      Maximum Delivery
         (Note 1)                 Effective Dates           (Dth per Day)        Pressure (p.s.i.g.)   Pressure (p.s.i.g.)
--------------------------------------------------------------------------------------------------------------------------
<S>                               <C>                    <C>                     <C>                   <C>
EADS GROUP:

Brandon Station                   4/01/03 - 9/30/06              28                                            350

Eads City Gate                    4/01/03 - 9/30/06             207                                             60

Highline Taps:

Neoplan (Bent County)             4/01/03 - 9/30/06               3                                             LP

Penrose South(Fremont Cty)        4/01/03 - 9/30/06              11                                             LP

The Piggery (Fremont Cty.)        4/01/03 - 9/30/06               3                                             LP

L. J. Stafford (Baca County)      4/01/03 - 9/30/06               5                                             LP
                                                              -----
     TOTAL Eads Group                                           257
                                                              -----
McClave Delivery                  4/01/03 - 9/30/06             350                                            500
                                                              -----
Springfield                       4/01/03 - 9/30/06             700                                             LP
                                                              -----
     TOTAL                                                    6,121
--------------------------------------------------------------------------------------------------------------------------
</TABLE>

<TABLE>

                                                 Primary Point(s) of
Primary Point(s) of                              Delivery Quantity
 Delivery Storage                                   (Dth per Day)           Minimum Delivery         Maximum Delivery
Injection (Note 1)         Effective Dates         (Notes 3 and 4)         Pressure (p.s.i.g.)      Pressure (p.s.i.g.)
-----------------------------------------------------------------------------------------------------------------------
<S>                        <C>                   <C>                       <C>                      <C>
Storage Injection          4/01/03-9/30/06             2,814
-----------------------------------------------------------------------------------------------------------------------
</TABLE>

NOTES:

(1)      Information regarding Point(s) of Receipt and Point(s) of Delivery,
         including legal descriptions, measuring Parties, and interconnecting
         Parties, shall be posted on Transporter's Electronic Bulletin Board.
         Transporter shall update such information from time to time to include
         additions, deletions, or any other revisions deemed appropriate by
         Transporter.

(2)      Each Point of Receipt Quantity may be increased by an amount equal to
         Transporter's Fuel Reimbursement percentage. Shipper shall be
         responsible for providing such Fuel Reimbursement at each Point of
         Receipt on a pro rata basis based on the quantities received on any Day
         at a Point of Receipt divided by the total quantity Delivered at all
         Point(s) of Delivery under this Transportation Service Agreement.

(3)      The sum of the Delivery Quantities at Point(s) of Delivery shall be
         equal to or less than Shipper's MDQ.

(4)      Transporter's obligation to make Deliveries to Transporter's storage
         injection point under this Agreement and to Transporter's storage
         injection point under all other Firm Transportation Service Agreements
         between Transporter and Shipper providing for deliveries to
         Transporter's storage injection point shall be limited by the
         provisions of Rate Schedule NNT-1 and Shipper's NNT-1 service
         agreement(s).

<PAGE>

                                                          Contract No. 33182000D

                                   EXHIBIT "B"

                      Firm Transportation Service Agreement
                                     between
                         COLORADO INTERSTATE GAS COMPANY
                                       and
                            ATMOS ENERGY CORPORATION

                               Dated: APRIL 1, 2003

<TABLE>
<CAPTION>

Primary Point(s)      Primary Point(s)       R(1) Reservation      Commodity                           Fuel
   of Receipt           of Delivery                Rate(s)            Rate       Term of Rate      Reimbursement    Surcharges
------------------------------------------------------------------------------------------------------------------------------
<S>                   <C>                    <C>                   <C>          <C>                <C>              <C>
 As listed on          As Listed on                (Note 1)        (Note 1)     4/01/03-9/30/06       (Note 2)        (Note 3)
 Exhibit "A"           Exhibit "A"
------------------------------------------------------------------------------------------------------------------------------
</TABLE>

<TABLE>
<CAPTION>
 Secondary          Secondary
Point(s) of        Point(s) of       R(1) Reservation       Commodity                                Fuel
  Receipt            Delivery              Rate(s)             Rate       Term of Rate           Reimbursement      Surcharges
------------------------------------------------------------------------------------------------------------------------------
<S>                <C>               <C>                    <C>          <C>                     <C>                <C>
   All                 All                 (Note 1)          (Note 1)    4/01/03-9/30/06             (Note 2)         (Note 3)
------------------------------------------------------------------------------------------------------------------------------
</TABLE>

NOTES:

(1)      Unless otherwise agreed by the Parties in writing, the rates for
         service hereunder shall be Transporter's maximum rates for service
         under Rate Schedule TF-1 or other superseding Rate Schedules, as such
         rates may be changed from time to time.

(2)      Fuel Reimbursement shall be as stated on Transporter's Schedule of
         Surcharges and Fees in the Tariff, as they may be changed from time to
         time, unless otherwise agreed between the Parties.

(3)      Surcharges, If Applicable:

         All applicable surcharges, unless otherwise specified, shall be the
         maximum surcharge rate as stated in the Schedule of Surcharges and Fees
         in the Tariff, as such surcharges may be changed from time to time,

         GAS QUALITY CONTROL SURCHARGE:

         The Gas Quality Control Reservation Rate and commodity rate shall be
         assessed pursuant to Article 20 of the General Terms and Conditions as
         set forth in the Tariff.

         GRI:

         The GRI Surcharge shall be assessed pursuant to Article 18 of the
         General Terms and Conditions as set forth in the Tariff.

         ORDER NO. 636 TRANSITION COST MECHANISM:

         Surcharge(s) shall be assessed pursuant to Article 21 of the General
         Terms and Conditions as set forth in the Tariff.

         ACA:

         The ACA Surcharge shall be assessed pursuant to Article 19 of the
         General Terms and Conditions as set forth in the Tariff.