<PAGE>

                     NATURAL GAS SALE AND PURCHASE AGREEMENT


BETWEEN:



               SHELL CANADA LIMITED, A Canadian Corporation with 
               head office in Calgary, Alberta, Canada.
               (hereinafter referred to as "Seller")



                                       and



               GREAT FALLS GAS COMPANY, A Montana Corporation 
               with head offices in Great Falls, Montana USA
               (hereinafter referred to as "Buyer")

<PAGE>

                                      INDEX

     ARTICLE                                                               PAGE

         I     Interpretation. . . . . . . . . . . . . . . . . . . . . . . . 1

        II     Conditions. . . . . . . . . . . . . . . . . . . . . . . . . . 4

       III     Delivery and Ownership. . . . . . . . . . . . . . . . . . . . 5

        IV     Gas Specifications and Measurement. . . . . . . . . . . . . . 5

         V     Contract Volumes. . . . . . . . . . . . . . . . . . . . . . . 6

        VI     Term and Price. . . . . . . . . . . . . . . . . . . . . . . . 8

       VII     Payment . . . . . . . . . . . . . . . . . . . . . . . . . . .12

      VIII     Force Majeure . . . . . . . . . . . . . . . . . . . . . . . .15

        IX     Covenants, Warranties and Indemnities by Seller . . . . . . .18

         X     Arbitration . . . . . . . . . . . . . . . . . . . . . . . . .19

        XI     Default and Remedies. . . . . . . . . . . . . . . . . . . . .21

        XI     General Provisions. . . . . . . . . . . . . . . . . . . . . .22

<PAGE>

                     NATURAL GAS SALE AND PURCHASE AGREEMENT

This Agreement dated the 20th day of July, 1992 is made between:


               SHELL CANADA LIMITED, A Canadian Corporation with 
               head office in Calgary, Alberta, Canada. 
               (hereinafter referred to as "Seller")

                                       and

               GREAT FALLS GAS COMPANY, A Montana Corporation 
               with head offices in Great Falls, Montana USA 
               (hereinafter referred to as "Buyer")

WHEREAS, Seller has available for sale certain supplies of natural gas, and
Seller desires to sell and deliver to Buyer such natural gas supplies in the
quantities and under the terms and conditions hereinafter provided; and

WHEREAS, Buyer and it's subsidiaries desire to receive and purchase such 
natural gas in the quantities and under the terms and conditions hereinafter 
provided;

NOW THEREFORE, in consideration of the premises and mutual covenants and
agreements herein set forth, Seller and Buyer contract and agree as follows:

                           ARTICLE I - INTERPRETATION

1.01    DEFINITIONS

As used in this Agreement:

(a)     "ANNUAL CONTRACT QUANTITY" OR "ACQ" means the volume obtained when
        multiplying the number of Days in the Contract Year by the Maximum 
        Daily Quantity in effect for that Contract Year;

(b)     "BUSINESS DAY" means all calendar days excluding:

         (i)      Saturdays and Sundays;

         (ii)     All statutory holidays under the laws of Alberta, Montana,
                  Canada or the United States of America; and,
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                                      - 2 -

        (iii)     All calendar days on which the head office of Seller or Buyer
                  is not open for business, provided however that all such
                  calendar days during each calendar year shall be identified 
                  by notice from Seller to Buyer and vice versa on or before
                  February 15 of the calendar year in question;

(c)     "BRITISH THERMAL UNIT" OR "BTU" means the amount of heat required to
        raise the temperature of one (1) pound of water from fifty-nine degrees
        Fahrenheit (59 DEG F) to sixty degrees Fahrenheit (60 DEG F) at a
        constant pressure of fourteen and seventy-three hundredths pounds per
        square inch absolute (14.73) psia). Total BTU's shall be determined by
        multiplying the total volume of Gas delivered times the Gas Heating
        Value expressed in BTU's per cubic foot of Gas adjusted on a dry basis;

(d)     "MAXIMUM DAILY QUANTITY" or "MDQ" means the specified volume of Gas
        which Buyer contracts to purchase each Day under this Agreement as set
        out in section 5.02 herein, or as otherwise provided in this Agreement;

(e)     "DAY" means a period of 24 consecutive hours, beginning and ending at
        0800 hours MST;

(f)     "DELIVERY POINT" has the meaning as set forth in section 3.01; 

(g)     "INTERRUPTIBLE DAILY QUANTITY" or "IDQ" means the specified volume of
        Gas which Buyer may purchase on an interruptible basis, as set forth in
        section 5.06;

(h)     "Mcf" means the quantity of Gas occupying a volume of one thousand
        (1,000) cubic feet at a temperature of sixty degrees Fahrenheit (60 DEG
        F) and at a pressure of fourteen and seventy-three hundredths pounds 
        per square inch absolute (14.73 psia);

(i)     "MONTH" means a period beginning at 0800 hours MST on the first Day of 
        a calendar month and ending 0800 hours MST on the first Day of the next
        succeeding calendar month;

(j)     "GAS" means natural gas and or residue gas comprised primarily of
        methane;

(k)     "NOVA" means Nova Corporation of Alberta or any successor thereof;

(1)     "PARTY" means a party to this Agreement;

(m)     "YEAR" or "CONTRACT YEAR" means a period of 12 consecutive months
        commencing on November 1, 1992 and on each subsequent anniversary
        thereof;

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                                      - 3 -


(n)     "HEATING VALUE" means the quantity of heat, measured in Btu, produced 
        by combustion in air of one (1) cubic foot of anhydrous Gas at a
        temperature of sixty degrees Fahrenheit (60 DEG F) and a constant
        pressure of fourteen and seventy-three hundredths pounds per square 
        inch absolute (14.73 psia), the air being at the same temperature and
        pressure as the Gas, after the products of combustion are cooled to the
        initial temperature of the Gas and air, and after condensation of the
        water formed by combustion;

(o)     "CANADIAN REGULATORY AUTHORITIES" means the federal, provincial or 
        local governmental agencies or other authorities in Canada, which have
        jurisdiction over the sale, export or transportation of Gas or other
        matters in question, including, without limitation, the National Energy
        Board of Canada ("NEB"), the Energy Resources Conservation Board of
        Alberta ("ERCB"), the Alberta Petroleum Marketing Commission ("APMC"),
        and the federal and provincial Governors-in-Council; and,

(p)     "U.S. REGULATORY AUTHORITIES" means the federal, state or local
        government agencies or other authorities in the United States of 
        America which have jurisdiction over the sale, import, transportation 
        of Gas or other matters in question, including, without limitation, 
        the Office of Fossil Fuels of the United States Department of Energy 
        ("OFE"), the Federal Energy Regulatory Commission ("FERC") and the 
        Montana Department of Public Service Regulation ("PSR").

1.02    CUSTOM

In this Agreement, words, phrases or expressions which are not defined 
herein, and which, in the usage or custom of the business of the exploration, 
production, transportation, distribution or sale of Gas, have an accepted 
meaning, shall have that meaning.

1.03    SCHEDULES

Any and all schedules appended hereto shall constitute part of, and be 
incorporated into this Agreement.

1.04    CURRENCY

All conversions from Canadian currency to currency of the United States or 
vice-versa, shall be done by the parties using the average Bank of Canada 
posted noon spot exchange rates for the conversion of Canadian funds into 
United States funds or vice-versa, as quoted for the calendar month in which 
the transaction occurred.

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                                      - 4 -


                             ARTICLE II - CONDITIONS

2.01    CONDITIONS PRECEDENT

This Agreement is subject to the satisfaction of the following conditions 
precedent on terms and conditions satisfactory to the Party, acting 
reasonably, entering into or obtaining same:

(a)     Seller entering into firm, non-interruptible transportation agreements
        with NOVA and Seller and NOVA obtaining all necessary certificates,
        permits, licenses and authorizations from Canadian Regulatory
        Authorities for the transactions contemplated by this Agreement,
        including without limitation, the sale and removal of the Maximum Daily
        Quantity from Alberta, the export of the Maximum Daily Quantity from
        Canada and the firm, non-interruptible transportation of the Maximum
        Daily Quantity in Canada from Seller's facilities through the 
        facilities of NOVA;

(b)     Buyer entering into firm, non-interruptible transportation agreements
        with Montana Power Company and Buyer and Montana Power Company 
        obtaining all necessary certificates, permits licenses and 
        authorizations from U.S. Regulatory Authorities for the transactions 
        contemplated by this Agreement for the full term of this Agreement, 
        including without limitation, the purchase and importation of the 
        Maximum Daily Quantity from Canada and for the firm, non-interruptible 
        transportation of the Maximum Daily Quantity in the United States 
        through the facilities of Montana Power Company.

2.02    FULFILLING CONDITIONS

(a)     If by October 15, 1992, any condition precedent referred to in section
        2.01 has not been satisfied, or with respect to subsection 2.01(a)
        waived by written notice provided by Seller or with respect to
        subsection 2.01(b) waived by written notice provided by Buyer then
        either Party may thereafter, at any time, provide written notice to the
        other Party of its election to terminate this Agreement and unless such
        conditions precedent are so satisfied or waived within ninety (90) Days
        after the receipt of such notice, this Agreement shall thereupon
        terminate.

(b)     Both Buyer and Seller shall act with due diligence and exercise all
        reasonable efforts to fulfill all such conditions precedent.

(c)     Buyer and Seller shall notify each other forthwith in writing upon the
        conditions precedent in section 2.01 having been met.

(d)     Seller and Buyer shall cooperate with each other so as to assist each
        other in fulfilling the conditions precedent set forth in section 2.01
        in order that the delivery of Gas hereunder may commence on a timely
        basis.

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                                      - 5 -


                      ARTICLE III - DELIVERY AND OWNERSHIP

3.01    DELIVERY POINT

The Delivery Point for all Gas delivered hereunder shall be that point on the
Canada/United States of America border at the interconnection of the pipeline
systems of NOVA and Montana Power Company near Carway, Alberta.

3.02    TITLE AND POSSESSION

Property in and title to the Gas and all risk of loss respecting all Gas
delivered hereunder shall pass from Seller to Buyer and shall vest in Buyer at
the Delivery Point. As between Seller and Buyer, until delivery of the Gas at
the Delivery Point, Seller shall be deemed to be in control and possession of
the Gas and shall be responsible for all costs, losses, damages, injuries to
persons or property or liabilities arising from or out of Seller's title,
possession, custody or control of Gas hereunder prior to title to the Gas
passing to Buyer at the Delivery Point. As between Seller and Buyer, after
delivery of the Gas at the Delivery Point, Buyer shall be deemed to be in
control and possession of the Gas and shall be responsible for all costs,
losses, damages, injuries to persons or property or liabilities arising from or
out of Buyer's title, possession, custody or control of Gas hereunder after
title to the Gas passes to Buyer at the Delivery Point.

3.03    ROYALTIES AND TAXES

Seller shall pay or cause to be paid and shall be solely responsible for all
royalties, overriding royalties and payments out of production, together with
all applicable federal, provincial, municipal and local taxes, levies or
surcharges imposed by authorities that are applicable on Gas delivered 
hereunder before title to such Gas passes to Buyer at the Delivery Point. 
Buyer shall be solely responsible for the above enumerated payments, taxes, 
levies or surcharges that are applicable on Gas delivered hereunder when and 
after title to such Gas passes to Buyer at the Delivery Point.

                  ARTICLE IV - GAS SPECIFICATIONS & MEASUREMENT

4.01    GAS SPECIFICATIONS

Buyer and Seller each agree that Gas delivered hereunder will be in a 
commingled stream and shall be at the pressure and meet or exceed the minimum 
quality specifications required by NOVA and Montana Power Company.

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                                      - 6 -


4.02    MEASUREMENT

It is understood and agreed that neither Buyer nor Seller owns or operates 
measuring and testing equipment at the Delivery Point. Therefore, all Gas 
delivered to Buyer hereunder shall be measured at the Delivery Point as to 
volume and Heating value by Montana Power Company, in accordance with its 
filed and approved tariffs and standard Industry practice. All such 
measurements made (including all correction thereof) shall be final and 
binding upon Seller and Buyer as to the Gas delivered under this Agreement. 
Seller or Buyer may at their sole cost, risk and expense witness such 
measuring and the testing of measuring equipment if they so desire.

                          ARTICLE V - CONTRACT VOLUMES

5.01    SUPPLY COMMITMENT

Subject to Article VIII, Force Majeure, Seller has, or shall have and shall 
maintain at all times throughout the term of this Agreement, sufficient Gas 
reserves and deliverability with respect to the delivery of Gas to the 
Delivery Point, so as to enable Seller to meet its obligations hereunder.

5.02    MAXIMUM DAILY QUANTITY

The Maximum Daily Quantity shall be equal to 5,000 MMBtu/day (140 
10(3)m(3)/d). On each Day during the term of this Agreement, Buyer may 
nominate its Gas requirement and Seller shall be obligated to deliver the 
amount so nominated by Buyer up to the MDQ.

5.03    CATEGORIES OF GAS

The quantities of Gas to be purchased by Buyer hereunder shall consist of 
Tier I Gas and Tier II Gas which shall bear different prices as set forth in 
Article VI below.

5.04    TIER I GAS

Commencing with each Contract Year, Buyer will purchase the initial 
sixty-five percent (65%) of the ACQ ("Tier I Gas") at the then applicable 
price for Tier I Gas, as set forth in section 6.02 herein. If and when the 
Tier I Gas is taken by Buyer, the remainder of gas taken by Buyer in that 
Contract Year will be Tier II Gas.

5.05    TIER II GAS

Commencing with the completion of the Tier I Gas Volume (defined as the 
product of the MDQ and the number of Days in the Contract Year multiplied by 
0.65), all Gas taken thereafter by Buyer in that Contract Year will be Tier 
II Gas.

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                                      - 7 -


5.06    INTERRUPTIBLE DAILY QUANTITY ("IDQ")

On any Day Buyer may request, over and above the MDQ, up to an additional 
5,000 MMBtu/day (140 10(3)m(3)/d) and subject to agreement upon price, Seller 
shall endeavor, on an interruptible basis, to supply the difference between 
the IDQ and the MDQ. The price for the volume of gas that is the difference 
between the IDQ and the MDQ shall be established on a monthly basis by 
negotiation between Buyer and Seller.

5.07    GAS TAKE LEVELS

If, during any Contract Year, Buyer does not purchase at least eighty percent 
(80%) of the then applicable ACQ, a "Shortfall Year" will exist. The 
difference between eighty percent (80%) of the then applicable ACQ and the 
amount actually taken by the Buyer will be the "Shortfall Amount". Within 
ninety (90) Days of the commencement of the Contract Year following the end 
of the Shortfall Year (the "Make-up Year"), Seller may elect to provide 
notice to Buyer stating the Shortfall Amount and the proportionate reduction 
in the ACQ and MDQ that will be in effect at the commencement of the Contract 
Year following the Make-up Year. Subject to the limitation created by the MDQ 
and ACQ applicable during the Make-up Year, buyer may elect to avoid all or 
part of this reduction by first purchasing eighty percent (80%) of the 
applicable ACQ in the Make-up Year and then purchasing all or a portion of 
the Shortfall Amount prior to the end of the Make-up Year. The Commodity 
Charge for the Shortfall Amount will be the applicable rate (depending upon 
whether the Shortfall Amount being purchased represents Tier I Gas or Tier II 
Gas) in effect during the Make-up Year.

The ACQ and MDQ in the Contract Year following the Make-up Year will be 
proportionately reduced by the remaining Shortfall Amount, unpurchased, if 
any, at the end of the Make-up Year.

5.08    NOMINATIONS

Buyer or Buyer's nominee shall nominate to Seller or Seller's nominee, by 
written telecommunication each and every Day by 1200 hours MST, Buyer's daily 
requirements for Gas for the following Day. Failure to so nominate to Seller 
shall cause continuation of the last received nomination.

5.09    FAILURE TO TAKE NOMINATION

In the event that Buyer nominates quantities and Seller delivers such 
quantities into the NOVA pipeline system and Buyer is unable or unwilling for 
whatever reason to take delivery of such quantities at the Delivery Point, 
then Buyer shall pay the price calculated on a per MMBtu on a 100% Load 
Factor basis for such volumes so nominated and delivered to NOVA, including 
the actual associated transportation and inventory penalty incurred by Seller 
for such quantities of Gas, provided that Seller makes reasonable efforts to 
mitigate such transportation penalties.

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                                      - 8 -


5.10    FAILURE TO DELIVER

If Seller is unable to meet Buyer's nomination, Seller shall promptly notify 
Buyer of Seller's inability to deliver Gas, whether or not such inability 
covers all or part of Buyer's nomination. Seller shall use its reasonable 
efforts to obtain and supply from other sources the volumes of Gas that 
Seller is obligated but unable to deliver to Buyer at the Delivery Point 
("Replacement Gas"). Seller shall endeavor to arrange for delivery of 
Replacement Gas, to the Delivery Point on the same Day at a price which shall 
not exceed the delivered cost to Buyer of Gas that Seller was obligated to 
deliver in accordance with Buyer's nomination ("Buyer's Cost of Gas"). 
Notwithstanding the foregoing, if Seller is unable to deliver Replacement Gas 
hereunder, Buyer may purchase Replacement Gas and Seller shall reimburse 
Buyer for any unabsorbed demand charges incurred on the Montana Power Company 
system and the price of Replacement Gas, in excess of the price hereunder, 
that Buyer is required to pay to any other producer or local distribution 
company as a result of Seller's failure to deliver Gas nominated by Buyer, 
adjusted for transportation, if applicable. Buyer shall make reasonable 
efforts to mitigate the cost of Replacement Gas. Seller's sole liability and 
Buyer's sole remedy with respect to Seller's failure to supply Gas shall be 
limited to such cost of Replacement Gas. In no event shall Seller, it's 
directors, trustees, agents, officers or employees be liable to Buyer, it's 
directors, trustees, agents, officers or employees for any incidental, 
special, indirect or consequential damages of any nature including without 
limitation any claims of customers of Buyer, connected with or resulting from 
Seller's failure to supply Gas under this Agreement.

                           ARTICLE VI - TERM AND PRICE

6.01    TERM

(a)     Subject to the satisfaction or waiver of the conditions precedent set
        forth in section 2.01, deliveries of Gas under this Agreement shall
        commence on November 1, 1992 ("Commencement Date") and shall except as
        otherwise specifically provided for herein continue for a term of
        fifteen (15) Contract Years after November 1, 1992.

(b)     The Term of the Agreement shall consist of three (3) segments of five
        (5) Contract Year periods as follows:

             Segment 1      November 1, 1992 - October 31, 1997; 
             Segment 2      November 1, 1997 - October 31, 2002; 
             Segment 3      November 1, 2002 - October 31, 2007.

(c)     Unless either Party gives notice to the other Party at least
        twenty-seven (27) Months prior to the end of Segment 1 specifying its
        intention to terminate this Agreement at the end of Segment 1 the term
        shall continue into Segment 2.

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                                      - 9 -


(d)     Anytime on or after August 1, 1995, either Party may give notice to the
        other Party of at least twenty-seven (27) Months to terminate this
        Agreement prior to the end of the Term.

6.02    PRICE

The Price to be paid by Buyer to Seller for Gas purchased and sold and the
service provided hereunder for the period of time commencing with the
Commencement Date will consist of the sum of the four (4) components identified
hereunder. The Price will be in U.S. dollars.

(a)     Each Month, Buyer shall pay Seller a "Demand Charge" equal to Seller's
        actual cost for that Month of reserving the firm transportation 
        required to transport the MDQ on NOVA to the Delivery Point.

(b)     Each Month, Buyer shall pay Seller a "Reservation Charge" equal to the
        product of the MDQ times the number of days in the Month times the
        Reservation Charge. The Reservation Charge for the first two years of
        this Agreement shall be $0.06 U.S./MMBtu.

(c)     Each Month, Buyer shall pay Seller for each MMBtu of Tier I Gas
        delivered and received at the Delivery Point, a "Commodity Charge" 
        equal to a per MMBtu price fixed for at least one year by agreement of
        the Parties in advance. The Commodity Charge for Tier I Gas for the 
        first two Years of this Agreement shall be $1.31 U.S./MMBtu on a dry 
        basis.

(d)     Commencing with the completion of Tier I Gas purchases in each Contract
        Year, the Commodity Charge for Tier II Gas will be negotiated and 
        agreed to by the Parties prior to the end of each previous Month. The 
        Parties will take into consideration the prepaid Demand Charge when 
        arriving at the Commodity Charge for the following month.  Failing 
        agreement by the Parties, the Commodity Charge for the applicable Month
        will equal the price published by NATURAL GAS WEEK in their Canadian 
        Price Report Section, under the Empress Border - Contract Subsection. 
        In the event that such price is no longer published or such publication
        is no longer published then, failing agreement by the parties, the 
        Commodity Charge or a method of determining it shall be determined by 
        arbitration pursuant to Article X hereof. The prepaid Demand Charge 
        will be subtracted from the published price to arrive at the Commodity 
        Charge. Each Month Buyer shall pay Seller for each MMBtu of Tier II Gas
        delivered and received at the Delivery Point, the above applicable
        Commodity Charge.

If Buyer elects not to take gas during a Tier II Gas Month, Seller will be 
allowed to sell that gas on an interruptible basis to third party purchasers.

The Demand Charge and the Reservation Charge shall be paid each Month 
regardless of the quantity of Gas purchased and sold hereunder, except to the 
extent that Seller fails to deliver Gas nominated.

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                                     - 10 -


6.03    FUTURE PRICE DETERMINATION

(a)     The Parties agree that they will meet from time to time to negotiate 
        the Tier I Commodity Charge and Reservation Charge components of the 
        Price payable hereunder for subsequent Contract Years. In any such
        negotiations or resulting arbitration with respect to Price during the
        Term of this Agreement only the Tier I Commodity Charge and Reservation
        Charge components of the Price shall be redetermined and the Demand
        Charge component of the Price shall not be subject to redetermination.

(b)     Subject to 6.03 (a) The Parties agree, to establish a new Price for the
        next Contract Year at least one hundred and twenty (120) Days prior to
        the termination date of the current Contract Year and the Parties will
        commence procedures for such redetermination no later than one hundred
        and eighty (180) Days prior to the termination date of the current
        Contract Year by either Party giving fifteen (15) Days written notice 
        to the other, to meet and negotiate. Such Price, and the various 
        components making up that Price, will be effective for a period of 
        time, as then agreed to, and will become effective on the commencement 
        of the next Contract Year. If neither Party has given written notice 
        to the other to renegotiate at least one hundred and eighty (180) Days 
        prior to the termination date of the current Contract Year, then the 
        Price for the current Contract Year shall continue in effect for the 
        next Contract Year.

6.04    FAILURE TO REACH AGREEMENT ON PRICE

In the event that the Parties are unable to reach agreement on the Price, or 
the Price components at least one hundred and twenty (120) Days prior to the 
termination date of the current Contract Year, as provided pursuant to 
section 6.03 herein, either Party may, upon not less than fifteen (15) days 
written notice to the other Party, have the Price determined pursuant to the 
Arbitration provisions contained in Article X herein and exclusively in 
accordance with the principles set forth in section 6.05 herein. Should no 
notice for Arbitration be given at least ninety (90) days prior to the 
termination date of the current Contract Year, the Price for the next 
Contract Year shall continue to be the Price in effect for the current 
Contract Year.

6.05    PRICING PRINCIPLES

For each Contract Year subsequent to the Contract Year for which the Price of 
Gas to be sold and purchased hereunder has been established and specified, 
the Parties agree to determine Price by negotiation or by arbitration. If the 
Price for Gas delivered in any Contract Year is to be determined by 
arbitration, the arbitrators shall determine a Price that, under the 
prevailing market circumstances for long term firm Gas Supply and in the 
opinion of the arbitrators, is fair and reasonable to both Buyer and Seller. 
In making such determination, the arbitrators shall limit

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                                     - 11 -


their consideration to the evidence which is presented by the Parties, and to 
the extent that evidence is presented, shall base their determination upon 
and shall give due consideration to each of the following criteria:

        (i)  The weighted average cost of gas paid by Buyer during the next
             Contract Year for firm gas supplies with a term of two (2) years 
             or more;

       (ii)  The prices being paid during the next Contract Year for other firm
             gas supplies by local distribution companies with a term of two 
             (2) years or more in the state of Montana; and,

      (iii)  The prices being paid during the next Contract Year for other
             firm gas supplies by local distribution companies with a term
             of two (2) years or more in the province of Alberta;

provided that the arbitrators shall consider the above matters in light of the
following:

(a)     To the extent that evidence with respect to Prices for the next 
        Contract Year is not available or is insufficient, prices for the 
        current Contract Year will be considered;

(b)     The times at which the prices were agreed to between the respective
        buyers and sellers;

(c)     Differences in transportation costs relevant to establishing a point of
        comparison at the Delivery Point;

(d)     The similarities and dissimilarities between the service provided
        hereunder and the sales and transportation arrangements under which
        other gas is being sold for consumption in Buyer's market area and in
        Alberta, including in particular but not limited to the similarities 
        and dissimilarities between the quality of service and the security of
        supply provided hereunder and provided under such other arrangements;
        and,

(e)     Any other considerations in respect of which relevant evidence is
        adduced by the Parties and which is relevant to the determination of
        such matters.

In the event that a negotiated or arbitrated Price is determined for a 
Contract Year after commencement thereof, Seller shall retroactively adjust 
its invoices to Buyer to the first Day of that Contract Year, to take into 
account the revised Price. Until a new Price is concluded and retroactively 
implemented, the previous Price shall remain in effect. If the Price 
settlement date exceeds sixty (60) Days past the Contract Year commencement, 
the retroactive invoice shall be adjusted for interest at the prime rate 
pursuant to section 7.04.

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                                     - 12 -


6.06    REGULATORY INTERVENTION

If Canadian Regulatory Authorities or U.S. Regulatory Authorities take action 
by rule, order or other official means which materially and fundamentally 
alters the operation of this Article VI such that Gas cannot be sold and 
purchased hereunder at a market based price for long term firm Gas supply, 
then either Buyer or Seller may notify the other Party by the means 
identified in Article XII hereof of its intention to terminate this Agreement 
This Agreement shall then terminate in all respects one hundred and eighty 
(180) days after the provision of such notice unless within such one hundred 
and eighty (180) day period the regulatory action has been modified or 
revoked such that the operation of Article VI has been restored. The Parties 
shall use due diligence and exercise all reasonable efforts to oppose any 
regulatory action which might trigger the operation of this section 6.06.

                              ARTICLE VII - PAYMENT

7.01    MONTHLY BILLING

Once service or deliveries of Gas have commenced hereunder, Seller shall send 
by facsimile to Buyer on or before the fifteenth (15th) Day of each Month 
(the "Billing Month") with the original to follow by mail:

(a)     A statement for the preceding Month showing the daily and total amount
        of Gas delivered hereunder or, if such information is not available by
        that Day, an estimate of such daily and total amounts; and,

(b)     A bill in U.S. dollars with respect to the preceding Month together 
        with information sufficient to explain and support the amount billed.

7.02    PAYMENT DATE

Buyer shall pay Seller in U.S. dollars by direct electronic transfer to the 
account of Seller designated herein, within ten (10) Days of receipt of 
Seller's bill, the amount due to Seller with regard to Gas sold or reasonably 
estimated to have been sold hereunder and service provided in the preceding 
Month in accordance with the provisions of this Agreement as follows:

        The Chase Manhattan Bank, N.Y.
        Fedwire #0210-0002-1
        Account: 001-1-146305
        Bank of Montreal, Montreal
        For Transfer to: Calgary Main Office
        For Credit Account: 00109-4604-211

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                                     - 13 -


In addition, Buyer shall send a copy of payment record by facsimile to 
Seller. In the event that the tenth (10th) Day after receipt of Seller's bill 
is not a Business Day, then Buyer shall pay Seller as aforesaid on or before 
the Business Day immediately before such tenth (10th) Day. If Seller's bill 
for any Month is based on an estimate of the Gas sold in the previous Month, 
then the Parties shall make all necessary adjustments in the Month following 
the billing Month to reflect the actual volumes of Gas Sold.

7.03    EXAMINATION OF RECORDS

Subject to the confidentiality provisions of this Agreement, Seller and Buyer 
shall have the right, at any reasonable time and from time to time during the 
term of this Agreement, to examine the books, records and accounts of the 
other to the extent reasonably necessary to verify the accuracy of any 
statement, billing, computation or procedure made under or pursuant to the 
provisions of this Agreement.

7.04    REMEDIES FOR NON-PAYMENT

(a)     Should Buyer fail to pay all of the amount of the bill as herein
        provided when such amount is due, then commencing on the date such
        payment is due, late payment charges shall accrue daily on the unpaid
        part of such bill and be paid at a rate of interest per annum which is
        equal to the prime rate charged from time to time by The Chase 
        Manhattan Bank of New York for loans to commercial borrowers, plus 1% 
        compounded monthly until paid. All such late payment charges shall be 
        payable on demand by Buyer to Seller. If either principal or late 
        payment interest charges are due, any payments thereafter received 
        shall first be applied to late payment charges due, then to the 
        previously outstanding principal due and lastly, to the most current 
        principal due.

(b)     In the event of any such failure to pay, Seller may, in addition to any
        other remedies that it may have under the terms of this Agreement, upon
        10 Days written notice via facsimile and courier to Buyer, suspend
        further delivery of Gas hereunder until such amount is paid. During the
        period of any such suspension, Buyer shall continue to be liable to
        Seller for the amounts set forth in section 6.02 with respect to the
        Reservation Charge and Demand Charge attributable to such suspended
        deliveries and such suspended deliveries shall not be considered to be 
        a failure by Seller to deliver gas under section 5.10

(c)     Notwithstanding the foregoing, if Buyer shall in good faith dispute the
        amount of any such bill or any part thereof, if Buyer shall pay to
        Seller such amounts as it concedes to be correct and if Buyer at any
        time within ten (10) Days after a demand made upon it by Seller for a
        letter of credit with respect to the amount in dispute shall furnish
        security by way of a letter of credit in a form reasonably satisfactory
        to Seller assuring payment to Seller of the amount ultimately found to
        be due to Seller upon such bill by agreement or

<PAGE>

                                     - 14 -


        by a decision of a court of competent jurisdiction, as the case may be,
        then Seller shall not be entitled to suspend further delivery of Gas
        hereunder as a result of any such nonpayment unless and until a default
        occurs in relation to the conditions of any such letter of credit or 
        any renewal thereof. If it is determined that Buyer owes Seller the 
        disputed amount, Buyer shall pay Seller the disputed amount within five
        (5) Days of the determination thereof.

(d)     Notwithstanding the provisions of subsection 7.04 (b), if Buyer does 
        not in good faith dispute the payment of the amount of any such bill 
        or any part thereof not paid, Seller, in addition to any other remedies
        that it may have under the terms of this Agreement, at law or in 
        equity, may on written notice of at least thirty (30) Days, elect to 
        terminate this Agreement. Such notice may only be given after the 
        suspension of Gas deliveries referred to in subsection 7.04 (b) has 
        commenced.

7.05    ADJUSTMENTS

Subject to the provisions of section 7.02, if it shall be found that at any 
time Buyer has been overcharged by Seller in relation to this Agreement and 
Buyer shall have actually paid the bills containing such overcharge, then 
within thirty (30) Days after the final determination thereof, Seller shall 
refund the amount of any such overcharge and if such overcharge was the 
result of Seller's error, then interest shall be paid by Seller on the amount 
in question on the same basis as interest is charged under the provisions of 
section 7.04 from the date the overcharge was paid to the date Buyer is 
reimbursed for the overcharge. If any such overcharge is not a result of an 
error on the part of Seller, then no interest shall be charged to Seller. 
Similarly, if it shall be found that at any time Buyer has been undercharged 
under the provisions of this Agreement, then within thirty (30) Days after 
the final determination thereof, Buyer shall pay the amount undercharged. No 
interest shall be payable by Buyer on the amount of any undercharge unless 
Buyer shall fail to pay the amount thereof within such thirty (30) Day 
period, in which event interest shall be calculated and payable thereon on 
the same basis as is described in section 7.04 from the first Day after such 
thirty (30) Day period to the date of payment of the undercharge by Buyer.

7.06    EXTENSION OF TIME FOR PAYMENT WHEN BILL DELAYED

If presentation of the bill to Buyer is delayed after the fifteenth (15th) 
Day of the billing Month, then the time of payment shall be extended 
accordingly unless Buyer is responsible for such delay.

7.07    DISPUTES

Notwithstanding anything herein contained to the contrary, neither Party 
hereto shall be entitled to dispute the volume of Gas delivered, or the 
amount paid or payable with respect thereto, unless such dispute is raised by 
notice to the other Party within two years after the end of the Month in 
question.

<PAGE>

                                     - 15 -


7.08    CREDIT APPROVAL

Upon Seller's request at any time prior to commencement of Gas deliveries or 
during the Term of this Agreement, Buyer shall provide Seller with evidence 
satisfactory to Seller of Buyer's ability to perform its financial 
obligations under this Agreement. If Seller is not so satisfied, Seller may, 
acting reasonably, having provided Buyer written notice of suspension in 
accordance with section 7.04(b), suspend deliveries of Gas hereunder. During 
the period of any such suspension, Buyer shall continue to be liable to 
Seller for the amounts set forth in section 6.02 with respect to the 
Reservation Charge and Demand Charge attributable to such suspended 
deliveries and such suspended deliveries shall not be considered to be a 
failure by Seller to deliver Gas under section 5.10. Deliveries shall 
recommence upon Buyer providing to Seller an irrevocable stand-by letter of 
credit from a banking institution which is satisfactory to Seller. The letter 
of credit shall be a dollar amount reasonably specified by Seller which will 
cover the full Price for two (2) Months worth of Gas purchases at the MDQ or 
such other assurance as is acceptable to Seller. The letter of credit shall 
provide that it will be automatically renewed every twelve (12) Months unless 
notice of the issuer's intent to cancel the letter of credit as of any 
anniversary date of the issuance thereof is received by Seller no later than 
sixty (60) Days prior to such proposed expiration date.

                          ARTICLE VIII - FORCE MAJEURE

8.01    SUSPENSION

Subject to section 8.03 hereof, to the extent that either Party to this 
Agreement fails to observe or perform any of the covenants or obligations 
herein imposed upon it and such failure shall have been solely caused by 
Force Majeure, then such failure shall be deemed not to be a breach of such 
covenants or obligations and such covenants and obligations to the extent 
affected by such Force Majeure shall be suspended during the continuance of 
the event of Force Majeure.

8.02    FORCE MAJEURE

(a)     For the purposes of this Agreement, the term "Force Majeure" shall mean
        any acts of God, lightning, earthquakes, storms, strikes, lockouts or
        other industrial disturbances, acts of the Queen's or country's 
        enemies, sabotage, wars, blockades, insurrections, riots, epidemics, 
        landslides, floods, fires, washouts, arrests and restraints of 
        governments and people, civil disturbances, explosions, breakages of or
        accidents to machinery or lines of pipe, interruptions in 
        transportation service on any of the pipeline facilities required for 
        delivery of Gas not reasonably within the control of Seller or Buyer, 
        the orders of any court or government authority, agency or tribunal, or
        any other extraordinary cause, whether of the kind herein enumerated or
        otherwise, not within the reasonable control of the Party claiming 
        suspension and which, by the exercise of due diligence, such Party 
        could not have prevented or is unable to overcome.


<PAGE>

                                     - 16 -


(b)     For the purposes of this Agreement, the term "Force Majeure" shall also
        mean any action not caused by and beyond the reasonable control of
        either Party hereto which results in the interruption of deliveries or
        which prevents totally or partially the exportation of Gas from Canada
        by Seller or the importation of Gas into the U.S. by Buyer, or its
        transportation by NOVA or Montana Power Company, provided however, that
        where the exportation, importation or transportation is only partially
        prevented by the action, the parties' obligations hereunder shall be
        suspended only to the extent prevented by such action.

8.03    NO RELIEF

(a)     Neither Party shall be entitled to the benefit of the provisions of
        section 8.01 under any of the following circumstances:

        (i)       to the extent that the failure was caused by the negligence 
                  or contributory negligence of the Party claiming suspension;

        (ii)      to the extent that the failure was caused by the Party
                  claiming suspension having not made reasonable efforts to
                  remedy the condition and remove the cause or circumstances of
                  Force Majeure in an adequate manner, or having failed to
                  resume with all reasonable dispatch the performance of such
                  covenants or obligations;

        (iii)     if the event of Force Majeure was caused by lack of finances
                  or was related to the payment of any amount or amounts due
                  hereunder;

        (iv)      to the extent that the failure was caused by the 
                  insufficiency of Seller's Gas supply as opposed to an event 
                  of the nature described in section 8.02;

        (v)       to the extent that the failure was caused by the failure of
                  Buyer or Buyer's market to require Gas;

        (vi)      unless as soon as reasonably possible after the happening of
                  the occurrence relied upon, or as soon as possible after
                  determining that the occurrence was in the nature of Force
                  Majeure and would affect the claiming Party's ability to
                  observe or perform any of its covenants or obligations under
                  this Agreement, the Party claiming suspension shall have 
                  given to the other Party hereto notice to the effect that by 
                  reason of Force Majeure (the nature whereof shall be therein
                  specified) the claiming Party is unable to perform the
                  particular covenants or obligations.

(b)     (i)       Buyer's obligation to pay the Demand Charge and Reservation
                  Charge as set forth in section 6.02, shall be suspended in 
                  the event and to the extent that a claim of Force Majeure by
                  Seller hereunder reduces the quantity of Gas delivered

<PAGE>


                                     - 17 -


                  hereunder by Seller, however, in the event of a claim of 
                  Force Majeure by Buyer hereunder, Buyer's Demand Charge and
                  Reservation Charge payment obligation shall not be suspended
                  but shall remain its responsibility and obligation provided
                  that it shall be reduced to the extent of any reduction in 
                  the actual demand charges paid by Seller.

        (ii)      In the event of a claim of Force Majeure hereunder by Seller,
                  Seller shall not be liable for Replacement Gas costs or
                  unabsorbed demand charges as described in section 5.10,
                  provided however, that Seller will use reasonable efforts to
                  locate replacement natural gas supplies for the quantity of
                  Gas not delivered hereunder as a result of Seller's Force
                  Majeure, which replacement natural gas, upon and subject to
                  the negotiation and agreement between Seller and Buyer as to
                  the terms and conditions of the sale thereof from Seller to
                  Buyer, shall be sold and delivered by Seller and purchased by
                  Buyer.

        (iii)     In the event of and during a claim of Force Majeure hereunder
                  by Seller, Buyer shall have the right to locate an 
                  alternative supply of gas and direct Seller to use on Buyer's 
                  behalf Seller's firm NOVA transportation covered by this 
                  Agreement to move such gas, to the extent of any reduction in
                  the quantity of Gas and/or replacement natural gas pursuant 
                  to subsection 8.03(b)(ii), delivered by Seller under this 
                  Agreement, which reduction results from Seller's Force 
                  Majeure. Notwithstanding subsection 8.03(b)(i) hereof, to the
                  extent that Seller uses any such NOVA transportation on 
                  Buyer's behalf, Buyer shall pay the Demand Charge relating 
                  thereto.

8.04    END OF SUSPENSION

The party claiming suspension by reason of Force Majeure shall give notice to 
the other Party, as soon as possible after the event of Force Majeure shall 
have been remedied, to the effect that the same has been remedied and that 
such Party has resumed, or is then in a position to resume, the performance 
of the suspended covenants or obligations under this Agreement.

8.05    STRIKES OR LOCKOUTS

Notwithstanding anything to the contrary in this Article VIII expressed or 
implied, the settlement of strikes, lockouts and other industrial 
disturbances shall be entirely within the discretion of the Party involved 
therein and such Party may make settlement thereof at such time and on such 
terms and conditions as it may deem to be advisable and no delay in making 
such settlement shall deprive such Party of the benefit of section 8.01.

<PAGE>

                                     - 18 -


8.06    LIMITATION ON SUSPENSION OF OBLIGATIONS

If at any time during the Term hereof, either Buyer or Seller (the "Party 
Claiming Force Majeure") has claimed Force Majeure and (i) such Force Majeure 
remains in effect for at least one hundred and eighty (180) consecutive Days 
or (ii) such Force Majeure remains in effect for at least thirty (30) 
consecutive Days during which time such Party fails to deliver or take at 
least 10% of the Maximum Daily Quantity as a daily average over such thirty 
(30) day period, then so long as the Force Majeure event is still continuing, 
the other party hereto may by notice to the Party Claiming Force Majeure, 
terminate this Agreement effective as of the date of such notice. The Party 
Claiming Force Majeure shall not manipulate its performance under this 
Agreement in order to avoid the application of this section 8.06.

      ARTICLE IX - COVENANTS, WARRANTIES AND INDEMNITIES BY SELLER

9.01    WARRANTIES

With respect to the Gas sold hereunder, Seller hereby covenants, warrants and 
represents to Buyer that:

        (i)       Seller shall at the Delivery Point have good right or title 
                  to all Gas delivered hereunder, free and clear of all liens 
                  and adverse claims whatsoever, except those being contested 
                  in good faith by Seller, and,

        (ii)      Seller shall at the Delivery Point have the right to sell the
                  Gas delivered or tendered for delivery hereunder.

9.02    INDEMNITY

Seller shall indemnify Buyer and hereby agrees to save Buyer harmless from 
and in respect of all suits, actions, debts, accounts, damages, costs, losses 
and expenses of every nature and kind whatsoever arising from or in 
connection with any adverse claims of any or all persons to the Gas or to 
royalties, taxes, license fees or charges thereon, which are applicable 
before the title to the Gas passes to Buyer at the Delivery Point. In the 
event that any such adverse claim is prosecuted against Buyer in respect of 
any of the Gas as aforesaid, Buyer may retain the Price thereof up to the 
amount of such claim, until such claim has been finally determined, as 
security for the performance of Seller's obligations hereunder with respect 
to such claim or until Seller shall have furnished a surety bond or other 
form of security satisfactory to Buyer in connection with the subject claim. 
Buyer shall invest any amount withheld from Seller at any short term rate of 
interest available to the Buyer, acting reasonably, until the amount withheld 
is released to the Seller, at which time all interest earned thereon shall be 
paid to Seller.

<PAGE>

                                     - 19 -


9.03 PAYMENTS BY SELLER

Seller shall at all times pay all fees, rentals and royalties due and 
payments due to all mineral and all royalty owners and all amounts due under 
all documents, as may appear of record or otherwise to be binding upon 
Seller, and shall pay all other persons having any interests in the Gas sold 
and delivered hereunder, which interests arise prior to the Delivery Point.

                             ARTICLE X - ARBITRATION

10.01   PRICING DISPUTES

All disputes arising out of or in connection with the determination of the 
Price for Gas sold hereunder shall be referred to and finally resolved in a 
manner which shall be final and binding on the Parties hereto, by an 
arbitration pursuant to the principles outlined herein and subject to the 
criteria set forth in section 6.05 and pursuant to the International 
Commercial Arbitration Act, of the Province of Alberta, except to the extent 
that the provisions of such Act are contrary to the principles outlined 
herein.

10.02   APPOINTMENT OF ARBITRATORS

The Party hereto initiating the arbitration (the "Initiating Party") shall in 
its written notice of request to arbitrate, which notice shall be sent to the 
other Party hereto (the "Receiving Party"), name one arbitrator. Within 
twenty-one (21) Days after receipt of such notice, the Receiving Party shall 
serve notice on the Initiating Party, which notice shall contain the name of 
a second arbitrator.

10.03   ARBITRATION BOARD

If the Receiving Party fails to name a second arbitrator, then the Initiating 
Party's arbitrator shall function as a single arbitrator. In the event that 
both Parties appoint their own arbitrator, the two arbitrators so appointed 
shall name a third arbitrator, or, if they fail to do so within ten (10) Days 
of the second arbitrator's appointment, the Parties hereto shall promptly 
meet and attempt to agree upon and appoint such third arbitrator. If the 
parties hereto are unable to agree within ten (10) Days on the choice of the 
third arbitrator, then, on the request of either Party hereto, the third 
arbitrator shall be appointed by the consulting firm of Stone & Webster 
Engineering Corporation. If for any reason the third arbitrator is not 
appointed by the Consulting Firm or otherwise agreed upon by the Parties or 
the two arbitrators within thirty (30) Days of the second arbitrator's 
appointment then on the request of either Party hereto the third arbitrator 
shall be appointed by any Justice of the Court of Queen's Bench of Alberta.

<PAGE>

                                     - 20 -

10.04   QUALIFICATIONS OF ARBITRATORS

The single arbitrator (the "Arbitrator") or the three arbitrators (the 
"Board") appointed hereunder shall be qualified by education or experience to 
decide the particular pricing matters in dispute, and shall not be employees 
or agents of either Party hereto or any of their affiliates.

10.05   PROCEDURE

The Arbitrator or the Board shall proceed immediately to hear and determine 
the pricing question or questions in dispute. The decision of the Arbitrator 
shall be made within forty-five (45) Days after his or her appointment, 
subject to any reasonable delay due to unforeseen circumstances. The decision 
of the Board, or the majority thereof, shall be made within forty-five (45) 
Days after the appointment of the third arbitrator, subject to any reasonable 
delay due to unforeseen circumstances. Notwithstanding the foregoing, in the 
event the Arbitrator fails to make a decision within sixty (60) Days after 
his or her appointment or if the Board, or the majority thereof, fails to 
make a decision within sixty (60) Days after the appointment of the third 
arbitrator then either Party may elect to have a new Arbitrator or Board 
chosen in like manner as if none had previously been selected.

10.06   BINDING DECISION

The decision of the Arbitrator or the decision of the Board, or the majority 
thereof, shall be drawn up in writing and signed by the Arbitrator or by the 
Board members, or the majority thereof, and shall adopt the last position put 
forward in writing by Seller or Buyer in the negotiations preceding the 
request for arbitration and shall be final and binding upon the Parties 
hereto as to any pricing question or questions so submitted to arbitration, 
and the Parties shall be bound by such decision and perform the terms and 
conditions thereof.

10.07   COMPENSATION OF ARBITRATORS

Each Party shall pay the compensation and expenses of the Arbitrator 
appointed by that Party and the compensation and expenses of the third 
Arbitrator (unless otherwise determined by the Arbitrator or the Board) shall 
be paid in equal proportions by Buyer and Seller.

10.08   PLACE OF ARBITRATION

The place of arbitration shall be determined by the Arbitrator or the Board.

10.09   PRICING CRITERIA

Notwithstanding anything to the contrary contained in this Agreement, in any 
pricing arbitration the Arbitrator or the Board, as the case may be, shall 
use the criteria contained in section 6.05 in making a determination of the 
Price along with such other criteria, if any, as may then be agreed upon by 
Seller and Buyer and submitted to the Arbitrator or the Board.

<PAGE>


                                     - 21 -

10.10   OPERATIONS CONTINUED

Whenever there is an arbitration proceeding, operations under this Agreement 
shall continue in the same fashion as they were conducted before the 
arbitration proceeding was commenced, without prejudice to either Party, 
pending a decision in the arbitration proceeding.

                        ARTICLE XI - DEFAULT AND REMEDIES

11.01   EVENT OF DEFAULT

An Event of Default under this Agreement shall be deemed to exist upon the 
occurrence of any one or more of the following events:

(a)     Failure by either Party to make payment of any amounts due to the other
        Party under this Agreement, and that failure continues for a period of
        thirty (30) days after written notice of non-payment; or

(b)     Failure by either Party to perform fully any other material provision 
        of this Agreement, and (i) such failure continues for a period of 
        thirty (30) days after written notice of such non-performance from the 
        other Party is received, or (ii) if within such thirty (30) day period 
        the non-performing Party commences and proceeds with due diligence to 
        cure the failure and the failure is not cured within ninety (90) days 
        after written notice of nonperformance from the other Party is received
        or such longer period of time agreed to by the Parties in writing as 
        being necessary for the Party to cure the failure with all due 
        diligence; or

(c)     If by order of a court of competent jurisdiction, a receiver or
        liquidator or trustee of either Party or of all or any of the property
        of either Party shall be appointed, and such receiver or liquidator or
        trustee shall not have been discharged within a period of sixty (60)
        days after its appointment; or if by decree of such a court, either
        Party shall be adjudicated bankrupt or insolvent or any substantial 
        part of the property of such Party shall have been sequestered, or such
        decree shall have continued undischarged and unstayed for a period of
        sixty (60) days after the entry thereof; or if a petition to declare
        bankruptcy or to reorganize Buyer or Seller pursuant to any of the
        provisions of any Canadian or United States federal, provincial or 
        state bankruptcy law shall be filed against such Party and shall not be
        dismissed within sixty (60) days after such filing; or

(d)     If either Party shall file a voluntary petition in bankruptcy under any
        provision of any Canadian or United States federal, provincial or state
        bankruptcy law or shall consent to the filing of any bankruptcy or
        reorganization petition against it under any similar law; or if either
        Party shall make an assignment for the benefit of its creditors; or if
        either Party


<PAGE>

                                     - 22 -

        shall admit in writing its inability to pay its debts generally as they
        become due; or if either Party shall consent to the appointment of a 
        receiver or receivers, or trustee or trustees, or liquidator or 
        liquidators of it or of all or of any part of its property.

11.02   TERMINATION

Upon the occurrence and during the continuance of an Event of Default, the 
Party not in default shall have the right to terminate this Agreement upon 
ten (10) days' written notice to the defaulting Party.

                        ARTICLE XII - GENERAL PROVISIONS

12.01   NOTICES

Any notice, request, consent, direction, demand, waiver of condition, invoice 
or other instrument required or permitted to be given under the provisions of 
this Agreement shall be in writing. Written communications as aforesaid may 
be given by delivering same in person or by prepaid courier or sending same 
by facsimile, in each case addressed as follows:

        TO BUYER:      GREAT FALLS GAS COMPANY

        (i)            General     P.O. Box 2229
                                   Great Falls, Montana 59403 or,
                                   #1 First Avenue South
                                   Great Falls, Montana 59401
                       Attention:  Director, Gas Supply
                                   and Industrial Marketing
                       Facsimile:  (406) 791-7560
                       Telephone:  (406) 791-7504

        (ii)           Nominations GREAT FALLS GAS COMPANY

                                   P.O. Box 2229
                                   Great Falls, Montana 59403
                       Attention:  Director, Gas Supply and Industrial 
                                   Marketing
                       Facsimile:  (406) 791-7560
                       Telephone:  (406) 791-7504

        (iii)          Billings    GREAT FALLS GAS COMPANY

                                   P.O. Box 2229
                                   Great Falls, Montana 59403
                       Attention:  Director, Accounting
                       Facsimile:  (406) 791-7560
                       Telephone:  (406) 791-5206


<PAGE>

                                     - 23 -

TO SELLER:             SHELL CANADA LIMITED

        (i)            General     Natural Gas Business Centre
                                   400 - 4th Avenue S.W.
                                   Calgary, Alberta
                                   T2P 0J4
                       Attention:  Manager, Direct Marketing
                       Facsimile:  (403) 269-7818
                       Telephone:  (403) 691-3189
        (ii)           Billings    400 - 4th Avenue S.W.
                                   Calgary, Alberta
                                   T2P 0J4
                       Attention:  Supervisor, Natural Gas Accounting
                       Facsimile:  (403) 269-7818
                       Telephone:  (403) 691-4069

        (iii)          Nominations 400 - 4th Avenue S.W.
                                         Calgary, Alberta
                                         T2P 0J4
                       Attention:  Operations Analyst
                       Facsimile:  (403) 269-7818
                       Telephone:  (403) 691 -3044 or (403) 691-3878

Any written communication as aforesaid, if delivered in person or SENT BY 
facsimile, shall be deemed to have been given or made on the Business Day on 
which it was received as aforesaid, and, if delivered by prepaid courier, 
shall be deemed to have been given or made on the second Business Day 
following the Day on which it is so received. Any Party may give written 
notice of change of address in the same manner, in which event any written 
communication as aforesaid shall thereafter be given to it as above provided 
at such changed address.

12.02   FURTHER ASSURANCES

Each Party shall from time to time and at all times hereafter upon reasonable 
written request so to do, make, do, execute and deliver, or cause to be made, 
done, executed and delivered all such further acts, deeds, assurances and 
things as may be reasonably required for more effectually implementing and 
carrying out the true intent and meaning of this Agreement.

12.03   MORTGAGES

Notwithstanding anything to the contrary contained in this Agreement, either 
Party shall have the right to mortgage, pledge, hypothecate or otherwise 
encumber its interest in and to this Agreement as security for its 
indebtedness to any other person.

<PAGE>

                                     - 24 -

12.04   WAIVERS

Either Party hereto in its sole discretion may waive, without thereby 
prejudicing such Party's right to rely on any other conditions inserted 
herein for such Party's sole benefit, a breach or default of any covenant or 
condition inserted herein for the benefit or protection of such Party. No 
such waiver, however, shall operate as a waiver of any future breach or 
default, whether of a like or different character.

12.05   INTERPRETATIONS

In the event that Buyer or Seller are in disagreement as to the 
interpretation to be placed on any term, condition, covenant or agreement 
contained in this Agreement or the performance or satisfaction thereof by any 
such Party, or any such Party asserts that the other Party has committed a 
breach of this Agreement, Buyer or Seller, as the case may be, may give 
written notice of such disagreement or asserted breach to the other such 
Party. If Buyer and Seller are unable to settle the controversy or claim 
within (thirty) 30 Days of the delivery of such notice, the Parties may then 
agree to submit with all reasonable dispatch, such disagreement or asserted 
breach to a competent court of law for determination.

12.06   APPLICABLE LAWS

This Agreement for all purposes shall be construed in accordance with and 
governed by the laws of the Province of Alberta. The Courts of the Province 
of Alberta shall have exclusive jurisdiction in relation to any legal 
proceedings arising in connection with this Agreement. The Parties hereby 
expressly and exclusively submit to the jurisdiction of the courts of the 
said Province.

The Parties agree to share equally all travel and hotel expenses incurred in 
connection with disputes raised under this Agreement.

12.07   INVALIDITY OF PROVISIONS

The intention of the Parties to this Agreement is to comply fully with all 
applicable laws, and this Agreement shall be construed consistently with such 
laws to the extent possible. If and to the extent that any court of competent 
jurisdiction determines it is impossible to construe any provision of this 
Agreement consistently with any applicable law and consequently holds that 
provision to be invalid, such holding shall in no way affect the validity of 
the other provisions of this Agreement, which shall remain in full force and 
effect.

<PAGE>

                                     - 25 -

12.08   FULL UNDERSTANDING

The terms of this Agreement represent the full understanding between the 
Parties and replaces all other contracts, agreements or representations 
whether written or oral. No amendments to this Agreement shall be made or be 
binding on either Party unless made in writing and signed by each Party.

12.09   GENDER AND NUMBER REFERENCES

Whenever the singular, masculine or neuter is used in this Agreement the same 
shall be construed as being the plural or feminine or body corporate or vice 
versa where the context or reference so require.

12.10   CONFIDENTIALITY

All data, documents and information of a confidential nature concerning the 
business or assets of either Party to this Agreement which is made available 
or disclosed to either other Party hereto pursuant to the terms of this 
Agreement (the "Confidential Information"), shall be kept and maintained on a 
confidential basis by the Party hereto which is the recipient thereof. Each 
Party hereto shall implement such measures and shall take such precautions as 
may be reasonably necessary to endeavor to ensure the confidentiality of all 
Confidential Information. Notwithstanding the foregoing, either Party hereto 
may, without consultation with or notice to the other Party hereto, from time 
to time disclose Confidential Information to any court, government, 
governmental agency, regulatory body or quasijudicial agency ("Regulatory 
Agency") at any time and from time to time and may thereby cause the 
Confidential Information to become public if and to the extent that may be 
required by any Regulatory Agency or the rules, regulations, procedures, 
requirements or practices of any Regulatory Agency.

12.11   REQUESTS FOR CONSENT

Whenever a request is made hereunder by one Party hereto to the other for a 
consent, approval or authorization, such request shall be deemed to have been 
refused or declined if it is not granted in writing within thirty (30) Days 
after the request is made.

12.12   SUCCESSORS AND ASSIGNMENT

This Agreement shall inure to the benefit of and be binding upon the 
successors and assigns of the Parties, but no assignment shall release either 
Party from such Party's obligations hereunder without the written consent of 
the other Party to such release, which consent shall not be unreasonably 
withheld.

<PAGE>

                                     - 26 -


IN WITNESS WHEREOF the parties hereto have duly executed and delivered this 
Agreement as of the Day and year first above written.

SHELL CANADA LIMITED                    GREAT FALLS GAS COMPANY



Per: /s/ illegible                      Per: /s/ Larry D. Geske
    ------------------------                 ------------------------
                   92-07-29                                    8/6/92



Per:                                    Per:
    ------------------------                 ------------------------

<PAGE>

                                                                         [LOGO]

                                                                   [LETTERHEAD]


August 23, 1993


VIA COURIER



Mr. Lynn Hardin
Director, Gas Supply and Industrial Marketing
TransEnergy
#1 First Avenue South
Great Falls, Montana
59401


Dear Mr. Hardin

RE:     LETTER AGREEMENT FOR THE SHORT TERM AMENDMENT TO
        SECTION 6.02 OF ARTICLE VI OF
        THE NATURAL GAS SALE AND PURCHASE AGREEMENT
        BETWEEN SHELL CANADA LIMITED ("SHELL") AND
        GREAT FALLS GAS COMPANY ("GFG") DATED JULY 20, 1992
--------------------------------------------------------------------------------

The parties do hereby agree to temporarily amend the referenced Agreement
pursuant to the following terms and conditions:

        1.   TERM

             The term of this Letter Agreement shall commence on November 1,
             1993 and continue until October 31, 1995.

        2.   DEMAND CHARGE (6.02 (a))

             The Demand Charge component of the Price, as defined in section
             6.02 of the referenced Agreement shall not change. The Demand
             Charge shall be paid each Month regardless of the quantity of Gas
             purchased and sold hereunder, except to the extent that Shell 
             fails to deliver Gas nominated.

        3.   RESERVATION CHARGE (6.02(b))

             The Reservation Charge component of the Price, as defined in
             section 6.02 of the referenced Agreement shall be deleted for the
             term of this Letter Agreement.


<PAGE>

Page 2                                                                   [LOGO]
August 23, 1993


        4.   PRICING ELECTION

             On or before September 15, 1993, GFG will have the option of
             choosing a fixed or variable pricing mechanism for each of the 
             four periods pursuant to the following paragraph 5 of this Letter
             Agreement.

        5.   COMMODITY CHARGE (6.02(c))

             The Commodity Charge component of the Price, as defined in section
             6.02 of the referenced Agreement shall be deleted for the term of
             this Letter Agreement and replaced with the following:

             (a)  For the time period commencing November 1, 1993, for the 
                  first 755,000 MMBtus of Gas delivered:

                  (i)  A fixed price of $2.10 US dollars per MMBtu, less the
                       Demand Charge on a US dollar per MMBtu basis; or

                  (ii) A rolling three Month "average" of the Canadian Gas 
                       Price Reporter mid month index of "Alberta Short-Term 
                       Spot Prices at the Alberta Border (Empress)" converted 
                       to US dollars per MMBtu plus $0.25 US dollar per MMBtu, 
                       less the Demand Charge on a US dollar per MMBtu basis.

             (b)  After the fulfillment of 5(a) hereof, for the balance of the
                  1993 Contract Year:

                  (i)  A fixed price of $ 1.75 US dollar per MMBtu, less the
                       Demand Charge on a US dollar per MMBtu basis; or

                  (ii) A rolling three Month "average" of the Canadian Gas 
                       Price Reporter mid month index of "Alberta Short-Term 
                       Spot Prices at the Alberta Border (Empress)" converted 
                       to US dollars per MMBtu, less the Demand Charge on a US 
                       dollar per MMBtu basis.

             (c)  For the time period commencing November 1, 1994, for the 
                  first 755,000 MMBtus of Gas delivered:

                  (i)  A fixed price of $2.20 US dollars per MMBtu less the
                       Demand Charge on a US dollar per MMBtu basis; or

                  (ii) A rolling three Month "average" of the Canadian Gas 
                       Price Reporter mid month index of "Alberta Short-Term 
                       Spot Prices at the Alberta Border (Empress)" converted 
                       to US dollars per MMBtu plus $0.25 US dollar per MMBtu, 
                       less the Demand Charge on a US dollar per MMBtu basis.


<PAGE>

Page 3                                                                   [LOGO]
August 23, 1993

             (d)  After the fulfillment of 5(c) hereof, for the balance of the
                  1994 Contract Year:

                  (i)  A fixed price of S1.85 US dollars per MMBtu, less the
                       Demand Charge on a US dollar per MMBtu basis; or

                  (ii) A rolling three Month "average" of the Canadian Gas 
                       Price Reporter mid month index of "Alberta Short-Term 
                       Spot Prices at the Alberta Border (Empress)" converted 
                       to US dollars per MMBtu, less the Demand Charge on a US 
                       dollar per MMBtu basis.

        6.   PRICING DATA

             Pursuant to paragraph 5 of the Letter Agreement, in the event that
             such pricing data is no longer published or such publication is no
             longer published then, failing agreement by the parties, the
             Commodity Charge or a method of determining it shall be determined
             by arbitration pursuant to Article X of the referenced Agreement.

        7.   OTHER TERMS AND CONDITIONS

             All other terms and conditions of the referenced Agreement shall
             remain in full force and effect.

        8.   REGULATORY APPROVALS

             This Letter Agreement is subject to all applicable American and
             Canadian federal, provincial and state regulatory approvals.

If you are in agreement with the foregoing, please indicate your acceptance in
the space provided below and return one copy of this Letter Agreement to our
office.

Yours truly,

/s/ S. MacCulloch
------------------------
S. D. (Sandy) MacCulloch
Coordinator, Market Development

GREAT FALLS GAS COMPANY

Accepted and Agreed to this      day of             , 1993
                            ----        ------------

Per: /s/ Larry D. Geske
     ------------------------------------------------

Title:  President
      -----------------------------------------------


<PAGE>

                               AMENDING AGREEMENT





BETWEEN:





                         SHELL CANADA LIMITED ("SELLER")





                                       AND






                        GREAT FALLS GAS COMPANY ("BUYER")


<PAGE>

                                      - 2 -


THIS AMENDING AGREEMENT is made effective as of November 1, 1994.

        WHEREAS, Seller and Buyer are parties to a Natural Gas Sale and 
Purchase Agreement dated July 20, 1992 (the "Contract"), as temporarily 
amended by a Letter Agreement dated August 23, 1993, (the "Letter Agreement") 
regarding the long term firm supply of Canadian natural Gas from Seller to 
Buyer, and

        WHEREAS, Seller and Buyer wish to further amend the Contract and 
Letter Agreement so as to provide for a different pricing mechanism under the 
Contract effective November 1, 1994.

        NOW THEREFORE, in consideration of the premises and the mutual 
covenants herein contained, Seller and Buyer agree as follows:

1.      All words and phases as used in this Amending Agreement shall have 
the same meaning as attributed to them in the Contract.

2.      The Letter Agreement is hereby amended so as to reduce the term 
thereof to a one (1) year period by deleting from Article 1 thereof the words 
"October 31, 1995" and replacing them with the words "November 1, 1994", and 
by deleting paragraphs 5(c) and 5(d) thereof.

3.      The Contract is amended by adding thereto the following definition; 
"Pricing Period" means that period of time as set forth in Schedule "A" 
hereto for which a Price has been agreed to or otherwise established, and 
which shall not be less than one (1) Contract Year.

4.      The Contract is amended by deleting in their entirety Sections 5.03, 
5.04 and 5.05, without changing the numbering of any other Sections of the 
Contract.

5.      The Contract is hereby amended by deleting from the second last line 
of paragraph 1 in Section 5.07 the words "(depending upon whether the 
Shortfall Amount being purchased represents Tier I Gas or Tier II Gas)".

6.      Article VI of the Contract is amended by deleting therefrom Sections 
6.02, 6.03, 6.04 and 6.05 in their entirety and replacing them with the 
following:

"6.02   PRICE

        The price to be paid by Buyer to Seller for Gas purchased and sold 
and the service provided hereunder for the period of time commencing with the 
Commencement Date will consist of the sum of the three (3) components 
identified hereunder. The Price will be in U.S. dollars.

(a)     Each Month, Buyer shall pay Seller a "Demand Charge" equal to 
        Seller's actual cost for that Month of reserving the firm 
        transportation required to transport the MDQ on NOVA to the Delivery 
        Point.

<PAGE>

                                      - 3 -


(b)     Each Month, Buyer shall pay Seller a "Reservation Charge" equal to the
        product of the MDQ times the number of days in the Month times the
        Reservation Charge. The Reservation Charge shall be as set forth from
        time to time in Schedule "A" hereto.

(c)     Each Month, Buyer shall pay Seller for each MMBtu of Gas delivered and
        received at the Delivery Point, a "Commodity Charge" equal to a per
        MMBtu price on a dry basis as set forth from time to time in Schedule
        "A" hereto.

        In the event the parties utilize index data in determining the 
        Commodity Charge component and such index data is no longer 
        ascertainable, for whatever reason, then, failing agreement between 
        Seller and Buyer on a new Commodity Charge within forty-five (45) days 
        of such event, the new Commodity Charge shall be determined by 
        arbitration pursuant to Article X hereof. Until a new Commodity Charge 
        has been determined the parties agree to use the last ascertainable 
        Commodity Charge. The new Commodity Charge shall be retroactive to the 
        date the index data became unascertainable and any necessary 
        adjustments shall be dealt with in accordance with Section 7.05 hereof.

If Buyer elects not to take Gas during any Month, Seller will be allowed to 
sell that gas on an interruptible basis to third party purchasers.

The Demand Charge and the Reservation Charge shall be paid each Month 
regardless of the quantity of Gas purchased and sold hereunder, except to the 
extent that Seller fails to deliver Gas nominated.

6.03    FUTURE PRICE DETERMINATION

(a)     The Parties agree that they will meet from time to time to
        negotiate the Commodity Charge and Reservation Charge components 
        of the Price payable hereunder for subsequent Pricing Periods.  
        In any such negotiations or resulting arbitration with respect to 
        Price during the Term of this Agreement only the Commodity Charge 
        and Reservation Charge components of the Price shall be 
        redetermined and the Demand Charge component of the Price shall 
        not be subject to redetermination.

(b)     Subject to 6.03 (a), the Parties agree to establish a new Price 
        for the next Pricing Period at least one hundred and twenty (120) 
        Days prior to the termination date of the current Pricing Period 
        and the Parties will commence procedures for such redetermination 
        no later than one hundred and eighty (180) Days prior to the 
        termination date of the current Pricing Period by either Party 
        giving fifteen (15) Days written notice to the other, to meet and 
        negotiate. Such Price, and the various components making up that 
        Price, will be effective for a period of time, as then agreed to, 
        and will become effective on the commencement of the next Pricing 
        Period. If neither Party has given written notice to the other to 
        renegotiate at least one hundred and eighty (180) Days prior to 
        the termination date of the current Pricing Period, then the LAST 
        Price in effect for the current Pricing Period shall continue in 
        effect for the next one year period which shall then become the 
        next Pricing Period.


<PAGE>

                                      - 4 -

6.04    FAILURE TO REACH AGREEMENT ON PRICE

        In the event that the Parties are unable to reach agreement on the 
Price, or the Price components at least one hundred and twenty (120) Days 
prior to the termination date of the current pricing period, as provided 
pursuant to section 6.03 herein, either Party may, upon not less than fifteen 
(15) days written notice to the other Party, have the Price determined 
pursuant to the Arbitration provisions contained in Article X herein and 
exclusively in accordance with the principles set forth in section 6.05 
herein. Should no notice for Arbitration be given at least ninety (90) days 
prior to the termination date of the current Pricing Period, the Price for 
the next one year period, which shall then become the next Pricing Period, 
shall continue to be the last Price in effect for the current Pricing Period.

6.05    PRICING PRINCIPLES

        For each Pricing Period subsequent to the Pricing Period for which 
the price of gas to be sold and purchased hereunder has been established and 
specified, the Parties agree to determine Price by negotiation or, if 
unsuccessful, by arbitration. If the Price for Gas delivered in any Pricing 
Period is to be determined by arbitration, the arbitrators shall determine a 
Price that, under the prevailing market circumstances for long term firm Gas 
Supply and in the opinion of the arbitrators, is fair and reasonable to both 
Buyer and Seller. In making such determination, the arbitrators shall limit 
their consideration to the evidence which is presented by the Parties, and to 
the extent that evidence is presented, shall base their determination upon 
and shall give due consideration to each of the following criteria:

        (i)       The weighted average cost of gas paid by Buyer during the 
                  next one year period for firm gas supplies with a term of two
                  (2) years or more;

        (ii)      The prices being paid during the next one year period for
                  other firm gas supplies by local distribution companies with 
                  a term of two (2) years or more in the state of Montana; and,

        (iii)     The prices being paid during the next one year period for
                  other firm gas supplies by local distribution companies with 
                  a term of two (2) years or more in the province of Alberta;

provided that the arbitrators shall consider the above matters in light of 
the following:

(a)     To the extent that evidence with respect to Prices for the next one 
        year period is not available or is insufficient, prices for the current
        Pricing Period will be considered;

(b)     The times at which the prices were agreed to between the respective
        buyers and sellers;

(c)     Differences in transportation costs relevant to establishing a point of
        comparison at the Delivery Point;

(d)     The similarities and dissimilarities between the service provided
        hereunder and the sales and transportation arrangements under which
        other gas is being sold for consumption in Buyer's market area and in
        Alberta, including in particular but not limited to the similarities 
        and


<PAGE>

                                      - 5 -

        dissimilarities between the quality of service and the security of
        supply provided hereunder and provided under such other arrangements;
        and,

(e)     Any other considerations in respect of which relevant evidence is
        adduced by the Parties and which is relevant to the determination of
        such matters.

        In the event that a negotiated or arbitrated Price is determined for 
a Pricing Period after commencement thereof, Seller shall retroactively 
adjust its invoices to Buyer to the first Day of that Pricing Period, to take 
into account the revised Price. Until a new Price is concluded and 
retroactively implemented, the previous Price shall remain in effect. If the 
Price settlement date exceeds sixty (60) Days past the Pricing Period 
commencement, the retroactive invoice shall be adjusted for interest at the 
prime rate pursuant to section 7.04."

7.      The Contract is hereby amended by incorporating Schedule "A" attached
hereto as Schedule "A" to the Contract.

8.      As amended by this Amending Agreement, the Contract is hereby 
ratified and confirmed and shall continue in full force and effect.

        IN WITNESS WHEREOF this Amending Agreement has been executed by the
parties hereto effective as of the day and year first above written.


SHELL CANADA LIMITED                    GREAT FALLS GAS COMPANY

Per: /s/ Eric Le Dain                   Per: /s/ Larry D. Geske
     --------------------------              --------------------------

Name: ERIC LE DAIN                      Name: LARRY D. GESKE
      -------------------------               -------------------------

Title: MANAGER MARKETING -              Title:  PRESIDENT & CEO
       ------------------------                ------------------------
       NE/MIDWEST U.S.


<PAGE>

                                   SCHEDULE A

SCHEDULE A INCORPORATED INTO AND FORMING A PART OF THAT NATURAL GAS SALE AND 
PURCHASE AGREEMENT BETWEEN SHELL CANADA LIMITED ("SELLER") AND GREAT FALLS 
GAS COMPANY ("BUYER") DATED THE 20TH DAY OF JULY, 1992 AS AMENDED FROM TIME 
TO TIME (THE "AGREEMENT")

All words and phrases used in this Schedule "A" shall have the same meaning 
as provided for in the Agreement.

PRICING PERIOD:        November 1, 1994 to November 1, 1996

RESERVATION CHARGE:    During this Pricing Period the Reservation Charge as
                       defined in Section 6.02 of the Agreement shall be set at
                       $0.00 US./MMBtu.

COMMODITY CHARGE:

During this Pricing Period, the Commodity Charge component of the Price, as 
defined in Section 6.02 of the Agreement shall be as follows:

1.      For the period November 1, 1994 to November 1, 1995:

        For 50% of the volume of Gas delivered each Month up to 50% of the MDQ,
        the Commodity Charge shall be $1.58 US/MMBtu on a dry basis at the
        Delivery Point, less the Demand Charge calculated on a US dollar per
        MMBtu basis at a 100% load factor.

        For 50% of the volume of Gas delivered each Month up to 50% of the MDQ,
        the Commodity Charge shall be the Average Alberta Border (Empress) Spot
        (one month) Firm (100% LF) price for such Month as reported in the
        Canadian Gas Price Reporter published by Canadian Enerdata Ltd. plus
        $0.25 US/MMBtu for the period November 1, 1994 to April 1, 1995; and
        plus $0.05 US/MMBtu for the period April 1, 1995 to November 1, 1995,
        less the Demand Charge calculated on a US dollar per MMBtu basis at a
        100% load factor.

2.      For the period November 1, 1995 to November 1, 1996;

        For 100% of the volume of Gas delivered each Month, up to the MDQ, the
        Commodity Charge shall be the Average Alberta Border (Empress) Spot 
        (one month) Firm (100% LF) price for such Month as reported in the 
        Canadian Gas Price Reporter published by Canadian Enerdata Ltd. plus 
        $0.05 US/MMBtu, less the Demand Charge calculated on a US dollar per 
        MMBtu basis at a 100% load factor.

Accepted and agreed to as of the 1st day of November, 1994.

SHELL CANADA LIMITED                    GREAT FALLS GAS COMPANY

Per: /s/ Eric Le Dain                   Per: /s/ Larry D. Geske
     ------------------------                ---------------------------

Name: ERIC LE DAIN                      Name: LARRY D. GESKE
      -----------------------                ---------------------------

Title: MANAGER MARKETING -              Title: PRESIDENT & CEO
       ----------------------                  --------------------------
       NE/MIDWEST U.S.


<PAGE>

                                SCHEDULE "A"

SCHEDULE A INCORPORATED INTO AND FORMING A PART OF THAT NATURAL GAS SALE AND 
PURCHASE AGREEMENT BETWEEN SHELL CANADA LIMITED ("SELLER") AND GREAT FALLS 
GAS COMPANY ("BUYER") DATED THE 20TH DAY OF JULY, 1992 AS AMENDED FROM TIME 
TO TIME (THE "AGREEMENT")

All words and phrases used in this Schedule "A" shall have the same meaning 
as provided for in the Agreement.

PRICING PERIOD:        November 1, 1996 to November 1, 1997

RESERVATION CHARGE:    During this Pricing Period, the Reservation Charge as
                       defined in Section 6.02 of the Agreement shall be set at
                       $0.00 US./MMBtu.

COMMODITY CHARGE:      During this Pricing Period, the Commodity Charge
                       component of the Price, as defined in Section 6.02 of 
                       the Agreement shall be as follows:

                       $1.19 US/MMBtu on a dry basis at the Delivery Point.

FURTHER AMENDMENTS:

During the above Pricing Period, in place of the provisions dealing with 
incurring a Shortfall Amount as set forth in Section 5.07 of the Agreement, 
if on any Day Buyer does not purchase one hundred percent (100%) of the then 
applicable MDQ, a Deficit will exist.  The difference between the MDQ and the 
amount actually taken by Buyer on any Day will be the Deficit for that Day.  
On a Monthly basis, in accordance with Article VII of the Agreement, Buyer 
shall pay Seller, at the Commodity Charge rate then in effect, for the 
Deficit incurred on each Day during the preceding Month, regardless of 
whether or not Buyer has been able to take, as hereinafter provided, the 
Deficit Gas after it has been incurred.  Buyer shall have the opportunity to 
nominate and take Deficit Gas on any Day after it has been incurred, provided 
however, that:

        (i)       Buyer shall first purchase 100% of the MDQ;

        (ii)      Seller's obligation to deliver Deficit Gas shall only be on 
                  an interruptible basis;

        (iii)     Buyer shall pay Seller for any additional transportation
                  charges Seller incurs in delivering the Deficit Gas to the
                  Delivery Point; and

        (iv)      the maximum amount of Deficit Gas (or any Gas) that Seller
                  shall be obligated to deliver on any Day above the MDQ shall
                  be the IDQ limit set out in Section 5.06 of the Agreement.

If a Shortfall Amount was incurred in the Contract Year preceding the first 
above referenced Pricing Period, the provisions of Section 5.07 regarding 
Buyer's purchase of the Shortfall Amount in the Make-up Year shall apply in 
that Pricing Period, however, subject to the same conditions as outlined 
above in (i) through (iv) with respect to Deficit Gas, and further provided 
that any Gas taken above the MDQ shall first be applied to Deficit Gas, then 
to the Shortfall Amount and finally to any agreed upon interruptible gas

<PAGE>

pursuant to Section 5.06 of the Agreement.  The Commodity Charge for the 
Shortfall Amount shall be as specified in Section 5.07 of the Agreement.

Accepted and agreed to as of the     day of            , 1996.
                                 ---        -----------


SHELL CANADA LIMITED                    GREAT FALLS GAS COMPANY


Per:  /s/ James Chunn                   Per: /s/ Larry D. Geske
     --------------------------              -------------------------

Name:  James Chunn                      Name:  LARRY D. GESKE
      -------------------------               ------------------------

Title: MGR. - BC & WESTERN U.S.         Title: President & CEO
       ------------------------               ------------------------