1
Exhibit 10.21

Contract No. 36174000

Interruptible Transportation Service Agreement
Rate Schedule TI-1

between

COLORADO INTERSTATE GAS COMPANY

and

PETROGLYPH ENERGY, INC.

Dated: JANUARY 1, 1999

INTERRUPTIBLE TRANSPORTATION SERVICE AGREEMENT
RATE SCHEDULE TI-1
- -------------------------------------------------------------------------------

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

1. TRANSPORTER: COLORADO INTERSTATE GAS COMPANY

SHIPPER: PETROGLYPH ENERGY, INC.

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1, as the same may be amended or superseded from time to time ("the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

3. TERM OF AGREEMENT: BEGINNING: January 1, 1999
ENDING: December 31, 1999

[X] Month to month with 30-Day written notification of termination by
either Party

4. This Agreement supersedes and cancels: None.

5. Adjustments to Rate Schedule and/or General Terms and Conditions: None

6. NOTICES, STATEMENTS, AND BILLS:
TO SHIPPER:
INVOICES FOR TRANSPORTATION:
Petroglyph Energy, Inc.
1302 North Grand
Hutchinson, Kansas 67501
Attention: Craig Saldin

ALL NOTICES:
Petroglyph Energy, Inc.
1302 North Grand
Hutchinson, Kansas 67501
Attention: Craig Saldin

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

8. POINTS OF RECEIPT AND DELIVERY: Systemwide

All Point(s) of Receipt and Delivery included on Transporter's master list
of Point(s) of Receipt and Delivery as posted on its electronic bulletin
board.

For each Point of Receipt and Delivery, data posted shall include a
description of the legal location of the Point, pressure information, the
identity of the interconnected party and the measuring party, and such
other data as Transporter may include from time to time. Transporter's
master list of Point(s) of Receipt and Delivery shall be updated from time
to time in order to add or delete Point(s) of Receipt or Delivery and in
order to modify data pertinent to Point(s) of Receipt and Delivery, all as
deemed appropriate by Transporter.

9. Each month, Shipper shall pay Transporter for Transportation Service
provided hereunder at rates and surcharges set forth in Exhibit "A."

10. OTHER: Rates shall be as set forth in Exhibit "A."

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

TRANSPORTER: SHIPPER:

COLORADO INTERSTATE GAS COMPANY PETROGLYPH ENERGY, INC.

By /s/ Thomas L. Price By /s/ S.K. Smith
-------------------------------- ------------------------------------
Thomas L. Price
Vice President

S.K. Smith
---------------------------------------
(Print or type name)

Executive Vice President
---------------------------------------
(Print or type title)

EXHIBIT "A"

Interruptible Transportation Service Agreement
between
COLORADO INTERSTATE GAS COMPANY
and
PETROGLYPH ENERGY, INC.

Dated: JANUARY 1, 1999

POINT(S) OF POINT(S) OF COMMODITY FUEL
RECEIPT DELIVERY RATE TERM OF RATE REIMBURSEMENT SURCHARGES
- --------------------------------------------------------------------------------------------------------------------------

All All (Note 1) 01/01/99 (Note 2) (Note 3)
through
12/31/99
Evergreen

NOTES: (1) Unless otherwise agreed by the Parties in writing, the
Commodity Rate for service shall be Transporter's then-effective
maximum rate for service under Rate Schedule TI-1 or other
superseding Rate Schedule, as such rates may be changed from
time to time.

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

(3) Surcharges, If Applicable:

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

GQC:
The Gas Quality Control Surcharge shall be assessed pursuant
to Article 20 of the General Terms and Conditions as set
forth in The Tariff.

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

HFS:
The Hourly Flexibility Surcharge will be assessed pursuant to
Article 20 of the General Terms and Conditions as set forth
in The Tariff.

ORDER NO. 636 TRANSITION COST MECHANISM:
Surcharge(s) shall be assessed pursuant to Article 21 of the
General Terms and Conditions as set forth in The Tariff.

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