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                                                                    EXHIBIT 99.1


PETROGLYPH ENERGY, INC. SIGNS DEFINITIVE MERGER AGREEMENT WITH III EXPLORATION
COMPANY

HUTCHINSON, KANSAS, JUNE 20, 2000 -- PETROGLYPH ENERGY, INC. (NASDAQ: PGEI) AND
III EXPLORATION COMPANY, A WHOLLY-OWNED SUBSIDIARY OF INTERMOUNTAIN INDUSTRIES,
INC., jointly announced today that they have signed a definitive merger
agreement for III Exploration to acquire all of the outstanding shares of common
stock of Petroglyph that it does not already own. Pursuant to the merger
agreement, III Exploration will pay $2.85 in cash for each outstanding share of
Petroglyph common stock. Petroglyph currently has 6,458,333 shares of common
stock outstanding, 3,753,392 of which are owned by III Exploration.

The merger was recommended to the Board of Directors of Petroglyph by an
independent committee comprised of A. J. Schwartz, who is with the law firm of
Morris, Laing, Evans, Brock & Kennedy, Chtd. of Wichita, KS, which is being
advised by Prudential Securities, Inc.

Petroglyph Energy, Inc. is an independent energy company located in Hutchinson,
Kansas engaged in the exploration, development and acquisition of oil and gas
properties. Its properties are concentrated in Utah and Colorado. Information is
also available on the Company's web site at www.pgei.com.

Intermountain Industries operates, through its subsidiaries, the largest natural
gas distribution utility in Idaho, the largest end-use natural gas marketing
business in the Northwest and has producing oil and gas properties in the Rocky
Mountain region, including the Uinta Basin of Utah.

CONTACT: Robert C. Murdock, Chairman, President & CEO 316-665-8500, fax,
316-665-8577 at Petroglyph Energy, Inc.