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                                                                    EXHIBIT 99.a



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ONEOK FINANCIAL NEWS
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ONEOK, INC.                                 CONTACT: WELDON WATSON, 918/588-7158
P. O. BOX 871
TULSA, OK 74102-0871                        FOR IMMEDIATE RELEASE, JUNE 22, 1999




                      PUBLIC UTILITIES COMMISSION OF NEVADA
                       APPROVES ONEOK/SOUTHWEST GAS MERGER


         TULSA, Oklahoma - The Public Utilities Commission of Nevada has
approved the proposed merger between ONEOK, Inc., (NYSE:OKE) and Southwest Gas
Corporation (NYSE:SWX). The approval calls for Southwest Gas to maintain its own
identity as the Southwest Gas Division of ONEOK. The merger will be virtually
seamless insofar as day-to-day operations are concerned, and Southwest Gas
customers will benefit from the stipulated agreements worked out by the
commission staff, the Attorney General's office and the companies.

         The proposed merger must also be approved by the regulatory authorities
in Arizona and California and the shareholders of Southwest Gas Corporation.
Antitrust clearance under the Hart-Scott-Rodino Act has already been achieved.

         ONEOK Chairman and Chief Executive Officer Larry Brummett, said, "We
are very pleased with the approval by the Nevada commissioners. We continue to
work diligently on the other required approvals and are optimistic that we will
complete the merger in a timely manner.

         ONEOK, Inc., is an integrated natural gas company involved in
production, processing, gathering, storage and transmission. The company is also
the largest natural gas distributor in Kansas and Oklahoma, operating as
Oklahoma Natural Gas Company and Kansas Gas Service Company, serving 1.4 million
customers.

                                       ###

Statements contained in this release that include company expectations or
prediction as to the accretive nature of the transaction and its expected
consummation are forward-looking statements intended to be covered by the safe
harbor provisions of the Securities Act of 1933 and the Securities and Exchange
Act of 1934. It is important to note that the actual results could differ
materially from those projected in such forward-looking statements. Among the
important factors which could affect actual results are the timing and terms of
regulatory approvals and operating results of ONEOK and Southwest Gas. More
information about the ONEOK and Southwest Gas transaction can be found under
Company News on the ONEOK web site at WWW.ONEOK.COM. Service area maps and logos
are available under Media Kit.


