EXHIBIT 99.1

                            OREGON STEEL MILLS, INC.
                                Portland, Oregon

FOR IMMEDIATE RELEASE                                       September 13, 2004
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Contact:     Ray Adams
             Chief Financial Officer
             (503) 240 -5223


           OREGON STEEL MILLS ANNOUNCES FINAL SETTLEMENT OF LABOR DISPUTE
           AGREEMENT AND FILING OF S-3 REGISTRATION STATEMENT


HIGHLIGHTS:

[BULLET]        COMPANY FINALIZES LABOR DISPUTE SETTLEMENT
[BULLET]        COMPANY FILES REGISTRATION STATEMENT TO ISSUE NEW SHARES

Portland, Oregon, September 13, 2004/Business Wire/--Oregon Steel Mills, Inc.
(NYSE: OS) today announced the Company finalized the settlement of the labor
dispute ("Settlement") at its majority-owned CF&I Steel L.P. d.b.a. Rocky
Mountain Steel Mills ("RMSM"). The Settlement ends a labor dispute that has been
ongoing for more than six years between RMSM and the United Steelworkers of
America ("Union") and implements new five-year collective bargaining agreements.

The Settlement was conditioned on, among other things, (1) its approval by
stockholders of New CF&I, Inc. ("New CF&I), a majority-owned subsidiary of the
Company and the general partner of RMSM, (2) ratification of new collective
bargaining agreements between RMSM and the Union, (3) approval of the Settlement
by the National Labor Relations Board ("NLRB") and the dismissal of cases
pending before the NLRB related to the labor dispute, and (4) various pending
legal actions between the Company, New CF&I and RMSM and the Union being
dismissed. The Settlement resulted in the dismissal of all court actions between
the Company and the Union and the NLRB's issuance of an Order Withdrawing
Complaints and Conditionally Approving Withdrawals of Charges related to the
labor dispute and includes the ratification of new five-year collective
bargaining agreements at RMSM. The Settlement called for the establishment of a
trust and on September 10, 2004, the Rocky Mountain Steel Mills - United
Steelworkers of America Back Pay Trust ("Trust") was established. As part of the
tentative settlement, the Company, on behalf of RMSM, had originally planned to
issue four million shares of Company common stock to the Trust. On September 10,
2004, the parties agreed instead that the Trust would receive cash in an amount
equal to the gross proceeds from the sale of four million shares of Company
common stock in an underwritten stock offering (see below). The Company, after
consultation with the Union, will determine the price at which the four million
shares of common stock will be sold in the offering. The other terms and
conditions of the Settlement have not changed

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from those disclosed in the Company's quarterly report on Form 10-Q for the
quarter ended June 30, 2004. For additional details of the Settlement please
review the Company's Registration Statement on Form S-3 filed today with the
Securities and Exchange Commission ("SEC").

As in prior quarters, the Company will continue to adjust the Settlement charges
for the change in the price of the Company's common stock through the date of
pricing of the offering. In addition, as previously disclosed, the Settlement
includes an early retirement option with immediate enhanced pension benefit for
certain bargaining unit employees, based on seniority. As employees accept the
early retirement benefits, the Company expects to record an additional charge
during the remainder of 2004 estimated at approximately $6.8 million related to
these benefits. The enhancements to pension and post retirement medical benefits
for non-early retirees will be accounted for prospectively on the date at which
plan amendments occur pursuant to the new five-year collective bargaining
agreements in accordance with SFAS No. 87 and SFAS No. 106.

PROPOSED COMMON STOCK OFFERING

The Company also announced today that it has filed a registration statement on
Form S-3 with the U.S. Securities and Exchange Commission relating to a proposed
public offering of 7,500,000 shares of its common stock and an additional
1,125,000 shares that may be purchased by the underwriters to cover
over-allotments. All of the shares will be issued and sold by the Company.

The Company intends to use the net proceeds from the offering to satisfy the
obligation in connection with the Settlement of the labor dispute with the Union
noted above, to construct a spiral weld pipe mill at an estimated cost of $35
million, for general corporate purposes and for other uses as more fully
described in the registration statement.

A registration statement relating to these securities has been filed with the
SEC but has not yet become effective. The securities may not be sold under this
registration nor may offers to buy be accepted prior to the time the
registration statement becomes effective.

This press release shall not constitute an offer to sell or the solicitation of
an offer to buy nor shall there be any sale of these securities in any state in
which such offer, solicitation or sale would be unlawful prior to registration
or qualification under the securities laws of any such state. The registration
statement and all other SEC filings by the Company are available for review at
http://www.sec.gov/. A written prospectus, when available, meeting the
requirements of Section 10 of the Securities Act of 1933 may also be obtained
from L. Ray Adams, Vice President Finance, Oregon Steel Mills, Inc., 1000 SW
Broadway, Suite 2200, Portland, Oregon 97205.

FORWARD-LOOKING STATEMENTS

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Forward-looking statements in this release are made pursuant to the safe harbor
provisions of the Private Securities Litigation Reform Act of 1995. Such
forward-looking statements are subject to risks and uncertainties and actual
results could differ materially from those projected. Such risks and
uncertainties include, but are not limited to, general business and economic
conditions; competitive products and pricing, as well as fluctuations in demand;
costs and availability of raw materials; potential equipment malfunction; and
plant construction and repair delays. For more detailed information, please
review the discussion of risks, which may cause results to differ materially, in
our most recently filed Form 10-K, Form 10-Q and other SEC reports.

Oregon Steel Mills, Inc. is organized into two divisions. The Oregon Steel
Division produces steel plate, coil, welded pipe and structural tubing from
plants located in Portland, Oregon, Napa, California and Camrose, Alberta,
Canada. The Rocky Mountain Steel Mills Division, located in Pueblo, Colorado,
produces steel rail, rod, bar, and tubular products.

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