TransAlta provides update on offer for Canadian Hydro Developers, Inc.

CALGARY, ALBERTA, Aug 17 (MARKET WIRE) --
TransAlta Corporation (TSX: TA) (NYSE: TAC) announced today it has
received an Advance Ruling Certificate from the Canadian Competition
Bureau with respect to TransAlta's offer to acquire all of the issued and
outstanding common shares of Canadian Hydro Developers, Inc. (TSX: KHD)
for $4.55 per share in cash. With this ruling, the Canadian Competition
Bureau has confirmed that the acquisition of Canadian Hydro Developers by
TransAlta can proceed without further review under the Competition Act.

TransAlta also announced today the Alberta Securities Commission (ASC)
has set a hearing date to consider an application made by TransAlta for
an order to cease trade the Canadian Hydro Developers shareholder rights
plan. The hearing is scheduled for August 24, 2009 at 8:30 am MST. If
granted by the ASC, a cease trade order would effectively prevent the
application of the plan to TransAlta's offer and would enable TransAlta
to take up shares tendered to its offer without triggering the plan.

TransAlta will provide a further update with respect to the status of the
Canadian Hydro Developers shareholder rights plan following the August 24
hearing.

The TransAlta offer will remain open until 6:00 p.m. MST on August 27,
2009 unless withdrawn or extended. The offer represents a premium of 30
per cent over the $3.50 volume weighted average closing trading price of
the common shares over the 10 trading days immediately prior to July 20,
2009. The offering price also represents a premium of 25 per cent on July
17, 2009, the last trading day before TransAlta disclosed its intention
to make the offer.

TransAlta strongly encourages shareholders of Canadian Hydro Developers
to read the offer and circular mailed to all shareholders of Canadian
Hydro Developers on July 22, 2009. The offer and circular contain the
full terms and conditions of the offer as well as detailed instructions
on how shareholders can tender their common shares to the offer. Copies
of the offer and circular and related documents are also available online
at www.transalta.com.

Canadian Hydro Developers shareholders electing to tender their common
shares to the offer must complete the letter of transmittal or, if
necessary, the notice of guaranteed delivery (both of which accompany the
offering circular) and return the appropriate document in accordance with
the terms and conditions more fully set out under ''Manner of
Acceptance'' in Section 3 of the offer. If common shares of Canadian
Hydro Developers are held in the name of a nominee, such as a broker,
investment dealer, bank or trust company, the shareowner should contact
such nominee for instructions on how to deposit their common shares to
the offer.

For assistance in tendering shares to the TransAlta offer, Canadian Hydro
Developers shareholders are encouraged to contact Georgeson Shareholder
Communications Canada Inc. at 1-866-783-6752 (North American Toll Free
Number) or 1-212-806-6859 (Bank, Brokers and collect calls).

TransAlta is a power generation and wholesale marketing company focused
on creating long-term shareholder value. We maintain a low to moderate
risk profile by operating a highly contracted portfolio of assets in
Canada, the United States, and Australia. Our focus is to efficiently
operate our coal-fired, gas-fired, hydro and renewable facilities in
order to provide our customers with a reliable, low-cost source of power.
For nearly 100 years, we've been a responsible operator and a proud
contributor to the communities where we work and live. TransAlta is
recognized for its leadership on sustainability by the Dow Jones
Sustainability North America Index, the FTSE4Good Index and the Jantzi
Social Index.

Reader Advisory

This news release may contain statements that constitute "forward-looking
information" or "forward-looking statements" (collectively
"forward-looking information") within the meaning of applicable
securities legislation. This forward-looking information is subject to
numerous risks and uncertainties, certain of which are beyond TransAlta's
control including, without limitation, uncertainty related to the
completion of the offer to acquire Canadian Hydro Developers and the
effects of the transaction in the event it is completed on TransAlta, the
impact of legislative or regulatory developments, competition, global
capital markets activity, changes in prevailing interest rates, currency
exchange rates, inflation levels and general economic conditions in
geographic areas where TransAlta operates. Readers are cautioned that the
foregoing list of risk factors is not exhaustive. Additional information
on these and other factors that could affect TransAlta's results are
included in reports on file with the Canadian and United States
securities regulatory authorities. TransAlta's actual results,
performance or achievements may differ materially from those expressed
in, or implied by this forward-looking information and, accordingly, no
assurance can be given that any events anticipated by the forward-looking
information will transpire or occur, or if any of them do so, what
benefits that TransAlta will derive therefrom. Forward-looking
information is based on the estimates and opinions of TransAlta's
management at the time the information is released and TransAlta does not
undertake any obligation to update publicly or to revise any of the
forward-looking statements, whether as a result of new information,
future events or otherwise, except as may be required by applicable
securities laws.

This news release does not constitute an offer to sell or the
solicitation of an offer to buy any securities. No offering of securities
will be made absent registration under, or an exemption from the
registration requirements of, applicable securities laws.

Note: All financial figures are in Canadian dollars unless noted
otherwise.

Contacts:
TransAlta Corporation - Media inquiries
Michael Lawrence
Manager, External Relations
Phone: (403) 267-7330
Email: michael_lawrence@transalta.com

TransAlta Corporation - Investor inquiries
Jennifer Pierce
Vice President, Communications & Investor Relations
Phone: (403) 267-7622 or 1-800-387-3598 in Canada and U.S
Email: jennifer_pierce@transalta.com

TransAlta Corporation - Investor inquiries
Jess Nieukerk
Manager, Investor Relations
Phone: (403) 267-3607
Email: jess_nieukerk@transalta.com
Website: www.transalta.com

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