Exhibit 10(q)(iii)

ADDENDUM TO

EMPLOYMENT AGREEMENT BETWEEN

MICHAEL J. COVEY AND POTLATCH CORPORATION

THIS ADDENDUM to the Employment Agreement entered into on February 6, 2006 by
and among Potlatch Corporation and Michael J. Covey (the “Employment
Agreement”), is effective as of September 19, 2008. The purpose of this Addendum
is to clarify that any change in responsibilities as a result of the spin-off of
the pulp-based business will not constitute the first step in a constructive
termination under the Employment Agreement.

NOW THEREFORE the parties agree that the Employment Agreement shall be amended
by amending and restating Section 7(d)(i) thereof to read, in its entirety, as
follows:

“(i) the assignment to Executive of any duties inconsistent in any material
respect with Executive’s position (including status, offices, titles and
reporting requirements), authority, duties or responsibilities as in effect on
the Start Date, or any other action by the Company which results in a diminution
in such position, authority, duties or responsibilities or as a result of which
Executive no longer has a position substantially equivalent to Executive’s
position as of the Start Date, excluding for this purpose (A) an isolated,
insubstantial and inadvertent action not taken in bad faith and which is
remedied by the Company promptly after receipt of notice thereof given by
Executive, and (B) any diminution or change in Executive’s position, authority,
duties or responsibilities resulting from the transactions contemplated by the
Separation and Distribution Agreement to be entered into by and between Potlatch
Corporation and Clearwater Paper Corporation in connection with the spin-off of
Clearwater Paper Corporation.”

IN WITNESS WHEREOF, the parties hereto have duly executed and delivered this
Addendum to the Employment Agreement as of September 19, 2008.

 

POTLATCH CORPORATION By:   /s/ William T. Weyerhaeuser   Dr. William T.
Weyerhaeuser   Vice Chairman of the Board

 

EXECUTIVE: /s/ Michael J. Covey Michael J. Covey