Exhibit 10(q)

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, is effective as of
February 6, 2006. The purpose of this Addendum is to make the following changes
in the Employment Agreement: (i) increase the trigger point for determining
whether a change in control has occurred under certain circumstances from 20% to
30%; and (ii) to correct errors in the description of the calculation of the
severance benefits payable under certain circumstances.

NOW THEREFORE the parties agree that the Employment Agreement shall be amended
as follows:

1. “30%” shall be substituted for “20%” where it appears in Section 6(a) and
Section 6(c).

2. “1/24th” shall be substituted for “1/36th” in Section 8(b)(i)(B).

IN WITNESS WHEREOF, the parties hereto have duly executed and delivered this
Addendum to the Employment Agreement as of December 1, 2006.

 

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