POWER OF ATTORNEY
I, Shelette M. Gustafson, hereby appoints William Brierly,
Sarah K. Hilty and/or Christine Grawemeyer my true and lawful
attorney-in-fact to:
1. Execute for me and on my behalf Forms 3, 4, and 5 and any
Amendments thereto, in accordance with Section 16 of the
Securities Exchange Act of 1934, as amended, and the
rules thereunder;
2. Do and perform any and all acts for me and on my behalf which
may be necessary or desirable to complete and execute any
such Forms 3, 4, and 5 and any Amendments thereto and timely
file such Forms and Amendments with the Securities and
Exchange Commission; and
3. Take any other action of any type whatsoever in connection
with the foregoing which, in the opinion of the attorney-
in-fact, may be of benefit to, in the best interest of, or
legally required by me, it being understood that the
documents executed by the attorney-in-fact on my behalf
pursuant to this Power of Attorney shall be in such form
and shall contain such terms and conditions as the
attorney-in-fact may approve in his discretion.
I hereby grant to the attorney-in-fact full power and
authority to do and perform any and every act and thing
whatsoever requisite, necessary, or proper to be done in the
exercise of any of the rights and powers herein granted,
as fully to all intents and purposes as I might or could do
if personally present, with full power of substitution or
revocation, hereby ratifying and confirming all that
the attorney-in-fact, or the attorney-in-fact's substitute or
substitutes, shall lawfully do or cause to be done by virtue of
this Power of Attorney and the rights and powers herein granted.
I hereby acknowledge that the foregoing attorney-in-fact, in
serving in such capacity at my request, is not assuming any
of my responsibilities to comply with Section 16 of the
Securities Exchange Act of 1934, as amended.
This Power of Attorney shall remain in full force and effect
until I am no longer required to file Forms 3, 4, and 5 and any
Amendments thereto, unless I earlier revoke this Power of
Attorney in a signed writing delivered to the attorney-in-fact.
IN WITNESS WHEREOF, I hereby cause this Power of Attorney to
be executed as of this 15th day of February 2016.
/s/Shelette M. Gustafson
___________________________________
Shelette M. Gustafson
Chief Human Resources Officer
