Hamilton experienced chest pains during an afternoon run at the Keystone Ski Resort and the local coroner said his death was consistent with an underlying heart-related medical issue, according to local news reports.
The 54-year-old was confirmed as the agency's 15th director last July and assumed the position in September.
"Sam was a friend, a visionary, and a professional whose years of service and passionate dedication to his work have left an indelible
mark on the lands and wildlife we cherish," Interior Secretary Ken Salazar
said in a statement. "His forward-thinking approach to conservation --
including his view that we must think beyond boundaries at the
landscape-scale -- will continue to shape our nation's stewardship for
years to come. My heart goes out to Sam's family, friends, and
colleagues as we remember a remarkable leader and a compassionate,
wise, and eternally optimistic man."