Terry Barton, 38, admitted setting fire to federal land and making false statements to investigators in a plea agreement that calls for a sentence of six years in federal prison, according to court documents. She would serve five years and one month with time off for good behavior. Sentencing was set for Feb. 21.
There was no decision on how much restitution Barton should pay. Prosecutors claim $38 million in property damage to federal land, not including private homes and other structures.
Barton, whose job included watching for fires, told investigators she accidentally started the blaze in June while burning a letter from her estranged husband in a campfire ring. Authorities believed she started the fire deliberately.
Barton was fired after she was arrested.
During the hearing, U.S. District Judge Richard Matsch asked Barton if she believed the fire was extinguished before she left. "Yes, I did," she replied.
Barton remained free pending sentencing. She declined comment as she left the courthouse. Public defender Warren Williamson declined comment after the hearing.
No agreement was made on whether Barton would have to pay a fine. Each count carries a $250,000 fine.
The 137,000-acre fire southwest of Denver, which started June 8 and was contained July 2 and brought under control July 19, was one of several that raged in Colorado this year.
State officials are considering additional charges of arson against Barton for the homes and business destroyed in the fire.