The 25 year old, who has lived in the tree since Dec. 10, 1997 to protest logging, reached an agreement Friday with Pacific Lumber Co. and promised to climb down from her 18-story high perch, which is on company property.
Pacific Lumber spokesman Josh Reiss confirmed the deal but would not give specifics.
Two sources familiar with the pact said Hill and her supporters had been negotiating for her to pay $50,000 to Pacific Lumber to make up for lost logging revenue, while Pacific Lumber would spare Hill's redwood -- which she called "Luna" -- and a surrounding 200-foot zone from logging.
Hill had refused to come down until she received assurances that the tree in which she lived on a tarp-covered plywood platform would be spared within a buffer zone.
The company will donate the $50,000 to Humboldt State University for forestry studies, said a company employee who asked not to be identified.
Hill, now 25, spent the past two years bathing in a bucket, hauling up food and supplies by rope and sleeping under a tarp on an 8-by-8-foot plywood platform.
In the rainy northern California forest, she braved howling winds and damp winters, and become something of a celebrity. Television crews from Israel, Germany and England filmed her. Singers Bonnie Raitt and Joan Baez visited her.
She even became the "in-tree correspondent" for a cable TV show about the environment.
Using her cellular phone to communicate, she gave interviews and spoke at rallies against old-growth timber logging.
The 600-year-old tree is on a ridge above Stafford south of Pacific Lumber's headquarters in nearby Scotia.
The region has been the site of numerous logging protests during the past decade focusing on the Headwaters Forest Complex, a 94-square-mile region that includes thousands of acres of ancient redwoods.
In March, Pacific Lumber and the state and federal governments signed an agreement to turn about 10,000 acres of the forest, including nearly 5,000 acres of redwoods, into a public preserve.