The county must still finalize its mid-year budget June 20, but supporters said the support of Republican Councilman Max Burdick nearly guaranteed the county's commitment.
"It's been a tough one," Burdick said. "I just came to the realization that I need to support this."
The county won't use general fund money for the effort. Instead supporters including Mayor Ben McAdams found an existing pool of money raised through portions of various taxes for the Tourism, Recreation, Cultural and Convention fund.
Most of Bonanza Flat is in Wasatch County, and Republicans on the council who oppose sending county money toward the purchase said the county should look inward if it wants to buy land for open space.
Supporters countered that many of the area's users come from Salt Lake County, citing the easy access through Big Cottonwood Canyon just over Guardsman Pass.
The fundraising effort was complex.
"I have not seen this level of commitment from so many different entities," Democratic Councilwoman Jenny Wilson said recently.
Park City voters will spend the most on the purchase. They approved a $25 million bond toward the effort. At the same time, various nonprofits raised millions more from small donors, and companies contributed to the effort. Other public entities, including Wasatch County, paid in as well.
Park City officials announced on the eve of Tuesday's Salt Lake County Council meeting that as long as the council committed to kicking in $1.5 million, the effort would succeed.
"We have always been committed to saving this tremendous landscape," Park City Mayor Jack Thomas said in a news release. "We want the community to rest assured that we will step up to the plate and purchase the land, but we are reliant on all of the commitments made to date to truly get this across the finish line."