SALEM —The sole proposal to purchase a large swath of state forest in Douglas and Coos counties was submitted jointly by a Roseburg-based timber company, Lone Rock Resources, and the Cow Creek Band of the Umpqua Tribe of Indians, according to the Department of State Lands.

An 82,500-acre parcel of the Elliott State Forest is up for sale for $220.8 million, and although more than 40 groups had previously expressed interest in the land, only one acquisition plan was submitted to the state by its Tuesday evening deadline.

Jake Gibbs, a spokesman for Lone Rock Resources, said that the company plans to take on 83 percent of the costs of acquiring the land, while the Cow Creek Band will incur 17 percent.

Under the proposal, The Conservation Fund — a conservation group out based in Arlington, Va., — and the Confederated Tribes of Coos, Lower Umpqua and Siuslaw Indians, would hold conservation easement agreements to enforce the state’s public benefit requirements.

The eventual buyer will be required to provide 40 direct or indirect jobs for 10 years; maintain public access on half the land; keep 25 percent of old forest stands; and maintain riparian areas along streams for fish health.

In a statement, Dan Courtney, the Cow Creek chairman, called the partnership with Lone Rock “unique” and said it advanced the tribe’s goal of restoring land “for the community and tribe’s future generations.”

Courtney also said the sale would help provide a more predictable revenue stream for state schools while preserving public benefits.

The Department of State Lands is required under the state’s constitution to maximize revenue from natural resources on state trust lands for the benefit of public schools through the Common School Fund.

However, that fund has lost about $4 million since 2013, after new limitations to the state’s logging on the Elliott Forest were imposed, the department says. Environmental groups had sued the state challenging its logging in areas home to the marbled murrelet, which is protected under the Endangered Species Act.

Proceeds from the sale will be invested in the Common School Fund.

The department is next expected to evaluate the plan for responsiveness to its transfer criteria, and the State Land Board — which includes the governor, secretary of state and treasurer — is scheduled to meet Dec. 13. The board has the final sale in whether the sale goes forward.

Many environmental groups and activists have opposed the sale of the Elliott to private interests and wish to see it stay in public hands.