Aided by a $3 million donation from the Palo Alto-based Gordon and Betty Moore Foundation, conservation nonprofit Save the Redwoods League has acquired the 730-acre Harold Richardson Redwoods Reserve on the Sonoma Coast, according to an announcement released by the organization Tuesday.

The $9.6 million acquisition will ensure that the reserve's towering old-growth redwoods -- more than 300 of which are 250 feet or taller -- will be permanently protected from development, fragmentation, stream sedimentation and commercial harvesting.

The purchase also guarantees that the public will be able to hike through the reserve after the League plans and establishes trails over the next three years. It will be the first new old-growth redwood public park established in a generation, the League's press release states.

Nestled in wooded hills just a few miles inland from the Sonoma Coast and less than 100 miles north of San Francisco, the property was the largest old-growth redwood forest remaining in single private ownership, according to the announcement. The land previously belonged to Harold Richardson, a logger who refused to cut down the ancient giants and left the 730 acres to his heirs at his death in 2016.

Though likened to the famed Muir Woods National Monument, the new reserve is 30 percent larger than Muir Woods and contains 47 percent more old-growth redwoods, according to the League. The property is also home to the oldest known coast redwood south of Mendocino County and the widest coast redwood south of Humboldt County, estimated to be 1,640 years old with a trunk diameter of 19 feet, as wide as a two-lane street.

The acquisition included the transfer to the Richardson family of the 870-acre Stewarts Point property, protected coastal land that the League bought in 2010. The Gordon and Betty Moore Foundation's contribution included $2 million of new grant funds, as well as $1 million that the foundation gave in 2010 to acquire the Stewarts Point property in Sonoma County, according to Dan Winterson, the foundation's San Francisco Bay Area program officer.

"Acquisitions such as these are important because the outcomes are incredibly durable compared to other conservation projects," Winterson said. "Moreover, by encouraging Save the Redwoods League to acquire the land outright versus the conservation easement they had originally considered, we have helped open up a beautiful redwood forest for responsible public enjoyment."

The foundation, established by Intel co-founder Gordon Moore and his wife, Betty, in 2000, has supported the League since 2005. As a private foundation focused on environmental conservation and scientific advancements, the foundation's goal of "preserving the special character of the Bay Area" goes hand-in-hand with the League's work since its inception in 1918, according to the foundation's website.

The foundation has helped the League purchase forest lands in the Santa Cruz Mountains and create a conservation planning tool that facilitates real-time analysis of redwood forest threats in eight Bay Area counties, according to the foundation's website.

The Moore Foundation most recently awarded the league $350,000 in July 2015 for the league's Vibrant Forest Plan, which identifies which land needs to be protected in order to strengthen forests.

"We were so grateful for the role that Save the Redwoods League and our other grantees play in conserving high-priority landscapes in Sonoma County and around the Bay Area," Winterson said. "We are thrilled that the League was able to complete this transaction successfully and proud that we were able to support them in doing so."

The Redwood Reserve has retained much of its original appearance since it was part of the Kashia Band of Pomo Indians' territory thousands of years ago, the press release states.

"It's as if we've discovered an ancient civilization: an oasis of towering redwoods hidden from public view for over a century," Sam Hodder, president and CEO of Save the Redwoods League, said in the announcement. "Harold Richardson Redwoods Reserve, named to honor the legacy of the family's patriarch, will be the newest gem on California's crown of redwood parks, providing inspiration, recreation and clean air and water."

Among the factors that made the forest the League's highest conservation priority were habitation by species like the northern spotted owl, Townsend's big-eared bat and coho salmon and its proximity to other protected forests and the Wheatfield Fork of the Gualala River.