ANTIOCH -- It took the East Bay Regional Park District almost 50 years to amass the more than 3,000 acres that make up Anthony Chabot Regional Park.
But, for a similarly sized piece of land at the foot of Mount Diablo, it took barely 50 weeks to complete the feat.
Escrow closed last month on a pair of properties that will comprise the bulk of the future Deer Valley Regional Park, including a large piece once eyed for luxury homes. In all, the purchase takes up about five square miles of valleys and ridges just south of Antioch and east of Brentwood.
"We were able to move on it in one fell swoop. The timing was completely happenstance," said Liz Musbach, the district's land-acquisition manager. "It really provides the foundation for a big, beautiful park that will benefit East Contra Costa County and the East Bay as a whole."
All told, the district purchased the 1,885 acres known as Roddy Ranch for $14.24 million and the 960-acre oak forest-covered Dainty Ranch property for $5.4 million. About two-thirds of the cost for Roddy and 90 percent of the Dainty cost are from state and federal grant money through the East Contra Costa County Habitat Conservancy.
John Kopchik, the conservancy's executive director, said teaming with the park district helped stretch its funds further and establish more land for preservation.
"This definitely is a huge conservation success," district general manager Robert Doyle said.
Money from the park district's Measure WW bond funded the rest, along with $1 million from the Gordon and Betty Moore Foundation.
The future Deer Valley park land is being held unused, or in "land bank" status, as inventory is taken on native species and possible land uses, Musbach said. It is expected to be a low-key park featuring hiking and protected habitat for the California red-legged frog and other rare species.
The new additions will also recognize the historic coal-mining families and ranching heritage of the area and its pioneering families, while adding opportunities for new trail connections between Black Diamond Mines and Round Valley regional parks, said Paul Miller, the district's interpretive parklands manager.
The 656 acres of Roddy Ranch land within Antioch were long sought for Blackhawk-like estate homes. After development was saddled with red tape and financial challenges, and with a new development group at the helm, the idea resurfaced in April 2013.
The Roddy Ranch partnership received higher offers for the property, but with the park district, it "had the assurance of knowing" it would be paid, Musbach said.
Meanwhile, the trust for Anna Mae Diffin Smith in December explored selling adjacent Dainty Ranch to the park district. The grazing land was acquired in 1872 by James Ball Dainty, a rancher who once mined coal in the hills between Antioch and Pittsburg.
"We were really focused on Roddy, and then the Smith property came up out of the blue. The family approached us and wanted to see it preserved," Doyle said. "It was perfect timing, though it was a little challenging to scrape all the money together."
Dainty Ranch's sale closed July 15. Roddy Ranch's escrow followed a week later.
"I'm glad we did what we did, and be able to leave the land as we found it," Jack Roddy said.
Antioch officials have mixed feelings about the plan. While most are pleased to see the land turned into a park, some still lament it as a lost opportunity to attract jobs and business.
The Roddy Ranch acquisition does not include Roddy Ranch Golf Club, the personal 40 acres of Jack and Donna Roddy, and two other parcels totaling 240 acres inside the project boundary.
Contact Paul Burgarino at 925-779-7164. Follow him at Twitter.com/paulburgarino.