Filmmaker George Lucas has given the county of Marin a cattle tunnel.

The tunnel, which runs under Lucas Valley Road near Big Rock, is near where the county wanted to build a pedestrian, equestrian and bicycle tunnel in the early 2000s.

The idea was for the tunnel to link public trails on the north and south sides of Lucas Valley Road, just east of the Big Rock landmark, with trails on Lucasfilm’s property.

“That proved infeasible because there were special-status species in the area, and it also became enormously expensive to create a facility for bikes and pedestrians,” said Supervisor Steve Kinsey.

In addition to at least two threatened plant species — Marin western flax and the Mount Tamalpais jewel flower — there was also a wetlands area in the vicinity.

Lucas, however, was able to obtain the approvals necessary to build a smaller version of the tunnel.

“It went into the same general area, but it had to be relocated to keep clear of the special-status species,” Kinsey said.

Lucas created the tunnel so his cattle could move between pastures on either side of Lucas Valley Road.

Kinsey said Lucas raises a type of Wagyu cattle from which the highly prized Kobe beef is produced.

“He’s got quite a herd,” Kinsey said.

As part of the approvals for Skywalker Ranch, 3,096 acres of the Big Rock, McGuire, Loma Alta and Grady ranches on both sides of Lucas Valley Road were permanently preserved as open space; 2,296 acres were covered by conservation easements that anticipated continued grazing.

While the tunnel was constructed for cattle, Kinsey said it is well-used by hikers and bicyclists. But he said the real incentive for the county to assume ownership is to gain legal title to a patch of Lucas Valley Road that crosses Lucas’ property.

“What we discovered is there is no right of way through that area,” Kinsey said. “It’s just crossing his property.”

Kinsey and his fellow supervisors approved acceptance of the tunnel on Tuesday.

Max Korten, Marin County’s acting parks director, prepared no estimate of what it may cost to maintain the tunnel and cover liability for potential accidents, but said he would find the funds in the Open Space District’s existing budget.

Ernest Klock, a principal civil engineer in the county’s public works department, said the county has secured a $1.35 million federal grant to retrofit a curvy section of Lucas Valley Road less than a mile east of the tunnel where a county study found nine vehicles ran off the road between 2004 and 2014 and more since then. Klock said he expects the work to be done in the summer of 2018. He said an environmental study must be completed first.