UPDATE: In late October, the California Supreme Court declined to review the appeals court ruling, effectively upholding public access to the beach. Khosla's only remaining recourse to pursue his case for keeping it private would be the U.S. Supreme Court.

A ruling requiring a Silicon Valley entrepreneur to reopen Martins Beach near Half Moon Bay to the public was upheld by a state appeals court in San Francisco Thursday.

A three-judge panel of the 1st District Court of Appeal unanimously said closing the beach owned by venture capitalist Vinod Khosla would require a development permit from the California Coastal Commission because ending public access is a form of development as defined in state law.

The state's Coastal Act of 1976 states that a coastal development includes "any change in the intensity of use of water or of access thereto."

The appeals court said that definition and later court rulings show that the requirement for a development permit "should be broadly construed to encompass all impediments to access, whether direct or indirect."

The court ruled in a lawsuit filed by the San Clemente-based Surfrider Foundation against two beach management companies created by Khosla, Martins Beach 1 and Martins Beach 2.

Khosla bought the 53-acre property for $37.5 million in 2008. Beginning in September 2009, he closed it to the public by locking the gate to the only road to the shore and posting a "no trespassing" sign.

The previous owners kept the gate open most of the time during the day, had a welcome billboard, built a parking lot and sometimes charged a parking fee. The beach was popular with surfers, families and fishers.

The appeals court upheld a similar ruling and a preliminary injunction issued by San Mateo County Superior Court Judge Barbara Mallach in 2014.

The injunction requires that the gate "must be unlocked and open to the same extent that it was unlocked and open at the time defendants purchased the property."

However, Khosla has contended that his companies did not need to follow the injunction while they were appealing it, according to Eric Buescher, an attorney for the Surfrider Foundation.

Buescher said the gate has remained locked but some beach users have walked around it or reached the beach in other ways during the three-year appeal of Mallach's decision.

Khosla's companies could make a similar argument about a right to continued closure for the time being if they decide to appeal further to the California Supreme Court or U.S. Supreme Court.

Khosla's attorneys could not immediately be reached for comment.

"We think the decision is a vindication that the 1,100 miles of California coast are a public resource," Buescher said.

The appeals court also said it was too soon to rule on a second argument in which Khosla claims that opening the beach would be an unconstitutional taking of property without compensation.

The panel said Khosla could not make that claim until after the Coastal Commission acts on a development permit application.

The case is one of several lawsuits concerning the beach.

In another lawsuit filed by a group called Friends of Martins Beach, a San Mateo County Superior Court trial is pending on the question of whether the previous owners created a right of public access.

A third lawsuit alleging several constitutional violations was filed by Khosla's companies in federal court in San Francisco last year against the Coastal Commission, State Lands Commission and San Mateo County.

U.S. District Judge Jeffrey White is currently considering motions by the three agencies for dismissal and has said he wanted to see today's Court of Appeal decision before ruling, Buescher said.