Half way from LA to Monterey, about 8 hours north of San Diego
But most of the past 6 years was a legal battle because locals wanted it shut down to vehicles... and they had a clever legal method, by making a law about how much dust could be found in the air.
San Luis Obispo County's Air Pollution Control District's created and passed the "Dust Rule," which requires state parks like Oceano Dunes to reduce particulate matter - in other words, dust - blowing out of the park into neighboring areas.
Someone wasn't very sharp though, and wrote down a numerical limit that is lower than the amount of dust when there are no vehicles present, clearly illustrating that it was a scam. Once you've said that mother nature is the greater offender than the vehicles, you've made it clear you are both a moron, and that you aren't fighting for a real cause.
A group went to court to get this dust law overturned, and though it took 6 years, and appeals, the desired result was achieved.
The legal cost? $380,000.
Opponents of the APCD have gone so far as to say that the true motive behind the Dust Rule had nothing to do with public health at all, but that it's just pandering to homeowner's groups to keep up property values in the nearby luxury housing developments that have sprouted up around Pismo Beach in recent years.