The state high court, in an order issued in San Francisco Wednesday and announced today, declined to hear an appeal by the Naturist Action Committee.
The action leaves in place a decision in which a Court of Appeal in Santa Ana last summer overturned a 30-year-old state policy of allowing some remote state beaches to be clothing-optional.
Under that policy, the state parks system tolerated nudity at certain beaches unless a citizen complained.
Bay Area state beaches that were allowed to be clothing-optional included Red Rock Beach in Marin County and Gray Whale Cove State Beach in San Mateo County.
But the appeals court said the policy was an illegal "underground regulation" because the California Recreation and Parks Department never completed procedural requirements for public notice and comment.
With the informal policy struck down, beaches are now governed by a state law that bans nudity on all state property.
Recreation and Parks Department spokesman Roy Stearns said, "We're in agreement with the California Supreme Court" decision to let the appeals court ruling stand.
Stearns said state beach officers will enforce the nudity ban but have "a lot of discretion" as to whether to give a warning, issue a misdemeanor citation or do nothing if they spot nude sunbathing.
"Officers will look at all situations from the point of view of their own discretion, Stearns said.
The case stemmed from a lawsuit in which the Naturist Action Committee sued the parks department in an effort to block a plan to end nude sunbathing on San Onofre State Beach in San Diego County.
The committee is the political arm of the Wisconsin-based Naturist Society, which promotes the goal of achieving body acceptance through nude recreation.